Welding or Adhesive Bonding — is this a question for the future?
Modern light-weight structures are composed of most different materials. The joining of these materials with and among one another requires the application of different joining techniques with the focus on welding and adhesive bonding. In this paper, the advantages of both methods are discussed an...
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Інститут електрозварювання ім. Є.О. Патона НАН України
2013
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| Цитувати: | Welding or Adhesive Bonding — is this a question for the future? / U. Reisgen, M. Schleser // Автоматическая сварка. — 2013. — № 10-11 (726). — С. 38-42 — англ. |
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Reisgen, U. Schleser, M. 2016-06-14T17:48:45Z 2016-06-14T17:48:45Z 2013 Welding or Adhesive Bonding — is this a question for the future? / U. Reisgen, M. Schleser // Автоматическая сварка. — 2013. — № 10-11 (726). — С. 38-42 — англ. https://nasplib.isofts.kiev.ua/handle/123456789/103214 621.791/621.792 Modern light-weight structures are composed of most different materials. The joining of these materials with and among one another requires the application of different joining techniques with the focus on welding and adhesive bonding. In this paper, the advantages of both methods are discussed and possibilities for the combined application of welding and bonding techniques are presented. en Інститут електрозварювання ім. Є.О. Патона НАН України Автоматическая сварка Пленарные доклады Международной конференции Welding or Adhesive Bonding — is this a question for the future? Сварные или клеевые соединения — является ли это вопросом будущего? Article published earlier |
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Welding or Adhesive Bonding — is this a question for the future? |
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Welding or Adhesive Bonding — is this a question for the future? Reisgen, U. Schleser, M. Пленарные доклады Международной конференции |
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Welding or Adhesive Bonding — is this a question for the future? |
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Welding or Adhesive Bonding — is this a question for the future? |
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Welding or Adhesive Bonding — is this a question for the future? |
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Welding or Adhesive Bonding — is this a question for the future? |
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welding or adhesive bonding — is this a question for the future? |
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Reisgen, U. Schleser, M. |
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Reisgen, U. Schleser, M. |
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Пленарные доклады Международной конференции |
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Пленарные доклады Международной конференции |
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2013 |
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English |
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Автоматическая сварка |
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Інститут електрозварювання ім. Є.О. Патона НАН України |
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Сварные или клеевые соединения — является ли это вопросом будущего? |
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Modern light-weight structures are composed of most different materials. The joining of these materials with and among one
another requires the application of different joining techniques with the focus on welding and adhesive bonding. In this paper,
the advantages of both methods are discussed and possibilities for the combined application of welding and bonding techniques
are presented.
|
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https://nasplib.isofts.kiev.ua/handle/123456789/103214 |
| citation_txt |
Welding or Adhesive Bonding — is this a question for the future? / U. Reisgen, M. Schleser // Автоматическая сварка. — 2013. — № 10-11 (726). — С. 38-42 — англ. |
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2025-11-26T04:43:21Z |
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38 10-11/2013
UDC 621.791/621.792
WELDING OR ADHESIVE BONDING –
IS THIS A QUESTION fOR THE fUTURE?
U. REISGEN, M. SCHLESER
RWTH Aachen University, ISf Welding and Joining Institute, Germany. E-mail: office@isf.rwth-aachen.de
Modern light-weight structures are composed of most different materials. The joining of these materials with and among one
another requires the application of different joining techniques with the focus on welding and adhesive bonding. In this paper,
the advantages of both methods are discussed and possibilities for the combined application of welding and bonding techniques
are presented. 5 figures.
K e y w o r d s : laser beam welding, plasma soldering, friction stir welding, adhesive bonding, steels, aluminium alloys, auto-
motive car body, advantages of methods
Introduction
The joining technology is an interdisciplinary
technology which allows the combination of parts
which have most different geometries and which
are consisting of a wide variety of materials towards
complex structures and products.
Riveting has been the dominating joining technol-
ogy of the 19th century. Numerous impressive struc-
tures serve as demonstration, for example, the Eiffel
tower with more than 2.5 million rivets. In the course
of the 20th century, riveted structures were increasing-
ly replaced by welded structures. The production of
welded structures is, on the one hand, economically
more efficient and the structures have, on the other
hand, a higher strength. Besides welding, the adhe-
sive bonding technology is, nowadays, increasingly
used for many applications.
A major advantage of welding compared with ad-
hesive bonding is its advance of several decades in
research and industrial application. The welding tech-
nology is for many joining tasks still the called-for
method.
