| DRILLING PROBLEMS | POSSIBLE CAUSES | POSSIBLE SOLUTIONS |
| 1. CHIPPED CUTTING EDGE |
| | Excessive feed | Reduce feed. |
| | Excessive lip relief | Reduce lip relief to provide smaller chisel angle. |
| | Vibration | Frequently a worn drill bushing replace. |
| | Thermal cracking carbide | Maintain adequate coolant flow at all times to avoid thermal shocking carbide. |
| 2. SHORT TOOL LIFE |
| | Drill dwelling | Maintain adequate feed at all times. |
| | Only one lip cutting | Regrind with equal lip heights and chisel in center. |
| 3. DRILL WALKS OR DRIFTS |
| | Unequal lip heights | Regrind with equal lip heights and chisel in center. |
| | Worn drill bushing | Replace drill bushing. |
| 4. OVERSIZE HOLES |
| | Unequal lip heights | Regrind with equal lip heights and chisel in center. |
| | Excessive lip relief | Reduce lip relief to provide smaller chisel angle. |
| | Worn drill bushing | Replace drill bushing. |
| 5. ROUGH FINISH |
| | Dull cutting edge | Regrind with fine grit diamond wheel. |
| | Inadequate coolant | Review type of coolant and maintain adequate flow. |
BACK TO TOP OF PAGE |
| REAMING PROBLEMS | POSSIBLE CAUSES | POSSIBLE SOLUTIONS |
| 1. POOR FINISH |
| | Unequal chamfers | Regrind reamer with equal chamfer angle. |
| | Incorrect margins | Regrind reamer with narrow margins for reaming lower tensile materials. |
| | Excessive spindle runout | Increase reamer back taper (will lose size faster). |
| | Chatter | Reduce speed and increase feed rate. |
| | | Use power feed unless material is hard. |
| | | Use right or left spiral fluted reamer. |
| | | Grind secondary lead angle immediately back of 45º chamfer. |
| 2. OVERSIZE HOLE – TAPERED HOLE – BELL MOUTH HOLE – POOR FINISH |
| | Misalignment | Use bushing — .0002″/.0003″ over reamer diameter. |
| | | If hole location varies, use floating reamer holder. |
| | | Increase reamer back taper (will lose size faster). |
| | Insufficient cutting action | Specify reamer with positive radial rake to reduce cutting pressure — may produce slightly larger diameter holes. |
| 3. EXCESSIVE TOOL WEAR |
| | Insufficient stock for removal | Decrease previous operation drill size to allow more material for removal by reamer – leave about 3% of hole diameter for cast iron and more stock for non-ferrous materials. |
| | Excessive reaming pressure | Increase feed rate. |
| | | Reduce stock to be removed by increasing previous operation drill size — leave about 3% of hole diameter. |
| | Misalignment | See problem #2 above. |
| 4. CROOKED HOLES |
| | Not drilled straight | Correct previous drilling operation — reamer will follow the drilled hole. |
| | | Increase reamer attack angle (chamfer) to 120º/180º included angle. |
| 5. TOOL BREAKAGE |
| | Excessive reaming pressure | Reduce stock to be removed — see problem #3 above. |
| | Misalignment | See problem #2 above. |
| |
BACK TO TOP OF PAGE |
| MILLING PROBLEMS | POSSIBLE CAUSE | POSSIBLE SOLUTION |
| 1. ROUGH FINISH |
| | Dull cutting edge | Resharpen to original tool geometry. |
| | Wrong feeds & speeds | Increase speed — also try reduced feed. |
| 2. EXCESSIVE CUTTING EDGE WEAR |
| | Wrong feeds & speeds | Increase feed (should always be over .001″ per tooth) — especially when machining ductile or free machining materials. — Also try reduced speed |
| | Rough cutting edge | Lightly hone cutting edge with fine grit diamond hone. |
| | Insufficient coolant | Increase coolant flow — review type of coolant. |
| 3. CHIPPED CUTTING EDGE |
| | Poor chip removal — | Use tool with larger flute space — larger diameter or fewer flutes. |
| | Recutting work hardened chips | Increase coolant flow. |
| | Vibration | Increase rigidity of set-up, especially worn tool holders. |
| | Incorrect carbide grade | Change to tougher carbide grade. |
| 4. CHATTER MARKS |
| | Insufficient machine horsepower | Use tool with fewer flutes as correct speeds & feeds must be maintained. |
| | Vibration | Consider climb milling. |
| | | Use larger diameter cutter. |
| | | Resharpen tool with more clearance. |
| 5. GLAZED FINISH |
| | Feed too light | Increase feed. |
| | Dull cutting edge | Resharpen tool to original geometry. |
| | Insufficient clearance | Resharpen tool with more clearance. |
| 6. POOR TOOL LIFE |
| | Excessive cratering | Increase speed or decrease feed. |
| | | Change to harder grade of carbide. |
| | Milling abrasive material | Decrease speed and increase
feed. |
| | | Increase coolant flow. |
| | | Climb milling better than conventional milling. |
| | Milling surface scale | Conventional milling better than climb milling. |
| | Milling hard material | Reduce speed — rigidity very important. |
| | Insufficient chip room | Use larger diameter tool. |
| | Delayed resharpening | Prompt resharpening to original geometry will increase total tool life. |
| | Thermal cracked carbide | Increase coolant flow at all times. |
| | | Climb milling is cooler than conventional milling. |
BACK TO TOP OF PAGE |
