Troubleshooting for Stub Holder

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Troubleshooting for Stub Holder

Please see the operation manual

　

Unable to mount collet.

Cause	Solution / Countermeasures
Wrong choice of collet.	Check collet's type and size.

Unable to mount to spindle.

Cause	Solution / Countermeasures
Spindle dimension is different from standard dimension.	Check spindle dimension.
Seized or adhered chip and dust to holder shank, spindle I.D.	Cleaning of holder shank, spindle I.D.
Scratch or dent exists in spindle I.D. or holder shank.	・Replace holder or repair spindle. ・Touching up of area in question（rubbing off with sand paper ＃1000 and above）　 Correction (grinding) by NT TOOL is not possible.
In the case of KD series, end face to end face dimension between spindle and finger bolt is longer than specified dimension.	・Check spindle dimension. ・Make spacer thicker to specified dimension.
In the case of KH series, spindle collar thickness is larger than specified dimension.	Repair spindle.

Excessive play when mounting into spindle.

Cause	Solution / Countermeasures
Spindle dimension is different from standard dimension.	Check spindle dimension.
In the case of KH series, spindle collar thickness is smaller than specified dimension.	Repair spindle.
In the case of KH series, spindle mounting is not proper due to functional failure of operating sleeve.	・When installing, push operating sleeve down to bring it into position for secure mounting. ・Cleaning of operating sleeve I.D.
In the cases of KH-A, KH series, rubber damper is deteriorated.	Ask NT for repair.（In some cases, irrepairable.)
In the case of KH-E series, steel ball is worn.	Ask NT for repair.（In some cases, irrepairable.)
In the case of KD series, finger collet taper is worn.	Replacement of finger collet assembly.
In the case of KD series, finger collets are broken.	Replacement of finger collet assembly.
In the case of KD series, end face to end face dimension between spindle and finger bolt is shorter than specified dimension.	・Check spindle dimension. ・Make thickness of aspacer adjust to specified dimension.

Holder comes off from spindle.

Cause	Solution / Countermeasures
In the case of KH/EC series, coolant pressure is higher than specified pressure.	・Reduce coolant pressure. ・Check specified coolant pressure.
In the case of KH series, spindle mounting is not proper due to functional failure of operating sleeve.	・When installing, push operating sleeve down to bring it into position for secure mounting. ・Cleaning of operating sleeve I.D.

Coolant is leaking or there is no coolant output.

Cause	Solution / Countermeasures
KH/EC is not being used. (Stub holders other than KH/EC are not compatible with center-thru coolant.)	Use KH/EC. ・For high coolant pressure　KH/EC1type ・For low coolant pressure　KH/EC2 type
Coolant pressure is higher than specified pressure.	Use coolant at a pressure equal to or lower than maximum pressure allowed.
Collets compatible with center-thru coolan (OH or C type collets) are not being used.	Use OH or C type collets. ・OH type ・・・ Center through ・C type ・・・ Collet through
Coolant cap “O” ring is deteriorated or worn.	Replacement of O-ring.

Cutting tool comes off or slips.

Cause	Solution / Countermeasures
Large cutting resistance to chucking force.	・Revision of cutting conditions (Decrease cutting resistance.) a : Higher rotation speed or lower feed rate (Approx. 20%) b : Lower cutting depth ・Shorter tool projection length
Insufficient tightening of cap nut	・Keep recommended torque value for tightening cap nut. ・Use torque wrench.
Tightening not sufficient due to cap rotary ring failure.	Replacement of cap nut.
Insufficient tightening of cap nut because of increased friction in the thread part (Tightening of collets not enough.)	Apply oil (grease) on the thread part after cleaning it.
Tool tang does not fit into preset driver groove due to dimensional differences.	・Check tool tang dimension and preset driver groove dimension. ・Replacement of preset driver.

Poor accuracy.

Cause	Solution / Countermeasures
Spindle and holder have rattling.	See Problem: “Excessive play when mounting into spindle” in the trouble column and reduce play (clearance) to appropriate level.
Adhered chip and dust to spindle end surface or holder end surface.	Cleaning of spindle end surface or holder end surface.
Poor chucking accuracy of collet.	Replacement of collets.
Dust seizing in collet insertion area.	Cleaning of collet insertion area.
Scratch or dent in holder I.D.	Replacement of holder.
Scratch or dent on collet I.D. and O.D.	Replacement of collet
Insufficient chucking length.	Keep minimum insertion length. (collet ID length must be filled.)
Poor accuracy of cutting tool.	Tool replacemen.
Dust seizing in cap nut thread.	Cleaning of thread part, applying grease.
Malfunction of rotor ring of cap nut. (Rotor ring will not rotate smoothly.)	・Cleaning of cap nut. （so that rotor ring will rotate smoothly.) ・Replacement of cap nuts.

Chattering

Cause	Solution / Countermeasures
Cutting resistance is too high in comparison with chuck's rigidity	・Revision of cutting conditions (Decrease cutting resistance.) a : Higher rotation speed or lower feed rate (Approx. 20%) b : Lower cutting depth ・Shorter tool projecti
When end-milling with series KH-E, KD-T, The amount of cutting is a little, the end mill runs away, and the slipping phenomenon on the grinding surface has happened.	Revision of cutting conditions (Increase cutting resistance.) a : Higher feed rate or lower rotation (Approx. 20%) b : Higher cutting depth
Bending moment is too large.	Shorter tool projection length
Spindle and holder have rattling.	See Problem: “Excessive play when mounting into spindle” in the trouble column and reduce play (clearance) to appropriate level.

Holder does not come off from spindle.

Cause	Solution / Countermeasures
Deposition of fretting, rust and/or adhered coolant residual.	Cleaning of spindle and holder shank.
In the case of KH series, operating sleeve failure.	Cleaning of operating sleeve I.D.