Position tolerancing in reverse engineering: The fixed fastener case

Abstract

The present paper addresses the assignment of geometrical position tolerances in reverse engineering. Specification of manufacturing position tolerances for a reconstructed component of an existing mechanical assembly constitutes a complicated task that requires a well-grounded approach. Among features of size, cylindrical features such as holes in conjunction with pegs, pins, or screws are the most frequently used for critical functions, as are the alignment of mating surfaces or the fastening of mating parts. The relationship between mating features is classified either as a fixed or as a floating fastener type. The presented method focuses on the fixed fastener case. It is based on the systematic formulation of dimensional and geometrical relationships and constrains that allow for rational computer-aided processing and evaluation of the measured data from the reference parts, for which appropriately developed algorithmic tools are used. It is shown that the method is reliable, provides for realistic results, and is also time and cost competent as compared with the conventional trial-and-error methods. A case study demonstrates the concept and method.