0 9 | 2 015 09 | 2015

09 | 2015
Contents
Seating Comfort
Alfmeier bonds lordosis
valves with DELO adhesive
In Six Seconds
to +180 °C
New metal adhesive for electric motors
4
8
14
16
Adhesive-friendly Design
Laser Pretreatment
Tips & tricks for engineers
Bonding stainless steel
2 | DELO-News
Editorial
Light-weight
Design
Bonding replaces welding and riveting
10
Dear readers,
Maybe you’ve already
noticed? We’ve given
our customer magazine
DELO-News a makeover.
Decluttered, with a lot of
white space, modern fonts,
and attractive images – we
think it makes reading a lot
more enjoyable!
As for the content, the
feedback we received from
readers (and our thanks to
everyone who took part in our survey) told us that there was
the desire for a wide range of formats. You want information
about our new products as well as case studies for solved
applications, forecasts for trends in adhesive technology, and
practical tips about bonding.
We have also completely revamped our reference book on
bonding technology BOND it. In the 5th expanded and revised
edition of this book, discover all there is to know about the
theoretical background to adhesive technology, its application,
and our products. If you have not yet encountered BOND it or
only have an old edition, please get in touch with your contact
person at DELO or email us at contact@delo.de.
Happy reading!
Sabine Herold,
Managing Partner
18
Bonding PEEK
Imprint
Evonik Industries and DELO join
high-performance materials
DELO Industrial Adhesives, DELO-Allee 1, 86949 Windach, Germany
Phone +49 8193 9900-0, marcom@DELO.de, www.delo.de
DELO-News | 3
Cover Story
Comfort Seats in Good
Shape Thanks to Adhesives
4 | DELO-News
Cover Story
Seat comfort is becoming of increasing concern to motorists.
While massage seats are still the reserve of the premium
segment, lumbar supports are now breaking through into
the mass market. Alfmeier, a leading provider of the lordosis
valves for these, relies on DELO’s adhesives for reliable
products and rapid manufacturing.
ordosis valves play an important role for seat comfort. These little
helpers have primarily become known as pneumatic actuators
for lumbar supports. Initially reserved for the premium segment,
they are now increasingly found on the mass market. Another trend
is that they are becoming smaller and lighter, which means that they
can be installed as valve islands without taking up too much valuable
space. They are also becoming more multifunctional and are no longer
used just for backrest supports, but also for backrest width adjustment
and seat massage functions. In a current top-of-the-range model, for
an additional 2,000 euros, it is even possible to get 14 temperaturecontrolled air cushions that mold exactly to the contour of your body.
L
From Treuchtlingen in Germany out into the World
Alfmeier Präzision AG is headquartered in Treuchtlingen, Germany, and
is one of the most important providers of lordosis valves on the market.
Several hundred thousand units roll off its production lines every year.
The owner-operated family business also supplies the automotive,
medical technology, and electronics industries with actuators, pumps,
and molded plastic parts. From its development, production, and
distribution sites in Germany, the Czech Republic, China, Korea,
the USA, and Mexico, its two thousand employees serve European,
American, and Asian OEMs.
Every Second Counts
The seal between the electrical connection and the housing bushing
is crucial for the reliable functioning of Alfmeier’s valves – after all, the
operating pressure can be 1 – 1.5 bar, or even 2.5 bar in some cases. In
order to seal these contacts, Alfmeier uses an encapsulation technique
with adhesives. Other processes, such as insert molding, are out of the
question, because it’s not just reliability that is important to Alfmeier –
speed is of the essence here too. The focus here is on simple adhesive
dispensing and rapid curing. This is the only way in which the company
DELO-News | 5
Cover Story
Alfmeier lordosis valves
ensure good seat comfort
Light- / humidity-curing DELO-DUALBOND
adhesive is used to reliably seal off the pins
6 | DELO-News
Cover Story
can achieve the short cycle times required to implement
actual series production processes that include an in-line
functional check of the seal.
