Elastomeric (Soft Touch) Over-molding

This page still needs to be written. What follows is gas-assist description. Plastic parts produced by gas-assist injection molding have solid skins and hollow cross sections. The polymer is short-shot into the mold. Then inert gas is injected into the melt either through the nozzles or through mold mounted injector pins. The gas forces the melt against the cold walls of the mold, forming a solid skin. Gas follows the path of least resistance (normally the thickest, hottest core sections of the part) and forms hollow areas.

Advantages over alternative methods

• Smooth outer finish, hollow core

Gas Assist Advantages

Excellent surface finish.

Reduced cycle times. (Shorter cooling times.)

High stiffness-to-weight ratio. (Heavy cross sections with hollow cores.)

Improved flow strength. (Lower injections pressures.)

Eliminates sink marks in thick parts and parts with tubular shapes.

(Internal gas pressure packs out the part.)

Lighter weight.

Lower molded in stresses.

Lower cavity pressure.

Improved dimensional stability.

Transparent parts can be produced.

Material savings (weight, cost) for thick-walled parts up to 40%