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 |