Surface roughness is an important aspect of a machined piece and greatly influences its performance. This thesis presents the surface roughness of 7075 T651 aluminium plate of 30 mm thickness in stable and unstable machining conditions at various spindle speed and depth of cut.

The research is conducted by generating replicas using a high-resolution silicone compound applied on the aluminium plate and therefore obtaining its surface roughness. The replicas are then measured using the Profilm 3D microscope which uses the white light interferometery (WLI), a measurement technique to acquire a 3D scan of surface roughness for the Profilm3D from the replicas.

A study of surface roughness data generated and its representation in graphs shows that with increasing spindle speed especially at lower depth of cut the surface roughness is lower and the increase in depth of cut increase surface roughness.