Optimum surface roughness evaluation of dies steel H-11 with CNC milling using RSM with desirability function

Machinability aspect is of paramount importance for efficient process planning in manufacturing. Machinability of work materials is an imperative aspect which may affect the different manufacturing phases including product design, process planning and machining operation. Machinability of engineering materials may be evaluated in terms of process output variables like surface roughness (SR), material removal rate, cutting forces etc. CNC milling has become one of the most competent, productive and flexible manufacturing methods, for complicated or sculptured surfaces. With the more precise demands of modern engineering products, the control of surface texture has become more important. This paper reports mathematical model for correlating the milling machining parameters such as spindle speed, table feed rate, depth of cut, step over and coolant pressure, with the response characteristic, SR, while machining hot die steel, H-11 with titanium coated carbide end mill cutter. The response surface methodology in conjunction with face centered central composite rotatable design has been used to develop the empirical model for the response. The significance of the mathematical model developed was ascertained using desirability functions and confirmation experiments. The results obtained depict that the mathematical model is useful not only for predicting optimal process parameters for achieving the desired quality but also for achieving the process optimization. © 2016, The Society for Reliability Engineering, Quality and Operations Management (SREQOM), India and The Division of Operation and Maintenance, Lulea University of Technology, Sweden.