Grinding in motion

ISSUE 1/2009
MOTION
THE CUSTOMER MAGAZINE OF THE SCHLEIFRING GROUP
Grinding in motion
Special edition: SCHLEIFRING Grinding Symposium 2009
KNOW-HOW: SCHLEIFRING Group innovations
BEST PRACTICE: Presentations by highly respected experts
PROFILE GRINDING
WITH WINTERTHUR:
PASSIONATELY PRECISE
Switzerland
Winterthur Schleiftechnik AG
Oberer Deutweg 4
8411 Winterthur
Tel.: +41 (0)52 234 41 41
Fax: +41 (0)52 232 51 01
wst@rappold-winterthur.com
USA
Winterthur Corporation
10 Viking Road
Webster MA 01570
Tel.: +1 (508) 949 10 61
Fax: +1 (508) 949 20 86
info@winterthurusa.net
United Kingdom
Winterthur Technology UK Ltd.
2 Oakham Drive
Parkwood Industrial Estate
Sheffield S3 9QX
Tel.: +44 (0)114 275 42 11
Fax: +44 (0)114 275 41 32
info@winterthurtechnology.co.uk
Germany
WENDT GmbH
Fritz-Wendt-Strasse 1
40670 Meerbusch
Tel.: +49 (0)2159 671-0
Fax: +49 (0)2159 806 24
info@wendtgroup.de
Austria
Rappold Winterthur Technologie GmbH
St. Magdalenerstrasse 85
9500 Villach
Tel.: +43 (0)42 42 41 811 0
Fax: +43 (0)42 42 41 811 701
office@rappold-winterthur.at
Sweden
SlipNaxos AB
Folksparksv. 31
59383 Västervik
Tel.: +46 (0)490 843 00
Fax: +46 (0)490 146 00
support@slipnaxos.se
www.winterthurtechnology.com
Germany
Winterthur Schleiftechnik GmbH
Hundsschleestrasse 10
72766 Reutlingen
Tel.: +49 (0)7121 93 24 0
Fax: +49 (0)7121 93 24 24
info@rappold-winterthur.de
EDITORIAL
Technologies for the future
Dear Readers,
The economic and financial crisis has the world on tenterhooks. Even key sectors,
like the automotive, aircraft and machine construction industries, are severely
affected by the changes. Lots of people are asking: When will we emerge from the
crisis and how? And what will the future bring? Yet times of economic difficulty
also present opportunities. Firms that set the right objectives now will be in a good
position after the recession. Experts are sure that with expertise and cutting-edge
technology we can face the future with optimism.
The SCHLEIFRING Group is therefore aiming for technological leadership in all areas
of fine machining. See for yourself at the SCHLEIFRING Grinding Symposium 2009.
We will be demonstrating our latest products and developments live at 17 stations,
from solutions designed to increase productivity and quality to efficient software
tools and fully developed measuring technology. The demonstrations will be supported by presentations given by leading
industry experts. Their talks will provide insights into the
latest research findings.
This special edition of MOTION brings together the key
information. You can look forward to a varied mix of
scientific research and practical application. We hope
you enjoy reading this issue of MOTION.
Yours sincerely
rely
mmermeier
Dr Ralf Kammermeier
Managing Director
eifring GmbH
Körber Schleifring
MOTION 01/09
3
CONTENTS
20
30
TOO L S & T EC H N O LO GY
Cylindrical grinding
12
13
14
17
Station 4 – STUDERmodular
Surface grinding
08
Tool grinding
24
Station 13 – EWAG COMPACT LINE
From heavy-duty applications to
Optimum surface quality and accuracy.
The EWAG COMPACT LINE is
flexible production – the S22 leaves
Manufacturing printing rollers on an
designed for the flexible manufacture
nothing to be desired
MFP traverse table machine
of all types of inserts
Station 5 – STUDERmicro
10
Station 2 – BLOHM JUNG
25
Station 14 – EWAG EWAMATIC LINE
Precise, productive and reliable – the
Forward-looking surface and profile
Fully automated machining of
manufacture of small and micro parts
grinding with modern control and
PCD/PCBN equipped highly complex
on the S21 and S12
machining systems
round tools
Station 6 – STUDERinternal
11
Station 3 – BLOHM JUNG GEOID
26
Station 15 – WALTER
Flexible manufacture in small batch
The efficiency of diamond wear
HELITRONIC MICRO and HELICHECK
and large batch production
compensation using high-perfor-
PLUS – the high-performance double
mance blanking punches
act for micro tools
Station 8 – MIKROSA
Service
Complete machining: High-speed
grinding of jet needles on the
MIKROSA KRONOS S
19
Station 1 – MÄGERLE
Station 9 – SCHAUDT ShaftGrind S
16
27
Station 16 – WALTER
Station 7 – SERVICE Quality
Perfect cutting edges of PCD tools
Systematic servicing carried out
manufactured on the HELITRONIC
by SCHLEIFRING Service optimizes
POWER DIAMOND
machine availability
Machining of drive shafts with
28
swivel-in spindle technology
Station 17 – WALTER
Tapping the full potential
of tool grinding machines:
20
Station 10 – SCHAUDT CamGrind L2
HELITRONIC ToolStudio is
With swivel-in spindle technology
the no. 1 software
camshafts are machined complete in
one clamping
22
Station 11 – STUDERflexible
The STUDER S242 with three
cross-slides is the most flexible
hard fine machining center
23
Station 12 – STUDERintelligent
StuderTechnology optimizes the
grinding processes on the S 31 and
S33 by up to 50 per cent
4
MOTION 01/09
14
CONTENT
32
44
MARKETS & TRENDS
Technical Symposium I:
Innovative production
30
48
Lecture III-2 Dr Bernd Möller: New grinding spindles for
operation at extremely high rotary speeds
Lecture I-1 Prof. Thomas Straubhaar: The global
economy in recession: what can be done?
50
Lecture III-3 Harro Wörner: Global strategy of standard machines from the point of view of the large volume manufacturer
32
Lecture I-2 Prof. Eckart Uhlmann: Quo vadis
precision machining?
52
Lecture III-4 Udo Mertens: High performance grinding
wheels for external cylindrical grinding
34
Lecture I-3 Dr Hans-Werner Hoffmeister:
Technical Symposium IV: Tool grinding
Effective cooling and lubricating in grinding
54
36
Lecture IV-1 Prof. Wilfried Saxler: Tool grinding –
the industry of the future
Lecture I-4 Johann Noichl: Dressing grinding
wheels – a nice piece of work?
Technical Symposium II:
Surface and profile grinding
38
56
Lecture IV-2 Dr Dieter Kress: Multi-axis precision grinding
58
Lecture IV-3 Christoph Hübert: New methods for
Lecture II-1 Prof. Taghi Tawakoli: Advantages of ultrasonic
the manufacture and use of micro cutting tools
grinding and dressing compared to conventional grinding
and dressing
60
Lecture IV-4 Oliver Wenke: Measuring technology
guarantees cost-effective tool production
40
Lecture II-2 Prof. Wilhelm Schröder: Professionally
Technical Symposium V:
Universal cylindrical grinding
compensating for form deviations during profile dressing
42
Lecture II-3 Dr Christoph Zeppenfeld: Interactions of process
62
tools and processes
and machine when surface grinding
44
Lecture II-4 Dr August Kästner: Efficient grinding of
Lecture V-1 Prof. Konrad Wegener: Simulation of abrasive
64
Lecture V-2 Dr Frank Fiebelkorn: Efficient hard fine machining
66
Lecture V-3 Dr Carsten Russner: Precision grinding of brittle
components for vane pumps and motors
Technical Symposium III:
Production cylindrical grinding
46
Lecture III-1 Prof. Klaus Weinert: Innovative concepts for
internal cylindrical machining
hard ceramics under production conditions
69
Lecture V-4 Walter Graf: How do you choose the ‘ideal’
abrasive material?
IMPRINT
Publisher: Körber Schleifring GmbH, Hamburg Chief editor: Peter Lütjens Realization: JDB MEDIA GmbH, Schanzenstraße 70, 20357 Hamburg, Germany Project management:
Jan Hawerkamp Art direction: Claudia Schiersch Editorial board: Marc-Oliver Prier (dir.), Dania Müller, Ira Schroers Layout: Steffi Pfl ugbeil (Ltg.), Yvonne Vahland Proofreading, editing
and translation: SKH SprachKontor Hamburg GmbH Photos: ddp-archiv (2), F1 online (1), Getty Images (2), PR/Hersteller (142) Lithography: Fire Dept. GmbH, Hamburg Printing: NEEF +
STUMME GmbH & Co. KG, Wittingen
MOTION 01/09
5
MOTIONS & MORE
SCHLEIFRING GRINDING SY MPOSIUM 20 0 9
Grinding in motion
At the heart of things, between
the machine presentations and
the lectures, experts in the
mechanical engineering sector
can meet in front of the bar to
exchange news and views
SCHLEIFRING is showing its comprehensive services from May 6 to 8, 2009. The SCHLEIFRING
Grinding Symposium will be rounded off with lectures by well-known experts in the grinding sector.
T
he SCHLEIFRING Grinding Symposium 2009 is fully geared to for-
ward-looking development, effi cient
production and successful sales.
Technical symposium I, May 6, 2009, 14.00 to 17.00: The speakers on the
subject of Innovative Production are Prof. Thomas Straubhaar, Prof. Eckart
` A varied program
The eight SCHLEIFRING companies will
Uhlmann, Dr Hans-Werner Hoffmeister and Johann Noichl
Technical symposium II, May 7, 2009, 9.30 to 11.30: Prof. Taghi Tawakoli,
be present on 17 stands in all where
Prof. Wilhelm Schröder, Dr Christoph Zeppenfeld and Dr August Kästner are
visitors can have first-hand experience
our speakers on surface grinding and profile grinding
of the latest products and technical
Technical symposium III, May 7, 2009, 14.00 to 17.00: The subject of produc-
developments. In addition, there will be
tion grinding and cylindrical grinding will be dealt with by Prof. Klaus
presentations that clarify technological
Weinert, Dr Bernd Möller, Harro Wörner and Udo Mertens
improvements in productivity and qual-
Technical symposium IV, May 8, 2009, 9.30 to 11.30: Prof. Wilfried Saxler,
ity in finish machining and effi cient
Dr Dieter Kress, Christoph Hübert and Oliver Wenke are our experts on tool
software solutions. The machine pre-
grinding
sentations will be given in German,
Technical symposium V, May 8, 2009, 14.00 to 17.00: Visitors will hear all
English, French and Italian (see right-
about universal cylindrical grinding from Prof. Wegener, Dr Frank Fiebel-
hand column for details). In addition to
korn, Dr Carsten Russner and Walter Graf
these practical machine presentations
there is also a theoretical program of
` A relaxing end to the day
fi ve colloquia with a total of 20 talks
After the machine presentations and lectures the evenings will finish with a pro-
given by well-known experts in the field
gram including musical highlights and exceptional performances in the Kursaal
to round off the three days of the sym-
Casino at Interlaken. This also gives all delegates another opportunity for network-
posium.
ing and exchanging ideas with colleagues.
6
MOTION 01/09
ENTRANCE
INFO
Overview: Using this plan (above) you can easily
find your way to the various stands. The table
below shows when each machine presentation
will be given in which language
SCHLEIFRING GRINDING SYMPOSIUM 2009 – SCHEDULE OF EVENTS
Station
Subject
9.30
10.00
10.30
11.00
11.30
1
MÄGERLE: Optimum surface
quality and accuracy
D
F
D
I
2
BLOHM JUNG Forward-looking surface
and profi le grinding
E
D
F
3
BLOHM JUNG: GEOID diamond-wear
compensation
I
E
4
STUDERmodular
D
5
STUDERmicro
6
14.30
15.00
15.30
16.00
16.30
E
D
F
D
I
D
E
D
I
E
D
F
D
I
D
D
F
D
Press
E
D
F
D
I
I
E
D
F
I
D
E
D
F
D
F
D
I
E
D
D
I
D
E
D
F
STUDERinternal
D
F
D
I
E
F
Press
I
D
E
D
7
SERVICE Quality
E
D
F
D
I
D
F
D
I
D
E
8
MIKROSA: High-speed grinding
of jet needles
I
E
D
F
D
E
D
F
D
I
D
9
SCHAUDT: Machining of drive shafts
with swivel-in spindle technology
D
I
E
D
F
D
E
Press
F
D
I
10
SCHAUDT: Complete machining of
camshafts
F
D
I
E
D
I
D
E
D
F
D
11
STUDERflexible
D
F
D
I
E
D
I
D
E
D
F
12
STUDERintelligent
E
D
F
D
I
F
D
I
D
E
D
13
EWAG: Flexible manufacturing of inserts
I
E
D
F
D
D
F
D
I
Press
E
14
EWAG: Machining of PCD tools
D
I
E
D
F
E
D
F
D
D
I
15
WALTER: High-performance double act
for micro tools
F
D
I
E
D
D
E
D
F
I
D
16
WALTER: PCD tools – perfect
cutting edge
D
F
D
I
E
I
D
E
D
F
D
17
WALTER: HELITRONIC ToolStudio
E
D
F
D
I
D
I
D
Press
E
F
English
French
Italian
Lunch break
14.00
German
12.00
Press, May 6, 2009 only, otherwise in German
MOTION 01/09
7
TOOLS & TECHNOLOGY
Optimum sur face qualit y
A strong worker
The MÄGERLE hydrostatic guidance systems set standards in the matter of precision when
machining larger components.
E
xperts in evolving solutions exactly tailored to the customer’s
needs – this is the specialty of the
SCHLEIFRING company MÄGERLE. In
piece in the machine, and together with the processing forces calculates ap-
particular when handling large com-
propriate corrections. In the grinding process which follows, the machine then
ponents, the hydrostatic guidance sys-
travels fully automatically precisely in accordance with the values given. The
tems of the MÄGERLE machine ranges
make the highest levels of precision
possible.
` Automatic compensation
At the SCHLEIFRING Grinding Symposium 2009 the Swiss company is showing the ma-chining of large components using a plate cylinder for the
printing industry as an example. The
task of grinding is precise machining
of the start and end of print line which
is longitudinally arranged on the
chrome-plated plate cylinder. High
standards are set here both for accuracy and for quality of the surface fi nish. In components of this size and
weight (the cylinder measures 500 millimeters in diameter, is 1,600 millimeters long and weighs 1,000 kg), special
strategies are necessary for machining.
Due to its weight and also the forces
on the machining, the workpiece bends
and becomes misshapen. Where high
levels of accuracy are demanded, there
must be precise compensation for
these sources of error.
For this purpose MÄGERLE has developed a compensation algorithm which
measures the deflection of the work-
8
MOTION 01/09
Speaks for itself: Edges of the printing roller are ground absolutely precisely on the MFP-220
STAND
The combination professional:
The MÄGERLE MGC-L-330
with fully automatic tool changer
hydrostatic guidance concept makes it possible to move heavy workpieces almost without friction, which makes a decisive contribution to the
quality of the surface finish. The combination of machine concept with
hydrostatic guidance, integral measurement and fully automatic compensation guarantees the customer an optimum result, even for the heaviest
components.
We optimize your
grinding process
` Complex combined machining
However, modern MÄGERLE grinding centers don’t only solve pure grinding tasks in a reliable manner. They also handle complex combination
machining with geometrically-defined cutting edge such as hard turning,
hard milling or drill-ing too. Machining the workpieces in a single clamping also has decisive influence on productivity and on quality of the component. An ex-ample of such a combination machine is the MÄGERLE
MGC-L-330. The grinding center comprises a fully-automatic tool-changing sys-tem, a horizontal grinding spindle and a table dressing device.
Machining with geometrically defined cutting edges is carried out with
an additional vertical direct drive spindle, which can be swiveled through
90°. Due to the extreme rigidity of the large-area hydrostatic guides, impressive cutting values can be
achieved. The result speaks for itself:
FURTHER INFORMATION
reduced machining time and the
+++ sales@maegerle.com
greatest possible accuracy.
+ + + w w w.maegerle.com + + +
Meet us
Schleifring Grinding Symposium
2009
6.– 8. Mai
Thun/Schweiz
Dittel Messtechnik GmbH
Tel.: +49 (0)8191 3351-0
www.dittel.com
TOOLS & TECHNOLOGY
STAND
For ward-looking sur face and profile grinding
The next generation
Fast and outstandingly user-friendly – these are the convincing advantages of the modern
con-trol and machining systems by BLOHM JUNG.
W
ith the CNC-Light Control, BLOHM
5-SIDED-GRINDING ON THE PROKOS
JUNG introduces a new genera-
tion of controls. It can interpolate up to
Workpiece: Length × breadth × height = 100 × 70 × 40 mm – 3 grinding wheels
four axes at the same time and traverse
„ Operation stages 1 + 2
them towards each other. The technology
is thus perfectly suited for high-end ma-
Wheel No. 1 – traverse plunge – grinding wheel
set angle (A-axis) = 70°
„ Operation stages 3 + 4
chines with a limited number of axes. The
special feature of the CNC-Light Control:
both the FANUC control operator panel
and the functional scope of the machining
possibilities (cycles) were a complete inhouse development by BLOHM JUNG.
A new feature is the method of working
with the workstation editor, which is oriented towards the STUDER pictogramming (see Station 5). Broadly in line with
Wheel No. 1 – traverse plunge –
set angle 25°
„ Operation stage 5
Wheel No. 2 – traverse plunge –
set angle 45°
„ Operation stage 6
Wheel 2 – profile traverse grinding with
three interpolating axes – set angle 45°
„ Operation stage 7
the motto ‘more pictures – less words’,
BLOHM JUNG introduces the user-
Wheel 3 – flat grinding with continuous
traverse – set angle 20°
friendly working method of the new control on a PROFIMAT at Station 2.
outstanding performance and process reliability are thoroughly convincing. As
` Breathtaking speed
a basic machine equipped with three axes, it can be upgraded to a five-axis ma-
Also at Station 2: the latest news in
chine with a high-speed rotary table and a swiveling grinding spindle drive. It
speed-stroke technology, as exempli-
can grind different profiles in a single clamping – with concave or convex radii,
fied by the PROKOS, which grinds fi ve
as desired, and it can also be used for drilling, milling or grinding. Speed-stroke
sides of a workpiece in seven grinding
grinding is known for its fast traverse speeds and acceleration and a fast machin-
operations (see table). Its features of
ing process and very short cycle times. On account of the fast feed rate – 80 to
120 m/min at infeed rates of up to 0.01 millimeters per traverse stroke – a large
proportion of the process heat is carried away by the chips. The edges of the
workpiece remain undamaged even where the cooling and grinding conditions
are less than optimum. A well thought-out procedure for the process rounds off
the profile of the PROKOS. The selection of parameters is simpler, the coolant
feed is less critical and the performance limit can easily be determined from the
wear on the grinding wheels.
FURTHER INFORMATION
Right at the top: The speed-stroke technology of
the PROKOS means very short cycle times
10
MOTION 01/09
+ + + p e t e r. o p p e l t @ b l o h m j u n g . d e
+ + + w w w.blohmjung.de + + +
STAND
G EO I D d i a m o n d - w e a r c o m p e n s a t i o n
It all depends on the contour
GEOID wear compensation
eliminates faults on dressing
tools accurate to the last μ.
G
rinding wheel profiles cannot be
exactly dressed without the use of
a geometrically-perfect dressing tool.
Even new diamonds are not always perfect. At the SCHLEIFRING Grinding Symposium 2009, BLOHM JUNG pre-sents
for the first time ever under the expression GEOID a new development for
compensa-tion of contour faults in dressing tools. The example shows the quick
Swiveling: GEOID in combination with
flexible dressing systems guarantee perfect
contours on the grinding wheel [1 + 2]
[1]
manufacture of a blanking punch on the
VARIO D. GEOID was developed in concert with the Georg Simon Ohm Univer-
` Ready for use in six minutes
sity in Nuremberg. The software for
For profile grinding, different dressing systems are
com-pensation of uneven wear in dress-
available for the VARIO range of profile grinders by
ing tools is a further development of the
BLOHM JUNG. According to requirements, profiled
automatic diamond adjustment by
crushing units, fixed profile diamonds or swiveling
BLOHM JUNG and is used in conjunction
diamond wheels are mounted on the grinding table.
with the CNC PA37K profile dressing de-
Highlight is the CNC PA37K head dressing unit. The
vice and the table version PA130TM.
possibility of using both individual diamonds and
Topography of the cutting edge of the
driven diamond wheels for profiling is unique in the
dressing tool can be determined with
world. Even when preparing the diamond tools the
μ-accuracy using GEOID. The correction
automatic diamond adjustment saves a lot of time. A diamond star with six dia-
values calculated are fed directly into
monds is ready for use in only six minutes, a diamond wheel in ten. The function
the dressing program and create a per-
‘CD Abrichten’ (continuous dressing), or parallel dressing, cuts machining times
fect contour on the grinding wheel. Re-
by up to 50 per cent.
