Before doing the next injection, the screw of injection molding machine will transfer the melt material to the front of the barrel by rotation, and the screw will rotate back while conveying the material to the back pressure generated by the front part of the barrel and retreat. For adjustment and control The way the screw retracted can add a certain pressure to the screw opposite to the melt material, which is the back pressure.
The screw’s back pressure can improve the melting effect of the material, and at the same time ensure the complete filling of the melt material in the front of the screw to improve the correctness of the injection metering.
If the back pressure is too high, it will cause a decrease in the material handling capacity, and the temperature will rise due to the increase of the friction heat. On the contrary, the low back pressure will cause the measurement of the injection volume to be inaccurate.