Alfmeier selected DELO as its project partner. The midsized company, with its portfolio of high-end adhesives, was
brought on board at an early stage, bringing with it great
expertise in bonding processes for large unit volumes. The
project involved the setting up, testing, and validation of all
the production processes, as well as the special modification
of the adhesives to the requirements of lordosis valves.
“Bonding is an efficient, but sometimes complex joining
method. So it’s important not just to sell products, but to
thoroughly test them beforehand and discuss and plan
all production aspects with the customer on an equal
footing,” says Christian Walther, Head of Sales for
Germany at DELO.
Efficient in Series Production
After a few preliminary tests with numerous
products, the final decision was between a onecomponent adhesive and a two-component adhesive.
Due to the considerably quicker curing and simpler
handling, it was the one-component, dual-curing adhesive
that was selected, which also enabled an in-line tightness
test. Since then, Alfmeier has also installed a dual-curing
adhesive, a product with two curing mechanisms. All areas
of the adhesive that are accessible to light are cured with
LED lamps, which means that the valves can continue to
be handled immediately. In shadowed areas, where the light
cannot penetrate, the adhesive is cured by contact with
It is important to discuss and
plan production aspects with the
customer.”
humidity, which ensures good reliability. Alfmeier is relying on
DELO’s products for the LED lamps too. These are not only
tailored to the adhesive, but also offer a high level of intensity
and exceptionally uniform light distribution.
The valves are produced on a 6-meter-long linear
facility, a quarter of which is dedicated to the bonding
process. First, the valves are automatically fed in, then the
adhesive is dispensed from a pressure tank. Thanks to the
aforementioned light-curing process, the pin cast is cured
in about 10 seconds, so the total cycle time for dispensing,
curing, and quality control is just a few seconds. Alfmeier is
therefore well equipped for production growth – which is sure
to come, given the boom in comfort seats. 
Process video:
https://youtu.be/6KjxfwepiYU
DELO-News | 7
Product
In Six Seconds to +180 °C
Withstands High Temperatures, Allows Quick and Simple Curing
DELO has developed a new adhesive for metal
bonding used in high-temperature applications
requiring quick and simple production processes.
The DELO-ML DB154 adhesive retains its strength
at temperatures up to +180 °C.
esigned for use in electric motors, DELO-ML DB154
can easily bond buried magnets, rotor packages as well
as shafts to hubs. This new adhesive offers exceptional
temperature stability and heat resistance, achieving more than
twice the shear strength values of other methacrylates in the
same temperature range.
Many other adhesives on the market experience a strong
power drop at temperatures above +150 °C. DELO-ML DB154
retains its strength when it comes in frequent contact with high
temperature, corrosive fluids, such as gear oil, motor oil and
gasoline.
D
Cured by exposure to UV or visible light, the adhesive
reaches initial strength within six seconds, reliably fixing the
components and allowing the process to promptly continue.
This provides an even initial fillet strength for more reliable
bonding. Full strength of this adhesive is achieved when no
oxygen is present in the curing process.
Unlike one- or two-component epoxy resins, lightcuring methacrylates, such as DELO-ML DB154,
require shorter periods of time for curing. This enables a
faster production process and helps reduce the carbon
footprint made during production, since no energy is used
for heat curing. It also eliminates the mechanical fixing of
the components prior to heat curing, saving additional
process time.
This medium-viscous product adheres to steel and
aluminum as well as to magnets made of rare earth often
consisting of an iron-neodymium mixture. If an activator is
used, metals can also be joined to a component made of
plastic. 
Fast and resistant to
elevated temperatures:
DELO-ML DB154
for e-motors
8 | DELO-News
Product
First Liquid, Then Sealing
Sealants Cure in Seconds
DELO now offers liquid FIPG sealants that protect
housing covers from dust, air and water. This new
static liquid sealant can be light-cured within
seconds, making it superior to conventional liquid
sealants that need minutes, if not longer, to cure.
esigned to seal electronic and household
devices like telephone housings and loudspeaker
assemblies as well as automotive components
like oil pans, electrical controls, engine covers, pumps,
gear parts and door handles, DELO’s FIPG sealants offer
immediate final strength, enabling continuous production
and no downtime.
