Multi Regression Model for Cutting Force During Dry Turning of Duplex Stainless Steels Using Definitive Screening Design

Considering the current trend in environmentally friendly machining or dry machining, it is observed that it’s adverse effect on various surface integrity aspects is usually not covered adequately in the literature. This adverse effect leads to untimely in-service failure of components subjected to fatigue loads. This research work has advocated the use of dry machining with consideration on minimizing its adverse effects by selecting appropriate machining parameters for Duplex Stainless Steel (DSS). These materials pose various challenges during secondary processing operations, like machining, due to lower values of thermal conductivity, higher values of tensile strength, toughness, work hardenability & tendency for built-up edge formation. In such applications, higher values of cutting forces are generated, and efforts are required to minimize them in order to reduce the carbon footprint. A multiple regression model for cutting force, during turning of DSS was generated as part of the study, based on experiments conducted using Definitive Screening Design (DSD). Four process parameters, viz. cutting speed, tool feeding rate, depth per pass and radius of curvature of tool nose were varied at three different values independently and their effect on main cutting force was observed. The multiple regression model generated using the stepwise procedure has coefficient of determination (R2) of 99.7 %. Cutting depth followed by rate of feeding and radius of curvature of tool nose were found to be influential parameters in the model. Minimization of force by desirability optimization method was further carried out. This resulted in minimum value of force as 128.6 N. For this, cutting speed of 120 m/min, feed rate of 0.1 mm/rev, depth per pass of 0.5 mm and tool nose curvature radius of 1.6 mm should be selected. The composite desirability score for these optimum settings was 98.79 %.