Injection mold is working at a certain temperature and pressure. Common thermoplastic injection mold temperature is below 150 degrees, the cavity under the forming pressure is about 25 ~ 45MPa, thermoplastic engineering plastic injection molding, mold cavity pressure can be up to above 100MPa; thermosetting injection mold temperature is usually 150 to 220 degrees, the cavity pressure of about 30 ~ 70MPa.
　The flow scouring and friction cavity and runner will suffer the plastic melt in injection molding process, in the process of drawing, but also bear the grinding parts and condensed the cured material, resulting in wear and tear cavity and the flow surface, especially with glass fiber and other hard materials in the molding, wear is more serious.
　Injection mold in the work process, sometimes subject to corrosion. High temperature decomposition of plastics will be volatile corrosive gases, such as forming PVC, flame-retardant or flame type plastic (such as flame type ABS) and fluorine plastics, HCL, SO2 and HF gases under high temperature decomposition has a corrosive effect on the cavity and runner surface.