Analysis of changes in 3D surface texture anisotropy ratio parameter and friction during sheet rolling campaigns

In most manufacturing of flat sheet and similar products, the tool-to-metal interaction performance does not simply relate to surface roughness parameters. For example, the frictional behaviour in rolling mills is not always related to the measured transverse roughness of the work rolls. The evolution of a surface during a rolling campaign changes both the transverse roughness as well as the rolling direction roughness. We show that the mill friction changes occurring during a rolling campaign are reflected in the sheet surface topography. The friction in the roll bite is correlated to a 3D sheet surface texture parameter. We define a surface texture anisotropy ratio (STAR) parameter from the measured 3D surface texture parameters. A relationship is developed between measured STAR values and mill friction on aluminium sheet samples produced from two different rolling campaigns.