DETROIT - Injection molders of automotive components have been among the first to use die inserts and dies made of a new type of metal that is permeable to damaging gases. The material was developed by the Porcerax Division of Sintokogio Ltd. of Nagoya, Japan, and is sold as Porcerax II in this country by International Mold Steel Inc. in Erlanger, Ky.
Thomas M. Schade, vice president and general manager of International Mold, said the material is ultrapermeable and has an evenly distributed microporos-ity. He said most applications have been small inserts, generally on the core side of the mold.
``The porosity allows the gases to be extracted throughout the die surfaces, which eliminates gas-related defects like sink marks and irregular luster,'' Schade said.
Gas burning and short shots are eliminated as well, he said.
Schade said the material, priced from $80 a pound to $100 a pound, is not inexpensive. Still, since its introduction Jan. 1, International Mold has landed about 100 orders for Porcerax.
``The average mold uses one or two pounds. So for a couple of hundred bucks you've solved your venting problems,'' he said.
Dies made of the material produce items with low-gloss fin-ishes, and low gloss is considered desirable for automotive interior parts, said Tatsuhiko Katoh, chief engineer for the Porcerax Division. Parts often are painted to remove gloss, an added step in manufacturing. He and Schade discussed the new metal in the International Mold booth during the SAE International Congress & Exposition, held Feb. 27-March 2 in Detroit.
Among other characteristics attracting Detroit's attention, they said, is the fact molders are able to use etched die patterns like leather or satin. One SAE display sample was a one-piece radio speaker cover that had a delicate, almost lace-like surface pattern. Usually, that part is an assembly of several pieces.
In a paper presented at SAE, Katoh said high accuracy is possible because no air gaps form between the die surface and the resin. Other samples included an ashtray and door trim.
He said wear resistance and hardness of the die can be adjusted, depending on the resin and reinforcement to be used.
He said costs associated with the new material are more than offset by savings that come with elimination of defects and reduced manufacturing costs.
