NORGLIDE® Maintenance Free Bearings - Saint

Transcription

Innovation is
our nature
NORGLIDE®
Maintenance free bearings
• Minimum coefficient
of friction
• Low wear and size-ability
• Eliminates noise
• Vibration damping
• Heavy metal free
NORGLIDE®-advantages
at a glance
ö Minimum coefficient of friction for solid materials
ö Maintenance free and self-lubricating
ö Minimum stick-slip effect
ö High pU (PV) for absolute dry-running and stability
ö Takes up edge loading and compensates for misalignment
ö Eliminates noise
ö Vibration damping
ö No water absorption
ö Good formability
ö Excellent wear resistance
ö Temperature resistant
2 • Saint-Gobain Performance Plastics
Table of contents
NORGLIDE® range of bearings
4–5
NORGLIDE®-Types
6 – 11
Compounds
12
Coefficient of friction
13
Life expectancy of NORGLIDE® bearings
14 – 19
Design of the bearing
20
Tolerancing
21
Sizing
22
Torques
23
Installation of NORGLIDE® bearings
24 – 25
Measuring NORGLIDE® bearings
26 – 27
Corrosion resistance
28 – 29
Quality
30 – 31
Practical Application
32 – 35
Saint-Gobain Performance Plastics worldwide 36
3
The range of NORGLIDE® bearings
Fluoropolymers have been used as bearing materials for over 50 years. Since its discovery in 1938, Poly Tetra Fluoro Ethylene has continuously been developed and
improved. The addition of appropriate fillers gives the material specific properties
which alter its strength and coefficient of friction and enable it to perform a large
variety of tasks. Tape bearings modified this way (a blank of PTFE tape formed
under temperature) are the origin of our bearing program.
By encapsulating a metal fabric into PTFE, an important step forward was made:
NORGLIDE® MP is a plastic material which allows the large-scale production of bearings. For the first time our customers are able to produce a specific torque or clearance by sizing the bearing. This is also possible with NORGLIDE® S which uses stretch-
We develop customized solutions
that will help our clients succeed.
We offer a full line of high-performance bearing materials for the
most diversified requirements.
Selecting the proper material for
the individual application is the
core of our cooperation with the
customer.
You as the designer can count on
us when it comes to providing
custom service.
ed metal instead of the metal fabric.
The combination with a steel shell makes it possible to increase the load bearing
capability significantly. NORGLIDE® T combines steel and tape to provide noise and
vibration damping properties and light-weight construction. Similarly when bonded to steel NORGLIDE® MP turns into NORGLIDE® M, NORGLIDE® S into NORGLIDE®
SM. Both materials maintain their sizing capability to a large extent with the capability of higher loads. They take up edge loading and compensate for misalignment. NORGLIDE® materials with a steel thickness ≥ 0.5 mm are suitable for producing a press-fit in the housing.
The latest innovation is NORGLIDE® PRO the PTFE bearing with best load-carrying capabilities known today. With its complex composition - steel plate, structured
bronze layer with encapsulated PTFE sliding layer – its load-bearing capability is
almost twice as much as that of NORGLIDE® T, M and SM.
NORGLIDE® MP
NORGLIDE® S
NORGLIDE® T
NORGLIDE® PRO
NORGLIDE® SMTL
“ „
We specialize in
low coefficients
of friction,
low wear and
size-ability.
NORGLIDE® M
NORGLIDE® SM
5
NORGLIDE® MP and S
NORGLIDE® MP and S
Maintenance free, flexible bearing tapes
NORGLIDE® MP and NORGLIDE® S are maintenance free bearing materials made of
a metal support structure and a wear-resistant PTFE compound which offer high
load capabilities. This combination of materials enables easy manual or automatic
Standard thickness table NORGLIDE® MP
processing and installation. NORGLIDE® MP and NORGLIDE® S can be adapted to
Nom.
thickness
many applications, including severe chemical environments.
The materials allow excellent sizing so that an interference fit of the bearing to the
shaft can be designed to produce particular torques or eliminate play.
Material Structure
(mm)
CuSn 6 Fabric
1.4401 Fabric
0.48
ö
ö
Availability
0.78
ö
ö
The support structure is available in either tin bronze, stainless steel or aluminum. The
0.98
ö
standard PTFE compound contains glass fibers and graphite. Special PTFE compounds
are available on request. Fabricated parts include die-cuts, rolled cylinders, flanged cylinders and deep-drawn bearings. NORGLIDE® MP and NORGLIDE® S can be prepared
for bonding (etched one side). They can be supported or backed with steel or plastics.
NORGLIDE M
®
NORGLIDE® M
Maintenance free bearings with steel backing
Standard thickness table NORGLIDE® M
Nom.
thickness
(mm)
Material Structure
CuSn 6 Fabric
Steel backing
ö
NORGLIDE® M is a composite material of NORGLIDE® MP bearing tape and steel
0.75
backing. This combination of material improves load capabilities while maintaining
1.0
ö
the characteristics of NORGLIDE® MP, especially its sizing capability.
1.5
ö
The bearings can be designed to be clearance free. Bearings of 1 mm of wall thickness or greater can be produced with an interference fit in the housing. Various
methods are available to protect the steel shell from corrosion.
Availability
The standard PTFE compound contains glass fibers and graphite. Special PTFE compounds are available on request. Fabricated parts include rolled bearings with or
without an axial flange, deep-drawn bearings and die-cuts. The steel shell and
mesh can be offered in stainless steel for chemically harsh environments.
1.57
Stainless steel fabric
Stainless steel backing
ö
PTFE compound
Metal fabric
Material properties Norglide® MP
SG Test Procedure
Maximum permissible specific
bearing load at RT
SG PL 0044
Coefficient of friction at RT
on steel with ≥ 58 HRC
at 4.8 N/mm2 and 0.058 m/s
at 70 N/mm2 and 0.0065 m/s
SG PL 0003
SG PL 0003
Deformation under load
(230C, at 100 N/mm2, 1 h)
SG PL 0015
Value
N/mm2
100 to 140
0.09 to 0.19
0.06 to 0.10
Maximum continuous
operating temperature
K factor at RT
Units
µm
30 ≤ x ≤ 90
°C
260
10-6mm3/Nm 0.12 to 0.18
SG PL 0003
The above mentioned performance values were measured in laboratory tests.
