Abrasive Layer Cracking Analysis and Strength Evaluation of High-Speed Grinding Wheels

The design and production of high-speed grinding wheels should not only merely take into account their grinding performance but also their use safety. A batch of resin-bonded high-speed grinding wheels was manufactured through substrate grooving, gluing, and hot pressing. Abnormal cracking emerged between the abrasive layer and the substrate. To identify the cause of cracking, a series of physical and chemical analyses were employed to examine the cracked wheels. Fracture observation and density analysis indicate that different areas of the grinding wheels have a compact structure and uniform feeding. The hardness analysis reveals that the hardness of the cracked and uncracked areas is similar with no obvious distinction. The energy spectrum analysis demonstrates that no macroscopic foreign bodies remained on the bonding surface. The results of GC–MS, FTIR, DSC–TGA, and viscosity analyses indicate that the active ingredients of naphthol, 2-methyl-1-naphthol, and diphenol propane in the adhesive reacted or volatilized, leading to the alteration of the adhesive properties. Duplicate experiments show that the tensile strength of the old adhesive used in the failed batch is merely 11 MPa, which is significantly lower than the 65 MPa of the new adhesive. COMSOL simulation results suggest that the minimum bonding strength of the adhesive should not be less than 23.82 MPa to guarantee bonding between the substrate and the abrasive layer. The tensile strength of the old adhesive is insufficient to cope with the thermal stress generated during the forming and cooling processes of the grinding wheel, which is the root cause of the failure. The findings provide theoretical guidance for the upfront design, raw material control, and process control of high-speed grinding wheels, ensuring their safe use.