Analytical and Experimental Determination of the Ra Surface Roughness during Turning

In this article an analytical equation for calculating the theoretical arithmetic mean surface roughness, Ra, in the case of turning using a tool with a circular nose radius is presented. The deviation that often occurs between the expected and the obtained surface roughness during these machining operations is investigated. Influence of the minimum chip thickness is discussed especially in regards to the related phenomenon of so called side flow of material on the machined surface. Three different kinds of workpiece materials have been investigated in order to gain a better understanding of their influence on the obtained surface roughness. The obtained results show that the surface roughness could be considered as being inside an interval of two analytically determined Ra-values.