They must not be considered as a specification for design.
Material properties Norglide® M
SG Test Procedure
Units
Value
bearing load at RT
SG PL 0044
N/mm2
180 to 220
at 4.8 N/mm2 and 0.058 m/s
at 70 N/mm2 and 0.0065 m/s
SG PL 0003
SG PL 0003
(230C, at 100 N/mm2, 1 h)
SG PL 0015
Maximum continuous
K factor at RT
SG PL 0003
0.11 to 0.19
0.065 to 0.1
µm
≤ 30
°C
180
10-6mm3/Nm 0.12 to 0.18
PTFE compound
Metal fabric
Steel backing
7
NORGLIDE® SM
NORGLIDE® SM
NORGLIDE® SM is a composite material of compounded PTFE, bronze stretched
metal and steel backing. This material structure combines the bearing characteristics
of a PTFE compound tape with the sizing capabilities of stretched metal. These bea-
Standard thickness table NORGLIDE® SM
rings can also be designed to be clearance free. Bearings of 1 mm wall thickness or
available to protect the steel shell from corrosion.
Nom.
thickness
(mm)
Availability
0.75
The standard PTFE compound contains carbon and graphite. Special PTFE com-
1.00
ö
pounds are available on request. Fabricated parts include rolled bearings with or
1.50
ö
bigger can be produced with an interference fit in the housing. Various methods are
Material Structure
CuSn 6/Stretched metal
Steel backing
ö
without an axial flange, deep-drawn bearings and die-cuts.
NORGLIDE® SMTL
®
NORGLIDE SMTL
Standard thickness table NORGLIDE® SMTL
Nom.
thickness
(mm)
NORGLIDE® SMTL is a composite material of compounded PTFE, bronze stretched
Material Structure
CuSn 6/Stretched metal
Steel backing
ö
metal and steel backing. In contrast to NORGLIDE® SM, the bronze stretched metal
0.50
in NORGLIDE® SMTL is separately precompressed and the PTFE compound tape is
0.75
ö
thinner, which improves load capabilities while reducing tolerance compensation
1.00
ö
compared to NORGLIDE® SM. Bearings of 0.75 mm of wall thickness or bigger can
be produced with an interference fit in the housing. Various methods are available
to protect the steel shell from corrosion (page 28).
Availability
The standard PTFE compound contains either Ekonol® graphite or carbon and graphite. Special PTFE compounds are available on request. Fabricated parts include
die-cuts, rolled cylinders, flanged cylinders and deep-drawn bearings.
PTFE compound
Stretched metal
Steel backing
Material properties Norglide® SM
SG Test Procedure
bearing load at RT
SG PL 0044
at 4.8 N/mm2 and 0.058 m/s
at 70 N/mm2 and 0.0065 m/s
SG PL 0003
SG PL 0003
(230C, at 100 N/mm2, 1 h)
SG PL 0015
Value
N/mm2
150 to 200
0.13 to 0.30
0.07 to 0.10
Maximum continuous
K factor at RT
Units
µm
≤ 50
°C
180
10-6mm3/Nm 0.16 to 0.70
SG PL 0003
Material properties Norglide® SMTL
SG Test Procedure
bearing load at RT
SG PL 0044
at 4.8 N/mm2 and 0.058 m/s
at 70 N/mm2 and 0.0065 m/s
SG PL 0003
SG PL 0003
(230C, at 100 N/mm2, 1 h)
SG PL 0015
Maximum continuous
K factor at RT
SG PL 0003
Units
Value
N/mm2
240 to 300
0.15
0.10
µm
≤ 15
°C
180
10-6mm3/Nm 0.10
PTFE compound
Stretched metal
Steel backing
9
NORGLIDE® T
NORGLIDE® T
Maintenance free bearing with metal backing
NORGLIDE® T is a composite material of compounded PTFE tape on a metal shell. This
material structure enables machining of the bearing in the housing – which is an
alternative to the sizing process - to obtain tightest tolerances on the inside diameter.
Standard thickness table NORGLIDE® T
Nom.
thickness
(mm)
Steel
0.50
ö
0.75
ö
ö
ö
1.00
ö
ö
ö
pounds are available on request. Finished parts include rolled bearings with or
1.50
ö
without an axial flange (nominal thickness 0.5 mm and 0.75 mm), deep-drawn bear-
2.00
The very thick PTFE layer isolates noise and allows the design of clearance free bearings. Bearings of 0.75 mm thickness or bigger can be produced with an interference
fit in the housing. Various methods are available to protect the steel shell from corro-
Material Structure
Stainless steel
Alu
sion.
Availability
ö
The standard PTFE compound contains carbon and graphite. Special PTFE comö
ö
ings and die-cuts. The metal backing is available in steel, aluminum or even stainless steel for chemically harsh environments.
NORGLIDE® PRO
NORGLIDE® PRO
Maintenance free bearing with steel backing
NORGLIDE® PRO is a steel material with a polygon-structured bronze layer on one
side. Encapsulated in the polygon structure is a sliding layer of compounded PTFE
tape. This combination of materials provides much higher load-carrying capabilities.
The material is sizable and can be adapted to any clearance required for the specific
application. The whole range of NORGLIDE® PRO thicknesses can be designed with a
press fit in the housing. Several methods are available to protect the metal backing
from corrosion.
Availability
PTFE compounds are available with carbon or EKONOL®. Fabricated parts include
rolled bearings with or without an axial flange, deep-drawn bearings and die-cuts.
Standard thickness table NORGLIDE® PRO
Nom.
thickness
(mm)
Material Structure
Steel
0.50
ö
0.75
ö
1.00
ö
PTFE compound tape
Metal backing
Material properties Norglide® T
SG Test Procedure
Units
Value
bearing load at RT
SG PL 0044
N/mm2
180 to 200
at 4.8 N/mm2 and 0.058 m/s
at 70 N/mm2 and 0.0065 m/s
SG PL 0003
SG PL 0003
(230C, at 100 N/mm2, 1 h)
SG PL 0015
µm
≤ 30
Maximum continuous
SG PL 0048
°C
180 to 260
K factor at RT
SG PL 0003
10-6mm3/Nm 0.10 to 0.90
0.10 to 0.30
0.06 to 0.065
Material properties Norglide® PRO
SG Test Procedure
bearing load at RT
SG PL 0044
at 4.8 N/mm2 and 0.058 m/s
at 70 N/mm2 and 0.0065 m/s
SG PL 0003
SG PL 0003
(230C, at 100 N/mm2, 1 h)
SG PL 0015
Maximum continuous
K factor at RT
SG PL 0003
Units
Value
N/mm2
400
0.19 to 0.20
0.11 to 0.12
µm
≤5
°C
260
10-6mm3/Nm 0.18 to 0.20
PTFE compound
Bronze
Steel
11
Compounds
Pure (virgin) PTFE is a soft, electrically insulating material with a
minimum coefficient of friction
for solid materials.
