During a recent consultation, I was asked this question…
Could you explain how to pack-out a thin-walled part which requires a large amount of pressure to fill?
In such a case, the pressure to fill the part is typically very high… therefor, the pressure at transfer is also high. In such a case, you may have to complete the part filling at a pressure approximately the same as the pressure at transfer.
In some cases, this pressure is actually higher than the pressure at transfer… depending on the amount of pressure that is necessary to fill the remainder of the mold cavity. The benefit to this is you are using just enough pressure to fill the mold cavity, which will help reduce the amount of flash which is produced.
Some processors have a tendency to fill the mold completely during first stage because they are not used to using a high second stage packing pressure.