Fabrication of Porous Cast-Iron Bonded Diamond Grinding Wheels and Their Evaluation to Grind Hard-to-Grind Ceramics

Abstract

Porous cast-iron bonded diamond grinding wheels were fabricated and tested. Diamond grains of #100/120 were used as abrasive grains. Atomized cast-iron of various grain-sizes and carbon contents was used as bonding material. The capsule-free hot isostatic press (HIP) method was employed to obtain high mechanical strength and high porosity. Grinding tests were conducted under constant pressure grinding (CPG) conditions to avoid influences of Young's modulus of different grinding wheels and stiffness of grinding machines. The grinding ratio, grinding force and specific grinding energy were evaluated for the new and other commercial grinding wheels. Alumina and silicon nitride were ground for the evaluation. Grinding wheels bonded by cast-iron of low carbon content, i.e., 3.11mass%, and finer grain size, i.e., less than 20μm, had higher grindability. Scanning electron microscopic observation showed evidence of reaction between the diamond grains and the cast-iron particles, i.e., and diffusion of carbon from the diamond grains to the cast-iron particles. The total volume of diffused carbon from diamond to cast-iron affected the grindability. The porous cast-iron bonded grinding wheels showed an extremely higher grinding ratio and lower specific grinding energy than commercial resinoid wheels, vitrified wheels, and non-porous cast-iron bonded wheels.