Ceramic Bearings, to use, or not to use?

complete loser · May 1, 2016

I am rebuilding a cool old live center I found. Its much smaller in profile than most ive seen on the market except for the higher prices ones.

Anyways, one of the bearings in it is a 12x28x8 single row ball bearing. While shopping for replacements, I seen 'ceramic' versions.

Has anyone used these in such an application? Pro's and cons?

Monarchist · May 1, 2016

complete loser said:
I am rebuilding a cool old live center I found. Its much smaller in profile than most ive seen on the market except for the higher prices ones.

Anyways, one of the bearings in it is a 12x28x8 single row ball bearing. While shopping for replacements, I seen 'ceramic' versions.

Has anyone used these in such an application? Pro's and cons?

You can find them as extra-cost options from the major grinding spindle makers/rebuilders. Fischer Spindle / Precise jig grinder territory.

Mought be just the ticket to shorten the warm-up cycle ...if your live center has to operate at 45,000 RPM and above.

Otherwise, why bother?

Bill

complete loser · May 1, 2016

Monarchist said:
Otherwise, why bother?

Bill

Thats exactly what im trying to learn by asking the question. :rolleyes5:

Monarchist · May 1, 2016

complete loser said:
Thats exactly what im trying to learn by asking the question.

If your Google is busted, you might start here:

Hybrid ceramic ball bearings

CeramicSpeed Bearings - Why hybrid bearings

Not sayin' they are not 'better'.

Just can't see any pressing need for them in 'a cool old live center' that was 'found'.

Your shop. Your needs, though.

Bill

DavidScott · May 1, 2016

I think ceramic balls would be a bad idea in this application. Steel balls compress quite a bit, think ball screw preload, so they will have some "give", and they will be a lot tougher.

complete loser · May 1, 2016

Ya, that was my concern. Ceramic being much more brittle/hard. Worried it might not take a shock. But knowing, I know very little about these types of bearings and their construction, thought there might be a chance they might be a decent upgrade.

CarbideBob · May 1, 2016

In a live center? No unless you are planning on spinning at 50,000 or so. Then maybe.
The advantage of these is the ball weight at very high speeds.
They do not like low or zero speed impact as when your center comes in and picks up the part.
Bob

Monarchist · May 1, 2016

complete loser said:
Ya, that was my concern. Ceramic being much more brittle/hard. Worried it might not take a shock. But knowing, I know very little about these types of bearings and their construction, thought there might be a chance they might be a decent upgrade.

I ass u me 'ed that 'ceramic' - as-in floor-tile, kitchenware, or porcelain 'Steatite' electronics mounts so beloved at one time - would have poor shock characteristics as well. Silicon Nitride, OTOH ain't yer average ceramic, so.. maybe not so fragile after all.

That said, I can't see the gain even in a brand-new, store-bought, high precision live centre from one of the few remaining American makers.

If/as/when THEY start touting them? 'nuther story, and mayhap worth copying.

But - at least for 'all manual' lathes? I'd expect real claws instead of tires for a Jaguar motorcar will appear first... hooves for Impala's, or horseshoes for Mustangs..

Even then, what I pay for a set of four?

B'lieve I'll stick with Continentals. Or in your ap? Well-proven alloy steel bearings.

moonlight machine · May 1, 2016

We used to use them in place of steel wheel bearings, big money but good insurance. Check out U Tube "1998 CART Motegi Bobby Rahal crash". Steel right front wheel bearing failure was the cause.

Monarchist · May 1, 2016

moonlight machine said:
We used to use them in place of steel wheel bearings, big money but good insurance. Check out U Tube "1998 CART Motegi Bobby Rahal crash". Steel right front wheel bearing failure was the cause.

I've seen prices that were NOT 'big money' as well.

But who knows if they were remaindered, stale stock in no-longer-demanded sizes, or just cheap knock-offs from guess-where.

Have to trust a reputable distributor and traceable upstream when the app matters more than a seized live centre.

Bill

moonlight machine · May 1, 2016

Monarchist said:
I've seen prices that were NOT 'big money' as well.

But who knows if they were remaindered, stale stock in no-longer-demanded sizes, or just cheap knock-offs from guess-where.

Have to trust a reputable distributor and traceable upstream when the app matters more than a seized live centre.

Bill

20 years ago they were big money, maybe not now.

brucecu · May 2, 2016

Don't use

We used to use them in the workhead of a cylindrical grinder. Extra stiffness of the balls yielded no better results than steel balls. In fact, when the machine was crashed the races were instantly brinnelled to uselessness. A similar crash with steel balls gave us enough life to finish a job before rebuild.

dcsipo · May 2, 2016

Pure ceramic or hybrid ceramic bearings will be useful when you need to have reduced weight, high speed, or much lower rolling resistance at the expense of reduced radial and lateral loads for the same size bearings. Like everything it is a tradeoff. They are incredibly nice for bicycle wheel and crankshaft bearings. Gives you a much smoother feel. Are they really that much better, who cares they feel good

. In your application you would be better off with steel taper rollers of a higher grade (ABEC 5 or better). I think load is a bigger concern than how it makes your lathe feel about its tailstock.

dee
;-D

Vancbiker · May 2, 2016

As already noted above, a live center won't see a benefit from ceramic bearings as long as the same accuracy spec is maintained.

About 12 years ago we rebuilt a couple Mori Seiki M300L VMCs. When doing the spindles we had hybrid ceramic/steel bearings installed instead of the original all steel spec. Then with a couple spindle drive parameters and one Keep Relay change we were able to up the max spindle speed from 8k to 10k. Those machines are still in production with no spindle issues since.

complete loser · May 2, 2016

Excellent info. Thank you. Thats what I was looking for. Experience.

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