With the addition of fillers, properties like creep or electrical conductivity can be optimized while
maintaining the excellent sliding
characteristics of PTFE.
Some of these compounds are discussed here:
Glass fiber/graphite Compound
Glass fibers increase the load carrying capability and reduce wear and creep.
Graphite minimizes initial wear.
Carbon/ graphite Compound
Carbon assumes a similar function as glass fibers, but is less abrasive on the mating
contact surface.
EKONOL® Compound
This compound combines the outstanding wear resistance of EKONOL® with the
low initial wear of graphite. It is less conductive than the carbon/graphite compound.
Electrically Conductive Compounds
With the addition of selected fillers we can tailor the electrical conductivity of the
bearing. The total electrical resistance depends on the contact surface between the
bearing and shaft, size, active surface load and the material thickness.
Electrically conductive bearings are used for electrostatic discharge, not for conducting electrical current. They are most valuable in the cathodic dip-coating of assemblies
Non-Conductive Compounds
Electrically non-conductive bearings reduce paint build-up on the bearing surfaces
and help improve paint quality.
PTFE/Steel 100 Cr6
T= 23°C
T= 70°C
0,2
0,62
p
3,1
(M
Pa
)
µ dyn
0,1
6,2
0
10
10 -1
10 -3
0,17
0,017
0,00017
10 -5
U (m/min)
0,0000017 m/sec
According to Research Report 83,
Bundesanstalt für Materialprüfung,
Berlin July 1982
The coefficient of friction of a composite material is not a constant. It is dictated
by the materials of the mating contact surfaces and by the roughness of the harder one. With combinations that have very different strength values (such as polymer with steel) the coefficient of friction also depends on the load. In addition,
due to the polymers’ strong tendency to change all mechanical properties under
temperature, the coefficient of friction is also affected by speed and ambient temperature. The above shown graph demonstrates the influence of speed and load
on the coefficient of friction of a PTFE/steel bearing (100 Cr6 1.3505). The coefficient of friction drops as load increases and as speed decreases. It also changes as
the bearings wear.
During the wear-in period NORGLIDE® bearings are shortly exposed to higher
wear. A polymer transfer layer forms on the metal contact surface.
After wear-in a relatively constant performance range is found which is controlled
by the pure PTFE compound layer.
With bronze reinforced NORGLIDE® types, the coefficient of friction increases
slightly after prolonged service due to the exposure of bronze to the mating surface. The bronze may then have contact with the shaft. This factor should be
taken into account when selecting materials for applications with higher admissible wear or high pressure.
The coefficient of friction of NORGLIDE® T stays constant over the whole service
life. With NORGLIDE® PRO XL the bronze layer can be reached after a short period
and the coefficient of friction grows gradually.
Generally speaking, the coefficient of friction of NORGLIDE® materials is outstandingly low in comparison with other polymer bearings, due to the use of PTFE as
main component in the bearing surface.
13
Specific bearing load p and sliding speed U
The life expectancy of NORGLIDE® bearings is essentially dictated by the environment of the particular application. Simply stated, the life expectancy is dertermined
by the specific bearing load p [N/mm2] and the sliding speed U [m/s] of the application range. The product of both values is called pU (pV).
Equation 1
pU = p · U
For some bearing materials pU limiting curves exist. In addition to these, parameters typical of the particular application (bearing clearance, roughness and hardness
of the mating-contact surface, ambient temperature, etc.) affect the position of the
pU limiting curve.
1000
T-carbon/graphite
M-glass/graphite
PRO
100
Load [MPa]
MP
10
1
Graph A
0.1
0.001
0.01
0.1
1
10
Speed [m/s]
50
45
Deformation [µm]
40
Graph B
35
30
25
20
30
100
30
100
15
10
5
M Pa, 23 °C
M Pa, 23 °C
M Pa, 100 °C
M Pa, 100 °C
0
0.01
0.1
1
10
100
1000
10000
Time [h]
Graph C
Temperature
1.2
1.0
KT
0.8
0.6
0.4
0.2
0.0
0
50
100
150
200
Temp [°C]
250
Graph C shows the influence of temperature on the life expectancy which is
40 % lower if the bearing is exposed,
for instance, to a temperature of 100°C
(correction factor KT).
In principle, NORGLIDE® bearings can
be used below the curves shown in
graph A. Oscillating motions, intermittent operation, oil lubrication or low
demands on the life expectancy can
achieve higher limit values.
The static maximum bearing load depends on the material and describes
the maximum possible load the bearing can bear without sliding motion
before it is destroyed. When designing
the pivot point, the deformation of the
bearing by this load is to be taken into
account. Due to the visco-elastic behavior deformation depends on nominal
force, time and temperature (see
graph B).
The dynamic maximum bearing load
defines the load limit for the application (sliding speed > 0) above which
the bearing probably should not be
used. The load limit also depends on
the sliding speed (see graph A). The
permissible load decreases as the
sliding speed increases.
The pU limiting curves shown here
have been determined with continuously rotating shafts in stationary
NORGLIDE® bearings. The pU operating
range increases as the energy generated by friction and ambient temperature is absorbed by adequate cooling.
NOTE: pU = pV
Mating-contact surface
Life expectancy is influenced also by parameters such as material (table 1), hardness
(graph D) and roughness (graph E) of the mating-contact surface.
Adverse values of hardness and roughness promote early wear, i.e. life expectancy
of a bearing is substantially lower if shafts with a hardness value well below 50 HRC
are used.
Table 1
Steel
Low-corrosion steel
Hard-chrome plated steel
Gray cast iron
Hard-anodized aluminum
KJ, Mat
1
1
1,5
1
1
1.2
1.0
KJ,HRC
Shaft material
0.8
0.6
0.4
Same applies to roughness values well
above Ra = 0,4 µm.
