Cinpres Gas Injection Ltd., a gas-assisted molding supplier from England, used NPE 2003 to announce it will handle North American sales of Asahi Kasei Corp.'s External Gas Molding technology.
The company also demonstrated water-assisted molding.
Unlike traditional gas-assisted molding, which uses gas to push melted plastic out against the mold walls, the EGM process injects gas between the melt and the surface of the mold. EGM produces parts free of distortions such as sink marks from ribs and bosses - especially difficult to do on large panel-type parts.
Asahi Kasei, a Tokyo-based chemicals and plastics company, owns patents covering two types of EGM molding:
* A lower-pressure process dubbed ICP, for Injection Compression Process.
* GPI, for Gas Pressure Injection, which pre-pressurizes the plastic before injecting gas between the melt and the mold surface to apply uniform pressure while the plastic cools.
EGM gives part designers more freedom to use ribs and create parts with different wall thicknesses.
Cinpres Gas Injection has hired inventor Jim Hendry as a consultant specializing in EGM. Hendry is named in many gas-assisted molding patents.
Middlewich, England-based Cinpres Gas Injection is promoting the external gas process for a range of applications, including office and computer equipment, automotive and any other panel-type moldings.
Also at NPE 2003, held June 23-27 in Chicago, Cinpres Gas Injection demonstrated its WAM brand of water-assisted molding, producing a chain saw handle with an outer diameter of 11/4 inches. The material was a 30 percent glass-filled nylon developed specifically for water assist.
The process uses a short shot of plastic, followed by the injection of water. The 40-second cycle on the chain saw handle is 35 percent faster than gas-assisted molding, the company said. Using water also reduces part weight and produces a smooth inner surface.
To exhaust the water, gas or air is injected, and the water flows out through a separate channel in the nozzle. Dubbed the Combi, the Cinpres nozzle performs all three functions - injects water, injects the gas or air and handles the controlled exhaust of the water.
A Cinpres WAM controller runs three individually operated hydraulic valves.
Cinpres offers the complete system, including the Combi nozzle and the controller, with a license to operate the equipment.
Cinpres Gas Injection's U.S. headquarters is in Ann Arbor, Mich.