Abstract: The effect of two packing modes, constant pressure and pressure-temperature control (PT control) on the accuracy of part's weight were studied under three filling-to-packing switchover modes, transfer controlled by injection time, screw position, and cavity pressure. In PT control, the holding pressure was decided by cavity temperature. It showed that the PT holding mode resulted a better part surface quality and uniform part weight than traditional methods. When the switchover mode of cavity pressure and PT control were used, the accuracy of part's weight was the best, which reach 0.0665 %.

Key words: injection molding, parts' mass uniformity, paching mode, switchover mode, temperature control