### Title: Modelling of machining parameters and cooling conditions in hard turning of AISI p-20 tool steel using response surface methodology and desirability graphs

Authors: Aman Aggarwal, Hari Singh, Pradeep Kumar, Manmohan Singh

Addresses: Department of Mechanical and Automation Engineering, Maharaja Agrasen Institute of Technology, Sector-22, Rohini, Delhi 110085, India. ' Department of Mechanical Engineering, National Institute of Technology, Kurukshetra 136119, India. ' Department of Mechanical and Industrial Engineering, Indian Institute of Technology, Roorkee 247267, India. ' Solid State Physics Lab, DRDO, Delhi, India

Abstract: This paper presents mathematical models for correlating the CNC machining parameters such as cutting speed, feed rate, depth of cut, nose radius, with the cutting force acting on the cutting tool during turning of prehardened P-20 tool steel. The face centred central composite design module of Response Surface Methodology (RSM) has been used for conducting the experiments. Machining is done under three different environmental conditions – dry, wet (conventional coolant ILO cut 154 Indian Oil) and cryogenic (liquid nitrogen). The significance of the mathematical models developed was ascertained using desirability graph and confirmation experiments. The results obtained show that the mathematical models are useful not only for predicting optimal process parameters for achieving the desired quality but also for achieving the process optimisation. The cutting force contours have been generated from the model equations. Desirability graphs are also drawn giving minimum cutting force a value of one.

Keywords: response surface methodology; RSM; face centred central composite design; cryogenic cooling; prehardened tool steel; desirability function; CNC machining; machining parameters; cutting speed; feed rate; depth of cut; nose radius; cutting force; mathematical modelling.

International Journal of Machining and Machinability of Materials, 2008 Vol.4 No.1, pp.95 - 110

Published online: 24 Oct 2008 *