Particularly for thick-walled welded structures which
are joined on butt joint, T-joint or cruciform joint, the
application of the welding technique is unrivalled. In
this field, also methods which are as-
sumed to be out-of-date, such as elec-
tro-slag welding, can be applied with a
high efficiency. figure 1 depicts an im-
pressive example.
for the manufacturing of a large
press, a steel sheet structure has been
chosen instead of a cast structure. The
steel sheet structure was manufac-
tured with particularly lesser quantities
of material and was, thus, much more
cost-favourable. However, this type of
structure required to join the large-for-
mat steel plates with one another. Each plate had a
thickness of several centimetres. As a standard weld-
ing technology for this task, multiple-pass submerged
arc welding has been applied with a production dura-
tion of three up to four weeks just for the weld. The
application of electroslag welding allowed a reduc-
tion of the welding time down to 14 hours, compare
figure 1.
In working with modern designs it is often not pos-
sible to apply just one welding method. They are often
characterized by the use of many different materials
such as different steel grades, aluminium or fibre rein-
forced plastic. This applies in particular to light-weight
structures. The production of these applications requires
the control over the entire band width of industrially
available joining methods in order to identify and qual-
ify the best solution for a specific design under specific
production boundary conditions.
The complexity of this task can be clarified by the
example of automotive car body design. In the fol-
lowing text this example is used to discuss the ques-
tion which technology will prevail in the near future:
adhesive bonding or welding technology.
© U. Reisgen, M. Schleser, 2013 figure 1. Electro slag welding of large components for presses
3910-11/2013
Requirements of modern light-weight structures
to the joining technique, using the example of the
vehicle body construction
In the beginning of the automobile large-scale
production, complex structures such as the car body
have been joined using a few simple welding meth-
ods. figure 2 (left) shows the example of the car body
of a VW beetle from the fourties of the last century.
The car body has almost exclusively been made using
resistance spot welding, supplemented by gas metal
arc welding to a small degree. This is, nowadays, un-
thinkable. Besides increased demands made to corro-
sion protection, strength and production speed, also
the application of most different materials for a car
body is, here, particularly responsible.
In the nineties of the last century, aluminium
car bodies were to an increasing level introduced
to the market and, as a consequence, also alumini-
um-steel hybrid design structures. Besides this, also
pure steel bodies are, nowadays, in principle materi-
al mixed constructions. Other than in the car body of
the VW beetle where mainly two steel sorts, DC 01
and to a certain degree also DC 04, have been used,
modern steel car bodies are made of many different
steels, such as deep-drawing steels, high and high-
est-strength steels and hot-formed steels. Besides this,
also fibre-reinforced plastic materials are increasingly
gaining in importance in the field of automotive car
body construction.
from the perspective of joining, the following im-
portant challenges result:
1. Joining of materials which are difficult to
weld, e.g. highest-strength steels with a defined
micro-structure,
2. Joining of multi material-mixed compounds,
e.g. steel-aluminium, steel-CfK,
3. Joining of complex geometries, e.g. combina-
tion of plates, profiles, sandwich.
These requirements can no longer be fulfilled with
only one joining method. for the production of mod-
ern car bodies, therefore numerous joining methods
are applied. Besides the established methods resist-
ance spot welding and arc welding, also “younger”
welding methods such as laser beam welding, me-
chanical joining techniques such as clinch riveting
and riveting also also adhesive bonding are applied,
compare figure 2 (right).
Adhesive bonding vs. welding
Propelled by the request to apply also materials
which are difficult to weld or even multi material
compounds, research about alternative joining tech-
niques has been promoted. The focus is, on the one
hand, on the mechanical joining techniques and, on
the other hand, on adhesive bonding. Both technolo-
gies are capable of low-heat joining of most different
materials with one another.
Compared to the mechanical joining methods, ad-
hesive bonding has several process-related advantag-
es. Adhesive bonding allows the production of opti-
cally excellent, leakproof joints with a good corrosion
protection and a favourable load transmission using a
big joining area. In order to use the advantages also
under the high requirements of automotive serial pro-
duction, several generations of adhesive develop-
ments had been required. The most important devel-
opments comprise:
1. The washout resistance — modern car body ad-
hesives are, also in the non-cured state, not washed
out in the paint bath of the cataphoretic immersion
priming.
2. The oil tolerance — modern car body adhesives
are capable to develop good adhesion also on oiled
sheets. The expenditure for surface preparation is thus
drastically reduced.
