What is Injection pressure mainly has three aspects.

1) push the material in the drum to move forward, and mix and plasticize the melt, and the screw must provide resistance to the flow of solid particles and molten material in the material cylinder and nozzle.2) in mold filling stage, the injection pressure should overcome the gating system and the cavity of plastic flow resistance, and makes the molten material gain enough mold filling velocity and flow length, make molten material before cooling cavity.3) in the holding stage, the injection pressure should be compacted melt in cavity, make into the cavity of the molten material melt into an organic whole, and the molten material due to cooling contraction of fill material, keeping plastic precise shape, obtain the required performance.