Investigation on Grindability of Medical Implant Material Using a Silicon Carbide Wheel with Different Cooling Conditions

Zirconia is the preferred material used in many applications including biomedical implant. The zirconia in its sintered form is the most preferred one to manufacture a near net shaped implant material with minimal work. But it is very difficult to shape as the material chip away during the machining or grinding process. Hence zirconia in a pre-sintered form is used to achieve the required shape and size for a specific application. Then it is sintered and used. In this work, the grindability of the presintered zirconia was evaluated using a dense vitreous bond silicon carbide wheel. The grinding parameters such as wheel speed, radial depth of cut and feed rate are varied to investigate its grindability in terms of force ratio, specific energy, surface finish, G-ratio and ground surface under both wet and MQL cooling conditions. The forces produced during the grinding of pre-sintered zirconia was observed lower in the MQL (Minimum Quantity Lubrication) technique due to the reduction of friction, when compared to the wet cooling condition. The calculated specific energy was less in MQL cooling condition, due to the reduction in heat generation and friction. The surface finish of the workpiece obtained from the wet cooling condition was better due to the reduction in wheel loading. The percentage difference of the G-ratio between both the wet and MQL cooling conditions was observed to be 24 percent. This was due to the active participation of grains and less wheel loading in wet grinding condition. The ground surfaces obtained from the wet cooling condition were smooth and regular, compared to the MQL grinding condition.