Investigation of the surface quality and machinability of AISI 316LVM

Abstract

Surface quality has a significant effect on the reliability of an implant. The surface finish of the workpiece is influenced by machining parameters, tool wear and cooling–lubrication conditions. Typically, mineral oil-based conventional cutting fluids are employed for cooling and lubricating purposes in industrial machining processes. However, the use of these fluids places costly environmental and health responsibilities on companies. Consequently, it is preferable to utilize an affordable and environmentally friendly coolant/lubricant that does not generate liquid waste or have harmful side effects. In this work, we conducted experimental investigations to examine the effect of cutting forces, cutting temperature, tool wear and the quality of the machined surface on the machinability performance of medical grade AISI 316LVM austenitic stainless steel. Five different cutting conditions were employed in the machining experiments: dry cutting, flood, minimum quantity lubrication (MQL), cryogenic cutting with liquid carbon dioxide (LCO2) and cryogenic cutting with liquid nitrogen (LN2). Compared to the dry-cutting condition, the cutting temperature decreased by 42.1% under LN2 and flood conditions and by 40.4% under LCO2 conditions. The cutting tools exhibited small amounts of flank wear and nose wear, along with the formation of built-up edges (BUE); however, no crater wear was observed. The MQL method resulted in the lowest cutting forces, while the cryogenic methods yielded the highest cutting forces. Among the cutting conditions, the MQL and flood conditions produced the lowest roughness values and the best surface quality. Conversely, the cryogenic cutting conditions led to the highest roughness values and the poorest surface quality. Furthermore, the MQL condition resulted in the lowest dimensional deviations.