Application of feature technology to modeling and dimensioning the intermediate geometry of automotive powertrain components

Intermediate parts occur in between process steps during machining. In case of parts produced in high volumes, a detail documentation of intermediate geometry is required for the knowledge of operators, for gauging, as a specification for tooling design and for offline CMM programming & simulation. Currently, manually created approximate 2D drawings and/or manually created 3D models are used for representing the intermediate geometry. The commercial process planning systems provide NC code simulation technique for automatically modeling the intermediate parts. In this paper, we outline the challenges posed by this problem in case of large components in automotive powertrain. We present a system that uses feature technology to address them. The solid models of intermediate parts are generated by sequentially subtracting volumetric machining features from the cast part model and they are dimensioned using reference geometry. This system automatically generates models of intermediate parts independent of the design history and the NC code. It also makes use of the process plan data generated prior to the availability of final and cast part model.