관리 : 표준담당

  Troubleshooting for Milling Chuck (NT Tool)

Problem (문제점)

원인) ⇒ Solution(대책)

 ◈ Fretting corrosion of ID and tool shank (Seizing caused by rust)
Insufficient clamping
Insufficient tool insertion length
Tool shank diameter is smaller than h7.
Cutting resistance is too large. (Pull-out by pestle-like movement)
Bending moment is too large.  ⇒ Keep minimum insertion length.
  ⇒ Use h7 shank tool instead.
  ⇒ Cutting resistance should be lowered.
  a : Lower feed rate or higher rotation (Approx. 20%)
  b : Lower cutting depth
  ⇒ Bending moment should be lowered.
  c : Shorter tool projection length

 ◈ Deformation of needle rollers because tool is kept chucked for long.
  ⇒ First loosening may not be felt smooth.
  ⇒ Loosen clamping ring and give it a few more counterclockwise rotations.
(Rough touch will not be a problem in practice. If tightening is
  very difficult, however, return it to NT TOOL.)
  ⇒ A long-term state of the shuck remains generating the stress on the roller
and the taper side.
  ⇒ Please avoid leaving in the state of the chuck as much as possible.

Tool is pulled out
during cutting.

 ◈ Insufficient clamping   ⇒ Check if clamping is completed.
 ◈ Insufficient tool insertion length  ⇒ Keep minimum insertion length.
 ◈ Tool shank diameter is smaller than  ⇒ Use h7 shank tool instead.
 ◈ Cutting resistance is too large. (Pullout by pestle-like movement.)
Bending moment is too large.
  ⇒ Cutting resistance should be lowered.
  a :Higher rotation or lower feed rate (Approx. 20%)
  b : Lower cutting depth
  c : Shorter tool projection length
 ◈ Chuck rigidity is too low.
  ⇒ Use another type of tool holder. (such as side lock end mill holders)

Problem (문제점)

원인) ⇒ Solution(대책)

 ◈ Rollers for tight-up ring are worn or broken.
Tight-up ring is worn or broken.
  ⇒ Ask NT for repair. (In some cases, irrepairable.)
  No over-tightening or additional turn after a click sound is generated.

 ◈ Chattering by chuck's resonance
  ⇒ Shift rotation speed to vary resonance frequency. (± 10% and above)
 ◈ Insufficient clamping
  ⇒ Check if clamping is completed.
 ◈ Insufficient tool insertion length
  ⇒ Keep minimum insertion length.
 ◈ Tool shank diameter is smaller than h7
  ⇒ Use h7 shank tool instead.
 ◈ The amount of cutting is a little, and the slipping phenomenon on
the grinding surface by swinging of the blade is generated.
  ⇒ Revision of cutting conditions (Higher cutting resistance)
a : Higher feed rate or lower rotation (Approx. 20%)
b : Higher depth of cut
 ◈ Cutting resistance is too high in comparison with the chuck's rigidity.
  ⇒ Revision of cutting conditions (Lower cutting resistance)
  a : Lower feed rate or higher rotation (Approx. 20%)
  b : Lower depth of cut
  ⇒ Use bigger tool chuck.
  ⇒ Shorter tool projection length
  ⇒ Shorter tool chuck length
 ◈ Insufficient chucking force at nose because of using MC collet
(mainly 12mm and below)
  ⇒ Recommendation of collet chucks instead
 ◈ Holder withdrawing power shortage because of defective selection of
retention bolt
  ⇒ Use designated retention stud for M/C
 ◈ Defect per taper due to swelling of BT shank by tightening
retention bolt too much
  ⇒ Keep recommended torque value for tightening retention stud

Problem (문제점)

원인) ⇒ Solution(대책)

 ◈ Interference with ATC arm
  ⇒ Check L0 dimension on our catalog and maximum tool dimension
  for the M/C.
  ⇒ Revision of tool chuck size.
 ◈ Overload for ATC capacity
  ⇒ Check maximum load for ATC.
 ◈ Maximum allowable moment for the M/C is exceeded.
  ⇒ Check maximum allowable moment for M/C.
 ◈ Clamp movement of ATC is not synchronized.
  ⇒ Consult with the machine tool builder.

 ◈ Rust, damage or deformation of chuck ID and collet.
  ⇒ Replacement of chuck or tool
  ⇒ Touching up of area in question
  (rubbing off with sand paper #1000 and above)
  Correction (grinding) by NT TOOL is not possible.
 ◈ Insufficient tool insertion length ⇒ Keep minimum insertion length.
 ◈ Scratch or dent on tool shank  ⇒ Touching up of scratch or dent
 ◈ Notch or flat on tool shank   ⇒ Use tool without notch or flat.
 ◈ Expansion of BT shank because of over-tightening retention stud.
  ⇒ Keep recommended torque value for tightening retention stud.
 ◈ Poor accuracy of tool
  ⇒ Replacement of tools.
 ◈ Dust seizing in the chucking part
  ⇒ Cleaning of chuck ID and collet
 ◈ Deteriorated accuracy of tool interface
Large runout (2 micrometers and above) of spindle ID or end face
  (in the case of two-face contact)
Dust, scratch or dent on taper area or end face
(in the face of two-face contact)
  ⇒ Regrinding or correction of machine spindle
  ⇒ Cleaning of taper and end face
(in the case of two face contact), touching up of scratch or dent