Multi objective optimization of AWJM parameters for ZrO₂ coated MWCNTs reinforced HDPE nanocomposites using Taguchi Grey relational analysis

The machinability of High-Density Polyethylene (HDPE) reinforced with zirconia (ZrO₂)-coated MWCNTs via Abresive Waterjet Machining (AWJM) was investigated in this study. The composite was fabricated with 3 wt% ZrO₂-MWCNTs to enhance mechanical and thermal properties. A Taguchi L₉ orthogonal array was employed to evaluate the effects of waterjet pressure, traverse speed, and stand-off distance on surface roughness (Ra), kerf taper (KT), and material removal rate (MRR). Grey Relational Analysis (GRA) was applied for multi-objective optimization, integrating the individual responses into a single Grey Relational Grade (GRG). Results indicated that lower traverse speed (100 mm/min) minimized R_a (4.286 μm), while higher pressure (200 MPa) and intermediate speed (150 mm/min) reduced kerf taper (0.04727 radians). The optimal parameter combination yielded the highest GRG (0.7361), balancing superior surface finish, dimensional accuracy, and machining efficiency. This study provides critical insights into precision AWJM of polymer nanocomposites for high-performance engineering applications.