Investigation and optimization of drilled surfaces machined by abrasive water jet machining in Ti-6al-4V alloy

Titanium alloys are the most appealing material for aerospace, biomedical, and chemical applications due to their high specific strength and fracture resistance. Drilling of titanium alloy is required in the bolt/rivet assembly of aerospace components and bone plate, fracture bone for biomedical applications. The main objective of this study is to explore the drill rate, surface roughness and drill time during abrasive water jet machining (AWJM) of Ti6Al4 V alloy. Water jet pressure (WJP), standoff distance (SOD), abrasive flow rate (AFR) and feed rate (FR) are input variables, and the output responses are surface roughness (R-a), drill rate (DR) and drill time (DT). Experiments were carried out using the Taguchi L-27 orthogonal array. Analysis of variance (ANOVA) was used to investigate the most influential factor for DR, DT, and R-a. The most influential factor in reducing DT and enhancing DR is FR. WJP, SOD, and AFR are the most important factors influencing R-a. With increasing WJP, SOD, and FR selected cutting conditions, R-a was observed to increase. Increased FR results in higher DR for AWJM of Ti6Al4 V alloy. The surface morphology of an optimized AWJM sample was investigated. An EDS (energy-dispersive spectroscopy) result reveals the presence of carbon and oxygen on the machined surface. Grey relational grade is used to find the best AWJM process parameters for machining the Ti6Al4 V alloy. The AWJ machined surface was investigated with SEM to assess the quality of the optimized setting through GRA.