Examination of break out of grains of super-hard grinding tools

Failure of grinding and honing tools may be the result of continual wear, although their productivity can also be loot due to fracture, break out of grains from bond or other causes, i.e. generally because of breakage. The productivity of honing, grinding and other tools with bonded grains (regulating rollers, band grinders etc) depends significantly on the cutting productivity of the active grains (diamond or CBN). Cutting productivity-beside other factors-depends also on the bonding stability of the grains into the bond The quantity and direction of the force that is necessary for the individual grains to break out of the bond should be examined. The objective of the research summarized in the paper is to outline the process of fracture and its mechanical criteria. In the paper the theoretical and experimental new results, obtained so far, will be presented