Analysis of the asymmetric upsetting test with extremely high strain rate as tool for friction measurement

The upsetting of flat plates offers a way to analyse friction conditions in the interface area between tool and workpiece with regard to surface microstructure, lubrication, and material properties. If a plate is compressed between two punches and the friction conditions at both interfaces are different, the billet bends over at both sides of the punches. The final angle is a measure for the friction difference. In traditional friction tests the forming speed is too low or the specimen is deformed only at the surface. In most metal forming processes, e.g. rolling, friction conditions cannot be described precisely because of the unknown behaviour of the lubricant at high pressure or high deformation speed. The advantages of the test proposed here are simplicity, full deformation, and feasibility with high speed. The process is cost effective and does not require large scale equipment. (C) 1998 Elsevier Science S.A. All rights reserved.