Angular Contact Ball Bearing Race Detailing 2

[pabolton]

Does anyone know of a good reference for producing a detailed print of a bearing race (outer or inner) for an angular contact ball bearing?

 

[Tmoose]

exterior dimensions and tolerances are in the bearing catalogs.

Are you going to have races made?
The interior dimensions depend on the number of balls, which sometimes varies a bit between manufacturers or decade of production.
Also the race profile includes the "curvature" which is juggled a bit by application to buy speed capability or load capacity, so is proprietary and can vary between mfrs too.

 

[pabolton]

Yes, I'm looking to get the races manufactured seperately due to requring very low volumes that the bearing companies don't want to deal with

 

[Tmoose]

What's wrong with production bearings?

There have been some outfits that design and manufacture specialty bearings.

looks like these guys are still around

http://nhbb.com/

 

[tbuelna]

pabolton-

The operative word in your question is "detailed". Modern rolling element bearings are very highly engineered products, even "off-the-shelf" bearings. When purchasing custom bearing components or assemblies, such as those you are inquiring about, there are two ways to approach the documentation issue. One way is to use a "source control drawing", which defines certain requirements for the parts as delivered, but otherwise leaves the particulars such as heat treatment, QA, etc. to the discretion of the vendor. The other way is to provide a complete set of engineering documentation that defines every aspect of the manufacturing and QA processes.

The complete documentation needed for a high performance angular contact ball bearing race can be quite extensive. For example, specifying micro-inch level geometric (roundness, taper, runout, etc.) and dimensional tolerance limits and how they are to be measured (free state, constrained, etc.) is no easy task. Specifying the precise details of race surface finish (roughness, lay, etc.) can be critical for fatigue life or scuffing resistance. With angular contact ball bearings in particular, it is common to design the inner and outer races with slightly different operating contact angles. But the only way to verify that the bearing assembly has the correct operating contact angles is by using a specialized test fixture. Lastly, as Tmoose noted, the inner and outer races of angular contact ball bearings typically use slightly different "osculation" curvatures to help equalize contact stress levels and optimize efficiency. Do you know how to determine these?

Manufacturing quality rolling element bearing races requires highly specialized equipment, facilities, and expertise. There are lots of bearing companies that will make custom designs in small quantities. Since manufacturing bearings is a job best left to professionals, I'd highly recommend that you create a source control drawing for your bearing assembly that defines some basic dimensional and performance requirements, and then submit that to a competent vendor.

Best of luck to you.
Terry

 

[dinjin]

I would try more manufacturer's for a source of one of a kind bearing. How large or what size bearing are you making? Some of the small bearing companies survive by making one of a kind bearings. Certainly they are more expensive as you have to weigh in the one set up that cannot be amortizes by production quantities.

 

[MintJulep]

You are not doing anyone any favors by trying to become a bearing race manufacturer.

Design your whatever to use a stock bearing.

 

[pabolton]

The only reason I'm considering the project is that we presently have to replace either outer or inner races individually as wear dictates during overhaul and the prices/lead times are excessive. I agree with the comments above but just wanted to carry out an investigation into the feasibility of producing the races.

 

[pabolton]

To dinjin, who do you consider to be the "smaller bearing manufacturers"? Thanks

 

[dinjin]

I know Rotek in Aurora Ohio made many but I think they had to be 18 inches or larger in diameter. Maybe their new rolling mill allows them to make smaller rings but my guess is that they went the other way ie make larger rings. As to refurbishing, I think their new management is trying to keep the floor open to new production bearing even tho the market or margin was higher for refurbishing department. There is a large learning curve in making your own. If is just a matter or regrinding for oversize balls, I can see where it would be to your benefit assuming you have enough case depth originally. Depending on the manufacturer, the raceway conformity may be different for the outer and inner races. Some make them both the same.

 

[Tmoose]

So you are starting with purchased bearings?
Are they a standard part number?
How big are these bearings?

Do you have any details about the race "wear?"
If the races are wearing my first hunch is the lube or sealing could be improved. My second hunch is the balls are suffering too if they are steel.
In some conditions Ceramic balls running on steel races survive MUCH better.

Like dinjin said, there are houses that can refurbish bearing (races).

