Experimental Investigation and Multi-Objective Optimization of Drill Point Angle for Improving Hole Quality and Surface Finish using Taguchi–Grey Relational Analysis

Drilling is one of the most widely employed machining operations in modern manufacturing, where hole quality and surface finish are strongly influenced by drill geometry and machining parameters. This study presents an experimental investigation on the effect of drill point angle for improving drilling performance through multi-objective optimization. Experiments are designed using the Taguchi method, while Grey Relational Analysis (GRA) is employed to optimize multiple response characteristics simultaneously, including surface roughness, hole diameter accuracy, circularity, burr height, and thrust force. Statistical analysis is performed to determine the significance of process parameters and identify the optimum drilling conditions. Confirmation experiments validate the predicted results and demonstrate improvements in machining quality. The proposed Taguchi–GRA approach provides an effective, reliable, and economical methodology for enhancing drilling performance, making it suitable for precision manufacturing applications in automotive, aerospace, and general engineering industries.