DME University

Trapezoidal Runner Selection

Trapezoidal Runner - Selection

A plastic skin freezes against the cooled mold surface and causes molten plastic to flow through the center of the runner. Although the trapezoidal runner is easier to machine since it is cut into only one plate, this advantage can be outweighed by the greater flow restriction. Selection of this runner would be for a 3 plate mold or passing over a slide that would not allow a full round runner system.



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