plastic mould and custom injection moulding tips

If the plastic parts are unevenly shrinked, the internal stress distribution will be uneven. If the stress exceeds the rigidity of the plastic part, the warpage and deformation of the plastic part will be found, which will affect the dimensional stability of the plastic part. But what is warpage? When internal stress (due to uneven shrinkage) is bigger than material stiffness ,it will lead to warpage. Four reasons for uneven shrinkage: 1. The different melting temperature : the high melting temperature will lead to larger shrinkage. 2. Different cooling rates (crystalline materials): The shrinkage rate of the quick melt cooling is smaller than that of the slow melt cooling (Cause: The molecules with slow cooling rate have more time to cool down, so its amount of shrinkage is large) 3. The different flow direction of the melted (amorphous material): in short, the tensile internal force is large along the flow direction, so the amount of shrinkage is large. During the filling process,...

The temperature of the injection mold has a great influence on the filling, solidification , production efficiency, and the shape and dimensional accuracy of the plastic parts. Each kind of plastic material has a reasonable mold temperature arrange, which makes the melt flow easily fill the cavity. If the mold temperature is reasonable, the shrinkage and warping deformation of the plastic parts after demoulding will be small, the size will be stable, and the mechanical properties and surface quality will also be good. In order to control the temperature of the mold, a temperature adjusting system must be designed. Generally, the mold should be cooled or heated. If necessary, there are both needed.  In plastic injection molding, the temperature of the melt in the cavity is generally between 200 and 300 degree, the melt is formed in the cavity, cooled, and solidified into a product profile. When the injection molded product is taken out of the mold, the temperature is generally 60 d...