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русскийExtrusion
It is a molding method in which the plastic in a viscous flow state passes through a die with a specific cross-sectional shape at a high temperature and a certain pressure, and then is shaped into a continuous profile with the desired cross-sectional shape at a lower temperature. The production process of extrusion molding is preparation of molding materials, extrusion molding, cooling and shaping, traction and cutting, and post-processing (quenching and tempering or heat treatment) of extruded products. In the extrusion molding process, pay attention to adjusting the temperature, screw revolutions, traction speed and other process parameters of each heating section of the extruder barrel and the die in order to obtain qualified extrusion profiles.
Special attention should be paid 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 will become rough and tarnished , appear shark skin, orange peel, shape distortion and other phenomena. When the extrusion rate was further increased, the extrudate surface was distorted and even fragmented and fractured into melt fragments or cylinders. Therefore, the control of extrusion rate is very important.
Special attention should be paid 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 will become rough and tarnished , appear shark skin, orange peel, shape distortion and other phenomena. When the extrusion rate was further increased, the extrudate surface was distorted and even fragmented and fractured into melt fragments or cylinders. Therefore, the control of extrusion rate is very important.
Injection molding
Also known as die casting. It is to add plastic raw materials into the preheated feeding chamber, then put the pressure column into the charging chamber to lock the mold, and apply pressure to the plastic through the pressure column. The plastic melts into a flowing state under high temperature and high pressure, and enters the cavity through the pouring system. It gradually solidifies into a plastic part. This molding method is also called transfer molding. Injection molding is suitable for plastics that are lower than solid plastics and can be compression molded in principle, and can also be molded by injection molding. However, it is required that the molding material has good fluidity in the molten state when it is lower than the curing temperature, and has a larger curing rate when it is higher than the curing temperature.
