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
PROBLEMCAUSESOLUTION
BREAKAGEToo large cutting amountAdjust to smaller cutting amount per teeth
Too long flute length or long overall lengthHold shank deeper, use shorter end mill
Too much wearRegrind at earlier stage
Workpiece rigidityEnsure workpiece is secure and supported
Speed too lowIncrease the cutting speed (RPM’s)
Feed rate too highReduce FPT
Heavy depth of cutReduce RDOC & ADOC
Part entryReduce FPT on entry – implement radius in sweeping entrances – avoid 90º (perpendicular) entry
Milling strategyReview tool path and ensure there are no arbitrary moves, extreme angle of engagement increases & undesirable situations for the tool
Tool overhangUse shortest OAL, shortest LOC & reduce overhang from tool holder. Consider necked down tooling for long reach
Tool runoutCheck tool runout in holder/spindle. utilize collet, milling chuck or shrink fit holders if possible. Hand ground shank flats can be suspects
ReconditioningImproper regrind/reconditioning
Poor chip evacuationReposition coolant lines, use air blasting
Poor tool rigidityShorten LOC, place shank further up holder
BURRToo much wear on primary reliefRegrind at earlier stage
Incorrect conditionsCorrect milling conditions
Improper cutting angleChange to correct cutting angle
Tool wearReplace or regrind tool
Improper helix angleChange to recommended helix angle
Feed rate too highReduce feed rate
Depth of cut too largeReduce depth of cut
Incorrect feed and speed ratesCorrect cutting parameters
Improper cutting parametersAdjust feed and speed
BUILT UP EDGEChip weldingUtilize proper tool coating for material being cut
Feed rate too lowIncrease FPT
Speed too lowIncrease RPM’s
Coolant StrategyRe-adjust coolant flow & check coolant mixture percentage
CHATTER/VIBRATIONWorkpiece rigidityCheck that workpiece is secure and supported
Tool holder rigidityUse shortest holder possible and investigate for no tool slippage
Lack of rigidity (machine)Use better machine or change parameters
Poor spindle rigidityUse larger spindles or different tool
Tool overhangUse shortest length tool, shortest loc & reduce overhang from tool holder. Consider necked down tooling for long reach
Tool run outCheck 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 highLower the RPM’s
Feed rate too lowIncreased FPT
Angle of engagement violationUse smaller tools generating corner radi in pockets – avoid tool diameters that match corner diameter/radius
Too much surface contactUtilize a lower flute count tool
Chip ThinningUtilize chip thinning adjustment
Milling StrategyEnsure you are climb milling unless the material has hard/abrasive outer skin then conventional milling is preferred for breakthrough
Feed and speed too fastCorrect feed and speed
Poor set upImprove clamping rigidity
Cut is too heavyDecrease width and depth of cut
Overhang of tool is too muchHold shank deeper, use shorter end mill
Lack of reliefDecrease relief angle, make margin: (touch primary with oil stone)
Loose hold of workpieceHold workpiece tightly
Cutting too deepDecrease depth of cut
Too long flute or overall lengthHold shank deeper, use shorter end mill or try down cut
Cut too aggresiveReduce width and/or depth of cut
CHIP COMPACTIONInsufficient chip roomUse tool with less flutes, increase helix
Feed rate too highReduce FPT and increase RPM
Heavy depth of cutReduce ADOC/RDOC in side milling & ADOC in slotting
Coolant flushRe-adjust coolant flow, air blast or “op stop” to clear chip build up
Large chip sizeUtilize chip breaker style tool to better manage chip size, adjust feed or speed
Cut too heavyDecrease width and depth-of-cut
Not enough coolantUse higher coolant pressure and reposition nozzle to point of cut or use air pressure; Increase volume of coolant
Low cutting speedIncrease RPM or reduce feed rate
Too great cutting amountAdjust feed or speed
Feed and/or speed too aggresiveAdjust feed or speed
DEFLECTIONTool overhangUse shortest length tool, shortest loc & reduce overhang from tool holder
Milling strategyClimb milling can help reduce the amount of deflection in some cases
Too heavy of a RDOCReduce ADOC/RDOC in side milling & ADOC in slotting
Feed rate too highDecrease FPT
End mill diameterIncrease diameter of end mill for higher strength-to-length ratio
Increase number of flutesHigher number of flutes = larger core diameter = increased strength
DIMENSIONAL INACCURACIESCoolant StrategyRe-adjust coolant flow & check coolant mixture percentage
DeflectionRefer to deflection section above
Feed rate too highLower feed rate (clpt)
RDOC too highReduce RDOC
Tool Run outCheck 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 heavyDecrease 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 flutesUse multiflute end mills, use end mill with higher rigidity
Excessive cuttingDecrease 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 holderRepair of replace
Poor tool holder rigidityReplace with shorter/more rigid tool holder
Poor spindle rigidityUse larger spindle or different tool
Too tough conditionChange to easier condition
Cut too aggresiveReduce width and/or depth of cut
Feed rate too heavyReduce feed rate
Overhang of tool is too muchHold shank deeper , use shorter end mill
EXCESSIVE CORNER WEARNo Corner RadiusImplement corner radius on tool – adds strength & tool life
Speed too highReduce RPM’s
Tool Run outCheck tool run out in holder/spindle. Hand ground shank flats can be suspect and a common cause of run out. (<.0003 TIR desired)
Tool OverhangEnsure you are using the shortest OAL/LOC possible. Utilize necked tooling for longer reach
POOR FINISHFeed rate too highReduce FPT
Speed too lowIncrease RPM’s
Too light of a RDOCIncrease RDOC to stabilize tool in cut.