3. The crash resistance — modern car body adhe-
sives do not suffer brittle failure despite high stiffness
and strength. Through the embedding of elastic do-
mains into the stiff matrix, the stress-strain diagram
of the adhesives has, in the beginning, a high elastic
modulus and transforms in the crash case on a high
load level into a deformation plateau.
Due to these developments, the application of ad-
hesive bonding technology in vehicle car body pro-
duction has, meanwhile, become a standard. The
figure 2. Conventional steel design (left) and modern aluminium-steel-hybrid design (right)
40 10-11/2013
adhesive bonding technology is, thus, directly com-
peting with the welding technology. When working
with materials or material mixed compounds which
are difficult to weld, the advantages of adhesive
bonding will become obvious, also for laypersons.
But also pure metal joints are, to an increasing de-
gree, adhesively bonded.
As far as structural tasks are concerned, adhesive
bonding is preferentially applied together with spot
welding. Attention must be paid to the fact that the main
loads are transmitted from the adhesive layer. from the
point of mechanics, the weld spots are, above all, min-
imising the peel load which is unfavourable for adhe-
sively bonded joints. The main reason for the applica-
tion of spot welding is to guarantee a sufficient handling
strength and stiffness of the car body during the produc-
tion process for the period between adhesive application
and adhesive curing.
Having the many advantages of adhesive bonding in
mind, the question arises where the welding technology
is superior to adhesive bonding. It applies to the joining
of metal materials: Adhesive bonding requires a certain
expanse in order to transmit the necessary forces. The
strength of polymer adhesives is by at least one order
of magnitude lower than the strength of metal materials.
Especially in the case of only small flange widths or if
plate geometries are not to be joined overlapping but on
butt joint, the application of welding technology is rec-
ommendable. Welding allows, moreover, joining under
high thermal load, a robust manufacturing process under
rough conditions and the application of established re-
pair concepts.
furthermore recent developments in the field of
welding meet the demands for low expenditure for
devices, high productivity and lowest-possible influ-
encing of the base material by a defined heat input.
The latter is explained especially from the request
to weld also light-weight materials, such as high-
strength steels, aluminium or even mixed compounds
with good joining properties.
In the field of arc welding, increasingly controlled
short-arc processes are applied. Those processes are
capable of a defined heat input and allow thus even
the joining of aluminium and steel. In the field of la-
ser technology, solid-state lasers which allow high
production speed with, at the same time, excellent
beam qualities, are applied to an increasing degree.
Remote welding processes where the laser beam is
deflected via a scanner system with extreme speed,
allow meanwhile to achieve welding speeds of up
to 20 m/min almost without downtime. for the join-
ing of heat-susceptible materials which lose their
good properties permanently through fusion welding,
meanwhile joining technologies are used which are
capable of working below the fusion temperature, for
example ultra-sonic welding or friction stir welding.
figure 2 makes clear that welding technologies,
to a certain degree also mechanical joining methods
and also the adhesive bonding technology all have
their place with good cause. If sufficient flange are-
as are provided and especially if materials which are
difficult to weld and material compounds are to be
joined, the increasing degree of application of adhe-
sive bonding is anticipated.
Since the advantages of both methods are well
complementing one another, it is an interesting ques-
tion whether, in future, better combination possibili-
ties may be found for both technologies. A good ex-
ample for a successful implementation of this idea is
the above-mentioned resistance spot welding adhe-
sive bonding.
Adhesive bonding + welding
In resistance spot weld adhesive bonding, welding
and adhesive bonding are combined within one join-
ing zone. While the adhesive bonding guarantees high
strength values, stiffness and a good corrosion protec-
tion, the resistance spot welding provides above all
for the minimising of the peel load and for a high ini-
tial strength immediately after the joining process.
The ISf Welding and Joining Institute at RWTH
Aachen University (ISf) is working intensely on the
development of further possibilities for combining
welding and adhesive bonding. Thus, among others,
the combination of laser beam welding and adhe-
sive bonding and also the combination of friction stir
welding and adhesive bonding have been developed
and investigated. Both methods will be presented in
the following.
Laser beam welding + adhesive bonding
Laser beam welding allows the production of
high-quality welded seams with a small heat affect-
ed zone at high production speeds. Besides the high
investment costs for an industry-standard laser in-
cluding safety devices, the required clamping devices
for a specific joining task represent a substantial cost
factor.
