OPTIMIZATION OF RESIDUAL STRESSES IN CNC TURNING OF AISI 8620 STEEL

Abstract

In the present world, it is observed that quality and productivity plays a vital role in today’s industrial applications. Customer satisfaction remains the primary goal for industry which is directly under the influence of quality, whereas the profit margin of the industry relies subsequently on the productivity of the process. Thus for every industry to survive in this competitive world, optimisation is the key element to control the functional parameters simultaneously. This dissertation is focused on optimising quality characteristics through the use of Response surface methodology. Turning operation on CNC lathe machine is the centre of focus for the study, while the output factors chosen are surface roughness and residual stress. Surface quality is the major concern for every customer which is rather hard to quantify, thus surface finish is kept as a crucial indicator for CNC Lathe performance. Various input parameters considered for the experimentation is cutting speed, feed rate and depth of cut. Suitable design matrix is prepared using Central Composite Design through RSM including the input parameters for CNC turning on AISI 8620 steel. The effect of the selected process parameters on the surface finish and residual stress is prepared on RSM. Furthermore ANOVA is used to analyze the performance characteristics in CNC turning operation. Since the p value for the output parameter is less than 0.05 which indicates that model is maintained significant while lack of fit is kept insignificant. Eventually, for obtaining the optimum values for various responses, F value was taken in order to investigate the dominating parameter. Finally the conclusions were drawn which reveals that cutting speed should be raised while feed rate and depth of cut be dropped in order to optimise the output responses.