Hydraulic Chuck
(Trouble shooting)

관리 : 표준담당

  Troubleshooting for Hydraulic Chuck (NT Tool)

Problem (문제점)

원인)  ⇒ Solution(대책)

 ◈ Insufficient clamping force
  ⇒ Check clamping function. (No. of revolution of actuating screw)
 ◈ Insufficient tool insertion length ⇒ Keep minimum insertion length of tool.
 ◈ Tool shank diameter is smaller than h7 tolerance. ⇒ Use h7 shank tool.
 ◈ Cutting resistance (bending moment) is too large.
(Pull out of tool because of pestle-like movement.)
  ⇒ lower cutting resistance
  a. Higher rotation or lower feed rate (Approx. 20%)
  b. Lower cutting depth
  ⇒ Lower bending moment , c. Short  tool projection length
 ◈ Insufficient rigidity of holder ⇒ Use different chuck Trial of collet holder,

 ◈ Chattering by chuckr's resonance
  ⇒ Shift rotation speed to vary resonance frequency. (± 10% and above)
 ◈ Insufficient clamping force
  ⇒ Check clamping function. (No. of revolution of actuating screw)
 ◈ Insufficient tool insertion length ⇒ Keep minimum insertion length of tool.
 ◈ Tool shank diameter is smaller than h7 tolerance. ⇒ Use h7 shank tool.
 ◈ 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 speed (Approx. 20%)
  b. Higher cutting depth
 ◈ Bending moment is too large.
  ⇒ Shorter tool projection length , Shorter projection length of chuck
 ◈ Inappropriate choice of holder (chuck) for the cutting
(The chuck rigidity is lower than the processing load. )
  ⇒ Use different chuck (holder) Trial of collet holder
 ◈ Holder withdrawing power shortage because of defective selection
of retention bolt  ⇒ Use designated retention stud for the machine.
 ◈ 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)

 ◈ Holder withdrawing power shortage because of defective selection
of retention bolt  ⇒ Use designated retention stud for the machine.
 ◈ Defect per taper due to swelling of BT shank by tightening retention
  bolt too much
  ⇒ Keep recommended torque value for tightening retention stud

Deteriorated runout
accuracy during
cutting Guidelines
15 micrometers
and more at 4d
　

 ◈ Rust, scratch or deformation of chuck I.D.
  ⇒ 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.
  ⇒ Ask NT for repair. (In some cases, irrepairable.)
 ◈ Insufficient chucking length ⇒ Keep minimum insertion length of tool
 ◈ Scratch or dent on tool shank ⇒ Scratch or dent must be removed.
 ◈ Notch or flat of tool shank ⇒ Use a tool without notch or flat.
 ◈ Expansion of BT shank because of over-tightening retention stud
(BT30 in particular)
  ⇒ Keep recommended torque value for tightening retention stud.
 ◈ Poor accuracy of tool ⇒ Replacement of tools
 ◈ Dust seizing in chucking area ⇒ Cleaning of chuck I.D.
 ◈ 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

Deteriorated
runout accuracy
(flange type)
　

 ◈ Misalignment of installation part
  ⇒ Re-installation into the spindle
 ◈ Burr in the undercut at the deep end of ID mouth
  ⇒ Deburring (Sandpaper #1000 and above)
 ◈ Misalignment between flange part and chuck part (2-piece type)
  ⇒ Check runout of ID from the flange