Low Ra values (Ra < 0,1 µm) lead to increased wear as well.
0.2
0.0
20
30
40
50
Graph D
Load type
1.2
1.0
0.8
KJ,Ra
Dynamic loads, i.e. loads alternating in
size, reduce the life expectancy of the
bearing. This fact is taken into account
when determining the dynamic factor
or correction factor for the dynamic
load Kdyn. For correcting the life expectancy under dynamic load, refer to
graph F and proceed as follows:
60
Hardness [HRC]
0.6
0.4
0.2
0.0
0.0
0.2
0.4
0.6
0.8
1.0
Ra [µm]
1. Select the number of required
load cycles
Graph E
2. Read Kdyn
3. Use Kdyn for calculating the life expectancy
With radial bearings, distinction is also
made between point load and peripheral load, depending on whether the
load is applied in a single point or is
rotational. This influence is considered in
correction factor Kf :
Point load
Kf = 1
Peripheral load
Kf = 2
1.2
1.0
0.8
Kdyn
For applications without dynamic load,
use Kdyn = 1 (uniform load).
0.6
0.4
0.2
0.0
103
104
105
106
107
Load cycles
Graph F
15
Wear depth ( ∆ hmax) and
wear factors (KW factor)
The two wear sizes described in this
chapter depend on the material or
system used. Wear depth ∆ hmax is the
thickness of the bearing layer which,
when worn, indicates the end of the
bearing life. Wear factor is the volume
per energy unit (load and sliding distance) worn by the application. The
maximum permissible wear depths of
selected bearings materials and the
related wear factors are listed in table 2.
Table 2
Bearing material
hmax [µm]
NORGLIDE® MP
NORGLIDE® M
NORGLIDE® SM
NORGLIDE® SMTL
NORGLIDE® T
NORGLIDE® PRO
280
280
250
100
250
100
0.12 - 0.18
0.12 - 0.18
0.16 - 0.70
0.10
0.10 - 0.90
0.18 - 0.20
With the above mentioned parameters and the related correction or wear factors
the life expectancy can be calculated by the following equation:
Equation 2
tmax =
hmax
Kw · pU · 3.6
Kf
Kdyn
KT
KJ,HRC
KJ,Ra
KJ,Mat
Life expectancy
The influences described here have
been calculated empirically and other
unconsidered factors typical of the particular application may be of importance. Therefore, the theoretically calculated life expectancy of NORGLIDE®
bearings is an estimate rather than
exact value and should be verified in
practical tests for the individual application.
Kw [10-6 mm3/Nm]
· Kf · Kdyn · KT · K J,HRC · KJ,Ra · KJ,Mat
Correction factor load type
Correction factor dynamic load
Correction factor temperature
Correction factor hardness
Correction factor roughness
Correction factor shaft material
Determining the specific bearing load
Equation 3
p=
Equation 4
p=
F
D·B
4·F
π · (D02 - Di2)
Determining the sliding speed (bush, washer):
Equation 5
U=
π·D·N
60 · 103
Equation 6
U=
π·D
x
60 · 103
2 · ϕ · Nosc
360
Determining the nominal life expectancy for operation
under alternating stress
Determining the nominal life expectancy for operation under alternating stress tmax
is calculated by classifying loads and sliding speeds in groups within which both
sizes are approximately constant. tmaxi , the maximum life expectancy of each class,
is calculated, and then factored with the frequency of occurrence. The total of factored individual results corresponds to the maximum life expectancy of the bearing.
Equation 7
∑
tmax =
ti
· tmax i
tcycle
Calculation of life
expectancy
Example 1:
Oscillating motion
Known data:
Nominal bearing
diameter
A bearing is to be manufactured with
NORGLIDE® M. The shaft is made of
hard steel (55 HRC) with a surface finish
Ra=0,2µm. Required life expectancy:
1500 h. Load: uniform, in one direction.
Maximum permissible radial wear:
150 µm. To be determined is the maximum life expectancy
D
Nominal bearing width B
Bearing load
Slewing frequency
Slewing angle
Ambient
temperature
F
Nosc
ϕ
Tamb
12 mm
8 mm
1000 N
75 min- 1
60°
80 0C
The calculation of the specific bearing load p per equation 3 results in:
F
D·B
p=
1000
12 · 8
p=
MPa
p = 10.42 MPa
The speed is calculated per equation 5:
U=
π·D
x
60 · 103
2 · ϕ · Nosc
360
U=
π · 12 2 · 60 · 75
·
m/s
60 · 103
360
U = 0.016 m/s
Now the pU value can be determined with equation 1:
pU = p · U
pU = 10.42 · 0.016 MPa · m/s
pU = 0.17 MPa · m/s
A verification of the p, U and pU values for suitability (graph A) demonstrates that
they are within the recommended range.
The following values are determined as correction factors:
KJ,HRC = 1
(steel: 55 HRC)
Kf
=1
(lumped load)
KJ,Ra
(Ra= 0,2µm)
Kdyn = 1
(uniform load)
(steel)
KT
(temperature 30°C)
=1
KJ,Mat = 1
=1
The life expectancy can be determined with equation 2:
tmax =
hmax
Kw · pU · 3.6
tmax =
150
0.18 · 0.17 · 3.6
·1·1·1·1·1·1h
tmax = 1362 < tmax, required = 1500 h
By increasing the nominal width B (to 10 mm) p and pU can be reduced and hence
the nominal life expectancy be increased.
p=
1000
MPa
12 · 10
p = 8.33 MPa
pU = 8.33 · 0.016 MPa · m/s
tmax =
150
0.18 · 0.13 · 3.6
pU = 0.13 MPa · m/s
·1·1·1·1·1·1h
tmax = 1781 > tmax, required = 1500 h
The required life expectancy is exceeded. NOTE: pU = pV
17
Calculation of life expectancy
Example 2: Rotary motion
A bearing is to be manufactured with
NORGLIDE® SM. The shaft is made of
hard steel (55 HRC) with a surface
finish Ra=0,2µm. Required life expectancy: 1000 h. Load: uniform, but rotary.
Maximum permissible radial wear:
250 µm.
Question: Is it possible to reduce the
nominal bearing width?
