Abrasive waterjet hole trepanning of thick Kevlar-epoxy composites for ballistic applications - Experimental investigations and analysis using design of experiments methodology

Abrasive water jet (AWJ) is widely useful for producing cutouts/holes in difficult-to-cut materials. However, in AWJ hole trepanning, due to the jet trailback, the diameter of the hole tends to increase with an increase in workpiece thickness and striation marks are observed at the exit side. This results in an inferior quality hole due to poor dimensional tolerances, leading to assembly problems. Therefore, to obtain superior quality holes by AWJ trepanning, optimum selection of process parameters is absolutely critical. This paper embodies a Taguchi method based experimental investigation for finding the optimum parameter settings in AWJ hole trepanning of 6 mm thick Kevlar-epoxy composites, mainly used for anti-ballistic applications. Kerf taper and surface roughness has been chosen as the quality characteristics and four major operating parameters have been considered for experimentation. Visualisation studies using SEM and optical microscope have also been conducted for investigation of delamination induced during AWJ trepanning. Copyright © 2011 Inderscience Enterprises Ltd.