Measurement of chip morphology and multi criteria optimization of turning parameters for machining of AISI 4340 steel using Y-ZTA cutting insert

The study of chip morphology along with surface integrity is very important for any unknown work-tool combination in machining condition. The chip formation affects machining dynamics, cutting speed, life of insert and quality of the machined surface. Present research focuses to visualize the chip formation process with its morphology as well as surface finish in turning AISI 4340 steel with the yttria stabilized zirconia toughened alumina (Y-ZTA) ceramic cutting tool prepared at laboratory. Different statistical models of chip reduction coefficient (CRC), surface roughness and chip tooth height as a function of cutting speed, feed rate and depth of cut have been developed with the help of central composite design (CCD) of response surface methodology (RSM). The adequacy of the developed models and influence of each parameter have been checked by analysis of variance (ANOVA). While machining AISI 4340 steel, discontinuous chip with good surface finish has been obtained which proves the stability of the developed insert. Influential operating parameters have been well judged from the significance plots of the statistical models and their interactive effects. The optimum parameter combination yielding minimum chip reduction coefficient and minimum surface roughness, with 91.52% desirability comes around 250 m/min cutting speed, 0.20 mm/rev feed rate and 0.5 mm depth of cut. The novelty of this research is to correlate the chip morphology parameters with surface roughness and CRC of selected steel and an optimized set of data that has been put forward in the article. (C) 2019 Elsevier Ltd. All rights reserved.