August 17, 1998 Design News
Mold-steel vents gas
John Lewis, Northeast Technical Editor
Trapped gas has long been the bane of plastic molders.
It causes incomplete fills, gas burns, and knit lines,
and can ruin product quality. A new porous steel, called
Porcerax, vents trapped gasses through the plastic mold's
walls, while retaining the resin in the mold.
According to Tom Schade, VP at International Mold Steel,
"Porcerax eliminates the need for complex venting
systems normally required for fine hair-like parts such
as speaker grills or large complex assemblies such as
car doors. You don't have to build the entire mold from
Porcerax," explains Schade. Usually a small piece
(or pieces) in the right place, vents trouble-causing
gas. The material comes in two shapes--flat plates and
bars--providing a variety of design options for mold
According to Schade, choosing the right steel for the
mold is the most cost effective way to improve productivity
and quality. To this effect, the company offers several
new materials. One example is a new pre-hardened H-13
type, 40 RC mold steel called DH2F. The material reportedly
cuts fabrication costs for die and mold makers because
it machines about 30% faster than other H-13 steels
of similar hardness. "It also eliminates the need
for heat treatments," adds Schade.
Another example is PX5, a replacement for P-20, that
also machines about 30% faster, according to Schade.