Comparison of single nozzle and dual nozzle MQL performance in hardened steel turning: A case study

Abstract

This study focused on comparing the machining output performance of single and dual jet nozzle assisted MQL (Minimum Quantity Lubrication) in CNC hard turning. Two case studies were conducted using different hardened steels and cutting tools. The cutting parameters including feed rate (0.1 mm/rev), cutting speed (60 m/min) and depth of cut (0.1 mm) were maintained constant. In the first case study, AISI 4340 hardened steel workpiece and CVD-coated carbide cutting tool were used. The results showed that the dual nozzle MQL system achieved lower tool flank wear (30.54 %), cutting power (11.33 %), surface roughness (24.59 %), cutting temperature (22.36 %), and cutting sound (2.35 %) compared to the single nozzle system. The second case study used AISI D2 steel workpiece and PVD-coated carbide tool, and similar findings were observed. Cutting power observed during hard turning operations in a dual nozzle MQL environment was 0.360 kW for AISI 4340 Steel and 0.386 kW for AISI D2 Steel, respectively, which is very low in terms of hard turning concerns. Dual Nozzle Overall, the dual nozzle MQL system consistently demonstrated more efficient machining, regardless of the variations in tool material, workpiece material, and hardness. Therefore, it is suggested for further research in machining applications in the future.