Effect—Chatter or vibration marks (Figure L-107) Cause—Interrupted cutting due to wheel balance; wheel not concentric to spindle; external vibrations; or a “skipping wheel” resulting from loading or glazing
Solution—Rebalance wheel; true wheel; re-dress wheel; relocate grinding machine and isolate from external vibration
Effect—Irregular scratches or fishtails (Figure L-108) Cause—Swarf in the grinding fluid; swarf dripping from wheel guard; insufficient grinding fluid in the supply tank; sliding the workpiece off a dirty chuck Solution—Clean inside of wheel guard; clean grinding fluid; clean chuck before removing workpiece and tilt work up on edge, rather than sliding it off the chuck; maintain grinding fluid level Effect—Discoloration or burning of workpiece (Figure L-109)
Cause—Insufficient grinding fluid; wheel too hard or too fine; concentration of heat because of too heavy a cut in a small area Solution—Speed up table travel; lighten depth of cut; increase grinding fluid flow and volume for cooling Effect—Work not parallel Cause—Chuck surface not parallel to table travel (not ground-in); chuck dirty or burred Solution—Align chuck with dial indicator; follow grind- in procedure; deburr and clean Effect—Workpiece not flat Cause—Local overheating; internal stress relief; bent or twisted workpiece Solution—Use minimum amount of chuck holding power; place workpiece on chuck bowed side up; turn workpiece over and shim with paper; take additional light cuts; reverse workpiece; remove and repeat procedure until flat.
Use stress-relieved or annealed workpiece material, if possible.