welding and joining institute (isf) at jec world 2018 ... · adhesive bonding at isf ......

Welding and Joining Institute (ISF) at JEC WORLD 2018

Paris, March 06-07-08, 2018

Adhesive Bonding at ISF | JEC World 2018 | March 06-07-08, 2018

Univ.-Prof. Dr.-Ing. Uwe Reisgen | Welding and Joining Institute at RWTH Aachen

2

Working Fields and Competences in Adhesive Bonding

Selection and evaluation of the appropriate adhesive

and bonding process

Design and construction of adhesively bonded joints

Characterization and evaluation of performance

(ageing)

Surface pre-treatment before bonding, with special

focus on laser radiation and atmospheric pressure

plasma

Hybrid joints of fibre-reinforced plastics and pin

structured metals

Repair concepts for vehicles made of fibre-reinforced

plastics

Structural Health Monitoring systems for adhesively

bonded joints

Thermal direct joining with induction and conductive

resistance heating



3

Surface Pretreatment

Atmospheric pressure plasma (with process

gas, if applicable)

Low pressure plasma (with process gas, if

applicable)

Laser pre-treatment in association with partner

companies:

CO2 (10.600 nm; TEA und CW)

Nd:YAG (1064, 532, 355, 266 nm; UKP)

Blasting machines

Ultrasonic cleaning

Wet-chemical methods

Other methods, e.g. Pyrosil, SACO, flaming

© ika RWTH, SLCR

© ika RWTH, SLCR

CO2-Laser pre-treatment of FRP

components

Atmospheric

pressure plasma



4

CFRP laboratory for adhesive surface pretreatment of CFRP components

Equipment

High speed CFRP cutting machine with

suitable saw blade

Manual grinding machine with different grain

sizes

CNC 3-axis milling machine with milling

cutters optimized for CFRP for surface

contouring

Suitable CFRP vacuum cleaner for CFRP

particle

The number and size of particle

exposure is continuously

monitored and documented by

an optical particle counter



5

Testing Equipment at ISF

Processing of adhesive

1-K/2-K dosing equipment

Heating press (12 to, 300°C)

Mechanical testing equipment

Static/dynamic

Tension/compression,

(temperature control possible -130°C

up to 540°C)

Biaxial testing: tension/compression

+ torsion (static/cyclic)

Permanent load stand (temperature

control and moist climate)

peeling cleaving

F

F

F



6

Characterization of Adhesive and Surface

Tensiometer

determination of surface tension

(Wilhelmy method, Washburn method powder)

Contact angle measurement

determination of wetting behavior of surfaces

(determination surface energy, polar/dispersible portions)

Differential Scanning Calorimetry (DSC)

determination of thermo-physical adhesive properties

(melting point determination, cross-linking properties of

polymers, determination of heat capacity, crystallization, etc.)

Microscopy incl. analytics (SEM + EDX)

Material-, fracture pattern analysis

(morphology, element distribution, adhesion / cohesion

portions), Cross-linking

DSC



7

Measurement and testing technology

Aging Tests

Test climate according to standard or

requirement

Climate chambers

Salt-spray chambers

UV-chambers

Natural weathering

Laboratory furnace

http://www.tz.de/

http://revelwallpapers.net/

http://www.advopedia.de/

https://www.mietwagen-news.de/

Image: Different weather conditions



8

Initial situation

Lightweight constructions made of FRP and

metal

Adhesive bonding is the most important joining

technology for multi-material compounds

Surface pretreatments for FRP have high

process complexity

Not suitable for high-volume applications

Research objective

Laser as surface pre-treatment tool for FRP

Development of a robust adhesive bonding

process chain

Taking into account the constraints of the

automobile manufacturing holistically

BMBF- Research Project „ProPhoMuLA“ – Process-oriented process development of photonic tools for bonding multi-material lightweight structures in automobiles

The authors thank the Federal Ministry of Education and Research (BMBF) for funding the program "Photonic methods and tools for resource-efficient, lightweight design" to the sub-project "Exploration of an automated overall process" (FKZ:

13N12771). In addition, the authors would like to thank all involved project partners.

