METHOD FOR MANUFACTURING SYNTHETIC MATERIAL OBJECTS

摘要

The objects to be manufactured, particularly from partially crystallized plastic material are obtained by injecting liquid plastic material into a mould cavity through a feedhead; the plastic material is then allowed to cool and is removed from the mould. In order to obtain objects having a highly orientated crystalline structure without the need to apply extreme pressures, the temperature of the flowing plastic material during the injection operation is maintained at the most 50C above the melting point of the material or above the temperature at the start of the melting and a pressure is used at the beginning of the injection which is comprised between 1400 and 2000 bars, which pressure is maintained until the pressure inside the mould cavity falls down to a very small value following the solidification of the synthetic material. The feedhead is kept permeable and the pressure in the cavity is measured, preferably after the feedhead.