[2]
sult: an increased service life for the
dressing tool, reduced costs of tools and
` Determine, analyze, compensate
the contour accuracy is improved.
But even the best dressing tools wear, and this has an influence on dressing contours. BLOHM JUNG shows at Station 3 how the GEOID correction software
determines the actual contour of the diamond via a measuring probe and then corrects the dressing program accordingly. Thus GEOID compensates for the wear in
Best contour
accuracy:
Produce perfect
workpieces with
GEOID
individual diamonds and diamond
wheels, in-creases the usability of the
FURTHER INFORMATION
dressing tools by a multiple and re-
+++ achim.bauder@blohmjung.com
duces the costs of tools considerably.
+ + + w w w.blohmjung.c om + + +
MOTION 01/09
11
TOOLS & TECHNOLOGY
STAND
STUDERmodular
Your personalized S22
The customer’s workpiece is the focal point. The customer chooses what he really needs,
just like a construction kit. No more and no less. The choice leaves nothing to be desired.
T
he new production platform can be
configured for almost every grin-
ding task. Effi cient production grinding,
high-speed grinding or heavy-duty
applications – the S22 has a construction set at its disposal filled with every
component STUDER has ever developed and produced for CNC production
machines. From workpiece spindle
heads with chuck or universal design,
to standard or high-precision C-axes
with different power settings of belt or
motor spindle head, to tailstocks for
standard, synchronous or fine grinding
applications. Various dressing options
and accessories such as measuring
control and clamping devices complete
the range of services. In short, indi-
Modular design: Production grinding and dressing (top right), heavy-duty plunge grinding (be-low right),
high-speed grinding with two grinding wheels (below) or non-circular grinding (below left) – the S22 can be
configured flexibly and individually to customer requirements
vidually equipped to customer requirements, the S22 is the perfect machine
– for heavy-duty applications as well
as fl exible production.
„ High-speed grinding (HSG) with cutting speeds of 80 to 140 m/s or heavy-
` Sophisticated software
„ The S22 is compatible with various loading and unloading systems and can
duty applications for grinding wheels of 610 mm diameter and 160 mm width.
Sophisticated software completes
the mechanical concept of the S22.
StuderWIN operator interface and
StuderGRIND software modules guarantee the effi ciency of the machine.
Integral measuring system, handling
be loaded from both sides and from above. The platform is suitable for linking
several machines together
„ Two different axis drive systems are available. The X-axis has antifriction
guideways as standard and the Z-axis has guideways with a patented surface
structure. Both axes have ball screw linear drives
„ Direct drive and non-contact guideways are optional for both axes. The
system, sen-sor technology for process
combination of hydrostatic guides and linear motors permits axis movements
monitoring and automatic balancing
of up to 30 m/min. Precision to a tenth of a micrometer is easily achieved,
systems ensure standardized program-
thanks to the measuring system resolution of 0.01 μm
ming of the different systems. These
FURTHER INFORMATION
and the following performance fea-
The platform concept can be experi-
tures make the STUDER S22 a real all-
enced close up at the Grinding Sym-
+ + + m i c h e l e .f a h r n i @ s t u d e r. c o m
rounder:
posium.
+ + + w w w. s t u d e r. c o m + + +
12
MOTION 01/09
STAND
S T U D E R m i c ro
You can’t get more accurate than this
STUDER shows the machining of small precision parts for individual and production operations
with accuracies of up to a tenth of a micrometer.
M
anufacturers of small and micro
parts have known the secret for
some time: STUDER cylindrical grinding
machines impress with precision, pro-
an automatic swivel function. A tiltable dressing
ductivity and reliability. If all-purpose
unit ensures perfect dressing conditions for internal
and highly effi cient machining of small
grinding without compromising geometries.
parts is required, then the S21 universal
Using three grinding wheels brings distinct advan-
cylindrical grinder or the S12 cylindrical
tages. Machining the workpiece in one set-up guar-
production grinder is for you.
antees optimum concentricity and at the same time
eliminates downtime for re-clamping. Special
` Pressure piece with external
thread on the S21
STUDER grinding software helps to utilize the ma-
The largest external diameter of the
supports the operator when creating effi cient grin-
30-millimeter-long component is 18
ding and dressing programs. STUDER Quick-Set ®
millimeters; the internal diameter is 7
set-up software facilitates workpiece set-up and
millimeters. The S21 grinds workpieces
changeover. StuderThread software helps when
in one set-up and can be equipped with
programming the dressing program for thread
two external grinding wheels and one
grinding. Following the completion of this machin-
high-frequency spindle for internal
ing process, the workpiece is ready for the next
grinding. The B-axis is equipped with
process steps.
chine’s full potential. ‘Pictogramming’ software
Angular infeed grinding
Thread grinding
` Bearing inner ring on the S12
High-tech machine: The S12 with linear motors and
hydrostatic guideways
The high-tech S21 excels at machining a bearing
inner ring. A combination of linear drives and hydrostatic guideways gives excellent results
when traveling in interpolation mode. The position measuring system used also offers ma-
Internal grinding
Example: Machining of a
pressure piece with external
thread on the S21
jor advantages. A resolution of 0.01 μm can
achieve accuracies in the region of a tenth of a micrometer.
All the benefi ts of the S12 are demonstrated to their best advantage by
the example on show. Nowadays, radius dressing devices often guarantee
the dimensional accuracy of the radius. They prevent fl exible manipulation
of the radius, however. The S12 is definitely more fl exible in this instance,
thanks to the high traverse accuracy
of the guideway and the ability to
FURTHER INFORMATION
program the radius with the CNC
+ + + m i c h e l e .f a h r n i @ s t u d e r. c o m
control system.
+ + + w w w. s t u d e r. c o m + + +
MOTION 01/09
13
TOOLS & TECHNOLOGY
STAND
S T U D E R i n t e rn a l
From the inside out
STUDER further expands its portfolio with machines produced by COMBITEC, its new subsidiary. The
aim is to increase technical knowhow and application possibilities for internal cylindrical grinding.
S
trong partners for every possible
task: With the takeover of Com-
bitec AG of Switzerland, STUDER has
substantially increased its grinding
expertise in the internal cylindrical
grinding sector. Whether die grinding,
series production of precision parts for
the aerospace and hydraulics industry
or diesel injection technology, at Station 6, STUDER presents three technically mature production solutions: the
CT-450L, the CT-960 and the S120.
` CT-450L – entry-level
model for new users
The CT-450L CNC internal and universal
cylindrical grinder for new users is the
light version of the COMBITEC bestseller CT-450. With a wide range of applications, the CT-450L is equally suited to
Innovative injection technology: Just one of many uses in the application area of internal cylindrical grinding
universal internal grinding applications,
grinding collet chucks and machining brittle hard materials. Special features are
the linear spindle arrangement, use of either one or two belt spindles with speeds
of between 28,000 and 60,000 min -1 and cross-slide design. The CT-450 provides
a range of expansion options, such as a C-axis for grinding all types of threads.
` CT-960 – a high-end universal machine
The internal, universal and radius grinder CT-960 is a high-precision machine,
with a B-axis swivel to 91 degrees. A turret for up to four spindles permits effi cient grinding of small to medium-sized workpieces. In this particular design,
the machine is suited for universal grinding tasks as well as specifi cally for grinding complex workpieces of brittle hard materials like carbide, ceramics or sapphire. The optimum stability and rigidity of the CT-960 also permit grinding die
The light version of the CT-450:
The entry-level CT-450L
14
MOTION 01/09
with radii, cones or path contours. The finished workpieces have polished surface
quality. An optional CNC-controlled C-axis is available for grinding threads or
Internal cylindrical grinding: Efficient machining of
high-precision small parts
Excellent: The
STUDER S120
combines
productivity and
flexibility
non-circular shapes. Sim-CT software
dent grinding tasks. Optimally suited for an efficient machining of high-precision
helps with programming, set-up and
small parts, it is well established in large batch production. Typical applications
simulation.
are in the area of hydraulic components and increasingly in medical technology,
for example grinding ceramic balls for hip joints. Different handling systems can
` S120 – a speedy
production machine
be integrated via the well-defined loading interface without too much effort. The
The S120 production internal cylindrical
ly combines productivity with flexibil-
grinding machine is the ideal compact
ity and in addition, it impresses with
+ + + m i c h e l e .f a h r n i @ s t u d e r. c o m
internal grinder for one or two indepen-
short retooling times.
+ + + w w w. s t u d e r. c o m + + +
automated solution on show perfectFURTHER INFORMATION
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15
MOTION 01/09
TOOLS & TECHNOLOGY
STAND
SERVICE Qualit y
Fountain of youth for machines
Anyone who is familiar with possible wear phenomena starts to think about the health of his
machine. A professional overhaul extends its service life.
H
igh blood pressure is the number
one cause of illness in most indus-
trialized countries. If not detected and
left untreated, it can lead to serious consequences such as heart attacks and
Servicing with System TM
Life Cycle Monitoring
Diagnostics and
recommendations
More than 100 testing and
measuring points
The test measurements are
evaluated by specialists
Information on the current
state of the grinding machine
Maintenance cycle: Professional machine diagnostics in three steps
strokes. Yet high blood pressure cannot
be felt; only health checks can supply
the information as to whether it is higher than it should be even though every-
` Preventive SCHLEIFRING Service
thing appears normal. If caught at the
SCHLEIFRING machines are similar to our bodies in this respect: systematic
right time, medicines or a preventive
servicing carried out by SCHLEIFRING SERVICE (which can be compared to rou-
change in lifestyle can help. We often
tine checks by the doctor) extend machine running times and availability and in
do not realize how important our health
addition improve the grinding result. Preventive servicing documents the current
is until it is too late.
state of the machine. We recommend an annual service with SystemTM. Using
this, SCHLEIFRING SERVICE checks more than 100 points on a checklist and
New from old: An assembly before
and after overhaul
measures the geometric values and the hysteresis. All the wear parts in the material list are repla
replaced as a preventive measure. In addition to this, SERVICE
diagnostics and life cycle monitoring provide valuable insights into the condition
of the grinding m
machine and recommend that corresponding precautions are
taken. More than
tha 3,000 satisfied customers are already enjoying the benefi ts
of SERVICE Che
Check. The specialist knowledge of the SCHLEIFRING experts
means that you ccan avoid cost-intensive machine down times, particularly in
these economically
economica diffi cult times.
` Good and beneficial
After a complete overhaul by SCHLEIFRING SERVICE the machines once again operate just as precisely and reliably as
new machines. The modular overhaul system thus works
rather like a fountain of youth. And the process is even more
beneficial. The cost of a complete overhaul is between 40 and
70 per cent of the price of a new machine.
And by the way: more than 100 overhauls are carried out annually, using nothing but SCHLEIFRING original components.
They are only done in
the relevant produc-
16
MOTION
MO ION 01/09
MOT
FURTHER INFORMATION
tion factory of the
+++ sandro.botazzo@ser viceag.net
SCHLEIFRING Group.
+ + + w w w.s er v ic e ag.ne t + + +
STAND
M I K R O S A K R O N O S S 12 5
Fit for every challenge
In the high speed grinding of injector needles the MIKROSA KRONOS S 125 demonstrates an
unusually flexible ability to adapt to the grinding task.
he KRONOS S 125 centerless ex-
Two workpieces are
ternal cylindrical grinding machine
machined simultane-
is designed with a special construction
ously in two different
principle for the use of the CBN grin-
operations with CBN
ding technique. It is based on a ther-
wheels using the an-
mally stable and vibration-damped
gular plunging pro-
moulded mineral machine bed. The
cess. The cycle time,
cross-slide systems that are built onto
including a dressing
this bed for the grinding and regulating
component, is less
wheel side make the centerless grin-
than 13 seconds. The
T
ding machine enormously versatile.
The large number of variations, ranging from throughfeed grinding and
workpieces are transThe angular plunging process: Simultaneous grinding of injection nozzles
with CBN wheels using different operations on the KRONOS S 125
plunge grinding to reciprocating grin-
ported and sent on
using a paced triple
gripper system.
ding including angular plunging, cycle
One of the machine’s special highlights is the dressing system for the CBN
changing and offset grinding.
wheels. This uses software that MIKROSA has developed in-house. It uses integrated sound sensors in two directions to set the dressing start points. This
` Two operations at once
guarantees a preset dressing depth, not exceeding three μm, on the surface and
At the 2009 Grinding Symposium,
the shoulder of the CBN wheel.
MIKROSA is demonstrating the ma-
A standardized handling system uses the ‘keyhole principle’ to transport the
chine’s versatility, using the machining
workpieces into the machine and out again. External handling systems such as
of injector needles (Ø 4.0 × 48 mm) in
palletizing machines can easily be connected via an interface. Centerless precision
a high-speed process.
– if all its process technology features are fully utilized, the potential of the KRONOS
S 125 is enormous. The highest quality and productivity, the ability to process a
wide variety of different materials and
the use of versatile grinding techniques
FURTHER INFORMATION
– MIKROSA grinding machines meet
+++ irina.hafner@mikrosa.com
every requirement of the market.
+ + + w w w.mik rosa.com + + +
DESIGN HIGHLIGHTS
Vast potential: The KRONOS S 125 was designed from
the start with CBN grinding in mind.
Operation 1
„ CBN grinding by angular plunging
„ Pregrinding the shoulder
„ Pregrinding the tip
„ Securing with a pressure roller
Operation 2
„ CBN grinding by angular plunging
„ Contour grinding
„ Finishing the face
MOTION 01/09
17
Meister Abrasives AG · Switzerland · www.meister-abrasives.com
Meister Abrasives
Make A Quality Decision
International
STAND
S C H AU D T S h a f t G r i n d S
The perfect shaft
Transmission shafts up to 650 millimeters long are the province of the SCHAUDT ShaftGrind S
with tilting spindle technology
T
he SCHAUDT ShaftGrind S is designed to machine a variety of shafts
efficiently. It has WOP-S programming,
which is based on the Siemens 840D
control panel and helps to generate surface contours such as polygons, ellipses
and free profiles with ease. The machine
is also eminently suitable for high-speed
peel grinding (HSP) processes and slot
grinding with CBN.
Efficient machining
taken care of:
Machine configuration of the ShaftGrind
S with tilting spindle
that can be swung in
` Machining transmission shafts
Outstanding results: The ShaftGrind S
has cutting speeds of 200 m/s
Seats for transmission shafts are usually ground in an indexing process, either by straight plunging or high-speed
peel grinding. The ShaftGrind S with its
with wear-free drives enables the tool spindle to be positioned with extreme pre-
S2 tilting spindle enables different
cision and at the same time maximizes service life. This ensures the most accurate
widths of grinding wheel to be used and
grinding results, even in the case of camshafts. The CamGrind S version of this
permits the interpolation of undercutting
machine is already used successfully for camshaft grinding.
and plunge cutting with an electroplated
grinding wheel. This markedly increases
the productivity of the machine. When
high speed plunge grinding with CBN,
the ShaftGrind S reaches cutting speeds
of 200 m/s. This, together with the carbon-carrier system of the machine,
makes the process even more productive. The ShaftGrind S is designed for
ADVANTAGES AND PERFORMANCE
„ Machining of round and non-round materials up to 650 mm long,
weighing up to 50 kg
„ Programming with WOP-S is quick and easy
„ Hydrostatic guide for the X axis (optional extra)
„ Moulded mineral machine bed (Granitan® S 103) with optimized damping
properties and extremely high thermal stability
lubrication with emulsion or oil in com-
Technical specifications
bination with CBN grinding wheels.
„ Sinumerik 840D controller
„ Integral SPEED-LOAD loader (option)
„ Grinding length/tip height: 650 mm / 175 mm
Grinding wheels that are 480 millimeters
in diameter guarantee long tool life. An
optional hydrostatic guide for the X axis
FURTHER INFORMATION
+++ irina.hafner@schaudt.com
+ + + w w w.schaudt .com + + +
Spindle configuration
„ Grinding wheel diameters large/small wheel: 480 mm / 140 mm
„ Grinding wheel widths large/small wheel: 80 mm / 70 mm
„ Output using large/small wheel: 40 kW/8 kW
„ 2 grinding spindle locations (one spindle can be tilted)
MOTION 01/09
19
TOOLS & TECHNOLOGY
STAND
S C H AU D T C a m G r i n d L 2
Synchronicity wins on points
The SCHAUDT CamGrind L2 with swivel-in spindle technology and specially-designed
speed profile machines two cam contours synchronously – main and auxiliary machining
times are drastically reduced.
T
he
SCHLEIFRING
company
SCHAUDT shows the latest devel-
opment of the CamGrind L at Station
10. The current machine concept is designed to meet the requirements for
mass production of series components
– with the greatest possible fl exibility
and ease of refi tting. The two-crossslide version with its special speed
profi le makes it possible to machine
two offset cam contours at the same
time in one clamping. The new hydrostatically suspended workhead even
permits, with optimum machine spec-
ADVANTAGES AND PERFORMANCE
„ Simultaneous machining with two grinding wheels reduces working times
„ Reduction in the auxiliary times by one tool-change procedure
„ Low marginal costs for an additional investment with increasing production
quantities
„ Portal loading system or integrated loader SPEED-LOAD (option)
Technical specifications
„ Sinumerik 840D control
„ Grinding length/maximum height: 800 mm/220 mm
Spindle configuration
„ Grinding wheel diameter large/small wheel: 480 mm/250 mm
„ Grinding wheel thickness large/small wheel: 80 mm/55 mm
„ Output large/small wheel: 40 kW/30 kW
„ Three grinding spindle positions (one swivel-in grinding spindle)
ifi cation with four grinding spindles,
synchronous grinding of inclined cam radii. A forwardlooking machine concept.
` A successful design
principle
Know-how of camshaft grinding has for years been based
very successfully on the WOPS programming system. Highresolution glass scales guarantee the accuracy of the
X-slides. Hydrostatic guides
for the slides and the use of
the swivel-in spindle technology round off the well-thoughtout concept to perfection.
In this way, the new CamGrind
Fast and simple: Complete finishing in just one clamping
20
MOTION 01/09
L2 is suitable for cylindrical
Deep insight: [1] Example
of a machine configuration with a swivel-in
grinding spindle [2] View
of the inside of the
CamGrind L2 with the
two-slide version
[1]
[2]
and non-circular grinding as well as for
keyway plunge grinding and HSP-grinding with CBN. On this type of machine,
only CBN tools with ceramic, galvanic
or metallic bonding are used.
FURTHER INFORMATION
+++ irina.hafner@schaudt.com
+ + + w w w.schaudt .com + + +
Finished: A camshaft after the grinding process
When clamping becomes critical …
Extraordinary applications demand extraordinary solutions.
Many workpieces cannot be properly clamped by virtue of
their unique characteristics. We develop targeted customized
chucking systems.
FORKARDT SCHWEIZ GMBH
Industriestrasse 3, CH-8307 Effretikon
Tel. +41 52 355 31 31, info-ch@forkardt.com
an ITW Workholding Comp
W W W.FORK ARDT.CH
Highest quality and precision within the μm range
MOTION 01/09
21
TOOLS & TECHNOLOGY
STAND
STUDERflexible
Seven at one stroke
With the upgrade to three cross-slides, the unique combined machining system STUDER S242
has become the most flexible hard fine machining center available.
confi guration possibilities for external and internal grinding
(with up to three internal grinding spindles). External or internal
hard turning, hard reaming, milling (with up to twelve driven
tool positions) and drilling all benefi t from the wide range of
configurations. Equipped with two cross-slides, the S242 has a
center distance of 400 and 1000 millimeters. With the three crossslide version, an additional variant with a center distance of 800
millimeters is available. Unrestricted chip removal when hard
turning is ensured by the inclined GRANITAN ® machine bed. A
chip conveyor takes care of swarf discharge.
` Quick retooling
Flexible and multi-functional: S242 with three cross-slides (external
grinding, turret, internal grinding turret)
The S242 is mainly used in the sectors of machine tools and tool
making, pneumatics/hydraulics and the electrical/electronic
sector. High fl exibility of the machine and fast retooling with a
range of capabilities that is second
synchronous opposed spindle on the tailstock (W-axis) makes the S242 an in-
to none: ongoing continued devel-
teresting proposition, also for contract manufacturers who machine mainly in-
opment has meant that nowadays the
dividual components (part families) and small lot sizes. Newly developed control
STUDER S242 is capable of at least
measuring cycles with a measuring probe mounted in the revolving turret allows
seven machining processes: external
the automatic calculation of insert wear. This process allows measuring data to
hard turning and grinding, milling of
be recorded and printed. The well-proven in-house design STUDER easyLoad
small grooves, internal hard turning and
XL is offered for workpiece automation. Combining the machining processes of
grinding, external thread turning, drill-
cylindrical grinding and hard turning with parallel grinding spindles and a turret
ing and hard reaming. This means that
guarantees productive, accurate and reliable complete machining of workpieces.
the S242 is capable of machining spin-
STUDER demonstrates these processes
dles and guide pillars, pump pinions,
visually during the Grinding Symposium
armature shafts, tool holders and other
with machining shafts and chuck compo-
+ + + m i c h e l e .f a h r n i @ s t u d e r. c o m
specifi c components, among others.
nents at Station 11.
