New technology saves weight in composite structures

Until recently it has always been impossible to join aluminum to hot-formed steel. But now a new technology - resistance element welding - has achieved success. The new process has just been implemented for the first time in high-volume production, manufacturing the parcel shelf for the VW’s Passat B8 sedan.

It takes time and skill to develop and implement lightweight construction solutions that can be used in series production. It’s well worth making the effort to reduce weight, particularly in the bodywork, because the car’s body makes up around 40 percent of its weight. However, until recently there was no way of joining aluminum to deep drawing steels and heat-hardened martensitic steel. But now it has been achieved with what is known as resistance element welding (REW). In this process metallic resistance welding elements are inserted into the aluminum sheet. The traditional spot welding process within existing production systems can be used to join the aluminum sheets to steel.

“We were able to present a conclusive development concept that convinced the VW Group,” said Uwe Wolfarth, Marketing Director at ARNOLD & SHINJO.