 

[tbuelna]

.....The only reason I'm considering the project is that we presently have to replace either outer or inner races individually as wear dictates during overhaul and the prices/lead times are excessive....

pabolton-

With rolling element bearings, if any individual component of the assembly has any damage or wear, it is usually not a good idea to simply replace that component. Unless it is an emergency, it is better to replace the entire bearing assembly.

If you want to reduce the cost of bearing replacements, you might look into re-manufacturing your bearings. If the wear on the race surfaces is not too severe, they can be salvaged using thin-dense chrome plating and regrinding. The cages could probably be re-used and the only parts that would need to be replaced would be the balls.

 

[pabolton]

In reply to the comments above the bearings are non-standard sizes and the OEM manual allows replacement of individual components of the bearing during overhaul and we can presently buy individual parts of the bearing. I totally agree that replacing the full bearing is the way to go but I'm trying to reduce costs on an existing process by reverse engineering the bearing.

 

[Tmoose]

Hi pabolton,

Do you mind sharing more about the equipment?

How often are bearing components replaced? Less than 5 years?
I'm real interested in the fact rolling element bearings "wear" in service, and the OEM allows, let alone advocates piecemeal replacement.

Qualifying the races/balls of a conventional bearing as "re-usable" is along the lines of they have to look uniform and feel perfectly smooth in 3 dimensions, with light visual frosting permissible in the ball path. Anything less is likely to yield pretty short life before more serious deterioration begins and will likely progress rapidly.

Balls or rollers re-used because the "don't look to bad" are likely to have pretty short second lives along with their brand new step brothers, which would result in greater repair frequency.

If the "wear" is not from contamination, then I'm thinking the lube may be too thin to achieve a decent kappa and EHD lubrication. I'm guessing the rpm are low. Lube with EP and antiwear additives can drastically reduce "wear" when EHD can not be achieved.

 

[geesamand]

"In reply to the comments above the bearings are non-standard sizes and the OEM manual allows replacement of individual components of the bearing during overhaul and we can presently buy individual parts of the bearing. I totally agree that replacing the full bearing is the way to go but I'm trying to reduce costs on an existing process by reverse engineering the bearing."

If that's your aim, then I would reverse engineer it. Measure it yourself, convert the profiles to something that can be manufactured, cut it and do microhardness traverse tests. If the capabilities to reverse engineer it are not available, then the capabilities to make your own are also not available.

David

 

[pabolton]

In response to David, I have reverse engineered the bearing race, the initial point of the post was to get peoples feedback on whether or not there are any existing standards for the geometric and dimensional tolerancing of the drawings i.e. run-out on the bearing race, whether to define Ra, Rpk, Rvk etc as all of the ABEC standards relate primarily to bearing assembelies and their classification, I dont want to over complicate/tolerance the part as can generally happen with reverse engineering but I also want to communicate the print in a manner that bearing manufacturers will be comfortable with.
Tmoose I'm also surprised the OEM allows for piece part replacement on the bearings, the balls and inner race very rarely show the amount of wear seen on the outer race mainly due to the application.

 

[Tmoose]

Here is some info about ball tolerances

http://www.winball.com/tolerances.htm

The races need to be as good.


I have no idea if the grade you have been receiving is really required for your application.
There are many possible explanations for outer race "wear." Inadequate sealing, improper lubrication, improper race heat treatment, heat treatment damaged by aggressive or improperly cooled race grinding, etc. etc.

http://www.koyousa.com/brochures/pdfs/catb3001e.pdf

This link discusses some of the extreme finishing methods necessary when very accurate motion and low noise is required. I'm guessing your application (whatever it may be) is not concerned about those requirements, but it also hits on how the race surface must be nurtured and preserved. Also the relationship on speed and lube viscosity and even surface finish on "good" lubrication.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19710014473_1971014473.pdf

 

[pabolton]

Thanks tmoose there's some interesting information there

 

[tbuelna]

....In response to David, I have reverse engineered the bearing race, the initial point of the post was to get peoples feedback on whether or not there are any existing standards for the geometric and dimensional tolerancing of the drawings i.e. run-out on the bearing race, whether to define Ra, Rpk, Rvk etc as all of the ABEC standards relate primarily to bearing assembelies and their classification, I dont want to over complicate/tolerance the part as can generally happen with reverse engineering but I also want to communicate the print in a manner that bearing manufacturers will be comfortable with.......

pabolton- I've attached a sample SCD for a duplex angular contact ball bearing from a NASA document. You can download the whole document here:

http://hdl.handle.net/2060/20070018937