The extrusion molding in the plastic mold is to make the plastic in a viscous flow state, under a high temperature and a certain pressure, pass through a die with a specific cross-sectional shape, and then form a continuous profile of the desired cross-sectional shape at a lower temperature A molding method.
The production process of extrusion molding is to prepare molding materials, extrusion molding, cooling and setting, traction and cutting, post-processing of extruded products (tempering or heat treatment). During the extrusion molding process, pay attention to adjusting the temperature, screw rotation speed, traction speed and other process parameters of the heating section of the extruder barrel and the die of the die in order to obtain qualified extrusion profiles.
In particular, pay attention to adjusting the rate at which the polymer melt is extruded from the die. Because when the extrusion rate of the molten material is low, the extrudate has a smooth surface and a uniform cross-sectional shape; but when the extrusion rate of the molten material reaches a certain limit, the surface of the extrudate becomes rough and tarnished , Shark skin, orange peel pattern, shape distortion, etc.
When the extrusion rate is further increased, the surface of the extrudate is distorted, even splitting and breaking into melt fragments or cylinders. Therefore, control of the extrusion rate is crucial.