The calculation of the specific baring load p per equation 3 results in:
F
D·B
p=
p=
2000
MPa
25 · 15
p = 5.33 MPa
The speed is calculated per equation 5:
U=
π·D·N
60 · 103
U=
π · 25 · 31
m/s
60 · 103
U = 0.041 m/s
Now the pU value can be determined with equation 1:
pU = p · U
pU = 5.33 · 0.041 MPa · m/s
pU = 0.22 MPa · m/s
A verification of the p, U and pU values for suitability (graph A) demonstrates that
they are within the recommended range.
The following values are determined as correction factors:
Known data:
Nominal bearing
diameter
D
25 mm
= 2 (peripheral load)
Kdyn = 1
Nominal bearing width B
15 mm
Bearing load
F
Slewing frequency
Nosc 31 min- 1
Ambient
temperature
Kf
KT
(uniform load)
= 0,7 (temperature 80°C)
KJ,HRC = 1
(steel: 55 HRC)
KJ,Ra
(Ra= 0,2µm)
=1
KJ,Mat = 1
(steel)
2000 N
Calculation of life expectancy per equation 2:
0
Tamb 80 C
tmax =
hmax
Kw · pU · 3.6
tmax =
250
0.24 · 0.22 · 3.6
· 2 · 1 · 0.7 · 1 · 1 · 1 h
tmax = 1841 >> tmax, required = 1000 h
The nominal bearing width is related with the life expectancy so that a reduction by
one third (to 10 mm) is possible.
p=
F
D·B
pU = p · U
p=
2000
MPa
25 · 10
p = 8.00 MPa
pU = 8.00 · 0.041 MPa · m/s
pU = 0.33 MPa · m/s
A verification of p, U and pU values for suitability (graph A) demonstrates that they are within
the recommended range.
tmax =
hmax
Kw · pU · 3.6
tmax =
250
0.24 · 0.33 · 3.6
· 2 · 1 · 0.7 · 1 · 1 · 1 h
tmax = 1228 > tmax, required = 1000 h
The required life expectancy is reached.
The nominal bearing width can be reduced from 15 mm to 10 mm.
Calculation data and units (ISO 7904)
Nominal width of bearing (length)
B
[mm]
Nominal diameter of bearing
D
[mm]
Inside diameter of washer’s
retaining ring
Di
[mm]
Outside diameter of washer’s
retaining ring
D0
[mm]
Max. permissible radial wear
∆hmax [µm]
K-factor
Kw
[10-6mm3/Nm]
Bearing load
F
[N]
Rotational frequency
N
[min-1]
Slewing frequency
Nosc
[min-1]
Specific bearing load
p
[MPa]
pU value
pU
[MPa · m/s]
Wall thickness
s
[mm]
Ambient temperature
Tamb
[0C]
Max. life expectancy
tmax
[h]
Duration of approximately constant
pU conditions within
the load cycle
ti
[h]
Duration of load cycle
tcycle
[h]
Max. life expectancy at approximately
constant pU conditions within
the load cycle
tmaxi
[h]
Sliding speed
U
[m/s]
Slewing angle
ϕ
[°]
19
Design of the bearing
The life expectancy of a bearing is very much dependent on its design where factors
like load, dimensions, material selection, surface finish and geometry have to be
taken into consideration.
In many cases the dimensions of a bearing are dictated by the design environment.
An estimate of the life expectancy can determine which NORGLIDE® type is capable
of bearing a given load. If necessary, the pivot point has to be modified accordingly.
Requirements on the tribological properties and the knowledge of influences by
the bearing environment help to select the proper NORGLIDE®material.
Practically, the mating or contact surface can be made of any steel or plastic. Better
performance is achieved with surfaces in a hardness range of 50 to 60 HRC. The
use of plastics is, therefore, limited to a few isolated cases, whereas the selection of
metals focuses on various steel grades.
Another factor vitally important for the life expectancy of a bearing is the surface
finish. Sharp elements in the surface – even if tiny – can never be avoided in machined
parts. It is therefore recommended to choose drawn, rolled or milled surfaces.
Polished surfaces produce erosion damage and are not ideal contact surfaces. For
slowly oscillating movements, the value of mean surface finish Ra should range between 0.15 - 0.80 µm, for high frequency oscillating and rotating movement, it should
be in between 0.15 - 0.35µm. Corrosion alters the surface roughness appreciably and
hence increases wear so that suitable protection methods or a corrosion-resistant
steel should be used. In extremely dirty environments, the bearing should be protected with proper sealing systems.
Housings should have chamfers according to DIN 3547 to ease the installation of
bearings. The pins or shafts should be designed with a radius to avoid damage to
the bearing surface during installation.
Tolerancing
NORGLIDE® bearings are designed for either a heavy press fit into a housing or to be
inserted by hand. Bearings designed for hand insertion are usually flanged bearings
that require a secondary flange to retain the bearing in the housing.
See the “Installation of the bearings” section for more detail on this. The housing tolerance has a direct linear relationship to the mounted bearing ID tolerance. This tolerance can be reduced by sizing the ID of the bearing after installation. The “Sizing”
section covers this capability in detail.
Clearance fits (between bearing and pin)
The tolerance field on the inside diameter is controlled by the tolerance on the bore
size and the tolerance of the NORGLIDE® bearing. With some material types the tolerances between pin and inside diameter of the bearing can be adapted by sizing
(see page 22). This procedure allows producing a new bearing inside diameter with a
closer tolerance range. Extremely tight clearance fits can be obtained by using adequately toleranced pins (min. h7). For rotary motions, linear sliding motions or high
frequency oscillating motions the minimum clearance should not be less than 0.015
to 0.020 mm.
Interference fits (between bearing and pin)
NORGLIDE® materials offer the opportunity to design clearance free bearings. For
this purpose the combination of pin/NORGLIDE® bearing/housing is selected in a
way that always interference is obtained. This interference is possible, because
NORGLIDE® materials have an extraordinary thick PTFE layer which provides elasticity. When installed, this elasticity exercises back pressure onto the pin and hence produces a torque in slewing motions and isolates noise. Sizing and accurately toleranced pin diameters make it possible to limit the torque. After sizing the interference
should not be more than 0.01 mm including consideration of wear.
21
Sizing
What is sizing?
