Flattening of random rough surfaces in metal-forming processes

Flattening of random rough surfaces on a workpiece undergoing bulk deformat ion has been analyzed using a model of the surface consisting of just two w avelength components. Asperities are flattened at a rate which depends on t he 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 asperities is m uch greater than that of the shorter wavelength asperities. The surface mod ification was investigated experimentally by cold rolling of aluminium stri ps. The power spectral density of the roughness was used to extract appropr iate amplitudes for the short and long wavelength components of roughness. The change in roughness amplitudes showed excellent agreement with theory.