TROUBLESHOOTING

ANSWERS TO COMMON MILLING PROBLEMS

Here you will see our Troubleshooting Guide. In this section, end milling problems are addressed with potential solutions listed below. There can be many variables when encountering an issue and the charts listed below should narrow down your solution. These charts are not meant to be 100% accurate for your particular setup, as every application is different and may require a variety of adjustments. However, this information is a good start to determine your ideal conditions for your particular machining needs.

TROUBLESHOOTING
PROBLEM CAUSE SOLUTION
BREAKAGE 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
Workpiece rigidity Ensure workpiece is secure and supported
Speed too low Increase the cutting speed (RPM’s)
Feed rate too high Reduce FPT
Heavy depth of cut Reduce RDOC & ADOC
Part entry Reduce FPT on entry – implement radius in sweeping entrances – avoid 90º (perpendicular) entry
Milling strategy Review tool path and ensure there are no arbitrary moves, extreme angle of engagement increases & undesirable situations for the tool
Tool overhang Use shortest OAL, shortest LOC & reduce overhang from tool holder. Consider necked down tooling for long reach
Tool runout Check tool runout in holder/spindle. utilize collet, milling chuck or shrink fit holders if possible. Hand ground shank flats can be suspects
Reconditioning Improper regrind/reconditioning
Poor chip evacuation Reposition coolant lines, use air blasting
Poor tool rigidity Shorten LOC, place shank further up holder
BURR Too much wear on primary relief Regrind at earlier stage
Incorrect conditions Correct milling conditions
Improper cutting angle Change to correct cutting angle
Tool wear Replace or regrind tool
Improper helix angle Change to recommended helix angle
Feed rate too high Reduce feed rate
Depth of cut too large Reduce depth of cut
Incorrect feed and speed rates Correct cutting parameters
Improper cutting parameters Adjust feed and speed
BUILT UP EDGE Chip welding Utilize proper tool coating for material being cut
Feed rate too low Increase FPT
Speed too low Increase RPM’s
Coolant Strategy Re-adjust coolant flow & check coolant mixture percentage
CHATTER/VIBRATION Workpiece rigidity Check that workpiece is secure and supported
Tool holder rigidity Use shortest holder possible and investigate for no tool slippage
Lack of rigidity (machine) Use better machine or change parameters
Poor spindle rigidity Use larger spindles or different tool
Tool overhang Use shortest length tool, shortest loc & reduce overhang from tool holder. Consider necked down tooling for long reach
Tool run out Check tool run out in holder/spindle. Utilize collet, milling chuck or shrink fit holders if possible. Hand ground shank flats can be suspects
Speed too high Lower the RPM’s
Feed rate too low Increased FPT
Angle of engagement violation Use smaller tools generating corner radi in pockets – avoid tool diameters that match corner diameter/radius
Too much surface contact Utilize a lower flute count tool
Chip Thinning Utilize chip thinning adjustment
Milling Strategy Ensure you are climb milling unless the material has hard/abrasive outer skin then conventional milling is preferred for breakthrough
Feed and speed too fast Correct feed and speed
Poor set up Improve clamping rigidity
Cut is too heavy Decrease width and depth of cut
Overhang of tool is too much Hold shank deeper, use shorter end mill
Lack of relief Decrease relief angle, make margin: (touch primary with oil stone)
Loose hold of workpiece Hold workpiece tightly
Cutting too deep Decrease depth of cut
Too long flute or overall length Hold shank deeper, use shorter end mill or try down cut
Cut too aggresive Reduce width and/or depth of cut
CHIP COMPACTION Insufficient chip room Use tool with less flutes, increase helix
Feed rate too high Reduce FPT and increase RPM
Heavy depth of cut Reduce ADOC/RDOC in side milling & ADOC in slotting
Coolant flush Re-adjust coolant flow, air blast or “op stop” to clear chip build up
Large chip size Utilize chip breaker style tool to better manage chip size, adjust feed or speed
Cut too heavy Decrease width and depth-of-cut
Not enough coolant Use higher coolant pressure and reposition nozzle to point of cut or use air pressure; Increase volume of coolant
Low cutting speed Increase RPM or reduce feed rate
Too great cutting amount Adjust feed or speed
Feed and/or speed too aggresive Adjust feed or speed
DEFLECTION Tool overhang Use shortest length tool, shortest loc & reduce overhang from tool holder
Milling strategy Climb milling can help reduce the amount of deflection in some cases
Too heavy of a RDOC Reduce ADOC/RDOC in side milling & ADOC in slotting
Feed rate too high Decrease FPT
End mill diameter Increase diameter of end mill for higher strength-to-length ratio
Increase number of flutes Higher number of flutes = larger core diameter = increased strength
DIMENSIONAL INACCURACIES Coolant Strategy Re-adjust coolant flow & check coolant mixture percentage
Deflection Refer to deflection section above
Feed rate too high Lower feed rate (clpt)