NORGLIDE® bearings are made of compo-
diameter of the installed bearing by up to
of sizing and has to be deducted when
site materials.The individual components
0.150 mm, depending on the length of the
designing the bearing, otherwise the
display a more or less developed plastic
pivot point and the material type.
secondary flange will be too large.
and elastic deformation capability. Plastic
NORGLIDE® materials with metal fabric
NORGLIDE® T is the only product with a
deformation is used for sizing, i.e. altering
or stretched metal are ideal for sizing. A
limited sizing capability.When sized, the
the sizes to a certain degree.The material
steel backing limits the sizing capability of
bearing material adapts to the surface of
can be formed by sizing with tools (usual-
longer bearings. NORGLIDE®-PRO types
the housing wall and hence reduces the
ly a sizing pin). By sizing the bearing in the
are also sizable due to the PTFE tape
tolerance range.
original housing, the overall tolerance
which is encapsulated in the polygon
range (tolerance of housing + tolerance of
structure. Sizing alters mainly the radial
bearing material) can be very much redu-
thickness of the bearing material. At the
ced.This allows for wider production tole-
same time the bearing increases in
rances and the associated cost benefits.
length. This increase in length depends
Sizing allows for an increase of the inside
on the NORGLIDE® type and the amount
Sizing for clearance-fit
Sizing for interference-fit
Design of sizing pins
In addition to the permanent deforma-
Depending on the NORGLIDE® material
The geometry of sizing pins is described
tion of the radial wall thickness of a
begin with an interference of 0.150 to
on page 24 Detail „Y“. For the purpose of
NORGLIDE® bearing, an elastic defor-
0.250 mm. After sizing, the maximum
this study, only the active sizing range of
mation is to be taken into considera-
interference on the pin to be mounted
a sizing pin will be examined in detail.
tion when sizing. Consequently, the in-
should not exceed 0.010 mm. This
To calculate the pin’s diameter deduct
side diameter resulting from a sizing
interference is important if, for
twice the largest NORGLIDE® thickness
step is always smaller than the diameter
instance, a torque is to be generated in
from the smallest housing size. Add the
of the sizing pin. Therefore, to ensure a
a hinge. The suitable modification of
value of 0.05 mm to this calculated bea-
permanent clearance fit between bea-
housing and/or pin allows to design
ring inside diameter to have the diame-
ring and pin, sizing beyond the target
any fit between clearance-fit and inter-
ter of the first sizing pin. Sizing should
is needed. After this, due to the plastic
ference-fit.
take place in maximum steps of 0.06
recovery of the sliding layer, the final
mm to prevent damage to the bearing
inside diameter is achieved.
surface. Each sizing step should be made
in both directions to prevent delamination of the bearing layer. It is not recommended to combine several sizing steps
with the aid of a multi-step mandrel.
Continuous torque as a function of interference, exemplified by Norglide® MP
(qualitative illustration)
1.6
1.4
Torque [Nm]
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
0.11
0.12
Interference after sizing [mm]
Torques
Torques are dictated by the coefficient of friction, pressure, friction surface, speed
and finish of the rubbing-contact surfaces.
In contrast to the Coulomb law of friction, the coefficient of friction depends on
both pressure and sliding speed. Therefore, no universal value can be given (see
page 13).
For some applications, particular torques are specified. The material composition of
NORGLIDE® MP, S, M, SM and SMTL is such that an interference fit between the pin
and the bearing’s inside diameter (see page 21) is designed to produce torque.
The pressure depends on the pin’s interference with the inside diameter of the
bearing. This pressure in the cylindrical (radial) part of the bearing produces the
torque. With flanged bearings additional (axial) torque may be produced if pressure
is exerted on the flanged surfaces. By appropriate changes in the design, such as
proper adjustment of the riveting shoulder height, effects can be influenced in the
axial direction. Another factor that influences total torque and should be considered in the design is the riveting process.
Only the torque produced in the radial part of the bearing will be examined in
detail. The following test with NORGLIDE® MP may serve as an example: With a
bearing length of 19.3 mm and a pin diameter of 8.00 mm the range of interference
was varied between 0.02 mm and 0.08 mm. Torques in the range of 0.3 N to 1.4 N
were reached.
Interferences > 0.08 mm should not be used to prevent damage to the bearing surface. Unevenly spread wear of the sliding layer may lead to an uncontrolled increase
of the torque. Strong pre-stress may reduce the life expectancy of the bearing.
The following factors should be taken into account:
• The torque values should not be too high.
• Due to the material’s recovery the torque increases after installation.
• When a bearing with high interference between the bearing’s inside diameter
and the pin is exposed to temperatures > 200°C over a longer period, unstressing
of the PTFE layer is noticed. The torque drops accordingly.
Due to the vast variety of parameters that influence torque, the values retained for
the torque range should be verified in practical tests for the individual application.
23
Installation of
NORGLIDE® bearings
The process described below is somewhat idealized, but includes the most
important steps for installing NORGLIDE®
bearings into a housing. If and in which
order the individual steps have to be
made depends on the material type,
the application and the technical feasibility and should be discussed with our
application engineers.
How to feed the bearing to the installation point
The degree of automation decides on whether the bearing is inserted by hand or
by machine. With tangle-free bearings, a combination of vibration feeder and gripper can be used. Long distances between feeder and installation point are overcome by „shooting“ the bearing pneumatically through a profile tubing.
How to insert the bearing into the housing
Bearings with a loose fit in the housing do not necessarily need a mandrel for
installation. If a mandrel is used, calculate its diameter by deducting twice* the largest NORGLIDE® thickness from the smallest inside diameter of the housing; then
deduct the value of 0.05 mm. (*takes three times the largest NORGLIDE thickness
in the case of a MP bearing with overlap). Details of a mandrel design to accom-
Detail "X"
plish press fit of the bearing are shown in the drawing.
How to prevent movement of the bearing
To prevent bearing movement during all subsequent forming operations, so-called
“downholders“ are used which grip the axial flange and fix the bearing. A „dead
stop“ (spacer) prevents squeezing of the flange (see Detail Z).
Pressing in
Sizing
75% Nominal bearing length
Detail "Y"
F
F
Downholder
Y
Detail "Z"
Dead
deadstop
stop
Chamfer
How to size the inside diameter
The possibilities of modifying the bearing's inside diameter by sizing were discussed
in detail on page 22. The sizing pin must have all transitions designed with radii as
shown in Detail X. Its active sizing range must be hardened and polished. Additional
tapering of the pin may ease lead-in.
