Maintenance Views: 14

Signs a countersink is worn and needs replacement: 1) worse finish - rough chamfers, tool marks, chatter, burrs; 2) more cutting force - heavier machine load, duller sound, more vibration; 3) higher temperature - darker chips (carbon steel silver-white to yellow to blue), smoke; 4) size drift - smaller chamfers, shallower countersinks, frequent tool compensation; 5) more burrs after chamfering; 6) welding - built-up edge, scratched surface; 7) abnormal sound - squealing or dull thumping; 8) visible wear band on the edge - clear wear land, chipping, cracks. Three wear stages: initial wear (break-in) -> steady wear (normal working life - make full use of it) -> rapid wear (must replace). Replace when: finish fails, size out of tolerance, abnormal cutting, set life reached, visible edge wear. Do not wait for chipping - a chipped tool scraps batches and causes accidents. Record parts per tool and build a life log; replace at life. Worn tools can be re-sharpened 3-5 times, cutting costs significantly.