Effects of cold rolling process variables on final surface quality of stainless steel thin strip

In cold rolling some surface defects, known as pits, are due to lubricant that, entrapped in the deep valleys of the surface roughness, is nearly incompressible and acts like an inclusion avoiding microcavity elimination. During the rolling process, when specific favorable conditions can be set up, the lubricant may be expelled by the microplasto-hydrodynamic lubrication (MPHL) mechanism and pits may be recovered. In this paper the I >(m) parameter, index of the MPHL, is investigated together with the neutral point position to better understand the practical process recommendations for surface defect recovery. By means of finite element analysis of a Sendzimir'cold rolling process, the sensitivity of these objective functions are studied by means of a design of experiment analysis changing the major process variables like back tension, friction coefficient, reduction parameter, initial thickness, and roll diameter.