The Design, Fabrication, and Interfacial Microstructure of an Insert-Type Brazed Diamond/Resin-Bonded Composite Grinding Wheel

Rail grinding is an essential maintenance process for removing surface defects and restoring the designed rail profile, but conventional resin-bonded grinding wheels often suffer from rapid wear under heavy-load and high-impact conditions. In this study, an insert-type brazed diamond/resin-bonded composite grinding wheel was designed to combine the strong abrasive retention of brazed diamond with the toughness of a resin-bonded wheel. Brazed diamond inserts were prepared using HHD90 synthetic diamond, a Ni-Cr active brazing alloy, and 304 stainless-steel substrates. The effects of brazing temperature and holding time were evaluated, and the interfacial bonding mechanism was analyzed by SEM, EDS, and XRD. A geometric coverage model and grinding trajectory simulation were used to select the insert arrangement. Brazing at 1030 °C for 20 min provided a practical balance between abrasive retention and thermal damage. XRD phase identification, supported by EDS and thermodynamic analysis, was consistent with the formation of Cr3C2 and Cr7C3 at the diamond/alloy interface. A configuration of eight inserts was adopted as an engineering design choice, and a 45° installation angle produced the most uniform simulated trajectories among the tested angles of 30°, 45°, and 60°. Perforating the inserts increased the mean limiting rotational speed from 5210 r/min to 5847 r/min. Field tests showed that the composite wheel produced lower rail surface roughness than the conventional resin-bonded wheel under all tested grinding pressures. Its service life increased by approximately 20%, while the difference in material removal between the two wheels was only about 2.8%. These results demonstrate that the proposed composite structure can improve rail surface quality and wheel durability without significantly reducing material removal performance.