+ + + w w w. s t u d e r. c o m + + +
A
FURTHER INFORMATION
Complete machining of a variety of
workpieces in a single clamping makes
increases in productivity of up to 70 per
FLEXIBLE, PRODUCTIVE, ACCURATE, RELIABLE
cent a real possibility.
` Wide range of configurations
The S242 has parallel grinding spindles,
a turret as well as two or three crossslides. This results in ten or rather 15
22
MOTION 01/09
„
„
„
„
„
Less production time and down time due to quick retooling of the machine
High positional and rotational accuracy
Complete machining in a single clamping
Appropriate surface structures
In-process measuring of diameter and length
STAND
STUDERintelligent
Intelligent software pays off
StuderTechnology optimizes the grinding process – and increases the efficiency of universal
cylindrical grinding machines by 50 per cent or more.
I
ntelligent software makes it possible:
Achieving the best with StuderTechnology
machine operators can once again
concentrate on their key task – the quick,
8 : 24 : 00
program. At Station 12, STUDER dem-
7 : 12 : 00
onstrates with the S31 and S33 universal cylindrical grinding machines how
StuderGRIND software and the StuderTechnology module can contribute to
reducing cycle times by 50 per cent.
` Everything at the
push of a button
Some of the tasks of a machine opera-
Time [h:min:s]
safe and simple generation of a grinding
Documentation
Optimization time
Dressing time
Grinding time
Programming
6 : 00 : 00
– 25 %
4 : 48 : 00
3 : 36 : 00
– 90 %
2 : 24 : 00
– 75 %
1 : 12 : 00
0 : 00 : 00
E
es
al u
lv
a
c
ir i
mp 1 unit
S
d
tu
c
Te
er
h
E
es
al u
lv
a
c
ir i
mp 10 unit
S
d
tu
c
Te
er
h
E
es
al u
lv
a
c
ir i
mp 100 unit
S
d
tu
c
Te
er
h
tor are to choose the appropriate tooling, set up and retool the machine
quickly, develop the grinding process
and grind accurate parts. He should
StuderTechnology versus empirical values (after optimization): The software is most beneficial for small and medium
quantities. Example: a shaft is to be machined on three diameters. The surface accuracy should be Ra 0.3, the
roundness no more than 1 μm. A total of six values are measured. When grinding with empirical values the tolerances
were not achieved and time-consuming optimization was necessary
be able to leave everything else to
the StuderGRIND CAM software and
automatically calculates the process parameters. At the push of a button, the
StuderTechnology. He only has to enter
operator learns which in-feed speeds, changeover points, dressing amounts and
the type of material, specifi cation of the
spark-out time the system recommends.
grinding wheel, type of dressing tool
and certain other factors. The software
` Profiting from the knowledge of many
Behind all these intelligent functions is a technology database with invaluable
expert knowledge. It makes sure that the machine control is always able to choose
the best available data. Unlike most operators who often habitually work with
the same standard values and who rarely manage to keep to the tolerances on
their first attempt. Such a process is ineffi cient and requires time-consuming
optimization procedures. However, if StuderTechnology is used, near-optimum
values are reached straight away, resulting in reduced set-up times and grinding
times lowered by up to 25 per cent. In addition, the optimization time is often
zero and costly errors hardly ever happen. StuderTechnology with its many and
various functions like virtual machine set-up
and program simulation result in an early
Graphic visualization: User-friendly work with
StuderTechnology
FURTHER INFORMATION
detection of errors and is additionally ex-
+ + + m i c h e l e .f a h r n i @ s t u d e r. c o m
tremely user-friendly.
+ + + w w w. s t u d e r. c o m + + +
MOTION 01/09
23
TOOLS & TECHNOLOGY
STAND
E WAG C O M PA C T L I N E
Compact? Great!
The EWAG COMPACT LINE scores with its compact design, ergonomic operation and its
integrated robot system for flexible manufacture of inserts.
T
he EWAG COMPACT LINE is designed for the fl exible and highly
precise manufacturing or resharpening
of indexable inserts in all materials.
Whether the material is carbide, cermet, ceramic or super-hard CBN/PCD
– the CNC grinding machine meets all
of the requirements for precision and
speed – especially with the realization
of complex workpiece geometries. The
machine is fi tted with the new CBN/
Ergonomic: Control elements and machine
interior are accessible from one position
New measures: All grinding programs can be
programmed on the touch screen panel
PCD module for grinding super-hard
materials and now also for machining
diamond cutting materials, as EWAG
clamping systems are mechanically identically installed on the B-axis and are
demonstrates at Station 13.
identified by a ‘plug and play’ system. The result is maximum flexibility and
The COMPACT LINE sets new standards
shortest changeover times.
in small spaces with compact construction, ergonomic operation and an inte-
` Dressing, regenerating, crushing
grated robot system. Inside the ma-
The ‘three-in-one’ sharpening unit: dressing – regenerating – crushing provides
chine, everything is positioned close to
perfect grinding wheel concentricity and high repeat accuracy of processes. 3D
the working B-axis; the travel ranges
measuring of workpieces in one clamping ensures the required tolerances are
for axes and robots are thus kept to a
met starting with the first part. Loading is carried out with the integrated 6-axis
minimum, cycle and down times are
FANUC robot which increases the level of machine automation and permits
shortened considerably and productiv-
autonomous multi-shift operation. The
ity is increased. The entire machine
COMPACT LINE which incorpo-
interior as well as all control elements
rates 5-axis CNC kinematics,
are accessible from one position.
direct drive of the grinding
spindle and linear technology
` Fast, accurate, autonomous
allows users to effortlessly
A rapid change system allows the op-
keep pace with changing mar-
erator to exchange the grinding wheels
ket requirements.
effortlessly at the push of a button.
The HSKE 50 clamping system for
EWAG COMPACT LINE:
Grinding in the smallest space
grinding wheels ensures quick and accurate changeover of grinding wheel
FURTHER INFORMATION
sets. The workpieces are fixed to the
+++ thomas.fischer@ ewag.com
clamping device with a tension pin. All
+ + + w w w.ewag.c om + + +
24
MOTION 01/09
STAND
E WAG E WA M AT I C L I N E
The efficient one
EWAG presents the EWAMATIC LINE at the Grinding Symposium, a tailor-made tool grinding
machine for machining highly complex PCD tools
PCD. EWAG guarantees highest concentricity requirements and geometric tolerances by using a special chuck which allows automatic tool changing. Fully
automatic loading of the machine is carried out by a 6-axis robot. Each EWAMATIC
LINE meets specifi c customer requirements. Superior fl exibility makes a multitude of grinding operations possible in one clamping, guaranteed by the starshaped grinding head with its repeat accuracy of 2 μm. It can hold up to twelve
grinding wheels. Once the grinding wheel has been dressed on the machine,
concentricity and run-out are guaranteed at the highest level. Features such as
pressure-controlled grinding, automatic grinding wheel regeneration and integrated measuring cycles with adequate compensation make fully automatic
grinding of CBN and PCD tools possible. The machine can be equipped with an
eroding process for the production of PCD tools. Users achieve close shape and
positional tolerances with effi cient eroding and grinding in one clamping. Three
criteria are the core of the machine autonomy:
Q Automatic feed control
Q Integrated dressing of the grinding wheels
Q Dimensional measuring directly on the machine
Technology of the future: The operating system
carries out simulation directly on the machine
` Functionality
The EWAMATIC LINE has another big advantage: the user can employ grinding
wheels of up to 300 millimeters diameter and also the smallest mounted points.
A
t the Grinding Symposium, EWAG
The machine has a high-speed spindle to reach the cutting speeds necessary
demonstrates fully automated
for mounted points. It permits speeds of more than 20,000 rpm.
machining of PCD/ PCBN equipped
In this set-up, the machine
highly complex round tools on the
optimally grinds so-called
EWAMATIC LINE. The 6-axis CNC grin-
pockets for example, which
ding center has many applications:
are subsequently equipped
machining and regrinding of highly-
with CBN or even PCD blanks.
complex workpieces, rotationally sym-
A new operator panel with
metrical tools, indexable inserts from
hot keys already complies
HSS/carbide as well as the latest cut-
with the standard of tomor-
ting materials, like super-hard CBN/
row. Users are able to carry
out grinding simulation directly on the EWAMATIC LINE
FURTHER INFORMATION
with a Windows XP operating
+++ thomas.fischer@ ewag.com
system installed on a high-
+ + + w w w.ewag.com + + +
performance IPC system.
Practical turbo: The high-speed spindle can reach speeds of up
to 20,000 rpm without effort
MOTION 01/09
25
TOOLS & TECHNOLOGY
STAND
Micro tools
High-performance double act
The HELITRONIC MICRO and the HELICHECK PLUS are the perfect machine combination from
WALTER for the manufacture and measurement of micro tools of the highest surface quality.
T
he development of micro tools has
seen a rapid upswing in recent
years. They are used for machining the
smallest components in the electronics
trolled via integral high-resolution measuring systems which
industry and the medical and dental
produce precise movements with simultaneously high dy-
sector and they require the utmost pre-
namics. The grinding spindle head is equipped with three
cision. Without accurate measuring
grinding spindles guaranteeing a high degree of fl exibility.
technology the manufacture of preci-
A secondary X-axis allows for the precise and automatic
sion micro tools is no longer possible.
positioning of tools to the center of rotation of the C-axis.
At Station 15, WALTER shows how the
Additional guiding and support of the workpieces by hy-
[2]
surface quality of micro tools has a
draulically activated steady rests supports with fine adjust-
considerable influence on the service
ment ensure high dimensional and rotational accuracies.
0.2 mm diameter
magnifi ed 50 times
life of the machine as well as on the
The machine concept is complemented by an integrated
quality of the workpiece.
loading system served by a 6-axis industrial robot for work-
[1]
piece loading.
` HELITRONIC MICRO
The HELITRONIC MICRO provides all
` HELICHECK PLUS
[3]
the prerequisites for highly accurate
Optical, non-contact measuring technologies play a decisive
0.2 mm diameter
magnifi ed 400 times
grinding results for tools within the 0.5
role, especially with delicate materials and micro dimen-
to 10 millimeter diameter range. The
sions. WALTER sets new standards with the HELICHECK
machine has six CNC grinding axes
PLUS. The fourth camera with 400× magnifi cation provides
with linear motors and torque motors
the deciding PLUS element and increases the application
on all rotational axes. All axes are con-
range for tools as small as 0.1 millimeter diameter. Front
and top light cameras also magnify the object to be mea-
Ideal conditions: The HELITRONIC MICRO achieves
high-precision grinding results
[4]
sured by 400 times. Even the smallest details become visible and measurable. Primarily, it comes down to perfect
lighting of the micro tools which are barely visible with
the naked eye. WALTER sharpens your vision by effi cient image processing and easy-to-use measuring
control. A special edge detection system, optimized
lighting and image enhancement techniques ensure
that even high-gloss polished, coated or matt surfaces
can be measured with high repeatability.
FURTHER INFORMATION
+ + + c h r i s t o p h .e h r l e r @ w a l t e r- m a c h i n e s .d e
+ + + w w w.w a l t e r- m a c h i n e s .d e + + +
26
MOTION 01/09
[5]
Well measured:
First-class surface
quality with the
HELITRONIC MICRO [1].
The HELICHECK PLUS
magnifies object 50 to
400 times [2 + 3]
Result of the image
enhancement technique
with a micro tool
Ø 0.8 mm [4 + 5]
STAND
WA LT E R H EL I T R O N I C P O W E R D I A M O N D
Only the cutting edge counts
The two-in-one concept of the WALTER HELITRONIC POWER DIAMOND offers a risk-free
entry into the PCD business.
W
ALTER’s answer to the
ever-increasing stan-
dard of surface accuracy and
cutting edge quality is the
H ELI T RONI C
P OW ER
DIAMOND. The machine
impresses with a 4-stage
[1]
erosion process which
accurately produces
[2]
Immaculate: [1] The improved cutting edge quality is clearly visible [2] Edge rounding of
3.9 μm at the PCD tool cutting edge
perfect cutting edges
and extraordinary surface qualities of up to Ra =
0.1 μm when machining PCD
tools. It is quite impressive:
The
HELITRONIC
` Changer with 8 positions
POWER
DIAMOND achieves only minimum
The trend is towards an increasing range of geometries
stock removal rates due to a fine ad-
and longer unmanned machining cycles. WALTER takes
justment of power during the erosion
on this development with the electrode/grinding
process. The result is PCD cutting
wheel changer with 8 positions for the HELITRONIC
edges with perfect surface quality and
POWER DIAMOND which holds up to 24 electrodes
greatly improved chip resistance.
or grinding wheels respectively. This ensures ex-
Workpieces manufactured in this way
now almost achieve the quality of
ground PCD tools.
cellent machining properties of PCD and carbide
Superior
quality: PCD step
drill and carbide
full-radius milling
cutter with perfect
surface quality
tools with extremely complex tool geometries.
When eroding stepped contour tools with different
concave contour radii for example, the best-suited rotating electrode is simply selected.
The coolant supply manifold is connected to the electrode/grin-
ding wheel adaptors. This guarantees optimum cooling at all times during the
production process when tool grinding and optimum protection when eroding.
In addition, the tool changer extends unmanned machining time for night-shift
and week-end operation. The two-in-one concept of the HELITRONIC POWER
DIAMOND enables fl exible reaction to current production requirements. Automatic changeover from eroding to grinding, from machining PCD tools to processing or resharpening carbide tools
is possible. Furthermore, complete
Head-turner: The changer is loaded with up to 24
grinding wheels
FURTHER INFORMATION
machining of almost all types of
+ + + c hr is t oph.ehr ler @ w al t er- mac hines.de
tools is also feasible.
+ + + w w w.w al t er- mac hine s.de + + +
MOTION 01/09
27
TOOLS & TECHNOLOGY
STAND
WA LT E R H EL I T R O N I C To o l S t u d i o
The easy way to produce a tool
The new version of the HELITRONIC ToolStudio grinding software from WALTER is even more
efficient and simplifies grinding of complex tool geometries.
O
nly a few years ago, tools with
variable helix angles, uneven in-
dexing between the individual cutting
edges and constant flute width across
the body were categorized as special
tools. Nowadays, complex geometries
such as these are becoming part of the
bread-and-butter work of many tool
manufacturers and resharpening companies. HELITRONIC ToolStudio is the
efficient software package for the
HELITRONIC tool grinding machine
series from WALTER. It covers every
aspect of the configuration of tool geometries.
High precision 3D view: Graphic tool simulation with HELITRONIC ToolStudio
` Minimal effort
Using the integrated wizard technology, tools can be modeled in a simple
way. The required data input is reduced
ter how small, the tool can be individually tailored. Further key functions:
to a minimum. The system only re-
„ ‘Click & Edit’: Simply click on the 3D simulation to see the relevant
quests the most important tool parameters and automatically runs through
the necessary input screens. At the
same time the HELITRONIC ToolStudio
geometries and technology parameters
„ Time saving: Path-optimized calculation of positioning movements
between operations and cutting edges
„ Safety: Automatic collision check prior to manufacture
software accesses WALTER’s knowledge database which stores important
` Tool design made easy
tool grinding experience and helps to
The modular design of the new version of HELITRONIC ToolStudio permits
find a speedy solution for all produc-
variable and individual configuration of all important parameters. Using the
tion tasks. The software complements
modular principle, any number of operations can be added or copied – a huge
the entries with relevant geometry and
advantage when designing tools. All this extra flexibility comes in handy when
technology parameters such as grin-
processing step tools (for example step drills or stepped milling cutters).
ding wheel sets and grinding feed
WALTER has improved the tool wizard for step tools so that it can now be re-
rates, for example. Based on the basic
started at any time even after manually adding or copying individual operations.
tool model created and high-precision
The amount of work required by the operator has been considerably reduced;
3D simulation which is updated for
with just a few clicks he can replace an existing drill cutting edge on a special-
each and every modifi cation – no mat-
ized step drill.
28
MOTION 01/09
Virtual probing: HELITRONIC ToolStudio records individual diameters and steps as
well as the entire profile contour
Replaced with a few clicks: Drill cutting edge using the example of a special tool
with variable helix design and two steps
` Useful touch functions
tribution of measuring points can be freely confi gured. While the tool param-
In the production of step tools on
eters are being defi ned, the HELITRONIC ToolStudio software calculates the
WALTER machines two particular prob-
flute shape with specifi c focus on all the determining factors. The path of the
ing functions of the software are very
helical angle, the radius of the grinding wheel bond or the angle of the grinding
helpful. One serves in the alignment of
wheel are just some examples. Time-consuming checking of the flute shape is
coolant holes and measures the con-
not required. Accurately parallel clearance angles and land widths on the step
centricity of the blank. The other scans
are produced without the need for long-winded manual corrections. The capa-
the flute path along the contour of the
bility of the HELITRONIC ToolStudio
tool. It is possible to check individual
software is unrivaled in the market
diameters or steps as well as entire
for grinding software. Visitors to
+ + + c h r i s t o p h . e h r l e r @ w a l t e r- m a c h i n e s . d e
profile contours in this way. The dis-
Stand 17 can see for themselves.
+ + + w w w.w a l t e r- m a c h i n e s . d e + + +
FURTHER INFORMATION
MOTION 01/09
29
MARKETS & TRENDS
L e c t u r e I -1 | M a y 6 , 2 0 0 9 | 14 . 0 0
Production in the global economic climate
Sucked into the recession: Key industries like the
automotive sector have been affected
The global economy in recession – expertise and technological leadership secure exports of
high-quality capital equipment even in times of crisis.
By Prof. Thomas Straubhaar
T
here is no doubt that the global
economy is in a crisis. What is uncertain is how long the recession will
last and how deeply it will affect individual economies. The bad economic
tidings of recent months do not provide
much hope because, for the first time in
decades, the slowdown is affecting the
whole world at the same time. Even
emerging economies and exporters of
raw material are facing difficult times.
The crisis on the financial market has
become a global economic crisis. Whereas at the beginning it affected only a few
isolated sectors like the lending business, now there are hardly any areas that
are not being sucked into the whirlpool
30
MOTION 01/09
of the recession. The automotive industry, machine construction and the electronics industry are particularly severely affected.
` From product manufacturer to systems provider
However, there is one piece of good news amidst all the doom and gloom: the
global economic crisis finds German and Swiss industry in a comparatively stable condition. In recent years, many firms in both countries have undergone a
unique transformation from product manufacturer to systems provider. Instead
of just selling machines, electronic devices or vehicles, they are now selling endto-end, innovative solutions with an industrial core packaged in a wide range of
upstream and downstream services – from planning and organization to management, operation, financing, insurance, maintenance and modernization. German
and Swiss companies have become global market leaders in many industries,
offering very attractive high-quality, all-round packages of products and ser-
THE WHOLE WORLD IS AFFECTED
Slowdown in the OECD countries
108
106
104
102
100
98
96
94
92
115
Stability goals
110
105
100
95
90
Price level
85
Slowdown in the USA
Slowdown in the euro zone
110
108
106
104
102
100
98
96
94
92
90
108
106
104
102
100
98
96
94
92
98 99 00 01 02 03 04 05 06 07 08 09
Employment
98 99 00 01 02 03 04 05 06 07 08 09
Monetary
policy
98 99 00 01 02 03 04 05 06 07 08 09
Source: OECD
98 99 00 01 02 03 04 05 06 07 08 09
[1]
SOLUTIONS TO THE CRISIS
Slowdown in China
Fiscal policy
Labor market
policy
Foreign trade
policy
The psychology of expectations
[2]
What does the future hold? [1] For the first time in decades the slowdown is affecting the whole world simultaneously [2] There are many factors influencing the
economic equilibrium. Expertise and technological leadership secure exports of high-quality capital equipment, particularly in times of economic difficulty
vices. It is not so much low costs and
prices that give them their competitive
advantage. Instead, it is their effective
organization and effi cient management
of complex international value creation
networks that give them a monopoly
position that goes beyond cost leadership. Technological leadership enables
them to set the rules and to charge high
prices with generous margins. It makes
local firms less susceptible to shortterm economic problems. This means
that many German and Swiss firms are
not attempting to offer cheaper products and services than the international competition. Their aim is to be technological leaders, both now and in the
future. Technological leaders are not as
involved in the cut-throat international
price competition and are not as exclusively cost-dependent. They set their
own prices. This means that they remain internationally competitive and
can sell their products and services
even in times of moderate to serious
economic diffi culty.
` The future of the
global economy
The global recession will pass, hopefully sooner rather than later. Nevertheless, it is the cause of increasing uncertainty: Will the global economy be the
same after the recession? Does the
global economic crisis spell the end of
globalization? Globalization has swept
across the world like a hurricane in the
last twenty years. Protective fences and
iron curtains have been pulled down and national borders swept away. International division of labor and specialization have acquired a new, global dimension.
