CARBIDE TIPPED PROBLEM SOLVING GUIDE

DRILLING
PROBLEMS

REAMING
PROBLEMS
MILLING
PROBLEMS


AVOID
PROBLEMS
BY CAREFUL
ORIGINAL
SET-UP
   MACHINE CONDITION
TOOL CONDITION

FEEDS & SPEEDS
COOLANT
  • Tool holder in good condition & secure part holding fixture.
  • Use cutting tool recommended for material being machined.
    Avoid excessive tool overhang.
  • Start with feeds & speeds recommended for material being machined.
  • Where used, coolant flow must be adequate to avoid intermittent quenching and to flush chips promptly, avoiding the recutting of hardened chips.
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.

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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.

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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.

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