Grinding Journal - Summer 2007 - (Page 18)

Illustration Visible Grinding Error Grinding with feed marks: The centerline of the grinding wheel is not parallel to the table. Possible Cause Can be caused by a shifting dressing tool, thermal influence, or wear during the dressing cycle Remedy 1) Check dressing tool 2) Check coolant 3) Replace dressing tool if necessary. Mirror-like gloss on the surface, original pre-machining surface finish still visible Grinding wheel too fine or dressed with dull dressing tool Increase dressing feed speed or replace the dressing tool Grinding with source interference: Surface shows marks parallel to the workpiece axis that are partially or on the whole workpiece circumference. 1) External influences such as a forklift driving by, a punch press near the machine, or a heavy vehicle outside 2) A ventilator fan or centrifuge may also be a cause, if so, the bevels will be spread over the entire workpiece Eliminate or isolate the interference Geometrical grinding errors Roundness or concentricity issues take more analysis and patience. The easy way out is to say the machine manufacturer sold you a lemon or to call maintenance and blame them for not setting up the machine properly. The logical solution is to check the workpiece centers for nicks, burrs, dirt and pre-machining accuracy. The ideal center is within <0.0002 inch roundness, is not oval and has no burrs or nicks. It has an odd number of support points as shown in the illustration to the lower left. Small deviations are acceptable if they are within tolerances and The parts are <0.002” out of round. Concentric distribution of the deviations improves the success rate of grinding 1 Grinding Journal The unbalanced spread of the irregular centers may allow the piece to move in the workhead or tailstock centers when grinding

Table of Contents Feed for the Digital Edition of Grinding Journal - Summer 2007

Contents My Thoughts Exactly When Lives Are at Stake Walter Consolidating Production The Art of Grinding: Knowing the Source of Grinding Errors and How to Fix Them The How and Why of Conventional Vitrified Grinding Wheel Selection Grinding Glass Flat Problem Solver

Grinding Journal - Summer 2007

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