The links in the value chain have been broken down into smaller and smaller units
and distributed all over the world. ‘As long as it’s cheap’ became the guiding
principle. It seemed as if everything was possible. The Earth was reduced to a
flat disk. Long distances and the associated costs apparently no longer played a
part in the new economic geography.
Is the crisis on the financial market and the global recession leading to a reversal of this trend? Has the international division of labor passed its peak? Are
high export growth rates a thing of the past? And will we now return increasingly to local rather than global production? It almost looks like it. International
sales have collapsed. Emerging economies are facing a lack of demand for their
consumer goods and raw materials and therefore do not have the money to go
shopping on the world markets. The absence of power in the American growth
engine is putting the brakes on economic growth worldwide. This is particularly
true of Southeast Asia and Latin America, regions in which production is heavily
dependent on the U.S. market.
Despite all the economic trouble spots, there are enough grounds for optimism for
German and Swiss industry. This view is supported by the German and Swiss firms’
high level of expertise and technological leadership. Small and medium-sized
companies in these countries continue to be favorably positioned with a tendency
towards process-oriented rather than product-oriented innovations. Expertise and
technological leadership secure exports of high-quality capital equipment, particularly in times of economic difficulty. Demand for infrastructure investment,
capital equipment, machinery, devices and apABOUT THE SPEAKER
pliances in the emerging
economies of Southeast
Asia, the oil-exporting
Prof. Thomas Straubhaar has
nations of the Arab world
been Director of the Hamburg
and the new EU counInstitute of International
tries of Central and EasEconomics (HWWI) since 2005.
tern Europe will continue
His key research areas include
– despite, during and aftinternational economic relations,
er the financial crisis.
economic framework policy,
German and Swiss firms
economics of education and
will soon start to benefit
population economics
from it again.
MOTION 01/09
31
MARKETS & TRENDS
L e c t u r e I -2 | M a y 6 , 2 0 0 9 | 14 . 4 5
Precision machining, quo vadis?
Grinding processes are a
delicate balance of high
precision and high output.
By Prof. Eckart Uhlmann
C
onventional processes in grinding
technology are under constant pres-
sure to improve still further in answer to
the increasing performance of alternative cutting techniques. What we see is
that on the one hand, processes with
geometrically determined cutting are
competitive in the fields of cylindrical,
surface and profile machining because
they have great flexibility, high metal
removal rates and low consumption of
resources. On the other hand, the potential offered by metal removing processes is their high process reliability
when machining complex contours to
the highest quality specifications.
Opportunities for grinding
technology: Technological innovations secure
competitive advantages
` Sustainable production
The delicate balance between output
and precision provides an opportunity
for grinding technology. Against a background of runaway proliferation of tech-
resources assigned to specific operations largely determine the flexibility and
nological innovations, there are com-
suitability for innovation of manufacturing processes. The greater this commit-
petitive advantages that do not depend
ment, the higher the quantitative performance and process reliability that can be
on performance and precision alone.
achieved. However, there is also the risk that the required values cannot be reached
Future manufacturing strategies will
by changing the components or processing conditions. Therefore sustainable
only be successful in the long term if
process design must also integrate new technology into existing process chains
they save valuable resources and can
quickly and reliably.
react flexibly to changing technical and
economic constraints. Only innovative
` Potential for development
companies that are the fastest to imple-
Process improvements depend on three factors, innovative machine technology,
ment new results from research and
new developments in grinding and dressing tools and improved process condi-
development will be competitive in the
tions. The effi cient introduction of new techniques requires an in-depth knowl-
world markets of the future. The capital
edge of the effective relationships in the grinding process. Only when the inter-
32
MOTION 01/09
EXTERNAL CYLINDRICAL PLUNGE GRINDING
Workpiece: 100Cr6 (60 HRC); Grinding wheel: B126 V360
1600
˚C
1200
1000
800
5
10
15
groove width 15 mm
Specific grinding energy
groove width 5 mm
Possible increase in metal
removal rate
Maximum workpiece
temperature
without grooves
RAPID STROKE GRINDING OF A
NICKEL-BASED ALLOY
40
%
20
10
J
mm 3
5
10
15
mm 3 /mms 25
Single-crystal corundum
50
25
0
0
mm 3 /mms 25
100
ae = 12 μm
vc = 80 m/s
40
80
Sintered corundum
120 m/min
200
Table feed rate V ft
Related metal removal rate Q‘w
Informative: Slotted grinding wheels produce a higher metal removal rate than grinding wheels without slots
and do not increase the thermal stresses on the workpiece
Rapid stroke grinding: This gives high metal removal
rates with a low level of damage
actions between the machine, the tool
wheels without slots and do not increase the thermal stresses on the workpiece.
and the process are known can the en-
The slotting causes modulation of the machining forces and thus dynamic
gineer combine the solutions offered
excitation of the grinding process. This excitation only leads to process instability
by the wealth of innovations on the
if the speed ratio of the grinding wheel to the workpiece, multiplied by the number
market with maximum development
of grooves, comes to a whole number. For all other speed ratios, although the
potential. He is supported by innovative
grooving causes greater oscillation amplitudes than are obtained with ungrooved
process models from research and de-
grinding tools, they have no signifi cant effect on roughness and roundness when
velopment. An example is the explicit
used in machines that have high dynamic rigidity.
modeling of process conditions and
In rapid stroke profile grinding of materials that are diffi cult to machine, such as
their effects on the grinding process.
high-performance ceramic and nickel-based alloys, there are currently two chal-
What is the effect on process parameters
lenges to be faced. These are the analysis and implementation of the interaction
and the work result in external cylindri-
between kinematic parameters, coolant conditions and the grinding wheel spec-
cal plunge grinding if slots are made in
ifi cation. Because the grinding energies are lower it is possible to perform rap-
the grinding wheels at certain locations?
id stroke grinding with a reduced coolant requirement at high metal removal
A research project that is currently un-
rates and with a low level of damage. However, it is only possible to achieve
derway at the Institute for Machine Tools
suffi ciently true profiles if the combination of the thermal and mechanical stres-
and Factory Management (IWF) at Berlin
ses in the critical zone leads to microcrystalline splitting of the abrasive grit.
University of Technology is investigating
Grinding wheel design therefore depends on full knowledge of the mechanical
this very question. The purpose of the
fracturing and tribological properties of innovative abrasive grits.
research is to be able to specify the ef-
Here, too, system-
fective relationships explicitly. To do this,
atic analysis of the
the interaction between the tool and the
potential applica-
workpiece has been modeled in such a
tions of innovative
way as to use numeric simulation to
products makes a
quantify the thermal flow density in the
signifi cant contri-
workpiece for various groove configura-
bution in combina-
tions and process parameters.
tion with technological studies and
` Industrial application
ever more powerful
Slotted grinding wheels produce a
modeling
higher metal removal rate than grinding
niques.
tech-
ABOUT THE SPEAKER
Prof. Eckart Uhlmann is Head of the
Fraunhofer Institute for Production
Systems and Design Technology (IPK) in
Berlin and holds the Chair of Machine
Tools and Factory Management at the
Institute for Machine Tools and Factory
Management (IWF) at Berlin University
of Technology
MOTION 01/09
33
MARKETS & TRENDS
L e c t u r e I - 3 | M a y 6 , 2 0 0 9 | 15 . 3 0
Cool and greasy
The Institute for Machine Tools and Production Technology (IWF) at Brunswick Technical
University has researched new approaches for effective cooling and lubricating.
By Dr Hans-Werner Hoffmeister
S
o far, all attempts at substituting
cooling lubricants in grinding have
failed. Due to the high temperatures produced during the grinding process it is
conventional emulsions and oils in surface grinding and external cylindrical
not yet possible to abandon them. On
grinding. In this context, the grinding forces encountered, the workpiece surface
the contrary, the multitude of grinding
roughness, the grinding wheel wear and the temperature of the material subject
applications is constantly posing new
to material removal rate and cooling lubricant were examined.
challenges to the range and design of
coolant systems. Optimum process re-
` Polymer-based cooling lubricants
sults in terms of profile accuracy, grind-
The researchers ground a nickel-based alloy on a surface grinding machine for
ing wheel life and minimum processing
the basic experiments with polymer-based cooling lubricant. The variables
times can only be achieved if compo-
consisted of the material removal rate and the viscosity of the cooling lubricant.
nent, tool, process parameters and cool-
Comparison measurements were carried out using a six per cent mineral oil-
ing conditions are coordinated.
in-water emulsion. In all experiments, the coolant was supplied by an open jet
The Institute for Machine Tools and
nozzle with extended jet. Coolant pressure and coolant amount remained un-
Production Technology (IWF) of Bruns-
changed. The experiments showed that the preset viscosity of the polymer
wick Technical University studies the
lubricant largely determines process forces, grinding temperatures and work-
suitability of polymer-based lubricants
piece surface roughness. Increasing the viscosity resulted in a reduction of the
and liquid nitrate as an alternative to
process forces generated and minimized the grinding wheel wear slightly. How-
400
Process:
surface grinding with the creep feed method
Cooling lubricant:
emulsion – Hysol RD 6%, Castrol
Polymer A – Viscosity 1 mm2 /s
Polymer B – Viscosity 2.3 mm2 /s
Polymer C – Viscosity 6.5 mm2 /s
Quantity of cooling lubricant: 190 l/min, open jet nozzle
˚C
300
250
200
150
Emulsion – Hysol RD 6%
Polymer A – Viscosity 1 mm 2 /s
Polymer B – Viscosity 2.3 mm 2 /s
Polymer C – Viscosity 6.5 mm 2 /s
100
50
0
0
5
10
15
Specific material removal rate Q’w
mm 3 /mms
25
Material:
ae = 0.5 mm
ap = 16 mm
vc = 35 m/s
Vw = 125 mm 3 /mm
Inconel 718
aed = 0.8 μm/U
qd = 0.8 +
Grinding Wheel:
89A 60 H 9AV 55
Conclusive: Grinding temperatures measured with thermal elements show a decrease in grinding temperatures with increasing material removal rates
34
MOTION 01/09
Grinding wheel
Dressing roll
Nitrogen jet
MMS jets
Force measuring table
Insulated cryogenic pipe
Comparison tests with dry grinding: Special jets convey the nitrogen and the oil mist from the minimal lubrication system to the
contact zone
ever, the quantity of heat transferred
removal. Lower grinding axial forces had a positive effect on the dynamic and
to the workpiece increases at the same
static resilience in grinding, resulting in repeatable grinding behavior.
time. Here, a compromise between reducing the grinding temperatures and
` Liquid nitrogen
grinding wheel wear has to be found,
For the effi cient removal of the grinding temperature from the contact zone, the
depending on process line-up and job
team from IWF worked with liquid nitrogen and minimal quantity lubrication as
specifi cation. Evidently, the viscosity
an experiment. In order to be able to discuss the pure cooling effect better,
has no bearing on the surface quality
comparison tests were made with dry grinding. Special jets were used to sup-
when surface grinding. The research-
ply the nitrogen and the oil mist from the minimal lubrication system into the
ers noticed a slight improvement with
contact zone (see picture above). The liquid nitrogen had to be conveyed di-
external cylindrical grinding. Here, the
rectly into the contact zone through an insulated pipe.
cooling lubricant was also supplied via
As expected, the liquid nitrogen reduced the grinding temperature consider-
an open jet nozzle and was not changed
ably compared to dry grinding. Yet no definite improvements could be achieved
during the series of experiments. The
compared with emulsion cooling. Under the same grinding conditions thermal
variation in material removal rate clear-
interaction of the workpiece edge restricted the material removal conditions
ly shows a connection between in-
for emulsion as well as for liquid nitrogen lubrication. Liquid nitrogen lacks
creased output and increased material
any kind of lubricating effect. During the course of the experiments it became
removal rate. The idea of reducing
evident that the combination with minimal quantities of mineral oil got the best
grinding wheel wear signifi cantly with
results in respect of grinding
high viscosity index polymer lubricants
wheel wear and unaffected
was unsuccessful, however.
workpiece edge. The current
All in all, the grinding wheel wear was
price of liquid nitrogen, how-
so small for all the material removal rates
ever, and the complex design of
processed that there was no difference
jets and suction devices in the
between polymer cooling lubricant and
machines prohibit industrial ap-
emulsion. However, the polymer cooling
plication at the moment. But we
lubricant reduced the grinding tangential
can be sure to expect more in-
force and lowered the grinding output
teresting results about polymer
of the machine spindles required for chip
lubricants in the future.
ABOUT THE SPEAKER
Dr Hans-Werner Hoffmeister is Deputy Director
of the Institute for
Machine Tools and
Production Technology
(IWF) at Brunswick
Technical University
MOTION 01/09
35
MARKETS & TRENDS
L e c t u r e I - 4 | M a y 6 , 2 0 0 9 | 16 .15
Small cause – big effect
Round is not necessarily round: The knowledge of interaction of dynamic process variables is
a fundamental prerequisite for optimum adjustment of the grinding wheel.
By Johann Noichl
T
he effect of the dressing of grinding wheels on the workpiece has
already been investigated many times,
and often extremely scientifically.
the opposite direction without the support, the dressing forces caused the thin,
These investigations have usually been
unsupported diamond plate to vibrate. The vibrations were transmitted to the
carried out under laboratory condi-
grinding wheel, and were manifested as spirally-shaped chatter marks on the
tions, which is why the interactions
workpiece. Dressing had in fact not produced a round grinding wheel, but a
which arise during dressing between
polygon with numerous microscopic facets caused by the vibrations.
dressing tool, grinding wheel, grinding
machine and the setting parameters
` Ceramic-bonded CBN
of the process have not always been
Micro-facets also occurred when dressing ceramic CBN grinding wheels with a
adequately taken into account. Their
rotating diamond form roll. In the experiment, the grinding wheels were profiled
effects on the grinding results and the
at a peripheral speed of 60 m/s and put to work creep-feed grinding on a nickel
potential for process optimization have
recently been investigated by the WZL
Aachen in collaboration with TYROLIT
Schleifmittelwerke Swarovski on ce-
150
grinding wheels.
` Ceramic-bonded corundum
In preparation for an external cylindrical
grinding operation, a ceramic-bonded
corundum grinding wheel was dressed
Dynamic fl exibility
ramic-bonded corundum and CBN
F dyn
F dyn
y
y
90
60
30
z
85 Hz =^
40m/s
x
z
x
150 Hz
with an upright diamond dressing plate.
The grinding results were not impressive. Despite maintaining set constant
process variables, it was impossible to
produce a clean workpiece surface. As
it turned out, the feed direction of the
0
0
100 Hz 200
Frequency =^ speed of the
dressing roll
Grinding wheel: n = 0
Roll: n varies
0
20
40
60
80 Hz
Frequency =^ speed of the grinding wheel
60 m/s
100
80 m/s
diamond plate had a decisive influence
on the surface quality of the workpiece:
when the diamond dressing plate was
supported by the dresser support during transit of the grinding wheel, there
were no chatter marks on the workpiece. Where the diamond rotated in
36
MOTION 01/09
40 m/s
40 m/s
Modal analysis: The process recognizes high resonant vibrations and contributes to a reduction in wheel
wear and improvement in the workpiece surface
[1]
[2]
[1] Supported: A diamond plate dresses a ceramic-bonded corundum grinding wheel [2] Unsupported: Resonant vibrations from the grinding machine are transmitted
to the workpiece in the form of spiral chatter marks
alloy at a cutting speed of 80 m/s. With
increase in speed. The realization of these ideas makes very great demands on
this process setting it was quite impos-
the grinding machines in terms of their dynamic rigidity. On top of this, the dia-
sible, irrespective of the grinding wheel
mond dressing rolls will have to be used at much higher speeds. This has prompt-
specifi cation, to produce an accepta-
ed the question of whether it would be possible to dress a CBN grinding wheel
ble surface on the workpiece. It was
at a lower peripheral speed and then to use it at high cutting speeds. This how-
extremely rough and wear on the grin-
ever is not possible due to the dimensional error arising as a result of the radial
ding wheel was extremely high. A mo-
expansion of the grinding wheel.
dal analysis of the grinding machine
The ideal relationship between the peripheral speed of the dressing roll and that
revealed that both the selected speed
of the grinding wheel should be in the region of 0.8. In this way we obtain a rough
of the dressing form roll and the speed
wheel surface. This in turn gives good grinding performance and an acceptable
of the grinding wheel lay within the
service life for the diamond dressing roll. The use of this dressing speed ratio at
range of resonance of the grinding ma-
high cutting speeds also requires dressing units with very high spindle speeds.
chine. Because of the resonance of the
grinding machine itself, the dressing
` Surprising result
roll produced a polygonal grinding
Now however there has been a surprising result from another experiment with
wheel. When grinding, the micro-facets
ceramic CBN wheels. When creep feed grinding hardened ball-bearing steel on the
broke up and thus generated a high rate
Blohm AGNETA speed-stroke grinding machine, it was even possible to grind the
of wear in the grinding wheels and a
workpiece at a cut-
poor surface to the workpiece. The so-
ting speed of 200
lution was to use a dressing speed of
m/s and a very low
80 m/s. This prevented the resonant
dressing speed ra-
vibrations, and the grinding results
tio of 0.4 without
improved immediately.
causing it any thermal damage. This
` Higher speed
result requires fur-
In practice, ceramic-bonded CBN grin-
ther verifi cation,
ding wheels are normally used at cut-
but does indicate
ting speeds of up to 150 m/s. Efforts
that there is poten-
are being made, however, to increase
tial regarding prac-
machining performance by a further
tical realization.
ABOUT THE SPEAKER
Johann Noichl is Manager,
Application Technology and in
charge of the test center in the
precision grinding sector at the Austrian Tyrolit Schleifmittelwerke
Swarovski KG. Trained as an
electrical engineer at the HTL
Innsbruck, he has worked since 1974
for TYROLIT in the trials, application
technology and marketing sector
MOTION 01/09
37
MARKETS & TRENDS
L e c t u r e I I -1 | M a y 7, 2 0 0 9 | 9 . 3 0
Grinding and dressing with ultrasonics
Nature as an example: The
use of ultrasonic amplitudes
optimizes grinding processes
Additional high-frequency oscillations in the ultrasonic range during grinding and dressing
reduce forces, temperature and the wear on tools – and enhance the surface finish.
By Prof. Taghi Tawakoli
E
xperiments carried out at the Center
of Competence for Abrasive Tech-
nologies and Precision Workmanship
(KSF) at Furtwangen University of Ap-
cess. The principle of the technique consists of adding high-frequency (16–40 kHz)
plied Sciences demonstrate that ultra-
oscillations at amplitudes of two to 30 μm in or transverse to the direction of infeed.
sonic assistance can optimize processes
In this way, the use of ultrasonics has the effect of significantly reducing feed power,
when cutting metal with geometrically
chip size, wear on the tools and heat generation, and it also improves the quality
defined or with geometrically undefined
of the surface. The ultrasonic oscillations reduce the friction between the chip and
cutting edges. Compared with conven-
the cutting face of the tool. This leads to thinner chips and thereby to a reduction
tional processes, ultrasonically-assisted
in the cutting force and an improved surface finish when grinding.
grinding and dressing is a hybrid pro-
To investigate ultrasonic-assisted grinding, Professor Tawakoli and his team de-
Dressing with a static dressing tool and with a rotating form roll
Ultrasonic-assisted dressing with rotating dressing tools
Ultrasonic-assisted dressing with static dressing tools
Grinding wheel
Single-point
dressing diamond
Dressing plate
Cup dresser
Dressing roll
Comparison: Using a static dressing tool, ultrasonic assistance can be integrated relatively easily. Using a rotating dressing tool, as is the case with the form roll, it is
more complicated and calls for both know-how and more complex calculations and equipment
38
MOTION 01/09
veloped an addressable workpiece
Piezoceramic
converter
holder. The ultrasonic oscillation chain
consists of a piezoceramic converter, a
Booster
Sonotrode
Workpiece
booster, a sonotrode and a special workpiece clamping device (see picture
right). The ultrasonic generator converts
electric current into high-frequency
pulses, which are then converted by a
piezoceramic converter into mechanical oscillations with an ultrasonic frequency of 21 kHz. The sonic amplitude
is amplified by the booster and then by
the sonotrode and is transmitted to the
Dynamometer
workpiece, which is connected to the
sonotrode. The resultant oscillations of
Ultrasonic oscillation chain: Example of an experimental set-up
the workpiece in the tool-holder reach
an amplitude of between ten and 30 μm
at a frequency of about 21 kHz.
face of the grain. However, this smooth surface does not have the ideal gripping
` Inspecting the grinding
properties for creating chips. In ultrasonic-assisted grinding the grains are broken
In numerous inspections of work with a
into fine particles by the low-amplitude ultrasonic oscillations, but not smoothed
variety of tools, grinding wheels and
out. The small sharp fractures on the contact surface of the grain increase its cut-
stock, the research team compared
ting performance in grinding and this led to 30 to 50 per cent reduction in the
ultrasonic-assisted flat grinding using
grinding power required in the experiments. In comparison with conventional
traditional corundum grinding wheels
dressing the additional high-frequency motion of the dressing tool against the
with conventional flat grinding. Burn
grinding wheel in the micrometer range is characteristic of ultrasonic assisted
marks were produced in conventional
machining. In general, it is relatively easy to integrate ultrasonic assistance with a
grinding. In contrast, the workpiece
static dressing tool. By contrast, it is more complicated with a rotating dressing
ground with ultrasonic assistance dis-
tool, such as a form roll, calling for both know-how and more complex calculations
played no sign of thermal damage. The
and equipment.
high-frequency interaction between the
active grains and the high acceleration
` Advantages in grinding and dressing
of the workpiece in ultrasonic-assisted
„ Grinding power is reduced by 30 to 50 per cent
grinding simplifies the material remov-
„ Improved surface finish, reduction of the Rz values by 30 to 50 per cent
al process. Chips are more easily re-
„ The surface structure has a different appearance and a higher contact area ratio
moved because micro-cracks in the
„ Lower temperatures on the surface
contact zone between the grains and the
„ Optimized chip formation process with shorter chips
workpiece propagate more quickly as a
„ Less wear to the dressing tools
result of the impacts due to oscillation
„ Better profile retention
and positively influence the next chip
„ Reduction in grinding power and temperatures
formation. This reduces grinding forces
and frictional effects. There is less plastic deformation in the contact zone. In
ABOUT THE SPEAKER
addition, the ultrasonic assistance has
a beneficial effect on the finished surface of the workpiece. It is finer and has
a higher contact area ratio.
