Tapping Chuck
(Trouble shooting)

관리 : 표준담당

  Troubleshooting for Tapping Chuck (NT Tool)

Problem (문제점)

원인)  ⇒ Solution(대책)

Thread gauge (stop)
can go through.
(Enlarged
thread diameter)

 ◈ Miss choice of tap
  ⇒ Tapping chuck with length compensation is not suitable for
synchronic tap (eccentric relief).
  ⇒ Use normal tap (concentric relief) which has self-advancing action

Thread gauge (through)
cannot go through.
(Thread diameter
is small.)
　

 ◈ Burr has been generated at the entrance of tap hole.
  ⇒ Return timing is premature (before tap is pulled out)
  → Revision of approach point Guidelines : maximum tension + 5
  ⇒ Too much tension
  → Increase feed rate. Must be lower than tap pitch.
 ◈ Burr at the entrance of tap hole due to the reaction to compression.
  ⇒ Check if the compression of tapping chuck is working during operation.
  → Decrease feed rate less than tap pitch (85-95% of tap pitch)
  → If the problem is not fixed,
Feed for forward movement:85-95%
Feed for backward movement:100%
 ◈ Damage at the entrance of tap hole
  ⇒ Misalignment between tap and prepared hole
  → Correction of misalignment
  → Use tapping chuck with radial float
  ⇒ Chamfering at the hole entrance is too small.
  → Larger chamfering diameter
 ◈ Damage at the entrance of tap hole  ⇒ Replacement of tap

Tap is pulled out.

 ◈ Too much drawing force for tap
  ⇒ Check if tapping chuck's tension is exceeded
  → Increase feed per rotation (must be less than tap pitch.)
  ⇒ Return timing is premature.
  → Approach point should be distanced.
(Guidelines : Tapping chuck's maximum tension + 5)
 ◈ Deformation or breakage of steel balls in tap adaptor
  ⇒ Tap adaptor should be replaced.
 ◈ Ball locking mechanism of tap adaptor does not work
(in the case of carbide tap)
  ⇒ Use collet type tap adaptor

Problem (문제점)

원인)  ⇒ Solution(대책)

Thread is not
 deep enough.
(Variation of
thread depth)
　

 ◈ Cutting to prepared hole is difficult and compression of tapping chuck works.
  ⇒ Check the diameter of prepared hole. (Refer to table of prepared holes)
  ⇒ Small chamfering and large cutting resistance
→ Larger chamfering diameter
 ◈ Torque clutch of tap adapter (type WES) works.
  ⇒ Accumulated chips or dust at the bottom of the hole
  → Use spiral tap for evacuating chips. (Point tap tends to push out chips.)
 ◈ Variation caused by large inertia of machine spindle
  ⇒ Lower rotation speed(500rpm and below)
  ⇒ Check the "stationary" position of the spindle (Z-axis)
 ◈ Decreased preset length of tap
  - Malfunction of tapping chuck
  - Malfunction of tap adaptor with length adjustment (type WEN and WESN)
  ⇒ Tapping chuck will not return to the original length.
  → Check tension/compression of tapping chuck.
  ⇒ Length adjustment screw is not back to the locking position.
  → Check that adjustment screw will not turn after adjustment is completed

Thread is too deep
(Variation of
thread depth)

 ◈ Increased preset length of tap
- Malfunction of tapping chuck
- Chucking error of tap adaptor
- Malfunction of tap adaptor with length adjustment (WEN and WESN)
  ⇒ Tapping chuck will not return to the original length.
  → Check tension/compression of tapping chuck.
  ⇒ Length adjustment screw is not back to the locking position.
  → Check that adjustment screw will not turn after adjustment is completed
 ◈ Variation caused by large inertia of machine spindle
  ⇒ Lower rotation speed(500rpm and below)
  ⇒ Check machine spindle's stationary position (in Z-axia).

Breakage of tap
at the hole entrance

 ◈ Cutting by tap is difficult.
  ⇒ Enlarge chamfering diameter of prepared hole.
  ⇒ Use tap with more threads for chamfering

Problem (문제점)

원인)  ⇒ Solution(대책)

Breakage of tap
in the middle
　

 ◈ Diameter of prepared hole is too small and excessive torque is applied.
  ⇒ Optimization of prepared hole diameter
 ◈ Incompatibility of tap adaptor
  ⇒ Tap adaptor with torque clutch (type WES) is not suitable
  for tapping chuck with compression 1mm and below.
 ◈ Insufficient compression of tapping chuck when tap adaptor
with torque clutch (WES) is in use.
  ⇒ Use tapping chuck with more compression.
  ⇒ Adaptor with torque clutch (type WES) cannot be used.
  (Type WE or WEN is recommended instead.)

Breakage of tap
at the regular
bottom

 ◈ Tap hits the bottom of prepared hole and excessive torque is applied.
  ⇒ Check NC program
  ⇒ Check the clearance between tap's chamfering threads and prepared hole.
→ If there is not enough clearance, decrease the number of chamfering threads.
  ⇒ Deepen prepared hole.
  ⇒ Shallow thread depth.
 ◈ Accumulated chip or dust at the bottom of the hole
  ⇒ Use spiral tap to evacuate chips.
  (Point tap tends to push out chips forward.)
 ◈ Increased preset length of tap
- Malfunction of tapping chuck  - Chucking error of tap adaptor
- Malfunction of tap adaptor with length adjustment (WEN and WESN)
  ⇒ Tapping chuck will not return to its original length.
  → Check tension/compression of tapping chuck.
  ⇒ Tap has been pulled out of tap adaptor.
  → Check the locking mechanism of tap adaptor.
(See if tap cannot be pulled out by hand.)
  ⇒ Length adjustment screw has not been returned to the locking position
(lowest position).
  → Check if adjustment screw will not turn after adjustment is completed.
 ◈ Variation caused by large inertia of machine spindle
  ⇒ Lower rotation speed (500rpm and below)
  ⇒ Check the stationary position of machine spindle (in Z-axis).