Robot

Adhesive

dosing unit

Laser System

Induction

Heating

Robot Control

3D Measurement-

system



9

AIF-Research Project “ProKleb” - Process monitoring and control for surface preparation of PUR- and thermoplastic FRP with laser

Initial situation

Adhesive bonding is the most important joining

technology for multi-material compounds

Surface pre-treatment especially for PUR- and

TP-FRP necessary for excellent and durable

bond quality

No process monitoring and control of laser

surface pre-treatment for FRP available

Research objective

Development of a controlled laser pre-

treatment process with spectrometry and

pyrometry as monitoring tools

Detection of ablation products by means of

spectrometry

Indirect control of the process via a

temperature-based process window

Achieving short process times and high

reproducibility for pre-treatment of FRP, even

for complex 3D geometries

z

Variable

parameters:

power, line

spacing, scanning

speed, etc.

Laser system for

processing the

surface

Optical detection of

surface contours

Inline process

monitoring by

surface analysis

Position-

control:

variable z-

axis

Component with

any contour

coarse contaminants

Feed direction



10

AIF-Research Project “ProKleb” - Process monitoring and control for surface preparation of PUR- and thermoplastic FRP with laser

Laser pre-treatment of FRP part with contaminations Results of inline process monitoring

High parameter without contaminations

Lower parameter with contaminations



11

AIF-Research Project “Key technologies for SMEs - Interactive workshop of the future for electric vehicles in FRP”

Initial situation

Need for FRP in automotive industry to

reduce the weight

Previous repair of FRP: generous

exchange of components

High cost and environmentally

questionable

Objective

Cost- and resource-efficient repair of FRP

components

Innovative production- and joining

processes under consideration of vehicle

workshop-conditions[Auto Zeitung]

[Auto Zeitung]

The IGF-projects 18.757N, 18.758N and 26LN of the research association "Vereinigung zur Förderung des Institutes für Kunststoffverarbeitung in Industrie und Handwerk an der RWTH Aachen e.V.” is funded through AiF within the framework of the

industrial collective research programme (IGF) by the Federal Ministry for Economic Affairs and Energy on the basis of a decision by the German Bundestag.

Damageassessment &

evaluation

Simulative design &

illustration of the damaged

area

Methods for economic

repair: Manufacturing

& joining process for

repair patches

Competences of bonding technology:

• Structure machining processes (e.g. milling,

grinding) scarf

• Surface preparation methods

• Joining processes to bond the repair patch



12

The IGF-project 19158 N/2 of the research association “DECHEMA Gesellschaft für Chemische Technik und Biotechnologie e.V." is funded within the framework of the industrial collective research programme (IGF) by the Federal Ministry for

Economic Affairs and Energy on the basis of a decision by the German Bundestag.

Exemplary building for the application of structural glazing (left) and schematic representation of a

structural glazing construction (right)

www.mainairportcenter.de www.koe-chemie.de

AIF-Research Project “GlasKleben“



13

AIF-Research Project “GlasKleben“

Initial situation

Load-bearing metal-glass/glass-glass

bonding (structural glazing) in construction

requires an approval in individual cases

(German: ZiE) or general building

inspection approval

No consistent methodology for the

interpretation and reliable simulation of

these bonds available

Research objective

Derivation of a consistent interpretation

method of adhesive bonds in construction

Consideration of model- and mechanical

stress-dependent material parameters

taking into account the damage (Mullins-

effect)

The IGF-project 19158 N/2 of the research association “DECHEMA Gesellschaft für Chemische Technik und Biotechnologie e.V." is funded within the framework of the industrial collective research programme (IGF) by the Federal Ministry for

Economic Affairs and Energy on the basis of a decision by the German Bundestag.

b‘

A

B

C

b

d

c

c‘

Ten

sio

n σ

Elongation 𝜀

d‘

Loading course

1. Loading and unloading



Mullins-Effect at cycled load



14

AIF-Research Project “SmartSHM” –Efficient Health Monitoring of Structural Adhesive Bonds

Source: Henkel AG & Co. KGaA

Cross section of a rotor blade

with adhesive bonds as a demonstrator

Image correlation of adhesive bondSchematic view of adhesive bond



15

AIF-Research Project “SmartSHM” –Efficient Health Monitoring of Structural Adhesive Bonds

Initial situation

Damage inside the component/adhesive

Direct inspection difficult

Damage evaluation problematic

Tolerances in production quality

Influence of environmental and aging

processes

Research objective

Nonlinear structural analysis

Rating of hotspots

Identification of sensitive structural damage

indicators

Optimization of sensor positions

Direct damage evaluation based on the

damage indicator

Manufacturing

Defects

Undamaged

Structure

Damaged

Structure

Remaining

Lifetime

Residual

Strength

Counter-

measures

Damage

progressCalculation

Undamaged

Structure

Calculation

Damaged

Structure

Optimal

damage

Indicator

Sensor

Network

Change in

Structural

Behavior

Big

(Damage)

Small

(Defect)

SmartSHM

How are damages evaluated?

