Cycle of gas-assisted injection molding
The cycle of gas-assisted injection can be divided into four stages: plastic injection period, inflation period, gas holding period and demoulding period.
(1) During the plastic injection period, the injection machine injects a certain amount of plasticized plastic melt into the mold cavity. The amount of plastic required shall be determined by test to ensure that the gas will not break the surface of the finished product and have an ideal inflation volume during inflation.
(2) Gas can be injected at different times in the middle or late stage of injection during the inflation period. The pressure of gas injection must be greater than the injection pressure to achieve the hollow state of the injection molding product.
(3) During the gas packing period, when the finished product is filled with gas, the pressure of the gas acting on the hollow part of the injection molding finished product is the packing pressure, which can greatly reduce the shrinkage and deformation rate of the finished product.
(4) With the completion of the cooling cycle during the demoulding period, the pressure of the gas in the mold decreases to atmospheric pressure, and the finished plastic injection molding products can be pushed out of the mold cavity.