Determination of the Feasibility of Using Eco-Friendly Walnut Shell Abrasive Particles for Pocket Milling of Titanium Workpieces by Abrasive Waterjet Technology

Abstract

Abrasive waterjet technology is nowadays a well established non-conventional method with significant capabilities for material removal with high productivity and minimum environmental impact compared to other processes. However, in order to be in line with the green transition directives, further steps are required to ensure the sustainability of manufacturing processes and reduce the risk of material depletion by employing recyclable materials. For this purpose, an eco-friendly abrasive material such as walnut shell is employed for pocket machining of a titanium alloy workpiece. Due to the relatively low hardness of this material, compared to common abrasive materials such as garnet or alumina, it is required to determine the appropriate range of process parameters in order to obtain high-quality pockets with high productivity. Thus, in this work, a comprehensive experimental study is conducted in order to determine the effect of various process parameters on pocket depth, pocket width, material removal rate, flatness and parallelism error of produced pockets. The results prove the feasibility of using walnut shell as abrasive material for pocket milling, although MRR is almost an order of magnitude lower than the values commonly obtained for usual abrasives. Moreover, it is not recommended to use jet pressure values over 250 MPa so dimensional accuracy, flatness and parallelism error are maintained in acceptable values.