In the injection molding process, it will often be difficult to solve the shrinkage of a certain part of the product. In this case, only the back pressure can be solved by appropriately adjusting the back pressure parameters.
The reason for using back pressure is that when the screw rotates, the heated plasticized plastic is pushed forward under the action of the screw, passes through the restrictor valve and reaches the front of the screw. Due to the advancement of the melt, the melt generates a reaction force. Acting on the screw and the restrictor valve, the screw is moved backward so that more molten material can be pushed forward. At this time, if the back pressure is adjusted, the cylinder has a certain pressure on the screw from back to front, providing The resistance of the screw back, the greater the back pressure, the longer the screw reset time, the pressure generated by the melt at the front of the screw must be greater than the back pressure to make the screw back. It must be pointed out that not all injection molding production must use back pressure, but if back pressure is adopted, the plastic can be fully melted and mixed evenly.
There are more advantages to using back pressure in the injection molding process:
1. Conducive to the discharge of volatile gas in the melt.
Second, make the additive and the molten material mix more evenly.
Third, make the plastic plasticization more uniform and so on.