D
Ideal for large production volumes, these light-curing liquid
sealants allow for short cycle times and easy automation.
Sealants are more advantageous than conventional gaskets
in the creation of complex component geometries because
they require less process steps, while providing quick
machine set-up time and little to no waste. In-line checks are
also possible, as potential leaks are detected with the help
of fluorescent light. As it is not necessary to keep a huge
number of seals on stock, storage costs can be cut down.
These run-resistant, high-viscous, silicone-free and
PWIS-free sealants (paint wetting impairment substances)
can be applied onto housing parts in any desired height.
The sealants’ good elasticity offers reliable sealing after
joining components. Its low compression set allows the
seals to spring back after being compressed. 
DELO-News | 9
Product
ONSERT®: The Best of Both Worlds
Joining of Composite Materials [Part 2]
In the last edition, we described the challenge of joining composite materials. In this issue, we introduce to
you a joining technology that combines screws and adhesive and is suited to a range of applications.
10 | DELO-News
Product
Process
advantages
Böllhoff and DELO Combine Bonding and Screwing
or joining composite materials to other materials,
DELO has developed a new method together with the
assembly specialist Böllhoff that uses stud welding
as its basis. To prevent complex drilling of holes, screwing
or riveting, threaded bolts are bonded to fiber composite
materials instead of being welded. The combination of bolt
and base is called ONSERT®. What makes this technique so
special is its speed and effective energy balance.
The process is as follows: First, a one-component
adhesive is applied to the thread base and then joined to the
composite material. The thickness of the adhesive layer is
adjusted by spacers and can range from 0.1 to 0.2 mm.
The thread base is made of an amorphous plastic,
creating a light-permeable bonding area. This ensures
the technique’s short cycle times. The adhesive is then
cured within about 4 seconds using an LED lamp.
This process can be fully automated as the bonded
connection can be loaded immediately, equipping
the plastic component with a stable thread
directly afterwards. Once these steps have been
completed, the thread can be screwed into other
materials (not the base) and removed again if
necessary.
Depending on the mechanical properties
required and the ambient conditions of use,
F
Perfect for automotive and
aerospace applications, and even
white goods: ONSERT®
ONSERT®
 Low mechanical stressing of the components
 High reproducibility
 Fast process
 No heat input
 Design freedom thanks to later joining
various plastics, such as polycarbonate, polyamide or
polyether sulfone, are used as material for the transparent
ONSERT® base. The only precondition is that the plastics
are amorphous. This will allow enough blue light with a
wavelength of 400 nanometers to be transmitted for curing.
Multiple Application Possibilities from
Retainers to Dampers
This new technique is suitable for a wide range of
applications, especially those where components must be
fixed but not structurally joined. For example, hundreds of
thousands of aircraft pins are installed in airplanes every
year. With this method, cover plates and insulating materials
can be fixed just like floor panels to adhere fire protection
components. In recent years, vehicle construction has begun
to increase its focus on CFRP, especially for B- and C-pillars.
For example, the cable harness in vehicles could be fixed
to the bolt and bonded to these pillars. Further
urther applications
include securing of clips, sensor retainers
ers or attachment
components. In addition, this method
can
be
d
considered as a beneficial alternative
to
welding
ive
as it increases production flexibility,
lity, since
the ONSERT® bonding areas are easy
to change even after a design
gn is
completed.
Video: ONSERT®s in
BMW i8 series production
https://youtu.be/VuLkVnoDm-A
DELO-News | 11
Product
Used in the
BMW i3
An example from series production that
demonstrates the wide range of applications
is not just theory. The process has proved its
worth in fastening cables, trims, and other
components for the two new electric BMWs,
the i3 and i8.
Flexible geometry: In addition to threaded
bolts of various sizes, ONSERT® can also
be used for plug-in connectors.
