Effect of conventional and non-conventional tool geometries to skewness and kurtosis of surface roughness in case of fine turning of aluminium alloys with diamond tools

Aluminium alloys are increasingly used by the automotive, aerospace and military sector. The most often used workpiece materials are the so-called Al-Si and Al-Mg-Si alloys, of which, the most widespread are aluminium alloys reinforced with silicon because of their numerous advantageous mechanical and chemical properties. In case of different types of workpiece materials made ready by cutting, surface roughness (R a, R z) as a criterion is as important as geometric sizes and tolerance or the mechanical features of the material, e.g. tensile strength and hardness. The expected functional and friction features are not defined properly by average roughness (R a) or surface height (R z). The expected functional behaviour can be described much better by skewness (R s k) and kurtosis (R k u) as statistical parameters of surface roughness. In this article, two types of aluminium alloys were cut with diamond tools using different edge geometries and edge materials. The statistical parameters of the surface roughness produced were analysed in order to find connections between these parameters and the circumstances of the cutting process, including edge geometry, tool material, workpiece material, and cutting parameters. The results show that surfaces with good tribological properties can be reached by a well-designed turning process.