In cooperation with the TU Braunschweig to-
gether with partners from industry, the ISf has com-
bined the processes laser beam welding with adhesive
bonding. While in spot weld adhesive bonding, the
bonded seam carries the main load and the weld spots
serve mainly for the fixation, it is, here, the opposite.
The used adhesives are pressure-sensitive adhesives.
These allow the immediate fixation without requiring
additional mechanical devices. Since it is not possi-
ble to weld straight through the adhesive layer, the
advantage of easy and inexpensive clamping comes
with larger flange widths, because a certain mini-
mum distance between adhesion and welding must be
maintained, compare figure 3.
Besides the fixation, there are also technical ad-
vantages as far as the welding process itself is con-
4110-11/2013
cerned. During the welding of galvanised sheets with
overlap joint, the degassing zinc layer often results
in pores in the weld if the sheets are pressed firmly
together. To avoid this problem a gap has to be pro-
vided between the plates which is so small that the
reliable running of the welding process is ensured
and which is, on the other hand, so large that the zinc
layer is still capable to degas reliably. Gap measures
of 0,2 x plate thickness have proven to be recom-
mendable. The clamping of plates with a defined gap
measure is extremely complex and requires expen-
sive preparation in terms of clamping devices. Here,
the combined process offers the ideal preconditions
since, via the adhesive layer thickness, it is be possi-
ble to comfortably set the degassing gap without any
additional expenditure.
Accordingly, very good weld qualities are
achieved. The advantages of the degassing gap and
of the reduced expenditure for clamping are, espe-
cially in the joining of galvanised sheets for small-
scale production, outweighing the disadvantages
of the larger flange widths and the expenditure for
the additional application of the adhesive bonding
technology.
It has, thus been possible to industrially imple-
ment this technology already during the first research
project which has been dealing with this subject.
Friction stir welding + adhesive bonding
Based on the successful implementation, the idea
has been transferred to friction stir welding. In fric-
tion stir welding, tools with a pin and a tool shoulder
are used. These tools are set into rotation, subsequent-
ly the pin is dipping into the workpiece until the tool
shoulder is reaming over the workpiece surface. Via
the mechanical rotation and the developing friction-
al heat, the material is stirred with one another below
melting temperature and firmly bonded. Process-re-
lated, very high forces are developing which, normal-
ly, require clamping devices close to the joining point
with high forces. Otherwise, there is the risk of plate
warping, figure 4 (right).
The application of the combined process allows to
weld almost completely without mechanical clamping
technology. It is from a technical point of view, more-
over, possible to join thinner plates due to the lateral
load transmission. It is even possible to weld directly
through the adhesive layer.
The applied pressure-sensitive adhesives are, at
that, pushed out and high-quality welded seams are
developing, figure 5. The strength values of the base
material are almost achieved.
further advantages, such as reduced cranny cor-
rosion are to be expected and are subject to current
research work.
figure 3. Laser beam welding combined with adhesive bonding
figure 4. Conventional friction stir welding
42 10-11/2013
Conclusion
Using the example of automotive car body man-
ufacturing, the application fields of the technologies
of adhesive bonding and of welding have been dis-
cussed. The application of the welding technology
is preferentially used for metal joints, particularly
if only small flange widths are available, plates are
to be butt-jointed, high application temperatures are
prevailing or if immediate strength under demanding
production conditions is required. If sufficient adhe-
sive surface is available, the adhesive bonding tech-
nology, on the other hand, allows the low-heat joining
of most different materials with excellent mechani-
cal properties. It is thus possible to join steels, alu-
minium alloys and fibre-reinforced plastic materials
with most different properties without loss of strength
in the base material. The application of the adhesive
bonding technology is due to the increasing applica-
tion of multi material mixed compounds currently
also strongly on the rise.
Hybrid technologies which combine the advantag-
es of both methods in one joining zone are particu-
larly advantageous. Besides the already established
resistant spot weld adhesive bonding, the ISf Weld-
ing and Joining Institute at the RWTH Aachen Uni-
versity has been developing also other process com-
binations. The combination of adhesive bonding with
laser beam welding as well as with friction stir weld-
ing was presented. Both of them offer, besides tech-
nical advantages, a considerable economical potential
through the minimisation of the required clamping
technique.
It can already be stated today, that the combined
approach between adhesive bonding and welding
holds great potentials for future developments.
Recieved 06.07.2013
figure 5. friction Stir Welding combined with adhesive bonding
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