Impressive Mechanical Properties
In order to check if this new joining method is suitable for
these types of applications, the technique’s manufacturers
bonded many materials to ONSERT®s, and subjected these
joints to a broad variety of tests common in the automotive
and aviation industries, including the 85 / 85 test, where the
components are stored at a temperature of +85 °C and an
air humidity of 85 %, and the VDA climate test. The CFRP
components were sand-blasted for pretreatment. The
lacquered aluminum and polypropylene were cleaned with
ethanol. The magnesium components remained untreated.
The tests demonstrated that the ONSERT® bases achieved
high pull-off strength and shear strength values, as well as
withstand the demanding test conditions.
In addition to these two tests, the stability of the ONSERT®s
was tested after salt spray exposure for 1,000 hours and
storage in Skydrol (hydraulic liquid used in aviation) for four
weeks. Even under these harsh environmental influences, the
bond strength did not drop significantly after the 1,000 hour
salt spray and not at all after four weeks of Skydrol. 
Pull-off-strength [N]
 Reference
 7 d 85/85
 10 d VDA
2,500
2,000
1,500
1,000
500
0
CFRP
12 | DELO-News
Lacquered
aluminum
Bare
magnesium
PP
Watch the video!
https://www.youtube.com/
user/DELOadhesives/
Tips & Tricks
Structural bonding has many advantages over
conventional joining technologies. It evenly
distributes tensions, and balances tolerances of
the parts while simultaneously bonding and sealing
components. To take full advantage of their potential,
adhesives should be considered early on in the
design phase. Achieving a perfect component design
increases the performance of a bond, accelerates the
production process and saves money.
ew materials and designs often require the use of
adhesives. Current material trends that foster adhesive
bonding are composite materials like carbon fiber
reinforced polymers (CFRP), glass fiber reinforced plastic
(GFRP) and various multi-material designs. Welding, screwing
and riveting are still good joining methods. However, they don’t
always create a reliable and durable connection. For example,
they are dependable for steel-to-steel or aluminum-toaluminum joining, but less reliable for polymers and multi-metal
mixes like steel to aluminum.
A typical mistake, made time and time again, is intending
to bond a component, which has already been screwed
or welded, without adapting its geometry accordingly. This
can cause problems in many areas, including adhesive
dispensing, joining of materials and bond strength.
Despite the advancements in bonding technology to
increase adhesion success, this science still remains on the
back burner of many engineering studies. Typical mistakes
made by engineers not familiar with bonding techniques, in
N
14 | DELO-News
the trial and error phase, can be easily avoided with some
upfront education.
The right bond makes all the difference
When choosing between an adhesive or a joint with a screw
or weld, the one main difference to remember between these
joining techniques is that the forces applied from an adhesive
effect the entire bonded laminar area, not just isolated
(punctual or linear) areas, as is the case when locking
with a screw or a weld.
That’s why it is important to note that you cannot
interchange screwing and welding with adhesive on the same
project. It won’t work. It won’t produce the strength needed to
hold the bond.
Take for instance two metal sheets measuring 1 ft. long
by 1 ft. wide that need to be joined. Only a small area of the
metal sheets need to be overlapped when welding or screwing
them together. Whereas, an area this small is not sufficient for
bonding. To achieve a strong bond, the components would
need to be designed to overlap a larger area. The larger
bonding surface results in a stronger bond with tension spread
more evenly throughout the components. (Figure 1)
Fig. 1: Enlargement of the bonding area
Tips & Tricks
Enlarging the bonding area depends a great deal on the
forces that arise in the actual application. Often, eccentric
force transmission is to be expected. As this force does not
act on one axis, it rotates to get balanced on the next axis,
causing a torque that results in peel stress.
Should this occur, an alternate to an overlap joint, is
tongue and groove. Similar to the dovetail design long used
in woodworking, tongue and groove joins and locks two
components together, making it more difficult for them to bend
or come apart. (Figure 2)
Fig. 2: Tongue and groove joint – important remedy of peel stress
As noted previously, when a structure originally constructed
to be welded will then be bonded, the design should be
modified. Although the adhesive will deliver proper tensile and
compression strength values, the occurrence of a slight peel
stress will lead to instability in the structure (Figure 3)
To overcome the design challenge in this example,
designers can use a larger cylindrical base along with a preengineered borehole in the baseplate. This will create a round
tongue and groove joint.
