Machining Troubleshooting

Category Problem Cause Remedy
Reaming Bad Hole finish (1/6) Excessive stock to remove Decrease the amount of stock to be removed
Reaming Bad Hole finish (2/6) Worn out tool Regrind to specification
Reaming Bad Hole finish (3/6) Too small cutting rake angle Regrind to specification
Reaming Bad Hole finish (4/6) Too diluted emulsion or cutting oil Increase % concentration
Reaming Bad Hole finish (5/6) Feed and/or speed too low Adjust cutting conditions
Reaming Bad Hole finish (6/6) Cutting speed too high Adjust cutting conditions
Milling Bad Surface finish (1/6) Feed too fast Slow down to correct speed
Milling Bad Surface finish (2/6) Speed too slow Increase the speed
Milling Bad Surface finish (3/6) Chip biting Decrease stock removal
Milling Bad Surface finish (4/6) Tool wear Replace or regrind the tool
Milling Bad Surface finish (5/6) Edge build up Change to higher helix tool
Milling Bad Surface finish (6/6) Chip welding Increase coolant quantity
Milling Breakage (1/3) Too high stock removal Decrease feed per tooth
Threading with taps Breakage (1/8) Tap worn out Use a new tap or regrind the old one
Milling Breakage (2/3) Feed too fast Slow down feed
Threading with taps Breakage (2/8) Lack of lubricant Use good lubrication in order to prevent built up edge and chip blockage.
Milling Breakage (3/3) Flute length or overall length too long Hold shank deeper, use shorter end mill
Threading with taps Breakage (3/8) Taps hit bottom of hole Increase depth of drilling or decrease depth of tapping
Threading with taps Breakage (4/8) Tap speed too high Reduce cutting speed.
Threading with taps Breakage (5/8) Work hardening surface Reduce speed. Use coated tool Use good lubrication.
Threading with taps Breakage (6/8) Tap drill hole too small Increase drill diameter up to maximum value.
Threading with taps Breakage (7/8) Too high torque Use tapping attachment with torque adjustment clutch
Threading with taps Breakage (8/8) Material closing in after tapping Adjust conditions
Drilling Breakage at flute run out (1/2) Choking of flutes Adopt a peck / series drilling concept
Drilling Breakage at flute run out (2/2) Drill slipping Ensure the drill is held securely in the chuck and spindle
Thread milling Broken cutter (1/3) Bad chip evacuation Use compressed air, emulsion or internal coolant
Thread milling Broken cutter (2/3) Load too big Reduce feed or Divide cut into 2 or 3 passes
Thread milling Broken cutter (3/3) Instability Check/change tool holder
Reaming Broken or twisted tangs Incorrect fit between shank and socket Ensure the shank and the socket are clean and free from damage
Drilling Broken or twisted tangs Bad fit between shank and socket Ensure the shank and socket are clean and free from damage
Drilling Broken outer corners Unstable component set up Reduce movement in the component
Threading with Dies Built up edge (1/3) Incorrect/lack of lubricant Adjust conditions
Threading with taps Built up edge (1/4) Wrong type of tap for application Use tap with lower rake angle and/or higher relief.
Threading with Dies Built up edge (2/3) Bar diameter too large Reduce to appropriate size
Threading with taps Built up edge (2/4) Lack of lubricant Use good lubrication in order to prevent built up edge.
Threading with Dies Built up edge (3/3) Speed too low Adjust conditions
Threading with taps Built up edge (3/4) Surface treatment not suitable Adjust conditions
Threading with taps Built up edge (4/4) Tap speed too low Adjust conditions
Counterboring and Countersinking Chattering (1/2) Insufficient machine horsepower Use tool with fewer flutes as correct feeds & speeds must be maintained
Milling Chattering (1/5) Feed and speed too high Adjust cutting conditions
Counterboring and Countersinking Chattering (2/2) Vibration Resharpen tool with more clearance
Milling Chattering (2/5) Flute or overall length too long Hold shank deeper and use shorter end mill
Milling Chattering (3/5) Cutting too deep Decrease depth of cut
Milling Chattering (4/5) Not enough rigidity (machine and holder) Check the tool holder and change it if necessary
Milling Chattering (5/5) Workpiece rigidity Hold workpiece tightly
Drilling Chipped cutting lips Excessive initial clearance Regrind to correct specification
Thread milling Chipping (1/3) Instability Check/change tool holder
Counterboring and Countersinking Chipping (1/3) Poor chip removal Use tool with larger flute space - larger diameter or fewer flutes
Milling Chipping (1/6) Feed rate too high Reduce feed rate
Threading with taps Chipping (1/7) Wrong type of tap for application Choose a tap with lower rake angle. Choose a tap with longer chamfer. Use spiral point taps for through hole and spiral fl ute for blind holes, in order to avoid chip blockage.

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