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Rapid adhesive cuRing using micRowaves and induction

Status quo

Adhesive bonding processes in virtually

all areas of industrial production require

that the adhesive curing process is rapid,

highly effective, and is adapted to the serial

production.

In addition to rapid curing using UV radi-

ation, which is only possible for substrates

that transmit light, thermally accelerated

adhesive curing is a suitable way for

integrating curing into the process chain.

The traditional supply of heat via ovens

is, however, too slow here and does not

provide location-specific or material-specific

heating.

Range of services offered by

Fraunhofer IFAM

Microwave radiation and inductive

heating offer much promise for the rapid

thermal curing of adhesives. Both methods

are being used and constantly further

developed by the Fraunhofer Institute for

Manufacturing Technology and Advanced

Materials IFAM.

The sections Adhesives and Polymer

Chemistry as well as Adhesive Bonding

Technology at Fraunhofer IFAM have exten-

sive experience in selecting and modifying

adhesives to meet the requirements of

specific processes. These adhesive systems

are used for accelerated adhesive curing,

with the focus being on the plant techno-

logy and process parameters.

In close cooperation with plant manu-

facturers we develop a solution for your

specific requirements and then integrate

the process into your production.

1+3 Microwave oven of the Fraunhofer IFAM

for qualifying curing processes.

2 Use of induction curing for selective

adhesive heating between non-metallic

components (glass/plastic).

Fraunhofer Institute for

Manufacturing Technology

and Advanced Materials IFAM

– Adhesive Bonding Technology

and Surfaces –

Wiener Strasse 12

28359 Bremen | Germany

Institute director

Prof. Dr. Bernd Mayer

Contact

Adhesive Bonding Technology

Dr.-Ing. Michael Adam

Phone +49 421 2246-542

michael.adam@ifam.fraunhofer.de

Adhesives and Polymer Chemistry

Dipl.-Ing. (FH) Andreas Lühring

Phone +49 421 2246-494

andreas.luehring@ifam.fraunhofer.de

www.ifam.fraunhofer.de

© Fraunhofer IFAM

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F R A U N H O F E R I N S T I T U T E F O R M A N U FA c T U R I N g T E c H N O l O g y A N d A d vA N c E d M AT E R I A l S I FA M

4 5

Microwave curing

The incorporation of microwave-absorbing

nanoparticles into adhesives allows subse-

quent targeted heating of the adhesive in

the joint area. The electromagnetic radia-

tion is converted by the particles into heat

and passed to the surrounding adhesive

matrix. The curing process can be carried

out at a specific location in a microwave

oven or by emitting the microwaves from

an antenna that is mounted on a mobile

robot.

For research purposes Fraunhofer IFAM

has a microwave oven (Figure 1+3) and an

antenna geometry with defined microwave

fields for qualifying materials and for initial

qualification of the process. In each case

power control is carried out contact-free by

measuring the substrate temperature.

Advantages | Significantly shorter curing time | Selective heating of the adhesive

Bonding of heat-sensitive components

Energy-saving| Versatile use

Fixed location: Microwave oven

Mobile: Antenna, e. g. on a robot| Can be used for components of very

different size

from microsystems to thick-film bonds

Induction curing

For components made of metal and

carbon fiber reinforced plastics (CFRPs),

rapid substrate heating is achieved via

induction-induced eddy currents. Specific

heating of the adhesive can also be realized

by customized formulation of the polymer.

Advanced power control allows a defined

temperature profile, adapted to the pro-

cess, to be set.

The induction unit of the Fraunhofer IFAM

not only allows feasibility studies to be

carried out tailored to your specific pro-

duction-technical requirements but also

allows the initial process parameters to be

determined.

4 Saw blade for cutting stone with adhesive

bonded cutting segments – adhesive curing

via induction.

5 Car headlight with bonded front glass

– adhesive curing via microwaves.

Adhesive curing via

Mikrowaves Induction UV Oven

Shorter curing time ++ ++ ++ –

Selective adhesive curing ++ ++ ++ –

Bonding of heat-sensitive components ++ (+) ++ –

Energy-saving ++ ++ ++ –

Adhesives with fillers ++ ++ (+) ++

Component of very different size ++ ++ ++ –

Versatile use ++ ++ ++ –

++ suitable | (+) suitable in some cases | – not suitable

Advantages | Significantly shorter curing time | Targeted local heating

Rapid heating of the substrates in

milliseconds

Energy-saving | Specific substrate or adhesive heating | Versatile use – fixed location or mobile | Can be used for components of very

different size

comparison of curing processes for adhesives