Fig. 3: If a welded joint is replaced by bonding, the design
should be adapted
And even though the magic word for structural bonding
seems to be “tongue and groove”, there are several other
design possibilities. Find out what they are in the second
half of this article in the next edition of DELO-News.
For more information or application-oriented training,
please contact the DELO Academy at academy@delo.de. 
DELO-News | 15
Technology
New Surface
Pretreatment Method
Stainless Steel Can Now Be Bonded in an Eco-friendly Manner Using Lasers
Stainless steel bonding made easy with lasers
t is well known that bonding stainless steel is very difficult,
and that permanent, reliable bonds are only possible with
pretreatment. Consequently, wet-chemical or tribochemical
methods such as the DELO-SACO process (sandblast
coating) have mostly been used until now. However, recent
tests have shown that components subjected to an intensive
laser pretreatment achieve tensile shear strength values
almost as high as DELO-SACO-treated components.
I
For this reason, lasers will become more important
despite the current high investment costs, as they
also enable in-line processes in production and
selective treatments. This requires no additional use
of consumables, which are still subject to labeling
requirements in conventional wet-chemical pretreatment
methods. 
/D\HURIGLUW
Tensile shear strength [MPa]
25
20
15
10
Degreased
Degreased, SACO
Laser
5
0
No aging
16 | DELO-News
Simulated aging
(500 h, +85 °C, 85 % r. h.)
Technology
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Advantages






Cleaning and pretreating are performed
in one work step
Bond strength comparable with
conventional pretreatment
High process reliability with automated
process
Selective pretreatment
Low running costs
Safe for users and the environment, as
no harmful substances are required
DELO-News | 17
Technology
PEEK Bonding
Withstands Strict
Environmental Conditions
Bonded VESTAKEEP® PEEK L4000G from Evonik Industries withstands strict operating environmental
conditions when DELOMONOPOX epoxies are used. This is the result of joint tests of Evonik and DELO.
onding high-temperature resistant, high-performance
thermoplastics such as PEEK (polyetheretherketone)
has been challenging for plastic manufacturers. In
general, PEEK possesses very low surface energy which leads
to poor wettability characteristics. As a result, the surface
is extremely resilient to chemical reaction and this makes
bonding PEEK a very difficult process. However, recent test
results have demonstrated that VESTAKEEP® PEEK L4000G
can be bonded very well using a heat-curing DELOMONOPOX
adhesive which was specifically designed to bond plastics.
B
High Bond Strength With or Without
Pre-plasma Treatment
To measure the bond strength of PEEK, the components
were exposed to a compression shear test after the
components were stored for 14 days at +85 °C with 85 %
humidity. When the component surfaces were pre-treated
with atmospheric pressure plasma, the compression shear
strength value was as high as 40 MPa. In a separate test
in which the component surfaces were not pre-treated
with plasma, the compression shear strength still attained
a value of approximately 20 MPa. Although this result is
lower compared to the plasma-treated component test, the
customer can benefit from a simplified production process
and lower overall manufacturing costs.
“The combination of PEEK and our epoxy-based
adhesives is a marriage of high-performance materials”,
explains Gudrun Weigel, Head of Engineering at DELO.
“The excellent bonding quality is demonstrated by the
fact that the test object was deformed before the bonding
failed during compression shear testing. These results
have opened up a whole range of new application areas”.
PEEK bonding is likely to benefit the aerospace industry
in the design of modular components. In the automotive
sector and from the mechanical engineering’s design
point of view, the PEEK bonding system offers
solutions for sealing challenges. 
Become an expert
with the new BOND it!
The 3rd English edition of the Reference Book on Bonding Technology is now available.
The BOND it provides everything worth knowing about adhesives in one handbook. The
new BOND it will answer all of your questions about adhesive-friendly design, pretreatment,
production processes, and many more.
What is new?
256 pages filled with expertise
One newly designed chapter
“Applications in specific areas”
Glossary, info boxes and tips from experts
http://www.delo.de/
en/bond-it/