There are many factors that affect the cooling of injection mold, such as the shape of plastic parts and the design of parting surface, the type of cooling medium, temperature, flow rate, the geometric parameters and spatial arrangement of cooling pipe, mold material, melt temperature, etc. The ejection temperature and mold temperature required by plastic parts, the thermal cycle interaction between plastic parts and molds, etc.

· Low mold temperature can reduce the molding shrinkage of plastic parts.

· Uniform mold temperature, short cooling time, fast injection speed can reduce the warping deformation of plastic parts.

· For crystalline polymers, increasing the mold temperature can make the size of the plastic parts stable and avoid the phenomenon of post-crystallization, but it will lead to the defects of prolonged molding cycle and brittle plastic parts.

· As the crystallinity of the crystalline polymer increases, the stress cracking resistance of the plastic decreases, so it is advantageous to reduce the mold temperature. However, for amorphous polymers with high viscosity, because its endurance cracking is directly related to the internal stress of the plastic parts, it is advantageous to improve the mold temperature and mold filling speed and reduce the feeding time.

· Increasing the mold temperature can improve the surface quality of plastic parts. In the process of injection molding, the mold temperature directly affects the filling of the plastic mold, the shaping of the plastic parts, the molding cycle and the quality of the plastic parts.

The temperature of the mold depends on the crystallization of the plastic, the size and structure of the plastic parts, the performance requirements and other process conditions such as melt temperature, injection speed, injection pressure and molding cycle.

For amorphous polymers, the melt solidifies with the decrease of temperature after injection into the mold cavity, but no phase transformation occurs. The mold temperature mainly affects the viscosity of the melt, that is, the filling rate. Therefore, for amorphous plastics with low and medium melt viscosity, such as polystyrene, cellulose acetate, etc., the use of lower mold temperature can shorten the cooling time.