Tuesday, July 23, 2013

CNC Lathe Chucks: Troubleshooting common problems

Possible causes and solutions for common chuck problems such as:
  1. Component slippage 
  2. Excessive Vibration
  3. Master Jaw not moving
  4. Poor Accuracy
  5. Base Jaw Breakage
Troubleshooting: Component slippage
  1. Lack of lubrication on master jaws & moving parts -Lubricate master jaws through the grease nipple
  2. Component Clamping at end of the stroke -Clamp the component at the middle of the Jaw stroke to avoid slippage.
  3. Speed is excessively high -Reduce the speed level to obtain necessary chucking
  4. Cutting forces too high -Calculate cutting force & check against chuck specifications
  5. Insufficient chucking force -Check hydraulic pressure setting
Troubleshooting: Excessive Vibration
  1. Run out on chuck body beyond permissible value-True the chuck body within permissible value as specified
  2. Top jaws holding the job not symmetric with the rotation axis and therefore causes imbalance -Chuck with the special jaws and component to be dynamically balanced
  3. Draw tube / Draw bar may be out of centre or out of alignment -Check and correct the alignment
Troubleshooting: Master Jaw not moving
  1. Chuck with dirt from burrs & chips - Dismantle & do periodic maintenance.
  2. Internal parts of Chuck broken/ jammed -Replace broken parts & do periodic maintenance.
  3. Check cylinder for malfunction.
Troubleshooting: Poor Accuracy
  1. Excessive height of top jaws -Reduce the height of top jaws as recommended by GMT
  2. Guide ways of the internal parts of the chuck could be worn out -Recondition the chuck /Replace the chuck with new.
  3. Too much chucking force - Reduce the chucking force to optimum level
Troubleshooting: Base Jaw Breakage
  1. Component  Clamping at end of the stroke -Clamp the component at the middle of the Jaw stroke.
  2. Excess Draw Bar pull (causing breakage of Master Jaw & Wedge) - Select suitable cylinder from ‘Selection Chart’ specified in GMT Instruction Manual and maintain the Draw Bar pull as specified.
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8 comments:

  1. isdsathyaJuly 17, 2015 at 11:32 PM

    Thank you. This post is very informative.

    ReplyDelete
  2. UnknownJuly 17, 2015 at 11:49 PM

    This comment has been removed by a blog administrator.

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  3. UnknownJuly 17, 2015 at 11:53 PM

    This comment has been removed by the author.

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  4. UnknownJuly 17, 2015 at 11:54 PM

    We have found oil leakage in our cylinder. Do you have any service agency in Pune or suggest a remedy?

    ReplyDelete
  5. UnknownJanuary 7, 2017 at 8:38 AM

    This comment has been removed by the author.

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  6. UnknownJanuary 7, 2017 at 9:08 AM

    We use ATS Bigmouth Chucks and keep breaking master jaws. Sometimes to front and sometimes the back. We have check the alignment of the rack. What are you thoughts on why this could be happening.

    ReplyDelete
    Replies
    1. webmasterJanuary 9, 2017 at 3:17 AM

      In order to respond to your question, we need a lot of details like about the machine used, the size of the chuck, the components, under what conditions breakage occurs, what are the cutting conditions, how actuated and so on. Even then, the manufacturer is best to answer product specific problems.
      Did you ask ATS?

      Delete
  7. UnknownJanuary 14, 2017 at 8:23 AM

    We are using these chucks on Mori Seki. The chucks are 14.8 air actuated. We turn pipe usually from 4 1/2 to 7 inch at lengths of 44ft. ATS has not been helpful at all. As to conditions when it fails the operators tell us that they hear a pop sometime while its running and other times when they are clamped or unclamping. Air pressure is at 90psi. Viewing parts of the Master Jaw that have failed all failures are at the same place. Master jaws have been sent to our R&D center.

    ReplyDelete

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