Injection-Compression Makes Thinner Parts

Injection-Compression Makes Thinner Parts

A new injection-compression technique for molding ultra-thin-walled parts is offered by Im-Pak Technologies Ltd. of Petworth, West Sussex, U.K. The Im-Pak process, launched at the NPE show in June, is the creation of Peter Clarke, developer of the Coralfoam selective-foaming process. By closing the mold at the same time that material is injected, unusual material distribution can be achieved. It is said to permit weight savings of up to 30% and cycle-time reductions of at least 25%. Im-Pak is working with toolmaker StackTeck Systems Inc. of Brampton, Ont., as a development partner. StackTeck aims to adapt the technology to multi-cavity and stack molds.

The process and special tooling design are designed to produce packaging that competes with thermoforming on a weight basis. It can make parts with profiled wall sections- allowing thicker trim and stacking shoulders with a thinner base than is possible with either thermoforming or conventional injection molding, according to Clarke.

A pre-measured dose of material is injected from a patented shooting pot while the mold is closing. The material forms a biscuit-shaped plug in the base of the cavity, which is then compressed by the core to form the part. A special sealing ring is said to prevent flash.

The process eliminates injection and hold time and permits molding at lower temperatures. It can utilize a wide range of materials, even extrusion or blow molding grades. Parts reportedly can have flow-length/thickness ratios 50% greater than with conventional molding. High-flow PP can be molded with “incredible” 600:1 ratio, Clarke says. StackTeck: (416) 749-1698, www.stackteck.com