The sprue bushing performs two functions, first it provides a flow channel for the plastics to flow from the machine to the mold parting line. Second, it acts as a seal preventing the injection pressure from causing a “Ieak” of plastics between the mold and the machine.
The sprue bushing is located on the top (“A”) side of the mold, typically in the center of the A plate. It is also centered inside the locating ring.
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