Method and apparatus for injection moulding plastics

摘要

To avoid surface defects during the production of injection moulded plastic products, the surface temperature of the metallic mould is raised above the injection transfer temperature of the plastic resin when the resin is non-crystalline or above the fusion point temperature if the resin is crystalline, using a temperature increase rate greater than 2 DEG C per second. This temperature is maintained during the resin charging period followed by cooling at a decreasing rate greater than 2 DEG C per second after the completion of charging. The temperature control is conducted using a feed back control with a detector for determining the surface temperature of the metallic mould and mounted close to the surface of the metallic mould. <IMAGE>