Fraunhofer Institute for Material and Beam Technology IWS
Fraunhofer Institute for Material and Beam Technology IWS

Projects

Innovative joining technology for automated butt joining of elastomer-based cavity seals

RMS technology and adhesive bonding processes for fast joining of elastomer seals
© Fraunhofer IWS Dresden
RMS technology and adhesive bonding processes for fast joining of elastomer seals
Trade fair demonstrator with EPDM seal joined on the front side
© Fraunhofer IWS Dresden
Trade fair demonstrator with EPDM seal joined on the front side

In automotive engineering, elastomer-based EPDM cavity profiles for sealing passenger areas are state of the art and widely used in industry. In an automated process, cut-to-size or continuous semi-finished products of the EPDM profile are adhesively bonded to doors or bodywork using robot control. Finally, the cavity profile is cut and the two butt ends are joined together. The permanent elasticity of the joining zone as well as an undisturbed sealing process are essential to ensure tightness when the doors are closed.

This project was designed to develop an efficient bonding mechanism for joining ethylene-propylene-diene rubber (EPDM) profiles. Here, material-locking joining technologies using reactive multilayer systems (RMS) and adapted adhesive systems are to be developed which are suitable for butt joints in automated production.

Solution

Measurement of the pore content of an EPDM seal cross-section
© Fraunhofer IWS Dresden
Measurement of the pore content of an EPDM seal cross-section

As an alternative to previous solutions based on cyanoacrylates, the researchers investigated other adhesive systems and developed a combination of bonding and thermal joining using reactive multilayer systems (RMS). The RMSs consist of a nanolaminate of two reactive materials (e.g. Ni and Al), which, when activated, generate an intermetallic reaction and release a precisely defined heat quantity within a very short time. This process was used to locally soften the EPDM as well as to melt the additive material and thus enabled very fast and precise joining.

In addition, the project analyzed other cost-effective and efficient methods of heat input by means of heat radiation and convection for alternative adhesive systems.

Results

Frontal joining of EPDM cavity seals by means of IR radiation
© Fraunhofer IWS Dresden
Frontal joining of EPDM cavity seals by means of IR radiation

Within the scope of the project, frontal EPDM joints could be fabricated using thermoplastic adhesive films. Heating was realized by means of reactive multilayer systems, thermal radiation as well as convection. The joints met the requirements of the end users with regard to mechanical strength even under alternating climatic loads. In contrast to the heating processes by means of heat radiation or convection, the RMS joining process offers the advantage of very fast heating which can easily be dosed. The joint can thus be created within a few seconds.

Research funding

This project was carried out in close cooperation with the company ATN Hölzel GmbH.

Funding body: Saxon state ministry for economy, work and traffic
Grant reference number: SAB100283656
Funding period: 01.01.2017 to 31.12.2018