Forming raw materials do not meet the requirements
If the molding raw material is mixed with impurities or different grades of raw materials during the packaging, transportation, preheating, and pre-drying processes, the raw material will not contain uniform or large particle sizes, and the molded plastic parts will contain foreign matter impurities. Sieving foreign material impurities in the raw materials, choose raw materials with uniform particle size. During the pretreatment and molding process, it is necessary to prevent dust and other foreign substances from mixing into the molten material from the hopper, the barrel and the mold.
(2) Improper control of process conditions
Its causes and handling methods are as follows:
A material temperature is too low, poor melt plasticization. Should raise the barrel temperature properly.
B material temperature is too high or the molding cycle is too long, the molten material degenerates. It should reduce the material temperature and shorten the molding cycle.
C mold temperature and nozzle temperature is too low to produce cold pellets. The temperature at the die and nozzle should be properly increased.
D injection molding machine lack of plasticizing capacity, plasticizing capacity close to the weight of plastic parts, making the molding time is very short. Should use a larger size injection molding machine.
E mold structure is unreasonable. If the mold's main channel and runners have no cold material or improper positioning, the cold material entering the cavity will form a deadlock in the plastic parts. In this regard, a cold material hole should be added. For direct feeding Molds, due to the lack of cold pockets, cold spots often appear in plastic parts.
In this regard, in the operation process, the cold material in the nozzle must be removed before the mold is closed. When opening the mold plastic part, the remaining cold material in the main runner should be removed to avoid the cold material entering the cavity.