Antec 2010 attendees learned about a new way to join plastic/metal components, without using bonding agents.
Dustin Flock, a welding and joining specialist from Germany's RWTH Aachen University, described experiments on a special machine that heats up a metal part, using conduction heating. Then a piston brings that into contact with the plastic component.
Scientists at RWTH Aachen University tested aluminum and various types of steel pretreated by sandblasting, laser-etching or lapping, Flock told attendees in a presentation at the Society of Plastics Engineers' Antec conference, held May 16-20 in Orlando. The RWTH researcher also used untreated steel for comparison.
They tried combinations of the metal with test parts from polycarbonate, nylon 6/6 and polybutylene terephthalate. They used both glass-filled and unfilled nylon and PBT.
Joining different types of material is important, especially in the automotive industry, Flock said.
The German government has funded the joining research under a program to boost the country's technology. RWTH Aachen University, in Aachen, is Germany's largest technology university.
The goal in the university's laboratory is to produce a weld with the same strength as an adhesive-bonded joint, without some of the disadvantages, Flock said in his paper. But the process is not intended to replace state-of-the-art processes such as insert molding around a formed metal sheet, he added.
Pretreating the steel improves its mechanical adhesion with the plastic part, because the plastic flows into the steel's surface and solidifies.
Flock said the highest bond strength came with sandblasted steel with glass-filled nylon 6/6. The German researchers think that is because the glass fibers mechanically bond to the rough metal surface.
However, since the shear test results were not as high as expected, that theory is not conclusive, according to Flock's technical paper.
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