Effect of Minimum Quantity Lubrication on Tool Wear and Surface Roughness in Micro-Milling

Abstract

Micro-milling is a suitable technique for manufacturing of microstructures with high aspect ratios and intricate geometries. The application of the micro-milling process in cutting hardened tool steel is particularly challenging. The low strength of the miniaturized end mills implies accurate control of the chip load in order to prevent the tool break and product dimension errors, which requires high positioning accuracy. It is known that the application of cutting fluids can improve the performance of machining operations. However, the supply of cutting fluids in a conventional way is not appropriate for miniature machine tools due to the plentiful electronic components used to construct micro-scale machine tools. Minimum quantity lubrication (MQL) presents itself as a possible alternative for micro-cutting with respect to the minimum impact on the electronic components as well as low tool wear, better heat dissipation, and machined surface quality in metal cutting. This study compares the mechanical performance of MQL to completely dry condition for the micro-milling of SKD 61 steel based on experimental measurements of tool wears and surface finish. The effect of MQL on the burr formation is also observed. Results indicate that the use of MQL leads to reduced tool wears, better surface roughness, and less burr formation.