This is another installment in a series of posts on improving process efficiency. Using the appropriate transfer from 1st Stage Injection to 2nd Stage Packing will help reduce equipment wear and overall energy consumption.
Regarding Energy: When you transfer when the mold is completely full, the pressure in the barrel increases sharply. This increase is caused by the machine’s attempt to maintain the programmed screw velocity. This increase in pressure causes a significant rise in cavity pressure during injection. This rise in pressure causes the need for additional clamping force to counteract injection forces.
Regarding Process Consistency: The process should be designed to use a 5-10% short shot at the time of transfer with enough packing pressure to pack out the part without flash. When normal viscosity fluctuations occur, the process should remain short during injection while enough pressure is available during packing to fill and pack the mold. This will provide a more robust and reliable process that compensates for normal variation.