Effect of Milling Technology on Selected Surface Layer Properties

Surface roughness of workpieces subjected to machining is a primary factor referred to in assessment and during execution of machining processes. In real conditions of production plants, only basic roughness parameters are typically analysed, i.e. Ra an Rz. However, from practical considerations, the analysis of the surface condition should include parameters accounting for the functional characteristics of a given surface (e.g. Rsk, Rku) or 3D surface texture (Sa, Sz, Sku, Ssk). Surfaces machined with tools equipped with PCD cutting inserts exhibit surface finish comparable to grinding or polishing. Despite satisfactory surface quality, the workpiece edge areas will typically require complementary deburring, performed with dedicated tools, such as special ceramic brushes. However, caution is required as deburring may result in modifying the surface topography in the workpiece edge area. The aim of the study was to analyse the effect of variable milling parameters on the roughness of machined surfaces and the energy state of their surface layer. The variable parameters were cutting speed and feed per tooth. The tests carried out in the study showed a significant impact of the modified technological factors on: selected surface roughness and surface free energy parameters. Another factor investigated in the study was the quality of surface finish following milling with PCD tools and after deburring by means of brush treatment with ceramic fibres. It was observed that the axial force occurring during brushing depends to a greater extent on the stiffness of the spring in offset adjustment sleeve rather than on the type of bristle fibre employed.