PO Box 934 | Wildomar, CA 92595

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Ball Assembly Maintenance: Keeping Your CNC Ball Screws in Top Condition

ball assembly looks cleanYour screw’s ball assembly has something to tell you.

As a CNC Operator, you know the importance of maintaining your machining equipment to ensure peak performance. Your CNC laser, router, or waterjet depends on you to complete preventive maintenance on schedule. You understand that meeting production demands relies on your ability to cut quality parts and maximize feed rates. And because you know all this, you regularly lubricate the ball assembly of your CNC machine as recommended by the manufacturer.

You keep your machine, including the entire motion system, clean.

Or so you thought.

We often get calls about noisy ball assemblies. Abnormal or sudden noise is a clue that something is amiss with your CNC motion system.

When ball screws fail to run smoothly, or if cut parts are not within accuracy tolerances, there is a problem.

Frustration looms when fabricators feel they have done everything right to maintain their equipment, yet they are not cutting quality parts.

ball screw grinding pasteWhat if we told you that despite the pristine outer appearance of the ball screw pictured above, the inside of the ball assembly told a different story?

Once this ball screw assembly was out, we removed and inspected the ball nut for contamination. Sure enough, there was a significant amount of metal debris that had mixed with the grease. When this occurs, a “grinding paste” is made. It does not take long for this grinding paste to cause wear or damage the bearings.

You can see from the grease slick the amount of gunk inside in the ball nut. This screw’s ball assembly was screaming, “Clean me!”

Your screw’s ball assembly needs PM too.

ball assembly inside viewIf you are keeping your ball screw clean, but still hear what sounds like a garbage disposal when you try to cut a part, you likely don’t need a new ball screw. A clean and flush is in order.

Adding this service as part of your PM schedule extends the life of your ball screw. If the cleaning shows galled or broken bearings, a replacement set is needed. It’s better to get this done before your machine seizes and you are down for an emergency repair.

Once this ball nut was cleaned/flushed, the bearing set did in fact require replacement, but this is not always the case. Complete clean/flush should be done on a regular schedule. We recommend every 4,000 machine hours or 2 years, whichever is first. Save yourself time and money. Add clean, flush and inspection to your preventive maintenance plan.