The KSF researchers achieved similar
positive results with ultrasonically-assisted dressing of conventional and CBN
grinding wheels. With conventional
Prof. Taghi Tawakoli is founder and head of the Center of
Competence for Abrasive Technologies and Precision Workmanship (KSF) at Furtwangen University of Applied Sciences. Prof.
Tawakoli has over 130 published papers and six patents to his
credit and has a laboratory ideally equipped for research in the
areas of grinding technology, superfinishing, mass finishing,
cutting of hard materials and milling
dressing, the tool smooths out the sur-
MOTION 01/09
39
MARKETS & TRENDS
L e c t u r e I I -2 | M a y 7, 2 0 0 9 | 10 .15
Compensating professionally
Even worn dressing tools can accomplish accurate grinding tasks, as long as exact
measuring of the tool cutting edge compensates tool errors directly.
By Prof. Wilhelm Schröder
I
n profi le grinding, dressing tools
sharpen the grinding wheel and pro-
duce the desired grinding wheel profile. Fixed and rotating diamond tools
curacy. The implications are high procurement costs and long downtimes for
are used for this process, particularly
installation and set-up. A joint project between BLOHM JUNG and Georg-Simon-
for small lot sizes and reprofi ling of
Ohm University in Nuremberg comes up with a new approach on how accurate
grinding wheels. These tools are inte-
grinding results can be achieved even with worn dressing tools by using mea-
grated in dressing systems which can
surement control.
feature up to three CNC axes. Dressing
systems which allow the dressing tool
` Correction of the tool radius
to swivel around the center of the dia-
For contour controlled grinding wheel profiling with diamonds, a CAD/CAM
mond radius are of particular benefi t.
system, such as the GRIPS 32 programming system, normally produces the NC
They enable complicated profiles to be
program for the desired grinding wheel profile. The radius of the dressing tool
dressed by a single dressing tool with-
is taken into account by the so-called tool radius correction. For dressing sys-
out colliding.
tems with swiveling axis the pivoting angle of the dresser must also be observed
In time, the radius of the diamond cut-
so that correct tool intervention is always guaranteed. If the dressing tool is
ting edge will wear as a result of grin-
worn, the original diamond radius takes on an irregular and blunt shape. The
ding wheel dressing. It will lose its ge-
tool radius correction performed by the control unit which always uses the
ometry. This geometry error transfers
ideal unworn diamond radius will lose its effectiveness, resulting in dressing
to the grinding wheel and consequent-
and processing errors. A dedicated tool correction facility in the NC program
ly to the workpiece. Only regular re-
takes tool wear into consideration and ensures that a consistently high level of
placement of the dressing tool will
process quality is maintained. The direct advantages of this kind of wear com-
therefore guarantee high process ac-
pensation are:
[1]
[2]
[1] Pivoting angle: Requirements for intervention between dressing tool and grinding wheel (R tool radius, Ѡ pivoting angle, ը pressure angle)
[2] Wear compensation: For contour-accurate dressing a correcting motion of the dressing tool on three axes (a, b, c) is required
40
MOTION 01/09
Accurate dedication to contour: Innovative measuring of dressing diamonds reduces set-up times and increases accuracy
„ Stabilization of process
control
„ Increase of process accuracy
aligned with the dressing contour. The effectiveness of the wear compensation
is increased and the potential of dressing systems with swivel axis is completely utilized.
„ Increased service life
„ Minimum downtime
` Grinding experiments
„ Lowering of procurement costs
The functionality of the compensation procedure has been proven by several
grinding experiments. To this end, a grinding wheel was profiled with a 2mm
In order to be able to compensate the
radius whereby the worn diamond rotates from –30 degrees to +30 degrees.
wear of the dressing tool, the exact
Through this particular dressing movement the diamond cutting edge is mir-
geometry of the diamond cutting edge
rored onto the grinding wheel during the dressing process. At the same time,
must be known. For this purpose, the
the calculated wear compensation compensates for every error on the dressing
dressing diamond is automatically
diamond. Checking the dressing results on a visual coordinate measuring ma-
measured by a measuring probe. With
chine shows that a contour accuracy within the tolerance range of ±2,5μm has
this reading, the actual shape of the
been achieved in spite of the diamond wear and the off-center diamond posi-
diamond cutting edge is calculated by
tion. If the same experiment is carried out without wear compensation, the
a mathematical process and the form
deviation clearly exceeds ±5μm.
deviation is made available through the
control. The grinding wheel profile is
` Conclusion
only dressed accurately if the diamond
Modern control technology facilitates continued use of diamond tools for highly
with its worn cutting edge is aligned
accurate grinding tasks, even
in such a way that grinding wheel and
if they are worn. The service
diamond have a common tangent at
life of the dressing tools is
the desired intervention point. At the
therefore extended and at
same time, the radius deviation has to
the same time the grinding
be radially compensated on two linear
process is stabilized by com-
axes. Wear compensation therefore
pensating for the dressing
requires a correcting motion by three
wear. As a consequence, us-
CNC axes. This shows the distinct ad-
ers have been given access
vantage of dressing systems with
to a hitherto untapped poten-
swivel axes. The swivelability enables
tial for cost reduction and
the worn dressing tool to be perfectly
quality improvement.
ABOUT THE SPEAKER
Prof. Wilhelm Schröder is
professor at the Georg-SimonOhm University in Nuremberg,
where he is responsible for the
fields of Engineering Mechanics,
Machine Dynamics and Machine
Elements in the Mechanical
Engineering Faculty
MOTION 01/09
41
MARKETS & TRENDS
L e c t u r e I I - 3 | M a y 7, 2 0 0 9 | 11. 0 0
Better understanding of grinding
The WZL (Laboratory for Machine Tools and Production Engineering) is taking part in a
research program to predict the interactions between process and machine during grinding.
By Dr Christoph Zeppenfeld
T
he German Research Foundation
(DFG) has launched a priority pro-
gram, with the aim of closing the knowledge gap regarding the influence on the
knowledge about the interactions between process and machine requires long
interaction between machine and proc-
iteration loops when setting up new processes. Understanding the causes of vibra-
ess. It focuses on the interactions at the
tion phenomena and the prediction of interactions help with the systematic im-
interface between structures and proc-
provement of manufacturing processes and machines and support efficient and
esses of technical systems. Within the
effective design of the production process.
framework of the program, the WZL in
Aachen is also carrying out in-depth
` Modeling approach for pendulum and high-speed grinding
research on innovative methods and
The approach chosen for the analysis and prediction of process-machine-inter-
approaches for predicting the process-
actions in pendulum and high-speed grinding processes assembles the complete
machine-interactions in pendulum and
model in two parts. On the one hand, we examine the process regarding the
high-speed grinding processes. Missing
forces generated during chip removal which are changing continuously. On the
other hand, the machine structure is reacting dynamically to the stimulation. Initially, the models for process and machine are built separately and are later
Maschinensteifi
gkeit
Machine rigidity
Control cycles
linked by suitable parameters. The key infl uencing
Grinding wheel
factors are identifi ed; generated forces are calculated
and transferred to a suitable machine model. This
model calculates the displacement of the grinding
wheel with the aid of the stored dynamic characteristics of the machine. The positional deviation is then
transferred to the process model. The next calculation
Machine model
step takes the modifi ed process conditions into conDisplacement
Forces
sideration when calculating the dynamic forces of the
process model.
High-speed grinding is characterized by high table
Process model
feed rates and low depth of cut, resulting in a large
number of overruns, frequent, very short run-in and
run-out periods and consequently a highly dynamic
performance of grinding forces. The run-in and runout periods must therefore be taken into account when
Process parameters
Cooling lubricant
Surface
Linked: Key influencing factors are identified, emerging forces are calculated
and transferred to a suitable machine model
42
MOTION 01/09
modeling. The transmission factors required for force
simulation are determined on the basis of experimental test runs. In addition, different high-speed grinding
processes are carried out and generated forces, ac-
MBS MODEL
SUB-ROUTINE FOR FLEXIBLE CONTACT FORCES
ILLUSTRATION OF MACHINE CONTROL
Control loop z
Movable body
Control loop y
Control loop x
Contact forces
Actual path
Linear guides
New path
Linear drive with impulse
decoupling
Workpiece table
Components of the MBS machine model: The system calculates the transmission of force of movable bodies towards fi xed structural elements by division of force on
discrete nodes of the model
celeration and structure-borne sound
chine characteristics in every operating point. The design of the model is based
signals with a sample rate of 20 kHz are
on the machine’s CAD data. An FEM is generated through abstraction of machine
recorded. The data obtained is evalu-
components and cross-linking the individual parts. The MBS machine model is
ated and stored in a simulation pro-
built by mapping of the feeding systems and is verifi ed by comparison with the
gram based in Matlab. Initial compari-
measured frequency of compliance operation of the machine. The machine
sons of the measured force paths
control reacts to positional deviation of the grinding spindle through induced
during run-in and run-out of the grin-
forces with a positional readjustment. In doing so, it also influences machine
ding wheel using the assumptions
dynamics signifi cantly. The model also takes this factor into consideration.
drawn up in the physical analytical
model show a good correlation be-
` Conclusion and outlook
tween the simulated and measured
On the basis of the modeling method presented the dynamic performance of the
force path.
complete system of machine and process can be recorded and mapped over
longer travel distances. Looking at it from a holistic perspective can lead to a bet-
` Machine models
ter assessment of machining results, which can help to identify and avoid critical
Classic fi nite element models (FEM)
processes prior to machining. Further research is still needed. One of the areas
describe the behavior of machines in
we are currently
only one operating point. High-speed
working on is fur-
grinding involves long travel distances
ther detailing of the
with high speeds and accelerations. A
models. We are also
movable, fl exible multi-body simula-
expecting a marked
tion model of the high-speed grinding
improvement in the
machine was therefore built for mod-
quality of prediction
eling the machine. It is capable of cal-
with the implemen-
culating the transmission of force from
tation of additional
movable bodies towards fi xed struc-
factors like cooling
tural elements by division of force on
lubricant and the
discrete nodes of the model. This ena-
material to be pro-
bles the recording of the variable ma-
cessed.
ABOUT THE SPEAKER
Christoph Zeppenfeld has been head
of ‘Production Technology & License
Support’ at MAN Diesel SE in
Augsburg since January 2009. Until
December 2008, he was manager of
the Manufacturing Technology
Research Area at the Laboratory for
Machine Tools and Production
Engineering at RWTH Aachen
MOTION 01/09
43
L e c t u r e I I - 4 | M a y 7, 2 0 0 9 | 11. 4 5
Grinding of components for vane pumps
Manufacturing components for vane pumps and motors demands close machining
tolerances while keeping production costs low.
By Dr August Kästner
V
ane pumps and motors are displacement devices. After intake,
the medium is enclosed in a defined
working chamber and is transported to
cosity of the medium and the operating pressure, which is between 3 and 180
the consumer, i.e. piston, accumulator,
bar depending on the application. The split is due to the difference between the
hydraulic motor or similar, on the pres-
rotor thickness tolerance plus the number and the geometry of the vanes.
sure side. During the entire working
stroke the vane is pushed against the
` Demands on machines and tools
rotor ring by centrifugal force or a vane
Vane pump and motor characteristics have a direct effect on effi cient process-
ring. Theoretically, the pumped medi-
ing, as complying with lower component tolerances means more diffi cult, i.e.
um cannot escape and the fl ow rate
more expensive manufacturing techniques. Christian Bauer GmbH + Co. KG of
stays almost constant across the adopt-
Welzheim takes on the role of a consultant and specifi c requirements are care-
ed speed range. Adjusting the rotor ring
fully discussed with their customers. Following these discussions, the compo-
radially from zero eccentricity to max-
nent tolerances have to be increased occasionally.
imum will vary the flow rate while keep-
For effi cient grinding of vane pumps and motors it is imperative that all deter-
ing the speed constant. This makes
mining production factors are examined in depth. It is also important that very
vane pumps and motors clearly supe-
rigid machines are used where the natural frequency of machine and grinding
rior to other types of displacement ma-
spindle is far outside the operating frequency range of the grinding process.
chines. As rotors and vanes are moving
This holds true for all movable equipment. When choosing grinding tools, a
between two lateral cover panels and
suitable abrasive layer must be selected depending on the workpiece and the
are not allowed to touch, the result is
grinding material, with ducts for chip removal if necessary. In the past, Christian
split fl ow. The fl ow loss is adversely
Bauer has carried out much development work in order to increase part capac-
affected by the size of the split, the vis-
ity while at the same time maintaining better quality with regard to dimensions
44
MOTION 01/09
Well-rounded: Diverse criteria ensure the best products
/
Coolant
nes e
ch i
m a f ac t u r
/
n
t i o an u
Too
d uc
/m
ls
P r o men t
p
i
u
q
e
Introducing innovative concepts
through contact with machine
manufacturers, tool manufacturers,
research facilities
Customer
Product
Price
Reliable
subcontractors
un fi
Ma
te
n i s r ial /
hed
p ar
ts
Minimize time
expenditure,
share in the
company’s
success, training
es
Work towards
accurate manufacture, dedicated measuring
equipment
E mploye
C os t o f in
spec tion
/
Inspec ti
on equip
men t
and motors
Minimize
expenditure
an d t s
n al
s
a t i o i v e co
r
e
Op is t r a t
in
ad m
Precision parts: Avoiding
flow losses in vane pumps
and surface roughness and to extend
` Permanently high quality of grinding results
dressing intervals. The choice of cool-
The machine’s response to temperature changes must be taken into considera-
ant and the supply jets which deliver
tion if grinding results on a permanently high-quality level within the tolerance
the coolant directly to the workpiece
range are to be expected. Appropriate technical equipment should be installed
can also signifi cantly affect the grin-
for this purpose. Another important item is the measuring equipment for each
ding result. The question whether it
process step including calibration. Training staff to maintain an individual ob-
would be sensible to use oil or emul-
servations chart or CAQ system within the realms of operator self-inspection
sion in the processes largely depends
is instrumental in the early recognition of process risks and intervention in the
on the number of grinding machines
machine control or initiating the dressing process if necessary.
available at the component manufac-
Constant documentation of the susceptibility of wearing parts like drives, bear-
turer’s facility. Lastly, a long-term prof-
ings, bellows, electric sensors etc. is needed for preventative maintenance.
itability study will determine whether
Early replacement of
a central or stand-alone solution and
these wearing parts dur-
whether oil or emulsion should be
ing quiet times will result
used. Christian Bauer has decided on
in effi cient manufacture
a central supply of emulsion for all their
as much as multiple ma-
machines. This particular technology
chine systems and run-
has been technically perfected and
ning without break peri-
works with residual particle sizes of
ods.
fi ve to six microns. As a result, the com-
tidiness, low stock levels,
pany is able to handle all kinds of grin-
short cycle times, elimin-
ding materials from high-speed steel,
ating waste, constant im-
100Cr6, sintered steel to other types of
provements and reducing
hardened or unhardened steel, with
set-up time complete the
great success.
picture.
Cleanliness
and
ABOUT THE SPEAKER
Dr August Kästner is
Managing Director of
Christian Bauer GmbH +
Co. KG. The Welzheimbased company manufactures disc springs and
precision parts for vane
pumps and camshaft
adjustment systems
MOTION 01/09
45
MARKETS & TRENDS
L e c t u r e I I I -1 | M a y 7, 2 0 0 9 | 14 . 0 0
Turning, grinding, honing
The Dortmund Institute of Machining Technology (ISF) examined innovative concepts for
combined machining and internal cylindrical peel grinding.
By Prof. Klaus Weinert
N
owadays, the combined turning
and grinding process is the pre-
ferred method for internal cylindrical
machining of hardened components.
It combines the advantages of turning
with those of grinding, i.e. a high
PROCESS KINEMATICS
CONTACT CONDITIONS
Workpiece
achievable stock removal rate and high
flexibility while maintaining high pre-
Grinding wheel
Grinding wheel
cision and surface quality. Over the
past years, the ISF has explored two
Workpiece
further concepts for internal cylindrical
machining: extending the existing
combined machining process by a honing process and internal cylindrical
peel grinding.
` Honing reduces production time
The basic advantages of honing are
reliability, high accuracy and excellent
axial feed rate
workpiece circumferential speed
total radial grinding allowance
effective infeed
axial feed rate
effective contact width
angle of scrubbing zone
width of smoothing zone
specific material removal rate
grinding wheel speed
workpiece speed
workpiece diameter
surface structures. Furthermore, honing can reduce edge damage caused
High material removal rate: Process kinematics and contact conditions in internal cylindrical peel grinding
by pre-machining, or even rectify it. In
addition, the process induces residual
compressive stress into the surface of
the component which extends the life
ciently rigid design it contributes to an improvement in roundness and cylindric-
of the functional surfaces. Expanding
ity and corrects any position errors. There is no need for a special feed attachment
an existing turning and grinding ma-
as the machine axes transpose all tangential, radial and axial movements. The
chine with a honing facility thus offers
design of the honing tool permits a split into two processing sides. Different
the possibility to reduce production
honing stone specifi cations can be used for a variety of processing steps, for
times and to react fl exibly to quality
example, a honing stone with rough grain for rough machining on the first process-
requirements.
ing side and a fine grain stone for finishing on the second side.
The honing tool developed specifi cally
With combined turning-grinding-honing machines it is possible to process ro-
for the combined turning-grinding-
tational symmetrical workpieces from blank to finished component on one ma-
honing machine is impressive due to
chine and in a single clamping. Depending on the required component quality,
its simple design without additional at-
combined machining can consist of turning and grinding, turning, grinding and
tachments for feed or measuring. It is
finish-honing, or turning, pre-honing and finish-honing.
integral to the machine and in a suffi -
The combined turning, grinding and honing process improves the surface qual-
46
MOTION 01/09
TWO PROCESSING SIDES
1st processing
side
Turning
Honing
2nd processing
side
Grinding
[1]
[2]
Combined machining: [1] Three operations on one machine [2] Rigid honing tool with two processing sides
ities of the components with each pro-
by dividing the grinding wheel into different functions, i.e. a cone-shaped
cess step. The final honing process
scrubbing zone for stock removal and a cylindrical finishing zone for perfecting
creates the surface structure typical for
surface quality.
honing. With the alternative turning-
Contrary to grinding, hard turning is characterized by high fl exibility and high
honing-honing process chain this struc-
material removal rates. A comparison with hard turning proves the advantages
ture has already been achieved after
of internal cylindrical peel grinding with regard to accuracy and effi ciency. While
the first honing operation. The struc-
internal cylindrical peel grinding uses an electroplated CBN grinding wheel and
ture shows greater surface roughness
grinding oil, the hard turning process is carried out dry with a CBN insert. Chip
though, which is reduced by finish hon-
formation and the circumferential speed of the grinding wheel have a consider-
ing. Both process combinations have a
able influence on the axial force in the process. Axial force in internal cylindrical
positive influence on the component
peel grinding is ten times as small as in turning while the amount of stock re-
shape and the cylindricity error ob-
moved stays the same. The high feed rates in turning also lead to higher surface
tained was less than 2 μm in both ca-
roughness compared with internal cylindrical peel grinding.
ses. However, the turning-honing-hon-
Constant striving for increasing productivity and flexibility strengthen efficiency
ing process combination did not achieve
and competition of a manufacturing business. Demand continues to move towards
the same surface qualities as the turn-
smaller lot sizes and an in-
ing-grinding-honing process chain.
creasing selection of op-
ABOUT THE SPEAKER
tions while product life cy-
` Internal cylindrical peel grinding
cles are constantly being
Internal cylindrical peel grinding also
reduced. To this end, hard-
produces high material removal rates
fine machining is taking on
whilst maintaining excellent surface
some of these processing
quality. In this process a specially
tasks. Thanks to new con-
shaped grinding wheel moves along
cepts like the one described,
the borehole by axial infeed. The
the efficiency of production
amount of stock to be removed is only
processes will continue to
set once. This has been made possible
be increased in the future.
