Troubleshooting Chucks

Troubleshooting Chucks

Problem  Possible Reasons  Countermeasures
Chuck will not operate.  The inside of the chuck is broken. Disassemble and replace part.
Slideway seizes.  Disassemble and repair damaged part with oil stone or replace it.
Hydraulic cylinder is not operating  Check that pressure reduction valve, change over valve and hose system are correct.
Insufficient master jaw strokes. Proximity sensing switch set incorrectly Reset switches.
Too much swarf in chuck. Disassemble and clean.
Drawtube is loose. Remove and retighten it.
Drawnut position is incorrect. Reset drawnut position.
Workpiece slippage. Insufficient master jaw stroke. Position master jaw so that it is in stroke centre when workpiece is gripped. 
Insufficient clamping force. Check that hydraulic pressure is adequately set.
Formed diameter of top jaw does not match workpiece diameter. Reform top jaw according to the correct method. 
Cutting force is too high. Calculate cutting force and reduce it to the correct chuck specifications.
Insufficient lubrication on master jaws and each slideway. Lubricate from grease nipple and grip and grip again jaws without workpiece in chuck. 
Speed is too high. Marking is found by mis-alignment such as work feeder, steady rest, tailstock, etc.  Reduce speed up to necessary gripping force. Secure alignment to eliminate marking. 
Poor accuracy  Periphery of chuck is run out. Tighten bolts correctly.
Foreign matter is caught in serrations between master and top jaws. Remove top jaw and clean serrations thoroughly.
Top jaw mounting bolts are inadequately tightened. Tighten bolts to correct torque.
Forming of top jaw is inadequate. Check that forming plug is parallel to chuck and face and plug is not deformed due to gripping force. 
Also check hydraulic pressure while forming and face roughness.
Top jaw is deformed and top jaw bolts are extended because top jaw is too high. Reduce height of top jaw by replacing with standard size jaw.
Workpiece is deformed by too much gripping force.  Reduce gripping force to prevent deformation.