INFLUENCE OF SURFACE-TOPOGRAPHY ON THE FRICTIONAL CHARACTERISTICS OF 3104 ALUMINUM-ALLOY SHEET

A sheet-metal forming simulator which stretches a strip around a cylin drical pin was used to investigate the relationship between friction a nd process variables including sliding speed, strip strain, and strain rate in the boundary lubrication regime. Measurements were conducted with 3104 aluminum alloy sheet of three different surface conditions o n D2 tool steel and cemented carbide tooling. Friction was found to in crease with the strain occurring during contact. This supports a frict ion model which treats the influence of plastic strain on the flatteni ng of strip asperities and real area of contact. The friction measured with stretching and sliding transverse to the rolling direction was 3 0% to 40% smaller than that measured along the rolling direction. No s ignificant difference in friction coefficient between sand-blasted wor kpieces stretched and slid along the rolling direction and transverse to the rolling direction was observed and the friction coefficients we re found to be close to those obtained with the original workpiece sur face transverse to the rolling direction.