Machine vision based burr length measurement in abrasive waterjet trepanning

Abstract

The demand for realizing products through near-net shape manufacturing routes, which eliminates the need for secondary finishing operations, is increasing in high-value industries. Making holes is one of the very frequent operations in realizing these products in various industries. On the other hand, burr formation is an issue in machining ductile material. Burr removal requires a secondary operation that increases manufacturing costs. In this context, abrasive waterjet (AWJ) machining suits better as the AWJs can realize near-net shape parts from ductile materials. Although the burr formation by the AWJs is considerably minimal relative to their conventional counterparts, the available cutting energy influence the burr shape and size. In this work, initially, the effect of waterjet pressure, effective standoff distance (SoDeff), and material thickness on the burr length and shape in AWJ trepanning were studied. A machine vision approach was used to measure the burr length and validated with the measurements from the confocal microscope. The result shows that the machine vision system captured the length of the burr with an error percentage of 11.05 % at the waterjet pressure of 300 MPa and 12.55 % at 350 MPa. Following this, the micrographs were taken to analyze the effect of material thickness on the burr and the material removal mechanism in the vicinity of the burr. Finally, a sacrificial layer-based solution is proposed and demonstrated to avoid even the minimal burr formed in AWJ trepanning.