Prof. Klaus Weinert has been
head of the Institute of
Machining Technology (ISF) at
the Technical University in
Dortmund since 1992 and he is
also a member of the research
association for manufacturing
technologies
MOTION 01/09
47
MARKETS & TRENDS
L e c t u r e I I I -2 | M a y 7, 2 0 0 9 | 14 . 4 5
Intelligent spindles
New grinding spindles for very high speeds reduce the use of
lubricants and increase durability.
By Dr Bernd Möller
P
rocessing small internal diameters
with optimum cutting speeds requires high rotational speeds. New
GMN spindle ball bearings with very
high speed characteristics permit
250,000 revolutions per minute, for instance, with comparatively high spindle rigidity and load capacity. Optimized lubrication of high-speed
spindles offers great potential for increasing performance. Furthermore,
on-demand minimal lubrication lowers
oil consumption and increases service
life. In future, integrated data loggers
will monitor the condition of the spindle, store the operating parameters and
guarantee high availability. GMN has
a long track record of supplying a wide
range of high-frequency spindles with
speeds of up to 180,000 min -1. However, around two-thirds of the spindles
supplied for internal grinding operate
with maximum speeds in the 30,000 to
90,000 min -1 range.
Sensors for
Intelligent spindle unit
Temperature
– bearings
– coil
– coolant
Speed
Tool clamping system
Vibration
SPIDER
• Record data
• Monitor spindle
• Monitor process
• Transfer measured data
SERIAL INTERFACE
• RS232
• RS485
• CAN
• PROFIBUS
A lot of knowledge in a small space: Intelligent electronics store sensor signals, process them and report any
exceeding of critical values to the overall machine control
` 250.000 min -1 for small bores
Maximum speed: GMN high-frequency
spindles achieve speeds of up to
180,000 min -1
48
MOTION 01/09
To operate effi ciently, a mach
machine tool spindle must have the appropriate load
capacity, rigidity and dynamic run-out. In order to guarcapa
antee these characteristics even for extremely high
ante
speeds, the GMN development department was
sp
f
faced
with extraordinary challenges. Breaking
points are reached due to high centrifugal forces,
a compact design has to ensure subcritical operation with suffi cient distance to the first critical
speed, high-precision hybrid bearings have to be
designed specifi cally for the demands of highspeed spindles. These challenges were met with
the help of current advances in motor technology
and the use of further developed GMN spindle ball
a
bea
bearings. It is now possible to effi ciently grind small
internal geometries with up to 250,000 min -1. The GMN
interna
300.000
Quantity of
Dosage element
lubricant
Spindle
bearing
Power loss
G 9L (s)
Cutting speed
[m/s]
Motor heat
Speed
200.000
Speed [1 min]
Bearing temperature
250.000
Process forces
Machine
control
Spindle drive
150.000
Spindle cooling
system
100.000
Speed
50.000
Lubrication
control
Stator
temperature
Coolant
temperature
Lubricating
fi lm estimated
Observer
0
0
5
10
15
20
25
30
35
40
45
Bearing monitor
Grinding wheel – Ø [mm]
Synchronous motor: Flexible use of grinding spindles in relatively high rotational
speed ranges
Important criteria for investment decisions: Control of lubricant quantity depending
on demand
grinding spindles used for this purpose
have a comparatively large and rigid
mounting – the speed characteristic
n·dm amounts to up to 4.5 ·10 6 mm/min
– and a powerful synchronous motor.
Consequently, they are suitable not
only for special applications at maximum speeds but can also be used fl exibly and effi ciently in a relatively large
rotational-speed range.
ideally requires no more external components. The problems associated with
waste oil disposal are also defused. Operating costs of machine tools can exceed
acquisition costs several times over if calculated over a normal life cycle. These
costs are therefore a decisive factor for many users when making investment
decisions. An integrated lubricant cartridge means that high-maintenance external components can be dispensed with. The lubricant reservoir only needs
replacing at relatively long intervals. An almost instant dosage of lubricant
ensures that the adjustment of the lubricant quantity matches demand based
on exact measurements of the bearing. This increases the reliability and effi ciency of the bearing and reduces the quantity of lubricant needed.
` Integrated lubrication module
` Third generation spindles for machine tool
These days, ball bearings with permanent grease lubrication or oil/air lubrication are predominantly used in main
machine tool spindles. Yet both methods have their disadvantages which
can be overcome by an innovative
micro-dosing system combined with
appropriate lubrication strategies.
Compared with today’s oil/air lubrication method, a signifi cant reduction of
the lubricant quantity necessary is to
be achieved and the systematic performance limits of grease lubrication,
i.e. limited usable life of grease at high
speeds and temperatures, are to be
exceeded. Minimizing lubricant quantities makes ecological and economic
sense. It facilitates the integration of
an oil reservoir into the spindle and
Spindles are also becoming more and more intelligent. Miniaturized electronics which are integrated in the spindle store the sensor signals, process them
and report any exceeding of critical values to the overall machine control
system. Important operating data can be accessed during the entire running
time of the spindle and can be analyzed with regard to optimizing the process,
machine and spindle. In addition, the aim is to go for bearing condition monitoring and consequently early damage detection, based on these intelligent
systems. Evaluating temperature
ABOUT THE SPEAKER
sensors, position sensors and vibration sensors will increase precision
and productivity of the production
process. Additional sensors, on the
Dr Bernd Möller is
other hand, harbor the risk of reduchead of the Engiing the availability of the spindle sysneering Spindle
tem further, therefore, as few addiTechnology division
tional sensors as possible should be
at GMN Paul Müller
employed and for the time being, a
Industrie GmbH &
more intelligent analysis of available
Co. KG in Nuremberg
signals should be aimed for.
MOTION 01/09
49
MARKETS & TRENDS
L e c t u r e I I I - 3 | M a y 7, 2 0 0 9 | 15 . 3 0
One concept for every site
The Hirschvogel Automotive Group uses a standard
machine concept in all its
production facilities throughout the world.
By Harro Wörner
E
very year some 200,000 tonnes of
massive formed components leave
the Hirschvogel Automotive Group’s
factories. The automotive supplier, from
Denklingen in Bavaria, Germany, has an
international presence, with sales offices in the USA, China, Brazil and India.
Three thousand employees generate a
turnover of more than 500 million euros.
This makes Hirschvogel one of the largest suppliers in this sector. The com-
A bundle of power: Many vehicles on
the road have components formed by
Hirschvogel Automotive Group
ponents are produced by forging, cold
forming, warm forming and combined
processes and weigh between 0.1 and
25 kilograms each. Hirschvogel has suc-
ties are expected to comply with. Hirschvogel Umformtechnik GmbH in Denklingen
cessively broadened its production ex-
is the master factory for forming and Hirschvogel Komponenten GmbH in Schon-
pertise to include machining with heat
gau is the master factory for machining. New components are developed in co-
treatment and now supplies components
operative partnership with the customer to optimize costs. The customer provides
ready to be installed directly on the cus-
the knowledge of the product and Hirschvogel provides manufacturing expertise.
tomers’ assembly lines.
The two can thus work together to develop the ideal components.
The company’s core business is the
The QM-online quality management system can be used to generate test batch-
large series production of extremely
es through the company’s own SAP system. All the test machines are connected
complex formed components. It sup-
to the system. When required, it is possible to export assessments, perform
plies the five product groups, namely
analyses and even, using the data matrix or clear text, assign the appropriate test
transmission, chassis, drive train, injec-
data to each individual component. As a rule, this is done for components that
tion and engine. Hirschvogel can offer
have a high added value.
its customers throughout the world, who
include virtually all original equipment
` Increasing standard machine capacity
manufacturers (OEM) plus first and
Machine planning is a particular challenge for an automotive supplier. The key data
second-tier suppliers, a uniform quality
for a new project and the capacity for series production must already be in place six
standard and identical technologies.
months before the start of production. Hirschvogel usually receives an order for 80
‘Master factory functions’ specify the
to 100 per cent of the customer’s requirement with a non-binding quantity estimate.
standards that all the production facili-
This can then vary by another ±15 per cent. These imponderables can only be con-
50
MOTION 01/09
[1]
[2]
[3]
Hirschvogel supplies components for five different groups of products: [1] Chassis [2] Drive train [3] Transmission [4] Engine [5] Diesel/Gasoline injection
trolled by having a scalable production
` Grinding and measuring
system on the modular principle. Hirsch-
For grinding, Hirschvogel uses ma-
vogel has opted for a standard machine
chines from a variety of manufacturers
concept that can produce goods at com-
in its internal module. The process that
petitive prices with appropriate automa-
is needed in each case, for example
tion. The decision regarding the best
centerless cylindrical or non-round
technology for the job is taken during the
grinding or a combination process, de-
course of the project. The machine is cho-
termines the machine that is chosen
sen and equipped from standard mod-
for it. Even though the grinding ma-
ules. This enables Hirschvogel to produce
chines are supplied with the appropri-
samples by hand that are close to their
ate technology for in-process measure-
series production counterparts. The re-
ment or for measuring component
quired capacity must be installed before
alignment, Hirschvogel uses addition-
production begins. It is only by this means
al forms of analysis and test methods
that the desired Run@Rate and process
to determine depth of roughness, twist
acceptance can be configured with the
and the properties of peripheral areas
customer. Capacity is increased by com-
in the workpiece, and also uses vibra-
missioning duplicate machines and using
tion analysis. The latter has proven
the corresponding automation.
worthwhile, particularly in the grinding
of roller bearing seats.
` Automation concept
Hirschvogel requires the future gen-
The automation concept is developed
eration of grinding machines to offer
from the value stream planning in each
a considerably higher
case. Hirschvogel usually uses stacking
potential for cost reduc-
cells or circulating conveyors. The reason
tion. The machines have
for this is that although direct linking is
to be able to offer much
usually best for a value stream, it is not
greater versatility of use
necessarily the most cost-effective solu-
and the ratio of basic
tion in respect of capacity, as the quan-
machines to type-spe-
titative data provided by the customer is
cifi c investment must be
not binding and can vary between zero
better, as the batch sizes
and a hundred per cent. Only the cost
and service life of the
calculation at the end of the project
products are also in-
shows whether the automation concept
creasingly subject to
was actually able to optimize the costs.
change.
[4]
[5]
ABOUT THE SPEAKER
Harro Wörner Harro Wörner is
CEO of Hirschvogel Komponenten GmbH in Schongau.
Since 2002, he has been
responsible for the global
production network for the
machining of formed components within the Hirschvogel
Automotive Group
MOTION 01/09
51
MARKETS & TRENDS
L e c t u r e I I I - 4 | M a y 7, 2 0 0 9 | 16 .15
Great potential savings
Al 2O 3: Abrasives such as
aluminum oxide influence
grinding and dressing behavior
Diagonal grinding with super-abrasive CBN wheels is not dependent on geometry.
The process reduces grinding time by up to 80 per cent.
By Udo Mertens
O
n all grinding tools, the abrasive
material used and how it is bond-
ed are of prime importance. Compositions vary depending on the application. Conventional abrasives such as
aluminum oxide (Al2O3 ) or silicon carbide (SiC) are bonded in ceramic or
synthetic resin materials. Super-abrasive materials such as CBN or diamond
Synthetic resin bonding materials are soft grinding universal binders with
phenolic resin and polyimide resin binding agents
Galvanic bonds hold the abrasive in a single-layer coat, the thickness
of which is roughly that of the average grain size used. Tools with this
type of bond cannot be dressed
Metallic sintered bonds are highly wear-resistant
are additionally secured in metal bonding materials. The type of bonding material used and its internal structure
largely determine the grinding and
dressing behavior.
Ceramic bonded CBN grinding
wheels are mainly used in series
and high-volume production. Their
high metal removal rates and
surface characteristics mean that
they are well suited to high-speed
grinding. Dressing is simple
52
MOTION 01/09
TRENDS IN GRINDING TECHNOLOGY
MARKET DEMANDS IN E.G.
THE AUTOMOTIVE SECTOR
Lower noise emissions
Lower CO2-emissions
More powerful engines
Lower consumption
Greater reliability
Longer service intervals
Lower purchase prices
Conventional grinding tools are made
entirely of abrasive material. CBN and
GRINDING SHAFT ENDS
diamond grinding wheels, on the other
hand, have a relatively thin coating of
abrasive that is bonded to a carrier material. The choice of this material depends on, among other things, the
grinding job and the conditions of use.
Straight infeed
grinding
In addition to good thermal conductivity and vibration damping it must possess suffi cient mechanical strength.
The following materials are available:
Aluminum
Steel
Synthetic resin, with or
Angular infeed
grinding
without metal fillers
Ceramic
Composites
Advantage of angular infeed grinding: Circumference and flat shoulder are machined simultaneously
` Examples: Camshaft bearings
To date the use of galvanically bonded
CBN grinding wheels for plunge-cut
to be machined in a single operation. Two grinding processes run simultane-
rough grinding of the bearing points on
ously with differing process kinematics. The advantages are:
a GGG camshaft in a centerless grinding machine has required a support
A shorter grinding feed traverse saves time
bushing, seven grinding wheels and
Shorter contact length at the flat shoulder minimizes the
four spacer rings. It is not economically feasible to dress the single layer
risk of thermal damage
Reduced loads on the edge of the abrasive coating
coating of these grinding wheels within a few micrometers. Saint-Gobain
Even so, there are disadvantages associated with the angular position and the
Diamantwerkzeuge GmbH & Co. KG has
geometry of the workpiece. A large area of abrasive coating is needed for grinding
therefore developed a grinding tool
the flat shoulder. Since it does not make economic sense to reprofile super-abra-
with a single carrier material which is
sive grinding wheels, a change of workpiece to one with a different profile means
far more durable. All the areas of the
that the CBN tool has to be changed as well. This involves a longer idle time. In
abrasive coating are machined without
addition, CBN grinding wheels with wildly differing geometries have to be kept in
re-clamping and there is no need to
stock – an additional cost factor. This is where diagonal grinding offers great sav-
dress the profiles. These are more eco-
ings potential. The axis of the workpiece is parallel to that of the grinding spindle.
nomical because they have a longer
The angular infeed is achieved by simultaneous movement in the radial and axial
tool life and they cost considerably less
directions. Thus the same tool can be used to grind virtually all geometries on the
to manufacture.
circumference and the flat
shoulder without the need
` Examples: Crankshaft ends
to change the geometry of
In practice, shaft ends are machined by
the coating. This is par-
external cylindrical angular infeed
ticularly advantageous for
grinding or infeed grinding with a
short runs. Studies by
straight cut. In external cylindrical an-
Saint-Gobain have shown
gular infeed grinding the grinding spin-
that the processing time
dle and workpiece axis are set at a de-
with diagonal grinding can
fined angle with respect to each other.
be up to 80 per cent short-
The angular position enables high flat
er than that required for
shoulders and circumferential surfaces
straight infeed grinding.
ABOUT THE SPEAKER
Udo Mertens is
responsible for product
management and product
development for ceramic
bonded CBN and diamond
tools at Saint-Gobain
Diamantwerkzeuge
GmbH & Co. KG
MOTION 01/09
53
MARKETS & TRENDS
L e c t u r e I V-1 | M a y 8 , 2 0 0 9 | 9 . 3 0
The cutting edge industry: tool grinding
In tool grinding, quick decisions and skill are demanded of cutting tool makers, so that short
delivery schedules can be maintained.
By Prof. Wilfried Saxler
W
hen resharpening a metalworking tool, the toolmaker has to
ONE STRENGTH OF THE TOOL GRINDING COMPANY IS THE SHORT DELIVERY TIME
decide anew every time whether the
costs of sharpening will exceed the
costs of replacement by a corresponding new tool. Take classic twist drills,
for example, these days, companies
set their own diameter limits below
which sharpening is no longer eco-
Receipt of order
Delivery date
Sales
nomical. These limits also depend on
the level of automation of the grinding
centers. No matter what the kinematics
Time
are behind the CNC tool grinding machine: with fi ve CNC axes, almost all
rotationally symmetrical machining
3–10 working days
tools can be ground. Here, apart from
the machine’s automatic handling
system, the fl exibility of the clamping
system has a major infl uence on the
Advantageous: An order is completed as a rule within a week, but in any case in a maximum of 14 days
economy of the grinding machine’s
operation.
The variety of parts stocked by tool
` Economic rise and fall
grinding companies is extensive. One
There always have been economic downturns, and there always will be. If a
customer order includes a number of
company depends on a single business sector for its customers, it’s also going
different drill-bits or mixed types of
to experience the ups and downs of this sector itself. This is why it is essential
tools, on another occasion it includes
for tool grinding companies to address a wider audience and serve different
a large number of identical special
sectors. Generally, tool grinding companies have two decisive advantages:
tools. Given this extreme variation in
The machine tool mechanic is trained both for the
orders, quick decisions and skill are
initial manufacture and for subsequent sharpening
demanded of the cutting tool maker. In
of cutting and machining tools
addition there is the maintenance of
short delivery schedules of a week to
CNC tool grinding machines are used for sharpening as
well as for the manufacture of various tools in different numbers
a maximum of a fortnight to be considered – one of the strengths of these
In this way, a range of different orders can be secured, accepted and processed
companies. But this is exactly where
and the growing market for special tools can be serviced. Most of the major tool
the danger lies: with no orders coming
manufacturers are not suitably equipped for manufacturing these special tools in
in, the turnover drops immediately.
penny numbers. This gives the tool grinding operators a major advantage. Never-
54
MOTION 01/09
THE CONDITIONS FOR MANUFACTURING AND SHARPENING TOOLS
Sharpening
Manufacturing
Stock material
Worn tool (from the customer)
Blank (purchased)
Tool drawings
Generally not present or required
Not available
Must be derived and created from the
workpiece drawing
Preparations
Visual check, cleaning if necessary
Shaft preparation
Determine amount of wear for grinding stock
Dimensioning on measuring machine
Possible edge fracture at the end of the
shaft
Clamping accuracy
(circular runout)
Dependent on previous history
(cannot be influenced)
Dependent on blank (can be influenced)
Programming expenditure
Dependent on geometry
Dependent on geometry
Control possibility using simulation
Defining the position of the
tool in the grinding machine
Complicated tool probing operations necessary
Specifications according to drawing
for helix angel, rotation position, unclamped
Grinding from the solid block
length, long tooth detection etc.
Only detection of the unclamped length
necessary
Resetting the open-face or cutting face without
influencing the tool function
theless, the conditions for manufacturing and sharpening a tool are very dif-
SIZE CLASSIFICATIONS OF GERMAN TOOL
GRINDING COMPANIES
ferent (see table).
` React fl exibly
6 to 15 staff
27%
The conditions and fi elds of activity
outlined above thus presuppose fl ex-
over 15 staff
5%
1-man-operations
7%
2 to 5 staff
61%
ibility in every respect. A business can
AN INCREASE IN CUSTOMER NUMBERS OFFERS
BETTER SECURITY IN TIMES OF ECONOMIC
FLUCTUATIONS
Sales /business
risk
Logistic /accountancy
expenditure and ancillary costs
Number of customers
only be regarded as fl exible if
it can handle differing technical
enquiries on types of tools
Well prepared: Tool grinders are mainly small
companies with between two and five employees
Reassuring: If a company has plenty of customers,
there is less risk that business will suddenly collapse
it is quick to react to customer
enquiries
in addition to sharpening tools, it
manufactures special tools
it can adjust its tool grinding
also improves fl exibility and enables crisis situations to be overcome more
easily. Grinding shops are an ideal size for this. They are generally small companies with an average of fi ve employees. A good quarter of them have between
machines quickly to perform new
six and fi fteen staff. If a company has a large number of customers, naturally
tasks
expenditure on sales and distribution work, logistics and therefore also for ac-
is a master of grinding technology
counting rises. But the risk that turnover is suddenly going to plunge is consid-
it can handle large production runs,
erably less. Well prepared, the
and in particular small runs
companies which have provided
ABOUT THE SPEAKER
for conditions like those menFor this it will require a large range of
tioned above will be able to handle
parts, short processing and delivery
the diffi cult economic situation.
times, improved staff productivity,
And any company which has so
shorter idle times and a suitably adjust-
far not faced this subject now has
able level of automation.
the opportunity to do so. Make
All these criteria can only be achieved
your company fi t for the next eco-
with highly-qualifi ed personnel. Coop-
nomic boom – now. Because it’s
eration with other grinding companies
on its way...!
