Comparative Analysis of Surface Roughness and Tool Wear under Dry, MQL, and Cryogenic Machining Conditions in Invar 36 Turning Operations

Invar 36 alloy is known for its exceptional stability, presents challenges due to its tendency to heat up while machining which can result in deformation and decreased precision. This investigation presents a comparative study of surface roughness and tool wear performance during dry, Minimum Quantity Lubrication (MQL) (using canola oil) and cryogenic (LN2) machining of Invar 36 alloy. The changes in surface roughness and tool flank wear with respect to varying feed rate have been evaluated. The results demonstrated that increasing feed rates resulted in rougher surfaces and higher tool wear. Compared to dry machining, MQL machining significantly reduced the surface roughness and tool wear by 14.31 % and 24.33 %, respectively. However, cryogenic machining performed exceptionally with a 20.6 % reduction in surface roughness and a 37.12 % reduction in tool wear based on number passes. Hence this work contributed to identifying suitable machining parameters along with a proper cooling technique for improving the tool life and surface finish during machining of Invar 36 alloy. Major Findings: According to this research, cryogenic machining reduced tool wear by up to 37.12% and surface roughness by 20.60% when compared to dry machining. Cryogenic machining has shown considerable advantages in turning operations, including longer tool life, higher surface roughness, making it a preferable cooling approach for machining of difficult to machine materials such as INVAR 36.