Thread: Kluber Isoflex Spindle Grease

My 13 mill spindles run in hydraulic oil. This is a question for the likes of GQ.

Grease was used rather than the specified oil in my ( and others) Hercus mill with disastrous results when the pulley cone seized on the spindle. Obviously far removed from the spindle lubrication on the Cincinnati but maybe something to consider if the grinder's spindle was intended to be oil lubricated.

I have read about the painstaking procedure involved in relubricating some Schaublin lathe bearings and have thought how fortunate I was to have oiled spindles.

If you have no joy here Ray you could try PM -

Abrasive Machining

BT

How fast is high speed on the Cincinnati Ray?

My Dumore spindle whips along at 38,000rpm and relies on an oil mist for lubrication.

BT

Hi BT,

Not that fast!... On 6" wheels, to get 5000 sfpm for cbn, it will be about 3-4000 rpm.

I've been thinking of using a seperate high speed spindle (like the ones used for cnc routers) for internal grinding, so this spindle wouldn't ever get much over 6000 say on 4" wheels...

Regards
Ray

I'd be sticking with oil myself - for a start grease is going to heat up more (thicker = more work to move through it = heat). The other thing is that grease is usually packed into a bearing where as the oil will flow. Have you a way of making sure that there is grease everywhere?
Michael

Originally Posted by RayG

I've been thinking of using a seperate high speed spindle (like the ones used for cnc routers) for internal grinding, so this spindle wouldn't ever get much over 6000 say on 4" wheels...

Good idea. I've got a high speed spindle for internal grinding, can't remember offhand its RPM but at least 3X the main spindle speed. The 'wheels' are approx 20mm dis IIRC.

Never used it yet, mind you.

PDW

If you can get on to a bearings company application engineer they can be a wealth of information if you can get hold of the right guy. NSK had a really good guy (George) from the UK but he's since moved on.

From what little I know about the topic it just devolves down to how long you want the bearings to last in the spindle, going from grease to oil lubrication more than doubles the service life of the bearings. Then you get into complicated aspects like how much lubrication to use, too much oil or grease will also shorten the life of the bearings.

Not that fast!... On 6" wheels, to get 5000 sfpm for cbn, it will be about 3-4000 rpm.

Ray, Indeed its not so fast. Did you notice in the ebay link the term “(over 1 million dN)”.

What’s a dN I hear you ask. That’s a speed mean, or a factor of how fast the bearings are going for any given size. Its also the easiest engineering calculation you will ever make.

Assuming your 7305’s. 25 x 62 x 17. Its a calculation of the Bearing Pitch Circle Diameter, multiplied by speed

In your case 25 + 62 / 2 x 4000 = 174,000 dN Your barely running under a 6th of the rating for that grease. We could actually come down a bit in the quality of the grease. But since its the best available, and you have to procure some any way, we might as well use it.

For those bearings you need 3.1 CC’s per bearing for a 30% fill. All up your looking for about 10 CC’s, thats a lot out of a 1,000 gram tin. Heat is not an issue at that level of fill. It does have a shelf life of 3 years, the oil comes out of suspension if its not agitated.

If a bloke was to drop me a postal address, I could send up a syringe of NBU15, ready to go. If you need it in a hurry, SKF might have something close to equivalent. There’s a branch on the road out to Furphy’s. Before the train line, near some sheep yards, or a tannery. SKF LGLT2 or LGLC2, would be the pick of them, Some years ago I was in there, I remember them having some small tubes. Be aware thats probably not a high turn over item, so it may be old stock. You would be better getting it from me.

The tables I’ve just looked up, suggest you would get 30,000 hours out of those bearings @ 174k dN

Regards Phil.

I thought that Phil would be your go-to source for info on that. My 7208 bearings in the lathe are rated to way more than the 4000 rpm in grease.

Happily my Deckel has solid bushed heads running in total loss oil. (happily I mean from a repair point of view should it ever be required)

Greg

Hi Phil,

Many thanks, the perfect answer and detailed explanation, so that's what dN rating means..

One of the thoughts behind going for high speed kluber spindle grease is that the oil lubrication system on this spindle is dodgy to say the least, this will make for a more reliable machine. 30,000 hours, that's going to be a problem for Josh in his old age.. I won't have to worry..

That said, I'm pretty sure I can manage an email with an address...

Regards
Ray

PS Thanks I'd forgotten about that SKF place out there, I must pay them a visit, I usually go to another bearing place.

Originally Posted by RayG

so that's what dN rating means..

You have to be careful who you ask. That’s a bug bear of mine. The correct term is Dm.. “m” for mean. Our American cousin’s, stuffed that up and are too pig headed to change, Barden started that. They de-rate those figures, because they only use the bore code in the calculation.

For instance, say a 25mm bore you can have 71905, 7005, 7205 & 7305. All 25mm bore, but 42, 47, 52 & 62mm Outer diameters. They only use 25 mm in the calculation of all of them.

For the same given speed a bearing with a 62mm outer, the ball velocity is going to be considerably higher than one with a 42mm outer.

Couple of examples here, from Stateside sites. Exact same grease as your link with a 1,000,000 Dm.

700,000 http://www.ahrinternational.com/KLUBER_GREASE.shtml

850,000 http://www.precisionspindle.com/datasheets/Kluber_Isoflex_NBU_15.htm

They have changed the data sheets to suit.The rest of the world uses the mean diameter to come up with that factor. Including Kluber.

Just thought I’d get that off my chest. They bug me.

Phil.

Thanks Machtool for the info on bearings and grease.

When I rebuilt(some 12 months back) the wheel head spindle for my Alex horizontal spindle surface grinder, I replaced the precision angular contact bearings with just a good quality brand "normal" precision bearing set. I also just used a good brand bearing grease.
I did these things because it's a 7 inch wheel and therefore it's only a slow spindle.

The set of bearings that came out of the wheel end were RHP 7206 CTRDUL P4 but I went with the lesser replacements because of cost and also I'm pretty sure that they will be all that I will ever need, hoping I'm right with my assumptions there.

The rebuild of the machine has been a work in progress for some time now but is slowly moving along.

Cheers.

If I'm not right, then I'm wrong, I'll just go bend some more bananas.