The process of injection molding is different from that of blow molding. Blow molding is injection blowing; injection molding is injection pressure; blow molding must have the head left behind by drawing the blow pipe. Injection molding must have a gate section. Generally speaking, injection molding is a solid core body and blow molding is an empty core body.The blow molding surface is uneven.There is an air vent for the blow molding.Injection molding, or thermoplastic injection molding, in which the plastic material is melted and then injected into the film cavity.As soon as the molten plastic enters the mold, it is shaped to a certain shape by the cavity of the cold die.The resulting shape is often the final product and no additional processing is required before being installed or used as the final product.Many details, such as protrusions, ribs, and threads, can be formed in one-step injection molding.Injection molding machine has two basic components: injection device and mould closing device for melting and feeding plastic into mould.The function of the model device is that of 1: 1.The mould is closed under injection pressure.Remove the product from the injection device and melt the plastic before injection, then control the pressure and speed to inject the melt into the mold.There are two kinds of injection device: screw type preplasticizer or two-stage device, and reciprocating screw.The screw type preplasticizer uses the preplasticizing screw (first stage) to inject molten plastics into the injection rod (stage 2).The advantages of the screw preplasticizer are constant melt mass, high pressure and high speed, and accurate injection control (using mechanical thrusters at both ends of the piston stroke).These advantages are needed for transparent, thin-walled products and high production rates.Disadvantages include uneven residence time (resulting in material degradation, higher equipment and maintenance costs.The most commonly used reciprocating screw injection device does not require plunger to melt and inject plastics