End Mill Troubleshooting Guide

PROBLEM CAUSE SOLUTION
Chip packing

 

Too great a cutting amount Adjust feed or speed
Not enough chip room Use end mill fewer flutes
Not enough coolant Apply more coolant. Use air pressure
 
PROBLEM CAUSE SOLUTION
Rough surface finish

  

 
Feed too fast Slow down to correct feed
Slow speed Use higher speed
Too much wear Regrind earlier stage
Chip biting Cut less amount per pass
No end tooth concavity Add margin (touch primary with oilstone)
 
PROBLEM CAUSE SOLUTION
Burr  Too much wear on primary relief Regrind sooner
Incorrect condition Correct milling condition
Improper cutting angle Change to correct cutting angle
 
PROBLEM CAUSE SOLUTION
No dimensional accuracy

 

Too tough condition Change to easier condition
Lack of accuracy (machine & holder) Repair machine or holder
Not enough rigidity (machine & holder) Change machine or holder or condition
Not sufficient number of flutes Use end mill with greater number of flutes
 
PROBLEM CAUSE SOLUTION
No perpendicular side

  

Feed too fast Slow down to correct feed
Too great a cutting amount Reduce cutting amount
Too long a flute length or long overall length Use proper length tool. Hold shank deeper
Not sufficient number of flutes Use end mill with greater number of flutes
 
PROBLEM CAUSE SOLUTION
Chipping

 

 

 

Feed too fast Slow down to proper feed
Feed too fast on first cut Slow down on first bite
Not enough rigidity of machine tool & holder Change rigid machine tool or holder
Loose holder Tighten tool holder
Loose holder (workpiece) Tighten workpiece fixture
Lack of rigidity (tool) Use shortest end mill available. Hold shank deeper. Try down cut
Teeth too sharp Change to lower cutting angle, primary relief
 
PROBLEM CAUSE SOLUTION
Wear

 

 

 

Speed too fast Slow down, use more coolant
Hard material Use higher grade, tool material, add surface treatment
Biting chips Change feed speed to change chip size or clear chips with coolant or air pressure
Improper feed speed (too slow) Increase feed speed. Try down cut
Improper cutting angle Change to correct cutting angle
Too low a primary relief angle Change to larger relief angle
 
PROBLEM CAUSE SOLUTION
Breakage

  

Feed too fast Slow down feed
Too large cutting amount Adjust to smaller cutting amount per teeth
Too long flute length or long overall length Hold shank deeper, use shorter end mill
Too much wear Regrind at earlier stage
 
PROBLEM CAUSE SOLUTION
Chattering

  

 

 

Feed and speed too fast Correct feed and speed
Not enough rigidity (machine & holder) Use better machine tool or holder or change condition
Too much relief angle Change to smaller relief angle. Add margin (touch primary with oil stone)
Loose holder (workpiece) Hold workpiece tighter
Cutting too deep Correct to smaller cutting depth
Too long flute length or long overall length Hold shank deeper, use shorter end mill or try down cut
 
PROBLEM CAUSE SOLUTION
Short tool life
(dull teeth)
Too much cutting friction Regrind at earlier stage
Tough work material Select premium tool
Improper cutting angle Change cutting angle & primary