Prof. Wilfried Saxler is
Managing Director of the
Fachverband Deutscher
Präzisions-Werkzeugschleifer (German
Precision Tool-grinders
Trade Association)
MOTION 01/09
55
MARKETS & TRENDS
L e c t u r e I V-2 | M a y 8 , 2 0 0 9 | 10 .15
Many axes ensure success
Without multi-axis precision grinding machines there would be no modern high-performance
tools. MAPAL Dr. Kress KG is relying on this technological advantage.
By Dr Dieter Kress
N
ew, specially developed tools are
often an important influence on the
success of a product because high-
which in turn results in effi cient manufacture of high accuracies whilst maintain-
performance tools help to transform
ing complex geometries.
machine effi ciency into high-quality
products. Grinding in particular plays a
` Innovative high-performance drills
central role in the efficient manufacture
Among the machining processes drilling is an important one because of its 40-per-
of innovative tools. Highest precision
cent share of production time. In addition, solid drilling when processing pilot holes
– reliable and guaranteed to be repro-
as a first process step is a determining factor in the achievable final quality. Con-
ducible – is virtually a basic require-
sequently, innovative high-performance drills like the MAPAL MEGA Quadro-Drill
ment. The multi-axis design of the
or the MEGA-Deep-Drill have to guarantee high cutting values and have to provide
grinding machine furthermore ensures
excellent results for roundness, straightness and diameter tolerance. That is why
the complete machining of high-per-
MAPAL is using modern multi-axis grinding machines with the appropriate software
formance tools in a single clamping,
in its production processes. Only these machines are capable of processing the
specific geometries which are
responsible for chip formation
and cutting behavior of the drill
in a single clamping.
MAPAL GIGA-Drill
Apart from the margins which
4 cutting edges for twice the feed rate
are situated directly behind the
cutting edges, the MEGA Quadro-Drill and the MEGA Deep
Drill have two additional guidMAPAL MEGA Quadro-Drill
4 margins for better drilling quality
ing margins which have constant contact with the wall of the
hole created while drilling. As a
result, roundness and straight-
MAPAL MEGA Drill-Reamer
ness of the hole produced are
Drilling and reaming – one operation
considerably improved. The
specific geometry also optimizes self-centering and brings
MAPAL MEGA Deep-Drill
Deep hole drilling up to 30×D
advantages when exiting drill
holes at an angle. Due to the additional support, the drill operates very quietly even with increased cutting rates for steel
MAPAL high-performance drilling tools
56
MOTION 01/09
and cast materials. The deep-
View of the MAPAL production facility: Multi-axis grinding technology for high-performance tools
Utmost precision: MAPAL high-performance drilling tools
hole drill has specific flute geometries
quire around 20 per cent less torque than conventional twist drills with feed rates
and flute angles which provide good chip
remaining the same. This means that the cutting speeds for cutting steel with up
clearance. Chips roll up tightly without
to 200 m/min can be doubled with tool life travel remaining the same.
jamming and are removed safely even
from great drilling depths thanks to high-
` Modern reamers
ly polished surfaces.
Modern multi-flute reamers significantly reduce processing times for precision
The MAPAL MEGA drill-reamer com-
drilling through high cutting speeds and very high feed rates. MAPAL sets new
bines drilling and reaming in a single
standards in this area with its high-performance reamers. In order to guarantee
operation. The process combines dou-
utmost precision in the μm range on all levels of the high-performance reamers,
ble-edged drill geometry with up to six
the complete cutting geometry including all angles of the entire tool has to be
reaming margins for finish machining
finished in one clamping following the cylindrical grinding process. Only multi-
the bore. The reaming margins protrude
axis grinders with measuring systems and in-process dressing facilities can solve
radially by a few hundredths of a mil-
this task efficiently. The same applies to PcBN reamers or cutters employed in
limeter above the drilling margins, re-
machining cast materials or in hard machining. When grinding PcBN, oscillating
sulting in a defined reaming allowance.
axes as well as compensation of wheel wear should be preset, in order to avoid
In contrast, the drilling margins are in
clogging and scoring of the grinding wheels.
front of the reaming margins along the
The new MAPAL reamers are equipped with PcBN cutting edges even in the di-
axis. Universally designed for use with
ameter ranges of less than 6 millimeters. In this instance, PcBN is applied to the
steel, cast iron and aluminum, the MEGA
front face and reproduc-
drill-reamer has an excellent self-center-
es the entire cutting ge-
ing ability and is an extremely efficient
ometry, resulting in big
tool for pinhole drilling.
advantages of tool life
The latest development in MAPAL’s
compared with conven-
solid carbide range is the MEGA Speed
tional carbide reamers.
drill. With its innovative face geometry,
When hard machining a
it guarantees safe chip control, reduced
hole with Ø 2.4 H7,
feed force and excellent self-centering
MAPAL managed to in-
ability. As the guidance lands are no
crease the output of a
longer arranged on opposite sides, the
carbide reamer from
drill can no longer get jammed in the
around 50 holes to over
hole. Measurements show that due to
1,300 holes with the
reduced friction MEGA Speed-Drills re-
PcBN reamer.
ABOUT THE SPEAKER
Dr Dieter Kress is managing
director of MAPAL Dr. Kress
KG. The company specializes
in precision tools for metal
working; it is the headquarters of the MAPAL group
which employs more than
3,000 staff in 20 different
countries
MOTION 01/09
57
MARKETS & TRENDS
L e c t u r e I V- 3 | M a y 8 , 2 0 0 9 | 11. 0 0
More power for microchip removal
The Institute for Machine Tools and Factory Management (IWF) at the TU Berlin examined characteristic phenomena of microchip removal with the aim of developing new
potentials for micro end milling cutters.
By Christoph Hübert
I
n micro milling, cutting edge rounding is of similar size to the chip thick-
ness. Therefore, variations of cutting
edge rounding due to geometric de-
milling tool ‘ploughs’ across the workpiece and reduces its surface quality. At
viation of the tool or the coating affect
the Institute of Machine Tools and Factory Management (IWF) at the Technical
the process results more than in mac-
University Berlin, these characteristic phenomena have produced several ap-
roscopic chip removal.
proaches for developing new potentials for micro chip removal.
Micro milling tools are fl exible due to
their small shank diameter. They warp
` Tool geometry
elastically during the process resulting
Macro-range tools cannot be scaled down randomly into the micro range (tool
in erratic variations in chip thickness
diameter < three millimeters). Geometric scaling produces unfavorable chip
which can lead to premature tool fail-
formation mechanisms, resulting in an increase in process forces which in turn
ure if exposed to extreme stress. If the
leads to premature tool wear. A wide range of tools from earlier micro end mill-
minimum chip thickness is undercut,
ing cutters are not involved in chip formation. Furthermore, these tools show
neither shear plane formation nor chip
a noticeable discrepancy between the effective tool length which has been
removal takes place; instead, plastic
prepared with cutting edges and the axial depth of cut.
strain of the workpiece occurs. The
New approaches in tool construction were able to eliminate these weak points.
Tool 6-I
z =3
ap = 0,1 mm
Area of most common
tool failure
Area where mainly
frictional force is
effective
500 μm
Not involved in chip formation: Subdivision of the cutting area of traditional peripheral face milling cutters
58
MOTION 01/09
Zone where the stock removal
process takes place
at their disposal as well as the
HELICHECK PLUS measuring system developed by WALTER which
includes high-resolution cutting
edge measuring sensors. The
measurement of process force is
an established and significant parameter in the characterization of
process behavior for procedures
involving the geometrically undeOverall view
Overall view
Overall view
fined cutting edge. The IWF utilizes the evaluation of internal
drive signals of linear direct drives
of the main thrust axes in order to
maintain a database for the effects of varying process parameters and grinding tool specifica-
Detail: fl ute base
Detail: fl ute base
Detail: fl ute base
tions for typical tool grinding
operations, in spite of existing
limitations of data collection.
Apart from the geometric characteristics, the process parameters
of the grinding operation influence
the rigidity of the micro tools and
Reference structures with varying machining results: Hardened powder metallurgy steel (1.2379, 54 HRC)
and brass (CuZn39Pb3) have proved to be a suitable sample material. Fluted microstructures for deep
milling and simple surfaces for the finishing process are used as reference structures
also, indirectly, the process reliability of the chip removal process.
The IWF investigated the quantifi cation of this relationship. First,
the effect of cylindrical grinding of
Parameterization of the tool geometry,
carbide on the rigidity was analyzed. With micro tools, the machining of the
for example, enables automatic gen-
diameter takes up most of the chip volume and the machining time at the cutting
eration of different geometry charac-
edge and the transaction piece. Secondly, the effect of the cutting edge on the
teristics and the use of the finite ele-
rigidity of solid carbide tools was studied. The grinding operation determines
ments method for optimizing tools
the edge-holding property and the rigidity of the tool through shape and qual-
according to demand. This makes the
ity of the cutting edge and the underlying edge.
manufacture of milling tools with varying diameters and geometric charac-
` Use of micro cutting tools
teristics much simpler as the geomet-
Currently, the IWF is studying the high-precision milling process in terms of
ric data can be entered directly into
its effects on the structure of machine tools. Apart from a better understand-
the machine tool used for manufac-
ing of the process /machine tool behavior, the objectives are the development
ture. Workpiece-dependent optimiza-
and application of a forecast model for predicting these interactions and to
tion can now be carried out quickly
establish a basis for:
ABOUT THE SPEAKER
and simply by varying the geometric
characteristics.
„ manufacturing microstructures
while observing tight
` Manufacture
The manufacture of solid carbide
shank tools with diameters < three mil-
tolerances and high surface
requirements and
„ guidelines for design and
limeters requires state-of-the-art ma-
confi guration of the
chine technology for both tool grin-
machine tool structure in
ding and tool measuring. The IWF has
terms of optimization of
a Schütte 5-axis tool grinding center
design and topology
Christoph Hübert is
chief engineer at the
Institute for Machine
Tools and Factory
Management at the
Technical University
Berlin
MOTION 01/09
59
MARKETS & TRENDS
L e c t u r e I V- 4 | M a y 8 , 2 0 0 9 | 11. 4 5
Metrology ensures profitability
Tight tolerances and improved accuracy in tool manufacture: Fully automated precision
metrology for the setting and monitoring of grinding machines and processes that is located
close to production improves precision and productivity.
By Oliver Wenke
T
hese days, reducing costs and increasing productivity is part of the
daily grind of manufacturing. To stay
competitive, tool production processes
ticularly for sensitive materials or very small dimensions. High-specification measu-
must continually overcome new chal-
ring devices, such as the HELICHECK series of measuring machines from WALTER,
lenges where quality, versatility and
work quickly, are non-destructive and have uniformly high reproducibility with no
costs are concerned. Increased costs can
operator intervention. All the relevant tool parameters can be measured. Optical
only rarely be passed on to the custom-
measurement permits the extremely rapid, almost simultaneous, recording of a
er in the form of higher prices. Costs can
very large number of measuring points. Special measuring and evaluation pro-
only be reduced by continually optimiz-
cesses even allow measurements to be recorded over 360 degrees. They thus
ing production and increasing productiv-
record the actual shell profile of the workpiece and transmit the measurements to
ity. For innovative toolmakers and
the process control, which makes appropriate corrections to the subsequent ma-
regrinders, this means very greatly
chining process where necessary. This reduces scrap and minimizes the time spent
shortened cycles for new products or
on traditional final inspection. Optical measurement is supported by powerful im-
services. This process can be success-
age processing and an easily operated measurement control system. Special edge
fully mastered with smooth coordination
detection processes, together with optimized illumination and image enhancement
of the experience of skilled tool develop-
software (see Figure 1, right) mean that even high-gloss polished surfaces, coat-
ers with the most up-to date manufactur-
ings or matt surfaces can be measured without difficulty.
ing technology and suitable metrology.
Contactless optical measuring tech-
` The ‘Closed Loop’ solution
niques play an important part here, par-
Absolute dimensional accuracy is critical for the performance of a shaping tool
and the result that it produces (see image left). The very tight workpiece tolerance,
sometimes less than +/- 3 μm, requires production and inspection processes to be
precisely matched. In the case of the HELICHECK, the measurement
program is based on the grinding program and can be prepared offline in advance. This saves the need for timeconsuming programming. Automatic correction is done
by DXF comparison of the theoretical and actual contours. The corrections are calculated automatically
and adopted by the grinding machine. This results in
‘good’ tools within the required tolerance and a stable
production process. Given a suitable automation solution
such as a loading robot, this can be a completely unattended process. In this
Absolute dimensional accuracy: Crucial for the
performance of a shaping tool and its results
60
MOTION 01/09
way, tight tolerances can be reliably and cost-effectively kept under control. With
an optical solution, a virtually unlimited variety of objects can be measured. Even
[1]
[2]
[3]
Advances: [1] Before-and-after results of the HELICHECK image enhancement system [2] Using optimally measured wheel sets on the HELICHECK, the fi rst tool is
usually already within the standard tolerance [3] The cutting edge rounding sensor enables accurate measurement of surface and contour cutting edge roundness
on metal-removing tools with μm precision
shafts and diamond dressing rolls can
cess. The size of the radii and the resulting sensitivity of the cutting edge require
be measured without the need for ad-
special measuring procedures. The development of the cutting edge rounding
ditional setting-up time. The optional
sensor (see Figure 3 above) opens up the possibility of accurately measuring μm-
lighting table extends the potential ap-
fine face and contour cutting edge roundness on metal removing tools. This new
plications to the measurement of non-
option can be used to determine the entire microgeometry of a cutting edge and
rotationally symmetrical forms such as
all the other profiles on microcomponents. The combination of a number of cam-
profile sheets or indexable inserts. With
eras simplifies orientation on the tool and thus contributes to accurate, compre-
standard tools too, the measure-grind-
hensible and reproducible determination of the measuring point. This is also pos-
measure control circuit has a beneficial
sible even if the tool has been unclamped in the meantime. There is no need for
effect on tool optimization. It contributes
time-consuming manual pre-positioning. The measuring process lasts less than a
to improvements in cutting behavior,
minute, with the actual measuring time being a mere 15 to 20 seconds. The rest of
tool performance and tool life.
the time is needed for the sensor to approach the component being measured. The
relationship with the other sensors ensures that measurements are absolute. In
` Faster and more economical
addition to the radius, width and form of the cutting edge the system also deter-
If the geometry of the cutting edges is
mines its exact position on the tool.
optimized, the effect on machining characteristics is highly beneficial. Excellent
` Summary
edge stability, fewer fractures and long-
The WALTER HELICHECK is a com-
er tool life make for improved machining
plete system for all measuring tasks.
quality and quiet running at high metal
Tool grinders benefi t from cost-
removal rates. The trend is towards
effi ciently monitored production
lesser rounding of edges and some
and can therefore react quickly and
asymmetrical radii. Another reason why
reliably to their customers’ wishes.
the cutting edge radius was previously
For both one-person businesses
generated in a rather random way was
and large companies, the potential
because it was difficult to measure the
savings are enormous and continue
result precisely and draw conclusions
to rise as the variety of tools in-
that could be incorporated into the pro-
creases.
ABOUT THE SPEAKER
Oliver Wenke is Head
of the Measuring
Technology Development Center at Walter
Maschinenbau GmbH
in Garbsen near
Hanover, Germany
MOTION 01/09
61
MARKETS & TRENDS
L e c t u r e V-1 | M a y 8 , 2 0 0 9 | 14 . 0 0
Process optimization using simulation
Abrasive tool materials: Simulation models at the Swiss Federal Institute of Technology (ETH)
in Zurich enable the number of active grains, their cutting surfaces, and the resulting forces, rugosity
and service life to be defined.
By Prof. Konrad Wegener
T
he use of empirical methods with
high-performance cutting tools is
not just time-consuming and expensive, it is complicated by the fact that
tolerance. The microgeometry is defined by the geometry of the grains and their
many infl uencing factors come into
arrangement. In the case of engineered grinding tools, where it is assumed that
play simultaneously, making it very
the grains are in defined positions, their actual locations are defined by the un-
diffi cult to assign the observed effects
certainty of the positioning process. The coolant and the chips occupy the clear
and derive rules for them. In contrast,
spaces between the grains. The stochastic tool model is fully defined in three
analytical and digital tools and process
models can provide scientifi cally based
findings.
` Modeling
The simulation model for single-layer
abrasive coatings of diamond or CBN
KINEMATIC MODEL
Grinding speed
Tool advance speed
Workpiece speed
STOCHASTIC TOOL MODEL
Grain morphology
Grain pattern
Pattern accuracy
Size and orientation of grains
grains consists of a stochastic model
of the tool, a kinematic model of the
Cutting data
Tool geometry
process, a material removal model and
a failure and wear model. It enables the
number of active grains, their cutting
surfaces, and the resulting forces, ru-
MATERIAL REMOVAL MODEL
Tool-workpiece interaction
Rigidities
Plasticity
gosity and service life to be defi ned
Proportion of active grains
Workpiece rugosity, chip space
Cutting area of grains
and the probability of their survival
under given conditions of use to be
evaluated. It is based on a simplifi ed
description of elementary events, obtained from tests on individual grains
and simplifi ed for the purposes of numerical treatment.
` Stochastic model
The modeling for the tool incorporates
MODEL OF COOLING
SYSTEM
Pressure, quantity
Coolant
Coolant flow
MODEL OF INDIVIDUAL GRAIN
Kienzle model
Clamping forces
Hardness
Forces on the grains
THERMAL MODEL
Temperature rise
Thermal conduction
its macrogeometric and microgeometric properties. The macrogeometry is
Tool/workpiece temperature
described using the nominal geometry
of the grinding tool and the associated
62
MOTION 01/09
Scientifically based: A view of the simulation model
Change in tool
topologyWear
Failure
WEAR MODEL
Blunting of grains
Grain fracture
Jagged grains
Clogging of interstices
er hand there must be suffi cient clear space for the
THEORETICAL CRYSTAL MORPHOLOGY OF
SYNTHETIC DIAMOND
chip that is removed to collect temporarily in the tool.
If overload occurs a greater or lesser proportion of
Cube/octahedron
the grain can break off, or even be completely torn
out of the bonding material. This is taken into account
in the model by load thresholds for the various types
of change in grain geometry. Allowance can thus be
made for macroscopic effects such as clogging, scorSimulated grain morphology
Diamond PDA989
ing and blunting of the grinding tool.
` Behavior of individual grains
THEORETICAL CRYSTAL MORPHOLOGY OF CBN
In practical cutting with individual grains it is possible
to determine the specific cutting force according to
Octahedron/tetrahedron
Kienzle from the correlation of the measured process
forces and the scoring that is formed in the workpiece.
The orientation of the grain with respect to the direction
of cut must be noted. The load threshold at which the
grain fractures can be found by increasing the depth of
Simulated grain morphology
penetration into the workpiece.
Practical grinding tests have shown that an increase
CBN ABN800
in the specifi c metal removal rate has an effect on the
rugosity of the workpiece. This is because a higher
Idealized geometry: Grain morphology of diamond and CBN
load on the active individual grains changes the surface topology of the grinding wheel, depending on
the grain fracture behavior, and therefore changes
cylindrical coordinates by the following
the distribution of active grains. Appropriate consideration of grain wear there-
parameters, arranged in order of prob-
fore has a critical influence on the quality of the rugosity that is calculated in
ability: grain size, grain shape, grain
the simulation. At high cutting volumes in particular, the difference between
orientation and positional deviations.
the numerical simulation and the measurement is greater when there is no wear
criterion. In the simulation model used, the active cutting surface of the grain
` Material removal
is used as the wear criterion. The critical cutting area at which the grain profile
The material removal model reduces
changes is correct when the measured number of fractured grains on the tool
the complex elastoplastic processes
and the workpiece rugosity are the same as the calculated values.
on the grain to the geometric interac-
The change in grinding wheel topology can also be seen in the distribution of
tion of the abrasive grains with the
the cutting surfaces of the grains. On tools that have not been ground there are
workpiece. This enables the new work-
a few grains that have a large cutting area and these have a considerable influ-
piece surface that is created and its
ence on rugosity.
rugosity to be determined in the material removal simulation. Using Kien-
` Summary
zle’s cutting force model we obtain the
„ The model enables
force acting on each individual grain
process and tool data
and, by summation of this for all the
to be harmonized.
active grains, the process force acting
„ The interaction of
on the workpiece.
different simple models
and parameter studies
` Failure and wear
improves our under-
When designing or selecting a grinding
standing of the process
tool the cutting and movement kine-
„ The effects of separate
matics of the machining process must
parameters on complex
be taken into account. On the one hand,
processes can be
the individual grains must not be me-
unambiguously
chanically overloaded, but on the oth-
investigated
ABOUT THE SPEAKER
Prof. Konrad Wegener is
CEO of the Swiss
company Inspire AG für
mechatronische Produktionssysteme und
Fertigungstechnik and
also Head of the Institute
of Machine Tools and
Manufacturing at the
Swiss Federal Institute of
Technology in Zurich
MOTION 01/09
63
MARKETS & TRENDS
L e c t u r e V-2 | M a y 8 , 2 0 0 9 | 14 . 4 5
Economic hard finishing
Shorter product cycles, niche products and site relocations require a high degree of standardization in plant procurement and plant reusability. This needs to be taken into account in the hard
finishing of precision components.