How to form the 2nd flange in one or two steps
Usually flanging is done in two steps: 1st step: 45°; 2nd step: 90°. In particular cases, if
the geometry of housing and pin allows, the 2nd flange can be formed in a single
step, but it will be narrower than a flange formed in two steps. This must be considered when designing the bearing. Also in this case all transitions must be designed
with radii (Detail Z) and the active sizing range must be hardened and polished.
Additional tapering may ease lead-in. A „dead stop“ prevents squeezing of the 1st
and of the 2nd flange (Detail XYZ).
Pre-flanging
Final flanging
Downholder
Downholder
Z
X
R = Material thickness + 0.75
X
R = Material thickness + 0.5
25
Measuring NORGLIDE® bearings
Drawings for NORGLIDE® fabricated parts do not only describe
the dimensions of the bearing,
but also state the measurement
methods used.
Measuring NORGLIDE® bearings with steel backing
Measuring NORGLIDE® bearings without steel backing
This method for testing the outside diameter can be carried out on all bushings
This group of bearings is made of flexi-
suitable for NORGLIDE® bearings with steel backing > 0.5 mm and for all PRO types.
ble materials. A master gauge is used to
With the gap up, the bushing is inserted into the master gauge. Using a given test
make sure the measurements are re-
force the two shell halves are pressed together so that the bushing is exposed to a
producible and comparable. To perform
pre-stressing force in the elastic range. Determined is the deviation of distance z
the measurement, the NORGLIDE® bea-
(from a standard value) between the shell halves. The exact procedure and evalua-
ring is inserted into a ring gauge.
tion of this method - which is known also as ∆z test - is described in detail in ISO
A plug gauge descends into the bearing
3547-2.
The diameter measurement is performed on the basis of the methods described in
standard ISO 3547-2. These are:
Test A per ISO 3547-2
that have an interference fit to the housing’s inside diameter. This means, it is only
and ensures it has a firm seating and
optimum roundness. The gauge is flattened on one side and has one or two
inspection windows. A gauge pin is
used to determine the gap size X. The
master gauge is designed to measure
both the length of the bush and the
maximum permissible flange diameter.
Test B per ISO 3547-2
This simplified method for testing the outside diameter can be carried out on all
NORGLIDE® bushes with steel backing and on bearings with and without a flange
regardless of the material thickness.
The test uses GO and NO GO ring gauges. The GO gauge must take up a NORGLIDE®
bearing when pressed in by hand. The NO GO gauge must not accept the bearing
when pressed in with the same force. The diameters of the gauges are selected
according to standard 3547-1.
In this GO gauge, the flange diameter can be tested.
Test C per ISO 3547-2
This method is used for testing the inside diameter. It can be carried out on all
NORGLIDE® bushings with steel backing and on bearings with and without a flange
regardless of the material thickness.
The test uses a gauge. In this master gauge the inside diameter of the bearing can
be tested with plug gauges. The GO plug gauge should fit with a minimum of force.
The NO GO plug gauge must not fit by hand. The fitting forces and diameters of
these plug gauges have to be agreed upon with the user.
Measurement gages for ∆z
27
Corrosion resistance
The NORGLIDE® bearing steel shell can be provided with an anti-corrosive coating
combined of zinc plating, Cr6 free passivation and sealing, depending on what kind of
protection is needed. In a few special cases, other corrosion-protection systems can be
used to avoid contact corrosion. All systems comply with the European Union End-ofLife directive for automotive vehicles 2000/53/EG.
In comparison with components of solid refined metal, specially structured NORGLIDE®
bearings have a shorter corrosion resistance when exposed in the salt spray chamber.
The corrosion resistance of the individual components is not necessarily identical with
the life expectancy of the assembly. For choosing the proper anti-corrosive coating,
the composition and operating conditions should also be taken into account. Actual
corrosion resistance should always be verified in the assembled condition.
Some NORGLIDE® types use a stainless steel backing and do not need additional corrosion protection. Some NORGLIDE® types use a backing of aluminum which also
does not require further protection because it passivates itself. In both cases however
the electro-chemical chain must be taken into account to prevent contact corrosion in
the assembled condition.
Flexible NORGLIDE® variants are reinforced by mesh or stretched metal structures of
tin/bronze CuSn6 (material No. CW452K), of stainless steel FeCr18Ni10Mo3 (material
No. 1.4401), of aluminum AlMg3 (material No. 3.3536) and do not need additional corrosion protection. Also in this case the electro-chemical chain must be taken into
account to prevent contact corrosion.
The resistance to red and white corrosion of NORGLIDE® bearings is tested to DIN EN
ISO 9227 during production in our own salt spray chamber. In special cases the salt
spray test is conducted on parts in the assembled condition.
Salt Spray Chamber
29
Integrated Management
Quality
… we team with our customers:
All quality related criteria of NORGLIDE® bearings are established with the customer in our NORGLIDE® drawing.
… we achieve certifications:
Our modern quality management complies with international standards. Certificates are provided on request.
… we plan quality:
With our quality preplanning systems we identify and plan all criteria and their
risks - from the drawing board to delivery.
… we inspect and test quality:
Alongside our reliable production processes and statistical process control techniques, our highly trained staff is responsible for a continuous improvement program in compliance with the Six Sigma philosophy.
EHS
Environment, Health and Safety
… we ensure compliance:
While considering environmental protection as a key element our company is committed to maintaining health and safety, because health and motivation of our staff
are the core of highly efficient performance.
… this means to our customers:
We are, and will remain, an attractive, highly reliable partner for sustained success.
Quality, Environment, Health and Safety
(QEHS) Policy
Future by sustainability
In order to sustain our company's success
•
We focus on the protection and the inviolacy of employees and environment
and on complying with customers' requirements.
•
We accompany new developments with integrated QEHS concepts.
•
We pursue a zero-defect strategy in all departments.
•
We take care of our products all the way from the technical concept to the
start of production at our customers.
•
We want to exceed our employees' and our customers' expectations.
In order to assure this sustainability
•
We set QEHS and economic goals and evaluate achievement.
•
•
We provide capable, controlled and reliable processes and procedures while
steadily reducing the distribution (6σ).
We continuously improve our products, our processes and our management
system.
We prevent defects and accidents by suitable programs.
•
We strictly comply with the requirements made by customers, norms and laws.
•
We have our management system certified and audited according to ISO/TS
16949, DIN EN ISO 14001 and OHSAS 18001.
