Selection of optimal process parameters for gear hobbing under cold air minimum quantity lubrication cutting environment

Cold air minimum quantity of lubrication (CAMQL) in machining is a preferable alternative to conventional flood lubricating systems from the viewpoint of cost, ecology and human health issues. Therefore, it is necessary to select proper process parameters in order to enhance machinability for a given work material. The present study aims at determining the optimum amount of MQL and the most appropriate cold air temperature and feed rate during hobbing of medium carbon steel(C45, DIN) using YG6X hard alloy tool. The Taguchi technique with the utility concept, a multi-response optimization method, has been proposed for simultaneous minimization of tooth-face roughness and tool wear. The experiments were planned as per Taguchi-s L9 orthogonal array with each experiment performed under different conditions of MQL, cold air temperature and feed rate. The analysis of mean (ANOM) and analysis of variance (ANOVA) on multi response signal-to-noise (S/N) ratio were employed for determining the optimal parameter levels and identifying the level of importance of the process parameters. The optimization results indicated that MQL of 40 ml/h, cold air temperature-45 Cand a feed rate of 0.2mm/r is essential to simultaneously minimize tool wear and tooth-face roughness.