Comparison of the Surface Roughness and its Geometric Model in Case of Z-level Milling

Abstract

The Z-level milling technology is one of the most often used finishing milling strategy in case of the CNC milling of the steep free form surfaces. A main spindle parallel end-milling cutter can be used with or without corner radius, and the depth of cut means the axis parallel distance between the tool paths. During the planning of machining process two main aspects should be considered: the productivity and the accuracy. The accuracy means macro and micro accuracy. In this article the surface roughness, as a part of micro accuracy, is investigated, and a geometric approach of its estimation is presented. The tool corner geometry, the depth of cut and the inclination of the surface are considered, and the critical inclination is introduced. The theoretical description of the surface roughness is compared with the results of milling tests. As concluded, the cusp height, as the geometric model of the surface roughness can be a good base of the estimation, but a detailed and case depend model is required. The results ensure a better selection of tool path parameters in CAM systems considering the properties of cutting tool and the surface.