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Excessive ballscrew backlash in the ballnut- Some screws must be stretched before checking for backlash.
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Fatigue or surface distress
Visually inspect for pitting or spalling which typically is from contaminants.
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Heat discoloration on lead or balls of ball screw. This is often cause by poor lubrication or
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Inspect wipers or seals to see if they are loose or missing and wiping the screw properly
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Vibration when moving caused by bent ball screws, misalignment of bearing housings or possibly just an unlevel machine.
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Loud clicking sound coming form ball nut tubes can also be a problem if there was excessive build up under way covers with chips and such causing tubes to be damaged, dented or bent.
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Excessive servo load increase due to improper circulation of ballscrew nut balls.
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For preloaded ball screw nuts- remove the nut from the table or turret and turn by hand. You should feel some resistance to turn approximately 6 pounds of rotation force. If not then screw may have lost its preload causing some backlash.
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If machines have scales many times when the axis is jogged or in rapid you can feel a pulsing coming from the axis which may settle in after a foot or two. This is usually backlash either in the screw or bearings.
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Look for brinelling-typically caused by a crash on the screw threads.
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Look for ball bearing skid marks-typical this is caused by poor lubrication.
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Excessive ball nut preload-can be cause by crashing nut into bearing housings or endstops.
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Check all lube lines, fittings, connections for damage. See our diagnosing lube pump problems.
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Inspect lubrication tank for contaminants on bottom and inspect pump filters have been clean.
