Tap Troubleshooting

EMUGE Taps are very free cutting and will easily cut oversize threads if overfed or pushed. For the best results, we recommend the use of an EMUGE Quick-Change Tap Holder with built-in tension, compression and overload clutch features. Always utilize your holder's tension feature by programming spindle feed to 95-98% of the calculated feed rate.

Problem: Tapping oversized threads (no-go gage too loose)
Possible Cause Possible Remedy
Improper tap for material and thread application. · Use a suitable tap for the hole style and material being tapped. Reference the EMUGE Tap Finder for proper selection.
Cutting speed to high. · Reduce cutting speed.
· Improve coolant/lubrication.
Cold welding on the flanks of the tap (loading). · Use a new tool.
· Use surface treated taps.
· Improve coolant/lubrication.
· Grind away chipped and damaged teeth.
Chip packing in flutes. · Use tap with different flute geometry/angle.
· Possibly use set of taps.
Grinding burr. · Remove burr with soft wire or fiber brush.
Incorrect fixturing or positioning of part. · Use tap holders with axial and parallel floating.
· Check clamping of part for correct alignment.
Inconsistent feed of tap. · Tap with controlled feed.
· Check CNC programs.
· Check lead screw for backlash.
· Use compensating tension/compression tap holder.
 
Problem: Tapping oversized threads (no-go gage loose)
Possible Cause Possible Remedy
Tap selected too large for class of thread fit required. · Review markings on tap and determine if it is suitable for the class of fit required.
· If in doubt, contact an EMUGE Representative.
Improper reconditioning of tap. · Reconditioning of tap requires that all ground surfaces maintain the original geometry put on by the manufacturer.
· Contact an EMUGE Representative for instructive information.
 
Problem: Tapping bellmouthed hole (first few threads gage oversize)
Possible Cause Possible Remedy
Wrong initial starting pressure. · Work with controlled tap feed.
Axially hard working spindle. · Use a tap holder with length compensation.
Incorrect fixturing or positioning of part. · Use a tap holder with axial and parallel floating.
· Check clamping of part for correct alignment.
 
Problem: Torn and rough threads
Possible Cause Possible Remedy
Improper selection of tap for material and thread application. · Use a suitable tap for the hole style and material being tapped. Reference the EMUGE Tap Finder for proper selection.
Cutting speed too fast or slow. · Select proper cutting speed.
· Improve coolant selection to assist the effects of tap speed.
Cold welding on the flanks of the tap (loading). · Use a new tool.
· Use surface treated taps.
· Improve coolant/ lubrication.
· Find away chipped and damaged teeth.
Chips packing in flutes. · Use tap with different flute geometry/angle.
· Use set of taps.
Grinding burr. · Remove burr with soft wire or brush.
Tap drill too small. · Use correct size drill.
· Reference recommended sizes listed in EMUGE catalog. Note that cutting and roll form taps use different size tap drills for the same size thread.
· If in doubt, contact an EMUGE Representative.
Insufficient coolant/ lubrication. · Selection of suitable coolant/lubrication for material being tapped.
· Use adequate amounts of coolant lubrication.
Tool overloading due to coarse pitch, hard materials or short chamfers. · Use a set of taps.
 
Problem: Tapping undersized threads (go gage won't enter/binds up part way into hole)
Possible Cause Possible Remedy
Tap selected too small to do multiple regrinds. · Limit the number of regrinds a tap has.
· Use a new tap.
Area of wear not removed when tap was resharpened. · Grind tap again.
· Use a new tap.
Improper tap for material and thread application. · Use suitable tap for the hole style and material being tapped.
· Reference the EMUGE Tap Finder for proper selection.
Go gage binds up part way into hole. · Tap is dull - recondition or replace tap.
· Avoid too much axial force during tapping operation (this caused the tap to cut out of lead)
· Use tap holders with length compensation.
Tap selected too small for class of thread fit required. · Review markings on tap and determine if it is suitable for class of fit required.
· If in doubt, contact an EMUGE Representative.
 
Problem: Tap life too low
Possible Cause Possible Remedy
All reasons stated in torn and rough threads. · See torn and rough threads.
Loss of tap hardness by excess hear during regrinding. · Change the specification of the grinding wheel.
· Use coolant while grinding.
Loss of surface treatment from regrinding. · Retreatment of the tap surface.
· Check suitability of surface treatment for material being tapped.
Work hardened drill hole and hole chamfer. · Change or regrind tap drill more frequently.
· Check proper drilling speed and feed.
· Anneal part before tapping.
 
Problem: Torn and rough threads
Possible Cause Possible Remedy
Improper selection of tap for material and threading application. · Use a suitable tap for the hole style and material being tapped.
· Reference the EMUGE Tap Finder for proper selection.
Tap drill too small. · Use correct size drill. Recommended size drills listed in EMUGE catalog. Note that cutting and roll form taps use different size tap drills for same size thread.
· If in doubt, contact an EMUGE Representative.
Tap hole not deep enough. · Check actual drill depth, drill may have slipped back into holder.
Missing tap drill hole. · Ensure tap drill hole is present. Common problem in multiple spindle applications on transfer lines.
Chips packing in flutes. · Use tap with different flute geometry/angle.
· Use a set of taps.
Cutting speed too high or low. · Select proper cutting speed.
· Improve coolant/lubrication to assist the effects of the tap speed.
Cold welding on the flanks of the tap (loading). · Use a new tool.
· Use surface treated taps.
· Improve coolant/lubrication.
· Grind away chipped and damaged teeth.
Overload of the chamfer teeth. · Use longer chamfer.
· Increase number of tap flutes to provide more chamfered teeth.
Incorrect fixturing or positioning of part. · Use tap holders with axial/parallel floating.
· Check clamping of part for correct alignment.
Tap hitting the bottom of hole. · Use tap holder with length compensation and torque overload system.
Tapping hard or high tensile materials. · Check selection of tap, carbide tap may be more suitable then high speed steel taps.

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