RSM Based Investigations on the Effects of Cutting Parameters on Surface Integrity during Cryogenic Hard Turning of AISI 52100

Effect of cryogenic hard turning parameters (cutting speed, feed rate, and depth of cut) on surface roughness (Ra) and micro-hardness (mu H) that constitute surface integrity (SI) of the machined surface of alloy steel AISI 52100 is investigated. Multilayer hard surface coated (TiN/TiCN/Al2O3/TiN) insert on CNC lathe is used for turning under different cutting parameters settings. RSM based Central composite design (CCD) of experiment is used to collect data for Ra and mu H. Validity of assumptions related to the collected data is checked through several diagnostic tests. The analysis of variance (ANOVA) is used to determine main and interaction effects. Relationship between the variables is established using quadratic regression model. Both Ra and mu H are influenced principally by the cutting speed and the feed rate. Model equations are found to predict accurate values of Ra and mu H. Finally, desirability function approach for multiple response optimization is used to produce optimum SI.