The gas-assist injection process provides the designers of molded parts with a high-performance tool which makes it possible to produce parts of high quality and in a reproducible manner that cannot be produced by the standard injection molding process. A number of specific rules need to be observed during the design phase. It is particularly important to check the suitability of the part for the gas injection technique before the decision is taken to construct the mold. Part geometry will only be suitable if the gas channels have been specifically dimensioned to ensure propagation of the gas.

There are basically two design categories for the gas-assist injection molding technique, rod-shaped parts and panel-shaped parts. Rod-shaped parts have very thick cross sections and include articles such as handles, pedals, armrests and structural components. Panel-shaped parts are large area moldings that utilize ribs with gas channels to improve part stiffness and include articles such as automotive trim and business machine housings.