News from Molding 2000: Gas-assist PIM

In his annual summation of the major developments in gas-assist injection molding at the Molding 2000 conference, Jack A. Avery, manager of operational assets at GE Plastics, reported on investigations now under way at the Institute for Plastics Processing (IKV) in Aachen, Germany involving the application of gas assist to powder injection molding.

Avery reported that initial tests have shown that gas assist can eliminate material orientation issues because it supplies constant pressure over the flow length of the feedstock. The result is green parts that have better dimensional stability and less molded-in stress and warp.

Gas assist also has been found to cut costs by reducing the amount of feedstock required to mold a part. Thirty-four percent less feedstock was needed to mold an IKV test sample than a similar compact sample. Debinding and sintering times also were reduced. Flexural strength increased.

"Even though this investigation demonstrates that it is possible to apply gas-assisted molding to powder injection molding, processability is strongly dependent on the thermal properties of the feedstock," Avery concluded.