Effect of Customization Temperature of Injection Mold on Products
There are many factors affecting the cooling of injection mould, such as the shape of plastic parts and the planning of the parting surface, the variety, temperature and flow rate of cooling medium, the parameters and space placement of cooling pipeline, the mould material, melt temperature, the ejection temperature required by the plastic parts and the temperature of the mould, the thermal cycle interaction between the plastic parts and the mould, etc.
(1) Low die temperature can reduce the shrinkage of plastic parts.
(2) Temperature uniformity, short cooling time and fast injection speed can reduce the warping deformation of plastic parts.
(3) With regard to crystalline polymers, improving die temperature can stabilize the size of the plastic parts and prevent post-crystallization, but it will lead to prolongation of the forming cycle and brittleness of the plastic parts.
(4) With the improvement of crystallinity of crystalline polymers, the stress cracking resistance of plastics decreases, so it is advantageous to decrease the temperature of mould. However, for amorphous polymers with high viscosity, it is advantageous to improve the temperature and filling speed of moulds and reduce the filling time because the resistance cracking is directly related to the internal stress of plastic parts.
(5) Mould temperature improvement can improve the surface quality of plastic parts. In the process of confirming the temperature of the mould, the temperature of the mould directly affects the filling of the plastic, the setting of the plastic parts, the molding cycle and the quality of the plastic parts. The concave and convex temperature of the die depends on the crystallinity of the plastic, the size and structure of the plastic parts, the functional requirements and other technological conditions such as melt temperature, injection speed, injection pressure and molding cycle. As for amorphous polymers, the melt solidifies with the decrease of temperature after injection into the cavity, but there is no phase transition. Mold temperature mainly affects the viscosity of the melt, i.e. filling rate. Therefore, for amorphous plastics such as polystyrene and cellulose acetate with low melt viscosity and medium melt viscosity, lower die temperature can shorten the cooling time.