Optimization of machining parameters for kerf angle and roundness error in abrasive water jet drilling of CFRP composites with different fiber orientation angles

Abstract

In this study, carbon fiber-reinforced polymer (CFRP) composites with three different fiber orientation angles (M1: [0°/90°]s, M2: [+ 45°/− 45°]s, and M3: [0°/45°/90°/− 45°]s) were drilled (with and without pilot holes) on an abrasive water jet (AWJ) machine and the effect of the drilling parameters on the kerf angle (K) and roundness error (Re) of selected holes was investigated to determine quality characteristics. The first aim of the study was the single-objective optimization of drilling parameters for minimum K and Re individually. The second aim was the multi-objective optimization of drilling parameters for the simultaneous minimization of both K and Re. The Taguchi method was applied for single-objective optimization, while all steps of the Taguchi-based gray relational analysis were used for multi-objective optimization. Drilling experiments were performed using the L16 (44) orthogonal array. Four levels each for water pressure, stand-off distance, traverse feed rate, and hole diameter were selected as control factors. Analysis of experimental findings revealed that pilot drilling improved the kerf angle of the hole by 12.4% and the roundness error by 22.87%. Minimum kerf angle and roundness error were realized in the AWJ drilling of the M3 CFRP. The most effective parameter on kerf angle and roundness error in AWJ drilling of M1, M2, and M3 CFRP materials was water pressure (80.6%, 76.9%, and 73.8%, respectively), followed by stand-off distance (11.7%, 12.0%, and 13.5%),while other drilling parameters remained below 10%. The statistical evaluation and optimization results in this study can contribute to the evaluation of the AWJ machinability of CFRP composites.