Trouble Shooting Guide

Dimensional Accuracy Surface Finish Tool Life
•Oversize Pitch Diameter
•Oversize Internal Diameter
•Undersize Pitch Diameter
•Undersize Internal Diameter
•Torn or Rough Thread
•Chattering on Tapped Thread
•Breakage
•Chipping
•Wear

Dimensional Accuracy
Specific Problem Cause Solution
Oversize Pitch Diameter Incorrect Tap
  1. Use proper GH limits of taps.
  2. Use longer chamfered taps
Chip Packing
  1. Use spiral point or spiral fluted taps.
  2. Reduce number of flutes to provide extra chip room.
  3. Use larger hole size.
  4. If tapping a blind hole, allow deeper holes where applicable or shorten the thread length of the parts.
  5. Use proper lubricant.
Galling
  1. Apply proper surface treatment such as steam oxide or TiN.
  2. Use proper cutting lubricant.
  3. Reduce tapping speed.
  4. Use proper cutting angle in accordance with material being tapped.
  5. Use larger hole size.
Operating Conditions
  1. Apply proper tapping speed.
  2. Correct alignment of tap and drilled hole.
  3. Use proper tapping speed to avoid torn or rough threads.
  4. Use lead screw tapper.
  5. Use proper tapping machine with suitable power.
  6. Avoid misalignment of the tap and drilled hole from loose spindle or worn holder.
Tool Conditions
  1. Obtain proper indexing angle for the flutes at the cutting edge.
  2. Grind proper cutting angle and chamfer angle.
  3. Avoid too narrow a land width.
  4. Remove burrs from regrinding.
Oversize Internal Diameter Hole Size
  1. Use minimum hole size.
  2. Avoid tapered hole.
  3. Use proper chamfered taps.
Galling Galling solutions 1 through 4 under "Tool Conditions" can be applied to this specific problem.
Undersize Pitch Diameter Incorrect Tap
  1. Use oversize taps:
    1. Use for cutting materials such as copper alloy, aluminum alloy, and cast iron.
    2. Use for cutting tubing which will have "spring back" action after tapping.
  2. Apply proper chamfer angle.
  3. Increase cutting angle.
Damaged Thread Use proper reversing speed to avoid damaging tapped thread on the way out of the hole.
Left-over Chips
  1. Increase cutting performance to avoid any left over chips in the hole.
  2. Remove left over chips from the hole for gage checking.
Undersize Internal Diameter Hole Size Use maximum drill size.

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Surface Finish
Specific Problem Cause Solution
Torn or Rough Thread Chamfer Too Short Increase chamfer length.
Wrong Cutting Angle Apply proper cutting angle.
Galling
  1. Use thread relieved taps.
  2. Reduce land width.
  3. Apply surface treatment such as steam oxide or TiN.
  4. Use proper cutting lubricant.
  5. Reduce tapping speed.
  6. Use larger hole size.
  7. Obtain proper alignment between tap and work.
Chip Packing
  1. Use spiral pointed or spiral fluted taps.
  2. Use larger drill size.
Chattering on Tapped Thread Too Free Cutting
  1. Reduce cutting angle.
  2. Reduce amount of thread relief.
Tool Conditions
  1. Avoid too narrow a land.
  2. Do not grind the bottom of the flute.

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Tool Life
Specific Problem Cause Solution
Breakage Incorrect Tap Selection
  1. Avoid chip packing in the flutes or the bottom of the hole. Use spiral pointed or spiral fluted taps or fluteless taps.
  2. Apply correct surface treatment such as steam oxide or TiN.
Excessive Tapping Torque
  1. Use larger drill size.
  2. Try to shorten thread length.
  3. Increase cutting angle.
  4. Use a tap with more thread relief and reduced land width.
  5. Use spiral pointed or spiral fluted taps.
Operating Conditions
  1. Reduce tapping speed.
  2. Avoid misalignment between tap and the hole and tapered hole.
  3. Use floating type of tapping holder.
  4. Use tapping holder with torque adjustment.
  5. Avoid hitting bottom of the hole with tap.
Tool Conditions
  1. Do not grind the bottom of the flute.
  2. Avoid too narrow a land width.
  3. Remove all worn sections when regrinding the flutes.
  4. Regrind tool more frequently.
Chipping Incorrect Tap Selection
  1. Reduce cutting angle.
  2. Use different kind of high-speed steel tap.
  3. Reduce hardness of the tap.
  4. Increase chamfer length.
  5. Avoid chip packing in the flutes or in the bottom of the hole by using spiral fluted or spiral pointed taps.
Operating Conditions
  1. Reduce tapping speed.
  2. Avoid misalignment between tap and hole.
  3. Avoid sudden return of reverse in blind hole tapping.
  4. Avoid galling.
  5. Use large hole size.
Wear Incorrect Tap Selection
  1. Use specially designed taps for tapping heat treated material.
  2. Change to a type of high-speed steel tap that contains vanadium.
  3. Apply special surface treatment such as steam oxide or TiN.
  4. Increase chamfer length.
Operating Conditions
  1. Reduce tapping speed.
  2. Apply proper cutting lubricants.
  3. Avoid work hardening.
  4. Use larger hole size.
  1. Reduce tapping speed.
  2. Apply proper cutting lubricants.
  3. Avoid work hardening.
  4. Use larger hole size.
Tool Conditions
  1. Grind proper cutting angle.
  2. Avoid hardness reduction from grinding process.

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NEWS
Technical Sections

Taps --
Technical information on tapping
Drills --
Technical information on drilling
End Mills --
Technical information on milling
Surface Treatments --
Surface treatment infomation
MSDS --
Material Safety Data Sheet
Thread Mills --
Technical information on Thread Mills