Mold cavity duplicate-plate

The channels through which the plasticized material enters the gate areas of the mold cavities are called runners. Normally, runners are either hill round or trapezoidal in cross section. Round cross section offers the least resistance to the flow of material but requires a duplicate machining operation in the mold, since both plates must be cut at the parting line. In three-plate mold designs, however, trapezoidal runners are preferred, since sliding movements are required across the parting-Hne ruimer face. 

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