Application of Box Behnken design to optimize the parameters for turning Inconel 718 using coated carbide tools

This paper discusses the use of Box Behnken design approach to plan the experiments for turning Inconel 718 alloy with an overall objective of optimizing the process to yield higher metal removal, better surface quality and lower cutting forces. Response Surface methodology (RSM) has been adopted to express the output parameters (responses) that are decided by the input process parameters. RSM also quantifies the relationship between the variable input parameters and the corresponding output parameters. RSM designs allow us to estimate interaction and even the quadratic effects, and hence, give us an idea of the shape of the response surface we are investigating. Box-Behnken design is having the maximum efficiency for an experiment involving three factors and three levels; further, the number of experiments conducted for this is much lesser compared to a central composite design. The proposed Box-Behnken design requires 15 runs of experiment for data acquisition and modeling the response surface. Design expert software was used to design the experiment and randomize the runs. Regression model was developed and its adequacy was verified to predict the output values at nearly all conditions. Further the model was validated by performing experiments, taking three sets of random International Journal of Scientific & Engineering Research, Volume 4, Issue 4, April-2013 621 ISSN 2229-5518 IJSER © 2013 http://www.ijser.org input values. The output parameters measured through experiments (actual) are in good match with the predicted values using the model. Using ‘Design-expert’ software, 2D and 3D plots were generated for the RSM evolved. Such plots explicitely give an idea of the dominating process variable over others and the order of dominance; further the plots exhibit the trend of variables’ interaction in the process. This work resulted in identifying the optimised set of turning parameters for Inconel 718 material using coated carbide tools, to achieve better surface roughness and higher material removal. This work gains significance in the sense with minimum number of experiments, reliable model has been generated, validated and further, the process has been optimised with two objectives.