Measurement and analysis of pocket milling features in abrasive water jet machining of Ti-6Al-4V alloy

The present work deals with the size effect of abrasive water jet milling parameters on the square pockets of Ti-6Al-4V alloy. In this study, the abrasive mesh size, water jet pressure and traverse rate were chosen as milling variables and their effect on pocket features such as depth of cut, undercut, material removal rate, and surface roughness were examined. This study also characterizes the milled pocket surfaces under different milling conditions. Most of the measurements and surface characterizations were done using the Dino-Lite Digital Microscope. For both #80 and #100 abrasives, the AWJ-milled pockets were formed with variations in depth milled and rugged surface by increasing the water jet pressure from 175 to 200 MPa under all the selected traverse rate conditions. Also, the variations of depth of cut in successive trajectories found to have a speed bump effect. At these settings, distribution of energy to the work material was more due to deceleration of jet in the boundary close by and changes made in the feed directions in raster path from 0° to 90° at a step-over distance of 0.2 mm. This yielded undercuts in the milled pocket corners. However, there was a significant reduction in the undercut with a water jet pressure of 125 MPa and a traverse rate of 3500 mm/min were employed. Besides, the abrasive mesh size #100 had a better surface topography, and also strong jet footprints were observed with mesh size of #80. Based on the experiments results, the size effect of different milling parameters was seen having influence on the pocket geometry and surface features.