What is the effect of injection mold temperature on injection parts?
There are many factors influencing the cooling of injection mold, such as the shape and parting surface design of plastic parts, types of cooling media, temperature, flow rate, geometric parameters and space layout of cooling pipes, mold materials, melt temperature, ejection temperature required by plastic parts and mold temperature, thermal cycle interaction between plastic parts and mold, etc.
Low mold temperature can reduce the molding shrinkage of plastic parts
Mould temperature uniformity, short cooling time and fast injection speed can reduce the warping deformation of plastic parts
For crystalline polymers, increasing the temperature of the mold can stabilize the size of the plastic parts and avoid the phenomenon of post-crystallization, but it will lead to prolonged molding cycle and brittle defects of the plastic parts.
With the improvement of crystallinity of crystalline polymer, the stress cracking resistance of plastic decreases, so it is advantageous to reduce the temperature of mold.However, for amorphous polymers with high viscosity, because their endurance cracking is directly related to the internal stress of plastic parts, it is advantageous to increase the mold temperature and filling speed and reduce the feeding time.
Increasing the temperature of the mould can improve the surface quality of the plastic parts.The determination of mold temperature in the process of injection molding, mold temperature has a direct impact on the plastic mold filling, molding, molding cycle and plastic parts quality.
The mold temperature depends on the crystallization of plastic, plastic parts size and structure, performance requirements and other technological 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 transition occurs. The mold temperature mainly affects the viscosity of the melt, that is, the filling rate.Therefore, for the melt viscosity of low and medium amorphous plastics such as polystyrene, cellulose acetate, etc., the use of lower mold temperature can shorten the cooling time