KoolGas(TM) is a range of novel gas-assisted injection moulding techniques investigated and developed at Warwick University. As an alternative the conventional gas-assisted moulding process, cryogenically cooled gas is injected into the polymer melt stream in a controllable fashion, at temperatures ranging from -20degreesC to as low as -196degreesC. As a result, heat transfer at the gas channel interface is enhanced and considerable cycle time reductions can be achieved. An overview of the process system as it has developed is presented. Also, the fundamentals of some of the methods investigated for the injection of low temperature gas is covered. One method employs the single injection of low temperature gas, using conventional gas-assisted injection moulding practices: The other methods relate to the cryogenic injection of gas in a conventional fashion and controlled manipulation of the low temperature gas during the cooling and packing stages, i.e. using time-controlled cyclic compression followed by adiabatic expansion. Cavity melt temperature profiles were measured at different locations of a test specimen and compared for the conventional gas-assisted process and the different low temperature methods. The effects of the low temperature gas on the residual wall thickness distribution and gas channel surface morphology are analysed. Finally, advantages and limitations on the application of KoolGas(TM) and current developments are presented
To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.