Grinding performances and failure analyses of electroplated Ni–B-diamond tools with a high density of single- or dual-layer D-150-diamond particles

This study explored the performance of electroplated grinding tools electroplated with single and dual-layer diamond particles (DPs). These tools were fabricated through a three-step electroplating process, involving Ni-undercoating, Ni-diamond co-electroplating, and Ni–B strengthen-electroplating, on AISI 440C steel rods. Grinding tool performance was assessed based on the maximum achievable ground length from slot-grinding Al₂O₃ plates. Dual-layer DP composite deposits with varying secondary Ni-undercoat thicknesses (0, 12, and 24 μm) all exhibited substantial improvements in tool’s grinding performance due to their self-sharpening effect. As the secondary Ni-undercoat thickness increased, the maximum ground length increased significantly, reaching values of 2234, 5366, and 9632 mm, respectively. Raman spectroscopy revealed the transformation of outer DPs into graphite structures during grinding tests, indicating the formation and subsequent delamination of these DPs, leading to morphological changes. Tool failure was attributed to the fatigue rupture of the AISI 440C tool shaft. During slot grinding, the tool shaft experienced cyclic stress due to a consistent grinding speed of 2 mm/min and spindle rotation of 15,000 rpm. High-cycle fatigue fracture, characterized by the absent of plastic deformation and a nearly perpendicular crack to the tool shaft, occurred after over 10⁷ stress cycles.