On-machine measurement of tool nose radius and wear during precision/ultra-precision machining

The tool state exerts a strong influence on surface quality and profile accuracy during precision/ultra-precision machining. However, current on-machine measurement methods cannot precisely obtain the tool nose radius and wear. This study therefore investigated the on-machine measurement of tool nose radius on the order of hundreds of microns and wear on the order of a few microns to tens of microns during precision/ultra-precision machining using the edge reversal method. To provide the necessary replication, pure aluminum and pure copper soft metal substrates were evaluated, with pure copper exhibiting superior performance. The feasibility of the measurement method was then demonstrated by evaluating the replication accuracy using a 3D surface topography instrument; the measurement error was only 0.1%. The wear of the cutting tool was measured using the proposed method to obtain the maximum values for tool arc wear, flank wear, and wear depth of 3.4 µm, 73.5 µm and 3.7 µm, respectively.