The following table lists some of the common problems encountered in machining operations. While it can be very helpful in indentifying the source of many problems, nothing replaces running a "sweet-spot test" for rapidly determining the optimum combination of machining parameters.
|
Problem |
Cause |
Solution |
Chipping |
- Feed rate too high
- Up milling (conventional)
- Cutting edge too sharp
- Chattering
- Loose tool
- Workpiece rigidity
- Tool rigidity
- Low cutting speed
- Loose toolholder
|
-
Reduce feed rate
-
Change to down milling (climb)
-
Hone cutting edge or allow break-in
-
Reduce RPM
-
Remove, clean, and retighten
-
Tighten workpiece holding method
-
Shorten LOC, place shank further up holder
-
Increase RPM
-
Remove from spindle, clean and replace
|
Wear |
- High cutting speed
- Low feed rate
- Up milling (conventional)
- Hard material
- Poor chip evacuation
- Improper cutter helix
|
-
Reduce RPM
-
Increase feed rate
-
Change to down milling (climb)
-
Use coated tool
-
Reposition coolant lines, use air blasting
-
Change to recommended helix angle
|
Breakage |
- Excessive spindle TIR
- Feed rate too high
- Depth of cut too large
- Poor tool rigidity
- Tool wear
- Poor chip evacuation
|
-
Reduce feed rate
-
Reduce depth of cut
-
Shorten LOC, place shank further up holder
-
Replace/regrind sooner
-
Use air blasting
|
Chattering |
- Speed and feed too high
- Poor toolholder rigidity
- Poor spindle rigidity
- Workpiece rigidity
- Relief angle too high
- Depth of cut too large
- Poor tool rigidity
|
-
Reduce feed rate
-
Replace with shorter/more rigid holder
-
Use larger spindle or different machine tool
-
Tighten workpiece holding method
-
Regrind with smaller relief angle
-
Reduce depth of cut
-
Shorten LOC, place shank further up holder
|
Short Life |
- Non-optimum combination of feed and speed
- Cutter/workpiece friction
- Hard material
- Poor material condition
- Improper cutter angle
|
- Use coated tool
- Use coated tool
- Use coated tool, clean material surface
- Regrind with proper primary relief angle
|
Chip Packing |
- Feed rate too high
- Low cutting speed
- Insufficient chip room
|
- Reduce feed rate or increase speed
- Increase RPM or reduce feed rate
- Use tool with less flutes, increase
helix
|
Poor Surface Finish |
- Feed rate too high
- Low cutting speed
- Tool wear
- Edge build up
- Depth of cut too large
- Chip welding
|
- Reduce feed rate
- Increase RPM
- Replace or regrind tool
- Increase RPM, switch to higher helix
tool
- Reduce depth of cut
- Increase volume of coolant
|
Burring or Workpiece Chipping |
- Excessive spindle TIR
- Tool wear
- Improper helix angle
- Feed rate too high
- Depth of cut too large
|
- Replace or regrind tool
- Change to recommended helix angle
- Reduce feed rate
- Reduce depth of cut
|
Workpiece Inaccuracy |
- Loose/worn toolholder
- Poor toolholder rigidity
- Poor spindle rigidity
- Insufficient number of flutes
- Tool deflection
|
- Repair or replace
- Replace with shorter/more rigid
toolholder
- Use larger spindle or different machine
tool
- Use tool with higher flute quantity
- Shorten LOC, place shank further up
holder
|