The Practical Approach to Freeform Shape Elements Reverse Engineering

Abstract

Element geometry can be restored with basic measurement techniques. However if the element geometry is too complex (free form surfaces), it is not possible to take all measurements in that way. Example presented in the paper is a drop forged element (car suspension link). In situation when spare element is out of reach (product withdraw from market, producer technological process tooling redesign), the element can be reproduced (singularly or in series, what depends on producer). Reconstructed element is slightly different from a master element (impossible existence of reliably identically designed and manufactured parts), because of measurement uncertainty. Another problem is that original element is usually worn out or during disassembly process can be damaged, so it has different geometry,(when worn out is not fitting to tolerances) than newly manufactured one. The practical approach for reverse engineering is based on: measurement uncertainty extrapolation, 3D part scanning, transformation of point cloud to solid model, composition examination of an alloy. The method is a complex solution that brings: geometrical description and material assignment and heat treatment. Important part of the method is typical measurement techniques. In cases when tolerances have to be preserved, additional tolerance assignment is needed according to linkage between redesigned part of element and parts of other elements in assembly. The insurance of measurement was checked according to typical tolerance of the drop forged element. The retrieved 3D model was compared with virtual mass to real master element mass. The technological tooling reconstructed prototype and element reconstructed prototype have been made. Finally the alloy material is assigned according to measurement result analysis (electron spectroscopy EDS). Proposed example shows many important clues that can be used in order to provide properly redesigned element.