Basic principle: After the raw material is heated and melted, it becomes a molten state fluid. Under the pressure of the molding machine system, the molten raw material is injected into a pre-designed mold cavity, and the product that meets various specifications and uses is taken out after cooling. In essence, it is the process of plasticizing, flowing, and cooling the material. (Plasticizing: refers to the process in which the plastic enters the barrel, softens to a flowing state after heating, and has good plasticity).