RDOC too high Reduce RDOC
Tool Run out Check tool run out in holder/spindle. Hand ground shank flats can be suspect and a common cause of run out. (<.0003 TIR desired)
Cut is too heavy Decrease width and depth of cut
Lack of accuracy (machine & holder) Repair machine or holder
Rigidity is not enough (machine & holder) Change machine or tool holder or change parameters
Too few flutes Use multiflute end mills, use end mill with higher rigidity
Excessive cutting Decrease depth and width of cut
Lack of accuracy (machine and holder) Repair machine or holder
Not enough rigidity (machine) Change machine or cutting conditions
Loose/worn tool holder Repair of replace
Poor tool holder rigidity Replace with shorter/more rigid tool holder
Poor spindle rigidity Use larger spindle or different tool
Too tough condition Change to easier condition
Cut too aggresive Reduce width and/or depth of cut
Feed rate too heavy Reduce feed rate
Overhang of tool is too much Hold shank deeper , use shorter end mill
EXCESSIVE CORNER WEAR No Corner Radius Implement corner radius on tool – adds strength & tool life
Speed too high Reduce RPM’s
Tool Run out Check tool run out in holder/spindle. Hand ground shank flats can be suspect and a common cause of run out. (<.0003 TIR desired)
Tool Overhang Ensure you are using the shortest OAL/LOC possible. Utilize necked tooling for longer reach
POOR FINISH Feed rate too high Reduce FPT
Speed too low Increase RPM’s
Too light of a RDOC Increase RDOC to stabilize tool in cut.
Tool Run out Check tool run out in holder/spindle. Hand ground shank flats can be suspect and a common cause of run out. (<.0003 TIR desired)
Helix Angle Change to tool with higher helix angle
Need more Flutes Choose end mill with higher number of flutes
Recutting Chips Redirect/evaluate coolant flush – or use less number of flutes
Built Up Edge Increase RPM, use higher helix tool
Wear is too much Regrind at earlier stage
No end tooth concavity Grind concave angle on bottom teeth
Depth of cut too large Reduce depth of cut
Chip welding Increase volume of coolant
Chip biting Cut less amount per pass
Speed not aggresive enough Increase RPM
Cut too aggresive Reduce width and/or depth of cut
Tool overworn Regrind/Recondition sooner
SHORT TOOL LIFE Cutting friction is too much Regrind at earlier stage
Hard work material Use Coatings ( TiN, TiCN,TiAlN)
Improper helix and relief angle Change to correct helix angle and primary relief
Poor coolant Replace coolant or correct mixture
Poor material condition Use coated tool, clean material surface
WEAR No Corner Radius Implement corner radius on tool – adds strength & tool life
Speed too high Reduce RPM’s, Decrease spindle speed, use another coolant
Tool Run out Check tool run out in holder/spindle. Hand ground shank flats can be suspect and a common cause of run out. (<.0003 TIR desired)
Tool Overhang Ensure you are using the shortest OAL/LOC possible. Utilize necked tooling for longer reach.
Hard work material Use higher grade tool material and coating
Biting chips Change feed and speed. Change chip size or clear chips with coolant or air pressure
Improper feed and speed (too slow) Increase feed and speed. Try down-cut
Improper cutting angle Change to correct cutting angle
Too small primary relief angle Change to larger relief angle
Low feed rate Increase feed rate
Up milling (conventional) Change to down milling (climb)
Hard material Use coated tool
Poor chip evacuation Reposition coolant lines, use air blasting
Improper cutter helix Change to recommended helix angle
Poor coolant Replace coolant or correct mixture
CHIPPING Workpiece rigidity Check workpiece is secure and supported – a common issue. Use better machine or tool holder or change parameters
Tool holder rigidity Use shortest holder possible and investigate for tool slippage. Use better machine or tool holder or change parameters. Clean or replace
Lack of rigidity (tool) Use shorter tool, hold shank deeper, try climb milling
Feed rate too high Reduce FPT
Tool Heavy of a RDOC Reduce RDOC
Part Entry Reduce FPT on entry – implement radius in or sweeping entrances – avoid 90º (perpendicular) entry
Milling Strategy Ensure you are climb milling unless the material has hard/abrasive outer skin then conventional milling technique is preferred for breakthrough
Tool Overhang Use shortest OAL, shortest LOC & reduce overhang from tool holder. Consider necked down tooling for long reach
Tool Run out Check tool run out in holder/spindle. Hand ground shank flats can be suspect and a common cause of run out. (<.0003 TIR desired)
Tool Coating Implement proper tool coating for material to be cut
Edge prep Ensure tool has proper edge prep
Built Up Edge (BUE) See BUE section for detailed explanation
Feed too heavy on first cut Reduce feed rate on first cut
Tool cutting corner too sharp Decrease primary relief and cutting angle, reduce radial width-of-cut
Up milling (conventional) Change to down milling (climb)
Chattering Redue RPM
Low cutting speed Inrease RPM
Feed too aggresive Reduce feed rate
Cut too aggresive Decrease width and/or depth of cut