PA is a semi crystalline thermoplastic material with low density and high thermal stability. Polyamide is one of the most important and best used technological thermoplastic materials because of its unique wear resistance, good friction coefficient, excellent heat and impact resistance. In addition, polyamide also has excellent chemical resistance, so it can be used as oil resistant plastics. Due to its excellent equilibrium characteristics, PA polymer has become an ideal material to replace metals in many fields, such as automotive components, industrial valves, track insulators and other industrial applications, because its design also includes the requirements of high strength, robustness and light weight. Because polyamide plastics absorb water easily, its dimensional stability is poor compared with other engineering plastics. Polyamides have different properties, from hard and tough PA 66 to soft and easy to bend special PA. In addition to the dimensional stability of parts after processing, polyamide products will have different moisture absorption according to the type used, which will affect their characteristics. In addition, the shape of polyamide products formed by extrusion and casting is also significantly different. Extrusion molding is usually used for small but large number of processing components, while casting molding is usually used for large components with small number and subject to low internal stress. Both extruded and cast polyamides can strengthen some properties by adding fillers.
