Multiobjective Optimization of Drilling Characteristics for NEMA G-11 GFRP/Epoxy Composite Using Desirability Coupled with Taguchi Method

GFRP/Epoxy composite NEMA (National Electrical manufacturers Association) G-11 possesses excellent physical, mechanical and electrical properties at both room temperature and elevated temperatures and finds wide applications in areas such as insulation in aerospace and defence systems. The material withstands temperatures in excess of 300 °C and is considered the premier material for use as Class F insulation in electrical power generation and transmission equipment. Drilling is one of the most widely used machining operation for assembly and fitting purpose. In this study, the effort is to optimise various drilling parameters with multiple performance characteristics based on the Desirability coupled with Taguchi method. Taguchi's L27 orthogonal arrays (OA) with factor 4 and 3 level have been used for the experimentation. Individual desirability indices of the three performance measures, viz. thrust force, delamination and surface roughness are converted into an overall desirability, which is then optimized using Taguchi analysis. The optimal parameters achieved are spindle speed at level 2 (1200 rpm), feed rate at level 1 (75 mm/min), thickness at level 2 (8 mm) and diameter at level 2 (8 mm) for achieving minimum thrust force, delamination and surface roughness.