Flattening of Random Rough Surfaces in Metal-Forming Processes

Flattening of random rough surfaces on a workpiece undergoing bulk deformation has beenanalyzed using a model of the surface consisting of just two wavelength components. Asperities are flattened at a rate which depends on the ratio of the initial r.m.s. amplitudes of the long and short wavelength components. The flattening behavior of the long wavelength asperities only becomes important when the amplitude of the long wavelength asperitiesis much greater than that of the shorter wavelength asperities. The surface modification was investigated experimentally by cold rolling of aluminium strips. The power spectral density of the roughness was used to extract appropriate amplitudes for the short and longwavelength components of roughness. The change in roughness amplitudes showed excellent agreement with theory.