Characterisation of a measurement system for reproducible friction testing on sheet metal under plane strain

The testing equipment can compromise the quantification of the friction on sheet metal. This paper focuses on a systematic analysis of the testing equipment as a measurement system of the friction phenomena. It is shown that the mechanical response of the system may be responsible for significant variations on the quantification of frictional effects. Historical and inter-laboratory testing data show that, upon proper design of the measurement system, friction can be quantified, reproduced, and replicated with a significant degree of accuracy. This paper discusses the requirements and the controls of the test needed to maintain the uncertainty at its minimum level. The results show the feasibility of characterising friction in order to study the effects of the sheet, lubricant, and forming tools. This study is based on tests where cyclic bending under tension resulted in significant stretching and thinning of the sheet, hilt with thr width remaining approximately constant Friction research under other sheet forming modes may however benefit from the significance of the findings presented here. (C) 2000 Elsevier Science Ltd. All rights reserved.