Investigation on size effect of surface roughness and establishment of prediction model in micro-forming process

In the micro-forming process, the surface quality of the parts is difficult to improve by the subsequent machining. This requires the micro-formed parts to get a qualified surface quality during the deformation processes. Therefore, study on size effect of surface roughness is the first step for an accurate prediction of surface roughness of micro forming. In this study, the polycrystalline models with rough surface are built to study the influences of grain size and grain orientation on surface roughness. By introducing the scale parameter, the size effect of contact normal pressure and its distribution uniformity under different grain sizes are determined. A prediction model of surface roughness for micro-forming considering size effect is established. By comparing the prediction results with the experimental ones, the rationality and accuracy of the surface roughness prediction model for micro forming were verified. The prediction model established in this paper can be used to predict the parts which are difficult to improve the surface quality by machining, especially that are affected by the size effect during deformation process.