What are the effects of mold temperature on injection molded parts

There are many factors that affect the cooling of the injection mold, such as the shape of the plastic part and the design of the parting surface, the type, temperature, and flow rate of the cooling medium, the geometric parameters and spatial layout of the cooling pipe, the mold material, the melt temperature, and the top of the plastic part. Output temperature and mold temperature, thermal cycling interaction between plastic parts and molds, etc.
Low mold temperature can reduce the molding shrinkage of plastic parts.
Uniform mold temperature, short cooling time, and fast injection speed can reduce warping deformation of plastic parts.
For crystalline polymers, increasing the mold temperature can stabilize the size of the plastic part and avoid post-crystallization, but it will lead to the defects of prolonged molding cycle and brittleness of the plastic part.
As the crystallinity of the crystalline polymer increases, the stress crack resistance of the plastic decreases, so it is advantageous to lower the mold temperature. However, for high-viscosity amorphous polymers, since the endurance cracking is directly related to the internal stress of the plastic part, it is advantageous to increase the mold temperature and mold filling speed and reduce the feeding time.
Increasing the mold temperature can improve the surface quality of plastic parts. Determination of the mold temperature During the injection molding process, the mold temperature directly affects the filling of the plastic, the shaping of the plastic part, the molding cycle and the quality of the plastic part.
The temperature of the mold depends on the crystallinity of the plastic, the size and structure of the plastic part, performance requirements, and other process conditions such as melt temperature, injection speed, injection pressure, and molding cycle.
For amorphous polymers, the melt solidifies as the temperature decreases after being injected into the mold cavity, but no phase transition occurs. The mold temperature mainly affects the melt viscosity, that is, the filling rate. Therefore, for lower and medium amorphous plastics such as polystyrene, cellulose acetate, etc., lower mold temperatures can shorten the cooling time.