Abstract

This paper presents a methodology for obtaining mold configurations, defined by cavity and core geometries, with a minimum number of undercuts in a molded part. The methodology identifies optimal draw directions and associated parting line locations that minimize the number of undercuts thereby obtaining a good mold configuration. The interaction of the allowable draw ranges of the concave regions of the part determines the allowable draw direction range for the part. The allowable draw range for each concave region depends on how the constituent surfaces are grouped. This grouping determines whether the surfaces are formed by one or two mold halves, depending on the draw direction. The grouping also identifies which surfaces, if any, form an undercut regardless of draw direction. This last grouping identifies which surfaces require modification so that either a side core or a mold halves can form the surfaces. The allowable draw direction range for the part and its interaction with surfaces within the convex region defines the parting line location for the part. Once the draw ranges and parting line locations are identified, an algorithm selects the optimum draw direction and parting line location that minimizes the number of undercuts and results in a mold that is easy to make.

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