Multi-response optimization of the thrust force, torque and surface roughness in drilling of glass fiber reinforced polyester composite using GRA-RSM

Glass fiber reinforced polymer (GFRP) composites are used in various applications across several industrial sectors. Drilling operation is an unavoidable machining process in the assembly zone dealing with GFRP composites as the composite structures are joined mainly through the fastening processes. GFRP drilling poses several issues compared to conventional metallic materials, which decreases the drilled hole quality. In this article, central composite design is used to provide the framework for the experimental runs on glass fiber reinforced isophthalic polyester composite slabs. Grey relation analysis is used to optimize the drilling parameters: speed, feed and material thickness based on three output performance characteristics: thrust force, torque and drilled hole surface roughness. Analysis of variance (ANOVA) is used to find the percentage contribution of the drilling parameters. The experimental results indicate feed to be the most influential factor in the drilling of glass fiber reinforced isophthalic polyester composites contributing 44.16% to the variation in the overall performance index, represented by the grey relation grade (GRG) for the given experimental range of control parameters.