Effect of Chip Morphology during Grinding Bearing Steel Using Single Layer Brazed and Galvanic Bonded Cubic Boron Nitride (cBN) Wheel

Chip formation in grinding involves high specific energy compared to other machining processes due to high negative rake angle of grains, adverse grinding process parameters and physical-mechanical properties of the workpiece material. This causes excessive friction between chip-grit and chip-bond interfaces as there are no free flow of chip between grits and work surface. It generates high heat, which can have harmful effects on workpiece surface in case of dry grinding. But single layer brazed type (BT) or galvanic bonded (GB) cBN wheel could be the solution for the above mentioned problem, as the protrusion and gap of the grits may be monitored during manufacturing. Unlike conventional grinding, the single layer counterpart produces favorable chips during grinding bearing steel in ductile mode with lesser grinding forces and specific energy. This investigation also shows that the chips of larger volume cannot be accommodated in the intergrit spaces, which are very small in the GB wheel due to dense grit distribution and shorter grit protrusion, whereas, even with such a large chip load, the BT wheel works effectively for wider and uniform spacing and larger protrusion of the grits.