Wheel lift-off in creep-feed grinding: thermal damage, power surge, chip thickness and optimisation

An investigation is made into the phenomenon of early lift-off in creep-feed grinding, where the wheel lifts away from the workpiece before reaching the end of cut. In single-pass operations, early lift-off can result in thermal damage. In multi-pass operations, there is a surge in material-removal rate just before lift-off, which can result in thermal damage and excess wheel wear. This study examines the current inadequate methods of dealing with lift-off. It then develops a geometric and kinematic model for analysing the lift-off phenomenon. It finally proposes a thermal-model-based optimisation method for achieving a constant maximum surface temperature, resulting in shorter cycle times and less risk of thermal damage. The power-surge model is validated experimentally in diamond grinding of tungsten-carbide rotary tools.