spindle bearings

[tilderdine]

I have replaced the spindle bearings on my Hwacheon lathe 2 years ago. I am about to order a new set and replace them again. How long do spindle bearings normally last?

[DMF_TomB]

bearing life is influenced by service factor. That is bearings used at higher speeds with unbalanced loads will have less life.
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some spindles rated for higher speeds continuously have the bearings set with more clearance. Some bearings get tighter as they get hot. Too tight can damage bearings. too loose can cause problems too.
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some lubrication like oil and grease needs a different type or viscosity depending on speed or loads. lubrication can effect bearing life.
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most machine shop equipment i work with have spindle bearings 10 to 70 years old. Industrial equipment with bearings should last at least 5 years with 24 hr/ 7 day a week usage.
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some variable frequency drives for speed control cause a high frequency induction of current in equipment that can cause electrical arcing at bearings. some fixes for this are a electrical grounding ring with brush, electrically conductive grease, ceramic balls in bearing , etc
...... also some VFD drives sometimes need to be remounted farther away from the machine to lower electrical induction of currents and or some sort of shielding.
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high frequency electrical currents like from a welding machine can use high frequency to start the electrical arc by jumping from TIG torch. any metal object even if not grounded will act as a partial ground. For example a high frequency arc going from a Tig torch to a metal hammer that is insulated from anything else. Granted the main electrical current will not arc but my point is high frequency arcing even if barely noticeable can destroy bearings.
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VFD drives destroying motor bearings started appearing when new equipment was installed decades ago. Sometimes these design flaws / weaknesses are not identified on new equipment for a few years.. often the factory that made / designed the equipment will have a fix or a recommendation how to fix / protect the equipment , sometimes you have to ask the factory. Sometimes recalls or problem fixes are not told to customers unless you tell them about the problem and ask if there is a fix for it.

[RICHARD ZASTROW]

You should probably do a good maintenance inspection on your machine. Unless you are abusing the machine, those spindle bearings should last a long time, as TomB said.

Sometimes there are orifices in the lube lines that get plugged with debris or other obstructions or "kinks" in lube lines. If it has greased bearings, there is a re-greasing schedule. Sometimes it's a failed oil or grease seal.

I'd definitely check it out while your in there to replace the bearings anyway.

If the bearings are tapered roller bearings (Timken type) they often need to be re-adjusted after a run-in period. Same CAN be true for angular contact ball bearings.

Dick Z

[tilderdine]

Thank you both for your reply. We have a high rate of crashes were the collet is getting hit by the turret. I talked with our service rep. and he said those crashes are most likely the main contributing factor in the bearings going out. He did say that he would be checking out the maintenance issues that you guys pointed out. We are working on training the operators, but you can't push the buttons for them. thanks again...