Indian Journal of Engineering & Materials Sciences Vol. 13, December 2006, pp. 484-488 Multi-response optimization in drilling using Taguchi’s quality loss function V N Gaitonde a* , S R Karnik b , B T Achyutha c & B Siddeswarappa d a Department of Industrial & Production Engineering, b Department of Electrical & Electronics Engineering, B V B College of Engineering & Technology, Hubli 580 031, India c Department of Mechanical Engineering, G M Institute of Technology, Davangere 577 006, India d Department of Industrial & Production, UBDT College of Engineering, Davangere 577 004, India Received 22 December 2005; accepted 11 September 2006 The exit burr formation in drilling is influenced by cutting conditions and drill geometry. This paper presents the application of Taguchi’s analysis for simultaneous minimization of burr height and burr thickness. The approach of Taguchi design for multi-response optimization problem is based on loss function of the quality characteristics. In the present investigation, optimal values of cutting speed, feed, point angle and lip clearance angle are determined to minimize burr height and burr thickness during drilling. The potential of the proposed methodology is demonstrated through a case study of drilling process using AISI 316L stainless steel workpieces. IPC Code: B23B Taguchi design is proved to be an efficient tool to produce high quality products at low cost. The objective of Taguchi robust design is to determine the optimal parameter settings and making the process performance insensitive to various sources of variations. The approach can economically satisfy the needs of problem solving and design optimization. Taguchi technique allows the process optimization with minimum number of experiments without need for process model development. Thus, by this method, it is possible to reduce the time and cost for experimental investigations and thus enhance the performance characteristics. Most of the investigations on Taguchi application are on the optimization of a single quality characteristic 1 , as the original technique was designed to optimize a single response. In the optimization process of multiple quality characteristics, the objective is to determine the best factor settings, which simultaneously optimize all the quality characteristics of interest in the process. Several modifications were suggested to the original Taguchi design for multi-response optimization. Desirability function approach 2 for multi-response optimization is basically a trade-off between the various performance characteristics. Thus, the method is not suitable for simultaneous optimization of all the performance characteristics 3 . In the principal component analysis (PCA), a smaller set of uncorrelated principal component variables are derived through transformation of a set of correlated response variables 4 . However, when more than one principal component is selected, trade-off to select a feasible solution is unknown. Also, when the chosen principal component with only less variation can be explained by total variation, the multi-response performance index is not evident enough to replace multi-response 5 . The methodology of Taguchi’s quality loss function has proved to be an efficient optimization tool for multiple characteristics. The method has been employed in the past for optimization of several processes such as gas tungsten arc welding 6 , face milling 7 and hot turning 8 . Multi-performance characteristic optimization using Taguchi’s quality loss function employs weighting factors in the total loss function to obtain multi-response signal-to-noise ratio 9 . This paper presents the methodology of Taguchi’s loss function concept for simultaneous minimization of burr height and burr thickness in drilling as a case study. Multi-Response Optimization using Quality Loss Function Taguchi optimization procedure begins with selection of orthogonal array 10 with distinct number of levels (l) defined for each of the factors (k). The minimum number of trials in the array is: ___________________________ *For correspondence (E-mail: gaitondevn@yahoo.co.in)