Coolant flow in surface grinding with non-porous wheels

A parameter that is often used in the assessment of cooling efficiency in grinding is the amount of fluid that flows through the grinding zone. This paper shows that when grinding with wheels possessing no bulk porosity, only a portion of the flow through the grinding zone is effective. Even at the highest wheel speeds employed, it is observed that ample fluid travels on the wheel surface and is re-directed into the grinding zone — a phenomenon that may adversely affect cooling and wheel cleaning. Therefore fluid rejection off the wheel is important. A theoretical model for fluid rejection is proposed, that describes the drop formation process, presents the operating instabilities, identifies characteristic time and length scales, and predicts the amount of rejected fluid. Although the surface roughness of the wheel is important in quantifying coolant flow rates, a smooth wheel is employed in this work to study first order effects. Preliminary experimental results obtained for a rough grinding wheel are in conformance with those for a smooth wheel.