A comparison between two wear models

Two wear models are compared. The first model constitutes the classical mod el which assumes that wear is proportional to die pressure and sliding leng th, while the second model assumes that wear is proportional to the energy dissipated on the tool/workpiece contact interface. The models are applied to the counter-blow hammer forging of a pinion. The upper die cavity is fur nished with a bottleneck. Five blows are needed for forging the component. The process is analysed by full-scale experiments and a commercial FE-code, FORM2D. In order to evaluate the two models for different positions of the upper cavity, each blow is divided into a number of incremental time steps . For each of them, the sliding velocity, the contact pressure and the cont act shear stress is determined. In this way it is possible to predict which part of the upper die is exposed to the most serious conditions. Both mode ls show satisfactory agreement with the results of full-scale experiments. However, the model based on energy dissipation indicates the location of th e wear-sensitive parts of the tool more distinctively. (C) 1999 Elsevier Sc ience S.A. All rights reserved.