Carbide Tipped Problem Solving Guide
MILLING
PROBLEMS || DRILLING
PROBLEMS || REAMING PROBLEMS
| MILLING
PROBLEMS |
POSSIBLE
CAUSES |
POSSIBLE SOLUTIONS |
| 1. ROUGH
FINISH |
Dull cutting
edge Wrong feeds & speeds |
Resharpen
to original tool geometry. Increase speed - also try reduced feed. |
| 2. EXCESSIVE CUTTING EDGE WEAR |
Wrong feeds
& speeds Rough cutting edge Insufficient coolant |
Increase
feed (should always be over .001" per tooth) - especially when machining ductile or free machining materials. - Also try reduced speed. Lightly hone cutting edge with fine grit diamond hone. Increase coolant flow - review type of coolant. |
| 3. CHIPPED CUTTING EDGE |
Poor chip
removal Recutting work hardened chips Vibration Incorrect carbide grade |
Use tool
with larger flute space - larger diameter or fewer flutes. Increase coolant flow. Increase rigidity of set-up, especially worn tool holders. Change to tougher carbide grade. |
| 4. CHATTER
MARKS |
Insufficient
machine horsepower Vibration |
Use tool
with fewer flutes as correct speeds & feeds must be maintained. Consider climb milling. Use larger diameter cutter. Resharpen tool with more clearance. |
| 5. GLAZED
FINISH |
Feed too
light Dull cutting edge Insufficient clearance |
Increase
feed. Resharpen tool to original geometry. Resharpen tool with more clearance. |
| 6. POOR
TOOL LIFE |
Excessive
cratering Milling abrasive material Milling hard material Insufficient chip room Milling surface scale Delayed resharpening Thermal cracked carbide |
Increase
speed or decrease feed. Change to harder grade of carbide. Decrease speed and increase feed. Increase coolant flow. Climb milling better than conventional milling. Reduced speed - rigidity very important. Use larger diameter tool. Conventional milling better than climb milling. Prompt resharpening to original geometry will increase total tool life. Increase coolant flow at all times. Climb milling is cooler than conventional milling. |
| DRILLING
PROBLEMS |
POSSIBLE
CAUSES |
POSSIBLE SOLUTIONS |
| 1. CHIPPED
CUTTING EDGE |
Excessive
feed Excessive lip relief Vibration Thermal cracking carbide |
Reduce feed. Reduce lip relief to provide smaller chisel angle. Frequently a worn drill bushing - REPLACE. Maintain adequate coolant flow at all times to avoid thermal shocking carbide. |
| 2. SHORT
TOOL LIFE |
Drill Dwelling Only one lip cutting |
Maintain
adequate feed at all times. Regrind with equal lip heights and chisel in center. |
| 3. DRILL
WALKS OR DRIFTS |
Unequal lip
heights Worn drill bushing |
Regrind with
equal lip heights and chisel in center. Replace drill bushing. |
| 4. OVERSIZE
HOLES |
Unequal lip
heights Excessive lip relief Worn drill bushing |
Regrind with
equal lip heights and chisel in center. Reduce lip relief to provide smaller chisel angle. Replace drill bushing. |
| 5. ROUGH
FINISH |
Dull cutting
edge Inadequate coolant |
Regrind with
fine grit diamond wheel. Review type of coolant and maintain adequate flow. |
| REAMING
PROBLEMS |
POSSIBLE
CAUSES |
POSSIBLE SOLUTIONS |
| 1. POOR FINISH
|
Unequal chamfers
Incorrect margins Excessive spindle runout Chatter |
Regrind reamer
with equal chamfer angle. Regrind reamer with narrow margins for reaming lower tensile materials. Increase reamer back taper (will lose size faster). 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 45° chamfer. |
| 2. OVERSIZE
HOLE TAPER HOLE BELL MOUTH HOLE POOR FINISH |
Misalignment
Insufficient cutting action |
Use bushing
- .0002"/.0003" over reamer diameter. If hole location varies, use floating reamer holder. Increase reamer back taper (will lose size faster). Specify reamer with positive radial rake to reduce cutting pressure - may produce slightly larger diameter holes. |
| 3. EXCESSIVE
TOOL WEAR |
Insufficient
stock for removal Excessive reaming pressure Misalignment |
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. Increase feed rate. Reduce stock to be removed by increasing previous operation drill size - leave about 3% of the hole diameter. 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 120°/180° included angle. |
| 5. TOOL BREAKAGE
|
Excessive
reaming pressure Misalignment |
Reduce stock
to be removed - see problem #3 above. See problem #2 above. |
