The plastic is first added to the heating barrel of the injection machine. The plastic is heated and melted. Driven by the screw or plunger of the injection machine, it enters the mold cavity through the nozzle and mold pouring system. It is hardened and shaped due to physical and chemical effects to become injection molding. products. Injection molding consists of a cycle consisting of injection, pressure holding (cooling) and plastic part demoulding processes, so injection molding has cyclical characteristics. Thermoplastic injection molding has a short molding cycle, high production efficiency, and little wear on the mold by the melt. It can mold large quantities of plastic parts with complex shapes, clear surface patterns and markings, and high dimensional accuracy; however, for plastics with large changes in wall thickness, parts, it is difficult to avoid molding defects. Anisotropy of plastic parts is also one of the quality problems, and all possible measures should be taken to minimize it.