The arrows on the picture represent the plastic flow from the nozzle of the injection molding machine through the sprue gate and then radially to fill the plate cavity. This style of gate is used for a large, single cavity mold. Gating at the center gives an even flow, minimum pressure loss, and eliminates trapped air and weld lines. Disadvantages are degating and no cold slug wells.
Almost any resin/filler may be used with this style of gate since the opening of the sprue gate to the cavity is large. There should not be a problem with viscosity or filled resins.
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