Damage

Evaluation

Intrinsic

Damage

Evaluation



16

Thermal direct joining of metals and (fiber-reinforced) plastics

Process flow:

Local resistance heating of metal

Conductive heating and melting of the plastic at the

contact surfaces

Wetting of the metal through plastic melt

Key Parameter:

Material combination and surface pretreatment

Joining temperature

Joining pressure

Process time

Pneumatic

cylinders

Counter holder

(cooled)

Ring-

electrode

Spot-

electrode

Connections for

power supply

Advantages:

No need for an additional adhesive

Process times < 15 sec

High bond strengths up to 25 MPa

Steel – PA 6

Sample



17

Equipment for thermal direct joining

Experimental set-up induction technique

Principle induction technique

p

Q Induction

coil

PlasticMetal

Experimental set-up resistance heating

Principle resistance heating

PlasticMetal

Elektrodes

Pressing tool

Displacement sensor

Sample holder

i

Plastic

Metal

Electrodes

p



18

Advanced joining technologies for hybrid composites of FRP and metal

AIF-Research Project

„SMMJ – Smart Multi Material Joint“

AIF-Research Project

„Welding-Island“



19

AIF-Research Project „SMMJ – Smart Multi Material Joint“

Process

Generating small-scale metallic interlocking elements

by a modified CMT process

Intrinsic joining process of FRP on textured steel

surface

Matrix polymer is used as an adhesive

Fibers "wrap around" Pins (FRP still malleable)

Advantages

Fibers of FRP remain undamaged

Power flow remains undisturbed

Force is transferred into deeper layers of the

laminate

Form-fitting elements allow ductile failure behavior

Joint can be monitored by an integrated sensor

system

Hybrid

composite

of concrete

and metalHybrid composite

of CFRP and metal

Different

pin geometries

Picture: opportunities

by the use of CMT-Pins

The IGF-project 17971 N/2 of the research association "Forschungskuratorium Textil e.V." and “Forschungsvereinigung Stahlanwendung e.V.” is funded within the framework of the industrial collective research programme (IGF) by the Federal

Ministry for Economic Affairs and Energy on the basis of a decision by the German Bundestag.



20

AiF-Research Project „Welding-Island“

Patent pending (DE 102015013402.7)

Initial situation

Ultra fast joining techniques for hybrid material joints of

FRP and metal that do not damage the textile structure

and enable a ductile post-failure behavior

Research objective

Small-scale pins moldable in CMT-Process (Cold-

Metal-Transfer) can be integrated into a FRP to enable

multi-projection welding processes

Small-scale pins do not require fiber damage. Ultra fast

multi-projection welding processes do not harm matrix

material

Metals: titanium, aluminum, steel

Quasi-homogeneous force transmission into deeper

fiber layers

Ductile post-failure behavior (fail-safe backup) enables

residual load capacity for countermeasures



21

Basic Seminar Adhesive Bonding at ISF RWTH Aachen

Booking details

English course: September 12th, 2018

German course: September 13th, 2018

Course fee: 580 € (incl. snacks & beverages)

Event location: Aachen, Germany

Binding application: [email protected]

Content-related questions: [email protected]

+49 (0)241/80 - 96275

Thank you for your attention!

ISF - Welding and Joining Institute

RWTH Aachen University

Pontstraße 49

52062 Aachen

Germany

Tel.: +49 (0)241 80-93870

Fax: +49 (0)241 80-92170

E-Mail: [email protected]

www.isf.rwth-aachen.de

Your contact:

Mr. Josef Weiland

Adhesive Bonding Technology

Phone: +49 (0)241/80-96275

E-Mail: [email protected]

welding and joining institute (isf) at jec world 2018 ... · adhesive bonding at isf ......

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