•
We involve our suppliers into our QEHS activities.
•
In order to be able to achieve our goals
•
We promote high-level qualification and a definite sense of responsibility of
our employees by continuous training and education.
•
We reduce environmental and health hazards for our employees by using
modern technologies.
•
We minimise our consumptions to preserve natural and corporate resources.
•
We regularly check, monitor and evaluate the results of our activities.
•
We work in interdisciplinary teams.
The Saint Gobain Performance Plastics Pampus GmbH management team
31
1
Door hinge
2
Seat adjustment systems
3
Two-mass fly wheel
4
Belt tensioner
5
Decoupled pulley
6
Steering gear
7
Pedal linkages
8
Light projection range adjustment
9
Shock absorber
10
Front hood hinge
11
Trunk hinge
12
Windshield wiper
13
Brake lever
14
Automatic mirror adjustment
15
Steering column adjustment
Two-mass fly wheel
11
9
10
12
13
15
14
3
5
1
4
7
6
8
2
Flap hinges
Convertible
systems
Pedal linkages
Hinges
Shock absorber
Belt tensioner
Sliding door
33
Ball joint
Expansion groove
Door hinge
Seat mechanism
Pump
We thank the following
companies for the
photografic material
provided:
Swivel drive
Valves
Bicycle brake
1
Front shock absorber
2
Rear shock absorber
3
Pivot points rear shock absorber
4
Pivot points rear shock absorber
AUMA Riester GmbH & Co. KG
Campagnolo
CR Hammerstein
Dr. Hahn
Edscha
GAT Gesellschaft für
Antriebstechnik mbH
ISE Innomotive Systems
Europe GmbH
Kirchhoff GmbH & Co. KG
Litens
Metso Automation
Maurer Söhne GmbH & Co.KG
SRAM
Trek
ZF Sachs AG
3
2
4
1
RA
M
EXT
RU
SIO
N
MA
C
& M HIN
E
CO OLDE D
MP
ON D
EN
TS
RU
LON
®
ME
LDI
N®
OM
NIS
EAL
®
OM
NIL
IP™
NO
RSL
IDE
®
NO
BEA RGLID
RIN E®
GS
I NJ
E
MO CTIO
LDI N
NG
EUROPE
* Saint-Gobain Performance Plastics Pampus GmbH
Willich · Germany
Phone: (49) 21 54 60 0
Fax: (49) 21 54 60 310
* Saint-Gobain Performance Plastics N.V.
Kontich · Belgium
Phone: (32) 34 58 28 28
Fax: (32) 34 58 26 69
Saint-Gobain Performance Plastics Asti
Nanterre · France
Phone: (33) 1490 70204
Fax: (33) 1490 69760
Saint-Gobain Performance Plastics
Agrate Brianza (Mi) · Italy
Phone: (39) 03 96 50 070
Fax: (39) 03 96 52 736
Saint-Gobain Performance Plastics España, S.A.
Barcelona · Spain
Phone: (34) 93 4948856
Fax: (34) 93 4948857
* Saint-Gobain Performance Plastics España, S.A.
Logroño · Spain
Phone: (34) 94 14 86 035
Fax: (34) 94 14 37 095
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
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•
•
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•
•
•
NORTH AMERICA
Phone: (1) 973-696-4700
Fax: (1) 973-696-4056
* Saint-Gobain Performance Plastics Corporation
Bristol, Rhode Island · USA
Phone: (1) 401-253-2000
Fax: (1) 401-253-1755
Garden Grove, California · USA
Phone: (1) 714-995-1818
Fax: (1) 714-688-2701
•
•
•
•
•
•
•
•
•
•
•
SOUTH AMERICA
* Saint-Gobain Cerâmicas & Plásticos Ltda.
Performance Plastics – Division
Vinhedo-SP · Brazil
Phone: (55) 19 3876 -8193
Fax: (55) 19 3876 -8038
•
•
•
•
•
•
•
ASIA
* Saint-Gobain KK-Performance Plastics
Tokyo · Japan
Phone: (81) 33 26 30 285
Fax: (81) 33 26 30 286
•
•
•
•
•
•
•
* Saint-Gobain Performance Plastics Korea Co., Ltd.
Seoul · South Korea
Phone: (82) 25 08 82 00
Fax: (82) 25 54 15 50
•
•
•
•
•
•
•
* Saint-Gobain Performance Plastics (Shanghai) Co., Ltd. Phone: (86) 21 54 72 15 68
Fax: (86) 21 54 72 23 78
Shanghai · China
•
•
•
•
•
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* Saint-Gobain Advanced Materials (Taiwan) Co., Ltd.
Taipei · Taiwan
Phone: (886) 22 50 34 201
Fax: (886) 22 50 34 202
•
•
•
•
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•
* Grindwell Norton Ltd.
Bangalore · India
Phone: (91) 80 2847 2900
Fax: (91) 80 2847 2905
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Phone: (66)26405435
Fax: (66)26405439
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Saint-Gobain Performance Plastics
Bangkok · Thailand
* Manufacturing Facilities
NORGLIDE® · NORSLIDE® · RULON® · MELDIN® · OMNISEALS® · EKONOL® are registered trademarks.
Warranty: The data and information in this catalogue or in our web sites are not binding and were correct and up-to-date at the time of
release. Technical modifications and developments as well as adaptations to comply with amended standards, norms and guidelines can
be made without notice. The product characteristics, especially load bearing capability and wear, depend on the application and the environment the product is used in. Therefore the data does not assure specific product characte-ristics or make reference to the suitability of
the product for a definite or fictitious application. In case of new applications users must test the product under these actual application
conditions and the application should be discussed with the manufacturer. Within the scope of law any liability for us, and all those acting
on our behalf, for the data and information in this catalogue or in our web sites shall be excluded. Any contracts are concluded on the basis
of our General Business Terms and Conditions, which could be downloaded from our web site, or forwarded to you as requested.
www.norglide.com
35
BSTE-4154-3K-0508 © 2008 Saint-Gobain Performance Plastics Pampus GmbH · Am Nordkanal 37 · D-47877 Willich · Germany · Phone: +49 (0) 2154/60-0 · Fax: +49 (0) 2154/60-310
Wayne, New Jersey · USA

NORGLIDE® Maintenance Free Bearings - Saint

Transcription

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