OPTIMIZATION OF THE GAS-ASSISTED INJECTION-MOLDING PROCESS USING MULTIPLE GAS-INJECTION SYSTEMS

Gas-assisted injection moulding has shown considerable advantages in t he production of complex hallow parts in the plastics industry. This p rocess is capable of reducing the pressure requirements as well as the shrinkage/warpage of the part and the cycle time. Due to gas-polymer interaction during the gas injection phase, the process has significan tly different characteristics from conventional injection moulding and , therefore, the control of the process requires a solid technical kno wledge in processing and materials. In this study the authors have dev eloped a numerical model capable of predicting the gas penetration usi ng multiple gas-injection units. The pressure and gas-injection durati on of these units can be controlled independently to obtain the optimu m gas penetration and to avoid undesired gas penetration into the sect ions. The advantages of using this kind of system are shown through th e analysis of an experimental part with three independent gas channels . (C) 1997 Elsevier Science S.A.