The first application of a new Landis CNC grinder combining crankshaft thrustwall and pilot bore grinding operations was recently supplied to a leading automotive manufacturer. Engineers at the company say they plan to eliminate two separate crankshaft turning operations using the new Landis multi-operational grinder.
According to Tim Hykes, Chief of Engineering for Cinetic Landis Corp., the quality of these features—pilot bore runout and thrust wall runout and finish—will improve as a result of the new grinding method and should help in meeting the auto maker’s goal of reducing engine vibration. “The Landis CNC grinder supports the crankshaft on the same journals as its engine will,” said Hykes. “This means that the pilot bore and thrust wall tolerances key directly off the journal centerline. That correlation is impossible to achieve with turning,” he said.
Dennis Peters, Cinetic Landis' director of simultaneous engineering, said the new machine is reducing runout tolerance from 50 microns down to 20 or 30 microns relative to the end main bearings. To better control flange face geometry and to reduce the possibility of thermal damage, the machine employs "kiss" grinding techniques, where a narrow-rimmed, large-diameter, cubic boron nitride (CBN) wheel, running in either a water-soluble coolant or mineral oil, abrades the thrust flange face without necessitating secondary polishing. The thrust wall can also be ground differentially, Peters explained, to improve its hydrostatic properties on the bearing.