By Dr Frank Fiebelkorn
O
ptimization of future fi nishing
processes requires an overall view
of the appropriate machine concepts
plus the ability to use advanced manufacturing technology. To achieve the
ideal synthesis of high productivity and
versatility, two strategies stand out:
complete machining and combined
Vast potential: The
prototype system for EDM
dressing
processing.
Using a modular machine structure it
is possible to pursue a consistent policy of complete machining. Often, it is
only by clamping the workpiece once
and for all that the required quality parameters in respect of surface finish
and accuracy of form and position can
be guaranteed. It is the only way to reduce throughput times. The machine
systems used in this way bring the functions of a number of special machines
together on just one platform. The most
up-to-date programming and control
modules also contribute to the ability
to machine even non-round profiles or
threads completely without re-clamping the workpiece (see Figure 1).
` Effi cient software modules
The comprehensive StuderGRIND programming system is an example of this
type of modern grinding software. Its
modules support the machine operator
in a process-oriented manner and consequently minimize the work prepara-
quired, for example contour editors designed for the workshop, interfaces for
tion of component manufacture. The
importing contour data, simulations or the store of in-house knowledge and
operator can use the functions as re-
skills. In addition to all this, the overall control system guarantees the integration
64
MOTION 01/09
[1]
[2]
[3]
[1] Using specific grinding processes to increase productivity [2] Grain projection after dressing by EDM [3] Combined processes lead to economies in production
of the operator interface of external
` Combined processes
modules such as sensor system pack-
Another strategy for increasing productivity is to combine hard finishing pro-
ages, measurement control or handling
cesses on a single machine. This enables the grinding process to meet the high
systems from third-party suppliers. The
accuracy specifi cations for close tolerance with guaranteed process capability
signifi cance of these person-machine
and highly specifi ed surface finishes. Hard turning scores highly because of the
interfaces for programming, setting up
great versatility of its geometrically defined cutting edge. The combination of
and managing finish machining pro-
the two processes offers the ability to select the most effi cient machining tech-
cesses is increasing all the time.
nique to suit the task in hand.
Combined hard turning and grinding has now established a place for itself for
` Productive carbide
machining
the manufacture of gears in the chuck, for universal use and for the series
Alongside the various traditional meth-
ters or in a chuck.
manufacture of precision components that need to be machined between cen-
ods, the technology of high speed grinding for carbides and ceramic with
` Minimizing changeover times
changing form elements on the work-
The potential user can therefore choose between a number of ideal process
piece has distinct productivity benefi ts.
strategies for machining precision components. In each case, minimizing the
The diamond grinding wheels that are
time spent changing over is a particular feature, particularly when batch sizes
used for this purpose generally have
are small. Toolholders, for instance, can be machined between driven centers
ceramic or metal-based bonds. The dis-
(see photo 3). It is therefore possible to start by turning both sides of the whole
advantage to be set against their high
contour including the tool changer fl ange, and then, without re-clamping, ac-
wear resistance, however, is that of
curately grinding the cones and fl at mountings with great process reliability
dressing. It is very time-consuming and
using measurement control systems. STUDER has been able to optimize the
expensive to profile and sharpen these
internal machining of workpiece-specifi c toolholder bores equally well with
tools, particularly if they have special
other types of holder with HSK interfaces. The process-specifi c steps of pre-
contour lines on the abrasive coating.
drilling and fi nish grinding of the bore have led to excellent bore quality param-
In cooperation with project partners,
eters with deviations of 0.3 μm for roundness, 0.2 μm for straightness, 0.6 μm
STUDER has therefore initiated a re-
for cylindricity and a mere 1.5 μm
search project to develop a new profil-
for dimensional accuracy.
ing and sharpening process using spark
The philosophy outlined here of
erosion (EDM – Electro Discharge Ma-
combined hard finishing (grinding
chining, see left-hand photo). Initial
and turning) expands the decision
studies and process tests have shown
matrix of production planners for
positive potential for profiling ability
future production processes. It not
and the creation of suffi cient grain pro-
only enables hard turning to be
jection for subsequent grinding (see
combined with grinding; it includes
photo 2). Further studies will follow,
milling with driven tools, hard
with a view to industrial application.
reaming and honing.
ABOUT THE SPEAKER
Dr Frank Fiebelkorn is
Head of Product
Development,
Research and
Technology at Fritz
Studer AG in Thun,
Switzerland
MOTION 01/09
65
MARKETS & TRENDS
L e c t u r e V- 3 | M a y 8 , 2 0 0 9 | 15 . 3 0
The final polish
In precision grinding of hard and brittle high-performance ceramics under production
conditions, everything depends on the design being suitable for ceramics.
By Dr Carsten Russner
H
igh-performance ceramic material
has many outstanding properties:
it is very hard and very light, and is
highly resistant to wear, pressure and
heat. Consequently, this material can
be used in conditions where steel or
plastic would not work. In manufacturing technical ceramics it is in particular
finishing, using product-specifi c grinding and polishing processes, which
represents a decisive time and cost factor. Precision production grinding will
be described using four different grinding processes:
„ Double face grinding of transverse
50 per cent less production time: Using a three-stage process in angular plunge-cut grinding, the
CeramTec specialists avoid inaccuracies
sides with planetary kinematics
„ Angular plunge-cut grinding with
centerless technology
` Double face grinding of transverse sides
„ Centerless grinding of pump rollers
In double face grinding of transverse sides, the infeed movement is made up of
„ Cylindrical grinding of ceramic
two components performed by different machine elements: the grinding speed
materials
and infeed speed running lengthways to the workpiece. The overlapping of the infeed movements is responsible for the good
grinding results and evenness of tool loading. Most important input parameters in double face grinding of transverse
sides with planetary kinematics are the grinding speed and
the grinding normal force in an axial direction. An increase
in the average grinding speed improves workpiece depth
pattern and surface, while an increase in grinding normal
force in an axial direction increases the depth of grain cut.
This has a negative effect on the surface quality. A decisive
part was played by selection of a suitable lubricant. This
made possible an increase in the metal removal rate by a
factor of three. Including automatic feeding and discharge of
Between centers: Grinding media being
ground on the KRONOS S
66
MOTION 01/09
the workpieces, there was an improvement in productivity overall of 200 per cent, while all the required tolerances for mass
production were achieved. The trend is
away from grinding wheels with extreme diameters in excess of 1,200 mm
and towards higher grinding speeds.
` Angular plunge-cut grinding
Grinding media of Si3N4 are ground on
KRONOS S machines from MIKROSA.
On these machines, the previous
[1]
[2]
processing between centers can be substantially reduced. The grinding tool is
a diamond grinding wheel, while the
dressing roll is a newly-developed diamond form roll from Messrs. SaintGobain Winter. Neither of these has any
problem in maintaining the required tolerances. It is a major challenge however
to profile the grinding wheel: wear of the
dressing roll cannot be measured. This
means that the CNC program miscalculates the corrections. This then results
in inaccuracies, and to avoid these, the
specialists from CeramTec AG divided
[3]
The CeramTec product variety: [1] Seals made of various high-performance ceramics [2] Wear parts, ground
with a diamond grinding wheel [3] Various special components
the process up into three stages:
„ Pregrinding the curved surface
„ Grinding the face and the
curved surface
„ Finishing grinding of the
curved surface
` Cylindrical grinding
CeramTec today grinds ceramic insulators for the CFC zirconium oxide highperformance brake in an HSG process on STUDER S32 machines at a grinding
speed of 125 m/s.
In this way, not only was a cmk-factor
Here too, ceramic-bonded grinding wheels are used. The stock removal rate is
of 3.86 achieved for the curved surface,
over eight mm³/mms and the G-ratio is better than 1,000. The tolerances achieved
process time was reduced by 50 per
in the diameter in ceramic mass production are less than six μm.
cent as well.
` Hard grinding costs and accuracies
` Centerless grinding
In general, the saying ‘the more accurate, the more costly’ does not apply. It
Extreme demands are made of pump
depends much more on a design suitable for ceramics, and the opportunities
rolls in respect of their stress gradient.
these designs offer for hard grinding. Thus centerless plunge-cut grinding is to
The roll must fall logarithmically from
be preferred to grinding between centers as in this way an intricate stage of
the center to the faces by 1.7 μm in or-
workpiece clamping is dispensed with. Admittedly this is at the expense of the
der to avoid extreme peaks of stress. If
achievable tolerances, specially
it is required to achieve these gradients
in coaxial work. It may be as-
in honing work, the preceding center-
sumed that fast automation con-
less grinding with ceramic-bonded dia-
cepts, higher grinding speeds
mond grinding wheels must lie within
and higher grinding normal forc-
a range of ± 0.002 μm. These toleran-
es will increase productivity by
ces can only be achieved by grinding
a factor of ten. In the manufac-
in a clamp and the use of ceramic-bond-
ture of workpieces with toler-
ed grinding wheels dressed in the ma-
ances in the μ range, new dress-
chine. Here, the dressing is of major
ing strategies will certainly play
importance.
a decisive role.
ABOUT THE SPEAKER
Dr Carsten Russner
is Manager Innovation
– Business Development in
the business sector
Systems Technology at
CeramTec AG with a focus
on product development
MOTION 01/09
67
Leading...
...results from
the perfect combination
of many factors
Gauging and
control for
grinding machines
Acoustic
sensors for
grinders
Grinding wheel
balancing
systems
Please visit our website where you will find more detailed information and your nearest Marposs office.
www.marposs.com
www.marposs.de
www.marposs.ch
If your targets are:
To encrease productivity,
To reduce production costs,
Then contact us!
L e c t u r e V- 4 | M a y 8 , 2 0 0 9 | 16 .15
The ideal grinding medium
When choosing the best possible grinding medium for a specific application there are many
parameters to be considered.
By Walter Graf
Ideal: The right
grinding medium
results in top product
quality
T
oday, users of grinding machines
have a wide choice of abrasive ma-
terials at their disposal. Each of these –
whether aluminum oxide, sintered aluminum oxide, CBN or diamond – has a wide
` Aluminum oxide
variety of variants. They all have their own
Aluminum oxide is made from melted bauxite, the basic material in the produc-
specific uses and the crucial problem is
tion of aluminum. It is characterized by its white color and in particular by its
selecting the ideal grinding medium for
hardness and splintering ability. The purity grade lies between 98.5 and 99.5 per
each task. Lot sizes, surface quality, fire
cent. In order to increase the tenacity of aluminum oxide, chromium oxide in
prevention and dressing tool wear play
quantities of 0.2 per cent (pink aluminum oxide) or up to 5 per cent (ruby red
an important part in this decision.
aluminum oxide) is added to the melt.
` Grinding media
` Single crystal aluminum oxide
The following abrasive types are mainly
Single crystal aluminum oxide which is somewhat tougher and therefore splinters
used today:
differently to aluminum oxide is produced in a special process. Grinding wheels
Aluminum oxide and single crystal
made from single crystal aluminum oxide can achieve a very long service life if
aluminum oxide
Sintered aluminum oxide
used in suitable applications. But the main use of single crystal aluminum oxide is
as support grain and filler grain in CBN grinding wheels.
CBN (cubic boron nitriole)
` Sintered aluminum oxide
These varieties of corundum are classed
In the early Nineties, a process was developed to manufacture the smallest pure
as conventional grinding media; they are
corundum grains with an average diameter of between 0.0002 and 0.0025 mil-
mainly used as a ceramic bond in preci-
limeters and to sinter them into blocks. The result was sintered aluminum oxide.
sion grinding operations.
During a controlled sintering process only the grain boundaries of the nano-
MOTION 01/09
69
MARKETS & TRENDS
sized grains are melted while the small
amount of bond will allow higher
single grain remains as such. In theory,
grinding performance. Sintered alu-
this results in one billion grinding par-
minum oxide is primarily used in
ticles with an average crystallite size
high- performance creep feed grin-
of 0.0005 millimeter (0,5 μm). Sintered
ding of diffi cult-to- grind materials
aluminum oxide is available in four types
like Inconel. The disadvantage of ex-
with different characteristics and per-
truded corundum is that dressing
formance potentials:
tool wear is particularly high.
Cubitron 321 (3M) for universal
` CBN
Uncrushed
[1]
Spread of grain sizes
Steel base
Crushed
Spread of grain sizes
applications
Cerpass 560 (Saint-Gobain) for
high grinding pressures
The superabrasive grinding medium
available ceramically bonded, resin-
Cerpass DGE (Saint-Gobain) for
bonded, galvanically bonded and
flimsy, unstable workpieces
metal bonded in monocrystalline or
Cerpass TGE (Saint-Gobain) for
microcrystalline versions, whereby
creep feed grinding, for Inconel etc.
Steel base
CBN comes in many varieties. It is
the monocrystalline version consists
of larger crystallites which break up
more coarsely with excellent, sharp
cutting edges. Microcrystalline CBN
[2]
3]
Established: [1 + 2] Crushing of galvanized CBN
grinding wheel [3] Firm, medium and high toughness
of CBN grains
behaves similar to sintered aluminum oxide. The crystallites are smaller and only split under higher pressure. Today, the monocrystalline version is
predominant and ceramic and galvanic bonds have taken over.
` Galvanically bonded CBN
Galvanically bonded CBN grinding wheels have a major advantage. They do not
require dressing, yet they achieve highly accurate profiles and surface qualities.
These results are guaranteed by the crushing process where the cutting edges
are fractured to size with a high-precision carbide roller. Regardless of bonding
variety or specifi cation, CBN grinding wheels should only be used on a highperformance machine. Racing tires do not turn a medium sized vehicle into a
fast Formula One car.
Sintered aluminum oxide: Cerpass 560 (Saint-Gobain)
for high grinding pressures and all grinding operations
When choosing the right grinding medium the
following issues should be clarifi ed:
1. CBN: yes or no?
The blocky grain shape of Cerpass 560
2. Is the machine powerful enough?
is particularly suited to grinding op-
3. Does it have a rotating dresser? If not, is the use of galvanically bonded CBN
erations with high grinding pressures,
such as pendulum surface grinding.
grinding wheels to be considered?
4. Is the cutting speed above 35
Cerpass DGE with its tapered grain
m/s? (High Q’w values can only
structure, on the other hand, is better
be reached at ≥ 80 m/s.)
suited to grinding flimsy, unstable parts
5. Is grinding oil an option? If yes,
and internal grinding where rigidity is
does the machine have a
limited due to the grinding quills. Rod-
CO2-fire extinguishing system?
shaped Cerpass TGE is in fact an extruded grain. This grain shape allows
Ultimately, there is not one ideal
a very small amount of bond, as the
abrasive but only the best possi-
grain shape is building up a reinforced
ble abrasive for each particular
wheel structure. With a high concentra-
grinding task and economic re-
tion of sintered aluminum oxide a small
quirement.
70
MOTION 01/09
ABOUT THE SPEAKER
Walter Graf is
Chief Marketing
Officer of the
Winterthur
Technology Group
in Winterthur,
Switzerland
CNC CONTROLS
DRIVE SYSTEMS
LASER SYSTEMS
SERVICE
10 Years Production
0 Failures
100 % Availability
Maximum machine availability:
with CNCs from Fanuc GE
Our CNCs are the most reliable controls in the world:
because statistics have demonstrated that the first failure
may not happen till 10 years have passed. This will save
expensive services and reduce the TCO (Total Cost of
Ownership) to a minimum. Your benefit: highest reliability
for maximum availability.
Just one of our strengths.
Fanuc GE CNC UK Ltd. / 15 Basset Court - Loake Close
Grange Park / UK-Northampton NN4 5EZ
Tel.: (+44) 1604 7441 30 / Fax: (+44) 1604 7441 31
info.uk@fanucge.com / www.fanucge.co.uk
Fanuc GE CNC Europe S.A.
Zone Industrielle / L-6468 Echternach
Tel.: (+352) 72 79 79 1 / Fax: (+352) 72 79 79 510
info@fanucge.com / www.fanucge.com
Blohm Jung GmbH
Kurt-A.-Körber-Chaussee 63–71
21033 Hamburg, Germany
Tel: +49-40-7250-02, fax: +49-40-7250-3287
sales-hh@blohmjung.com, www.blohmjung.com
Studer Mikrosa GmbH
Saarländer Straße 20
04179 Leipzig, Germany
Tel: +49-341-4971-0, fax: +49-341-4971-500
sales@mikrosa.com, www.mikrosa.com
Jahnstraße 80–82
73037 Göppingen, Germany
Tel: +49-716-1612-0, fax: +49-716-1612-170
sales-gp@blohmjung.com, www.blohmjung.com
Studer Schaudt GmbH
Hedelfinger Straße 137
70329 Stuttgart, Germany
Tel: +49-711-4014-0, fax: +49-711-4014-290
sales@schaudt.com, www.schaudt.com
Combitec AG
Lengnaustrasse 12, 2504 Biel, Switzerland
Tel: +41-32-344-0450, fax: +41-32-341-0671
info@combitec.ch, www.combitec.ch
Ewag AG
Industriestrasse 4, 4554 Etziken, Switzerland
Tel: +41-32-61331-31, fax: +41-32-61331-15
info@ewag.com, www.ewag.com
Mägerle AG Maschinenfabrik
Allmendstrasse 50, 8320 Fehraltorf, Switzerland
Tel: +41-43-3556-600, fax: +41-43-3556-500
sales@maegerle.com, www.maegerle.com
Körber Schleifring Asia-Pacific PTE. Ltd.
25 International Business Park
#01-53/56 German Centre
Singapore 609916
Tel: +65-6562-8101, fax: +65-6562-8102
michael.schmid@walter-machines.de
Körber Schleifring Machinery Shanghai Co. Ltd.
Beijing Branch Office
Room 10-04, CITIC Bldg. 19, Jian Guo Men Wai Da Jie
Beijing 100004, China
Tel: +86-10-6595-9934, fax: +86-10-6500-6579
info@schleifring.cn
Schleifring Brasil Ltda.
Av. XV de Agosto, 5.060
Sorocaba, Brazil, CEP: 18085-290
Tel: +55-15-322457-26, fax: +55-15-322813-66
vendas@schleifring.com.br
Körber Schleifring GmbH
Nagelsweg 33–35
20097 Hamburg
Germany
Tel: +49-40-21107-03
Fax: +49-40-21107-13
info@schleifring.net
www.schleifring.net
Fritz Studer AG
3602 Thun, Switzerland
Tel: +41-33-439-1111,
fax: +41-33-439-1112
info@studer.com,
www.studer.com
Walter Maschinenbau GmbH
Jopestraße 5
72072 Tübingen, Germany
Tel: +49-7071-9393-0, fax: +49-7071-9393-695
info@walter-machines.com,
www.walter-machines.com
United Grinding Technologies, Inc.
5160 Lad Land Drive
Fredericksburg, Virginia 22407, USA
Tel: +1-540-898-3700, fax: +1-540-898-2811
United Grinding Technologies, Inc.
510 Earl Boulevard
Miamisburg, Ohio 45342, USA
Tel: +1-937-859-1975, fax: +1-937-859-1115
ugt@grinding.com
Körber Schleifring UK Ltd.
B13 Holly Farm Business Park, Honiley
Kenilworth, Warwickshire, Great Britain
CV8 1NP
Tel: +44-1926-4850-47, fax: +44-1926-4850-49
neil.whittingham@walter-machines.de
info.wg@walter-ag.com
Körber Schleifring France
2 bis, Avenue du Président François Mitterrand
91385 Chilly-Mazarin, Cedex, France
Tel: +33-1-697921-21, fax: +33-1-697921-10
commercial@schleifring.fr
Körber Schleifring
Machinery (Shanghai) Co., Ltd.
No. 1128, Taishun Rd, Anting Town
Shanghai Jiading 201814, China
Tel: +86-21-39587333, fax: +86-21-39587338
info@schleifring.cn
Körber Schleifring Italia Srl
Via G. Garibaldi, 118
22073 Fino Mornasco (CO), Italy
Tel: +39-031-926-262, fax: +39-031-926-261
info.it@walter-machines.com
Schleifring Service AG
Thunstrasse 15
3612 Thun, Switzerland
Tel: +41-33-439-1212, fax: +41-33-439-1514
info@serviceag.net
Körber Schleifring GmbH – India Branch Office
No. 99, Spencer Road, First Floor, Frazer Town
Bangalore 560 005, India
Tel: +91-80-412504-25, fax: +91-80-55658-99
sales@schleifring.in
Schleifring Service GmbH
Hedelfinger Straße 137
70329 Stuttgart, Germany
Tel: +49-711-4014-100, fax: +49-711-4014-207
info@servicegmbh.net