Partial visibility for selecting a parting direction in mold and die design

Abstract Selection of an optimal parting direction in mold and die design is considered. Based on the condition for demoldability, two levels of visibility—complete and partial—are defined for a surface. If a surface is completely visible along a certain direction, it can be separated from the mold along the opposite direction. If a surface is not completely visible and theregore cannot be separated from the mold along any direction, it can be decomposed into two portions: those that are separable and those that are undercuts; the former is based on complete visibility and the latter on partial visibility. Algorithms are given for computing the undercut volumes of a polyhedral surface with respect to a particular parting direction and for selecting a parting direction that minimizes the number of undercuts.

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