Plastics can be divided into two categories according to their own properties: a thermoplastic which can be repeatedly subjected to melt molding processing to substantially maintain its characteristics, and a thermosetting plastic which can be melt-molded only once. According to its use, it can be divided into general-purpose plastics with wide surface area, low price and good comprehensive performance, such as PE, PP, PVC, PS, and amine-based plastics. It has good physical and mechanical strength and may be used instead of metal on construction machinery. Engineering plastics such as: ABS, nylon, polyester, POM, TPX-1, etc. And a class of engineering plastics that are particularly excellent in a certain performance, such as: special plastics with particularly good radiation resistance, high temperature resistance, etc., such as: polyaryl sulfone, liquid crystal polymer, and the like. The thermoplastic can be classified into two types, an amorphous polymer and a crystalline polymer, depending on the crystal size of the thermoplastic resin.