Machining Troubleshooting

Category Problem Cause Remedy
Thread milling Chipping (2/3) Wrong cutting data Reduce speed/feed
Counterboring and Countersinking Chipping (2/3) Recutting work hardened chips Increase coolant flow
Milling Chipping (2/6) Chattering Reduce the RPM
Threading with taps Chipping (2/7) Incorrect or lack of lubricant Use good lubrication in order to prevent built up edge.
Thread milling Chipping (3/3) Load too big Reduce feed or Divide cut into 2 or 3 passes
Counterboring and Countersinking Chipping (3/3) Vibration Increase rigidity of set-up, especially worn tool holders
Milling Chipping (3/6) Low cutting speed Increase the RPM
Threading with taps Chipping (3/7) Taps hit bottom of hole Increase depth of drilling or decrease depth of tapping
Milling Chipping (4/6) Conventional milling Climb milling
Threading with taps Chipping (4/7) Work hardening surface Reduce speed, use coated tool, use good lubrication.
Milling Chipping (5/6) Tool rigidity Choose a shorter tool and/or place shank further up holder
Threading with taps Chipping (5/7) Swarf trapping on reversal Avoid sudden return of tap on reversal motion
Milling Chipping (6/6) Workpiece rigidity Hold workpiece tightly
Threading with taps Chipping (6/7) Chamfer hits hole entrance Check axial position and reduce axial error of tap point on hole centre.
Threading with taps Chipping (7/7) Tap drill hole too small Increase drill diameter to maximum value.
Threading with Dies Chipping / Breakage (1/5) Wrong type of die Select the suitable die
Threading with Dies Chipping / Breakage (2/5) Speed too high Adjust conditions
Threading with Dies Chipping / Breakage (3/5) Bar diameter too large Reduce to appropriate size
Threading with Dies Chipping / Breakage (4/5) Bar end not chamfered Ensure bar end is chamfered
Threading with Dies Chipping / Breakage (5/5) Misalignment Correct alignment, ensure cleanliness
Counterboring and Countersinking Excessive Cutting Edge Wear (1/3) Incorrect feeds & speeds Increase feed - especially when machining ductile or free machining materials. Also try reducing speed
Counterboring and Countersinking Excessive Cutting Edge Wear (2/3) Rough cutting edge Lightly hone cutting edge with fine grit diamond hone
Counterboring and Countersinking Excessive Cutting Edge Wear (3/3 Insufficient coolant Increase coolant flow - review type of coolant
Counterboring and Countersinking Glazed Finish (1/3) Feed too light Increase feed
Counterboring and Countersinking Glazed Finish (2/3) Dull cutting edge Resharpen tool to original geometry
Counterboring and Countersinking Glazed Finish (3/3) Insufficient clearance Resharpen tool with more clearance
Drilling Hole size too large (1/2) Incorrect point geometry Check point geometry in regrinding section
Drilling Hole size too large (2/2) Ineffective swarf clearance Adjust speed, feed and peck length to achieve more manageable swarf
Reaming Oval and conical holes (1/3) Displacement in the machine spindle Repair and rectify spindle displacement
Reaming Oval and conical holes (2/3) Misalignment between tool and hole Use a bridge reamer
Reaming Oval and conical holes (3/3) Asymmetric bevel lead angle Regrind to correct specification
Threading with taps Oversize (1/6) Incorrect tolerance Choose a tap with lower thread tolerance
Threading with taps Oversize (2/6) Incorrect axial feed rate Reduce feed rate by 5-10% or increase compression of tap holder
Threading with taps Oversize (3/6) Wrong type of tap for application Use spiral point for through hole or spiral fl ute for blind hole. Use coated tool to prevent built up edge. Check Catalogue or Product Selector for correct tool alternative
Threading with taps Oversize (4/6) Tap not centered on the hole Check tap holder and position tap centre on the hole
Threading with taps Oversize (5/6) Lack of lubrication Use good lubrication in order to prevent built up edge.
Threading with taps Oversize (6/6) Tap speed too slow Adjust conditions
Threading with Dies Oversize / Undersize (1/2) Misalignment Correct alignment, ensure cleanliness
Threading with Dies Oversize / Undersize (2/2) Incorrect axial feed rate Ensure axial feed rate is controlled accurately
Reaming Oversize Hole (1/7) Excessive lip height variation Regrind to correct specification
Reaming Oversize Hole (2/7) Displacement in the machine spindle Repair and rectify spindle displacement
Reaming Oversize Hole (3/7) Defects on the tool holder Replace tool holder
Reaming Oversize Hole (4/7) Tool shank is damaged Replace or regrind the shank
Reaming Oversize Hole (5/7) Ovality of the tool Replace or regrind the tool
Reaming Oversize Hole (6/7) Asymmetric bevel lead angle Regrind to correct specification
Reaming Oversize Hole (7/7) Too high feed or cutting speed Adjust cutting conditions
Threading with Dies Poor finish (1/5) Incorrect rake angle for the material Try alternative dies or special die
Threading with Dies Poor finish (2/5) Incorrect/lack of lubricant Adjust conditions
Threading with Dies Poor finish (3/5) Incorrect speed Adjust conditions
Threading with Dies Poor finish (4/5) Bar diameter too large Reduce to appropriate size

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