Problems During Milling and Roughness Registration of Free-form Surfaces

Finishing machining of free-form surfaces is usually performed using ball mills. Constant rotational speed n and feed rate per wedge in axis of the mill f_z are applied most often for the whole surface. It causes long machining time and theoretical machined surface roughness Rz_t heterogeneity. In the paper we propose a milling method with variable parameters n and f_z which gives greater productivity and more homogenous roughness of free-form surfaces. Based on roughness parameter measurement of the samples, many problems have been enumerated: necessity of the surface curvature pre-filtering from primary profile, necessity of 2D roughness assessment in two perpendicular directions, requirement for a high vertical measurement range and special long tips in contact profilometers most often, roughness variability and necessity of milling technology knowledge, to find a region with maximal roughness.