Plastic is a polymer composite materials with the plasticity of materials performance in General, is based on synthetic resins as the basic ingredients, and then add ingredients to be kneading and granulating of plastic shaped material prepared. Plastic is made up of thermoplastic and thermosetting plastics. Thermoplastics: linear structure, heat can be repeatedly softened. Such as PVC, PE, PP, etc. Thermosetting plastics: stereoscopic netlike structure, heating and softening, cools hard, unrepeatable softened. Such as XLPE, etc. Plastic phase: which is the main phase of extrusion, in order to facilitate the study and control of the extrusion process, in accordance with the plastic process of continuous change of State, and plastic stages can be divided into three stages: the feeding of the (also known as broken), the melting zone (also known as plastic), pressure (also known as). Depending on the plastic variety, different manufacturers of plastic materials of different temperature requirements, this three-stage temperature control is the key to quality of extruded products.