Tool Run outCheck tool run out in holder/spindle. Hand ground shank flats can be suspect and a common cause of run out. (<.0003 TIR desired)
Helix AngleChange to tool with higher helix angle
Need more FlutesChoose end mill with higher number of flutes
Recutting ChipsRedirect/evaluate coolant flush – or use less number of flutes
Built Up EdgeIncrease RPM, use higher helix tool
Wear is too muchRegrind at earlier stage
No end tooth concavityGrind concave angle on bottom teeth
Depth of cut too largeReduce depth of cut
Chip weldingIncrease volume of coolant
Chip bitingCut less amount per pass
Speed not aggresive enoughIncrease RPM
Cut too aggresiveReduce width and/or depth of cut
Tool overwornRegrind/Recondition sooner
SHORT TOOL LIFECutting friction is too muchRegrind at earlier stage
Hard work materialUse Coatings ( TiN, TiCN,TiAlN)
Improper helix and relief angleChange to correct helix angle and primary relief
Poor coolantReplace coolant or correct mixture
Poor material conditionUse coated tool, clean material surface
WEARNo Corner RadiusImplement corner radius on tool – adds strength & tool life
Speed too highReduce RPM’s, Decrease spindle speed, use another coolant
Tool Run outCheck tool run out in holder/spindle. Hand ground shank flats can be suspect and a common cause of run out. (<.0003 TIR desired)
Tool OverhangEnsure you are using the shortest OAL/LOC possible. Utilize necked tooling for longer reach.
Hard work materialUse higher grade tool material and coating
Biting chipsChange 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 angleChange to correct cutting angle
Too small primary relief angleChange to larger relief angle
Low feed rateIncrease feed rate
Up milling (conventional)Change to down milling (climb)
Hard materialUse coated tool
Poor chip evacuationReposition coolant lines, use air blasting
Improper cutter helixChange to recommended helix angle
Poor coolantReplace coolant or correct mixture
CHIPPINGWorkpiece rigidityCheck workpiece is secure and supported – a common issue. Use better machine or tool holder or change parameters
Tool holder rigidityUse 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 highReduce FPT
Tool Heavy of a RDOCReduce RDOC
Part EntryReduce FPT on entry – implement radius in or sweeping entrances – avoid 90º (perpendicular) entry
Milling StrategyEnsure you are climb milling unless the material has hard/abrasive outer skin then conventional milling technique is preferred for breakthrough
Tool OverhangUse shortest OAL, shortest LOC & reduce overhang from tool holder. Consider necked down tooling for long reach
Tool Run outCheck tool run out in holder/spindle. Hand ground shank flats can be suspect and a common cause of run out. (<.0003 TIR desired)
Tool CoatingImplement proper tool coating for material to be cut
Edge prepEnsure tool has proper edge prep
Built Up Edge (BUE)See BUE section for detailed explanation
Feed too heavy on first cutReduce feed rate on first cut
Tool cutting corner too sharpDecrease primary relief and cutting angle, reduce radial width-of-cut
Up milling (conventional)Change to down milling (climb)
ChatteringRedue RPM
Low cutting speedInrease RPM
Feed too aggresiveReduce feed rate
Cut too aggresiveDecrease width and/or depth of cut