GEOMETRIC INFLUENCE OF A MOLDED PART ON THE DRAW DIRECTION RANGE AND PARTING LINE LOCATIONS

This paper presents a methodology based on the geometry of the injecti on molded part to identify the draw direction range and parting line l ocations. These parameters are shown to be a function of the interacti on of the outward normals of the surfaces that have been divided into concave and convex regions of the part, This approach can also be appl ied incrementally to determine these mold parameters for a part as des ign features are added. The designer can then select from the choices provided to find the optimum parting line location and draw direction using heuristic rules. An absence of an allowable draw direction indic ates the presence of an undercut that complicates the mold by requirin g a side action so that the mold cost increases. The designer can eith er redesign the part or accept the undercut by specifying a side core or cavity. Design examples are provided which illustrate the effective ness of the developed approach.