Bearing interference fit question

[vwhammer]

I have a bearing with a 80.000mm OD.
I am machining a housing from 1018 steel that the bearing will go in.

There is enough load and stress on the bearing that I believe it needs and interference fit.

The bearing will be pressed in until it seats against a lip. Then a snap ring will go in place so it can not back out.

My only real question is how much of an interference fit do I need?

 

[MikeHalloran]

Look in the bearing manufacturer's catalog.
The technical/engineering section will tell you exactly.



Mike Halloran
Pembroke Pines, FL, USA

 

[JJPellin]

MikeHalloran is correct. The bearing manufacturer will provide fit tolerances based on the load and mounting characteristics. If the bearing is on a rotating shaft, it is very unusual to have it mounted with an interference fit in the housing. It would be more important in that configuration to have an interference fit to the shaft. For a typical pump installation, we would have a light interference fit to the rotating shaft and a slip fit to the stationary housing. Your configuration may require different fits based on the load and arrangement.

Johnny Pellin

 

[vwhammer]

I have searched all over for this type of info and am unable to find it.

The part number according to Timken's site is 513180.

I am unable to find that part number in any of their PDF files in relation to engineering references and tolerances.

The bearing is being used in an automotive wheel bearing application.

As such, the "shaft" in this instance consists of a hub and a CV flange that bolt tightly through the center of the bearing.

And the bearing is mounted in the spindle.

I will continue to look but I am not having too much luck.

 

[GregLocock]

http://www.timken.com/EN-US/products/Documents/Engineering Section.pdf

p118 or thereabouts

See how much easier it is when you tell us what is going on- engineers not being famously telepathic.

Only problem is that the desired fit in reality is a function of the location of the bearings axially, and heat buildup, and materials. In practice ones I have developed have tended towards /very/ light press fits or sliding fits.

Cheers

Greg Locock

I rarely exceed 1.79 x 10^12 furlongs per fortnight

 

[JJPellin]

I apologize for my ignorance about car design. But, I still can't tell if this bearing is on a rotating shaft or a stationary one. The terminology may be confusing that question since the car's axle (shaft) obviously rotates. So, let me rephrase the question. Will the inner race of the bearing rotate or will the outer race rotate. I believe that the outer race is the one that spins. If so, the housing fit should be a light press fit. I would use an ISO grade H6 fit which would be 0.0002" to 0.0013" interference for that bearing. This is the standard fit class that we used for pumps and other rotating machinery in an oil refinery.

Johnny Pellin

 

[vwhammer]

I have gone through the engineering materials from Timken and am unable to fine any reference to my bearing number.

So I just picked the fit that most closely matches my bearing type and size with a fixed housing and a rotating shaft.

The info I am going with is on page 128

http://www.timken.com/EN-US/products/Documents/Engineering Section.pdf

The numbers for the 79.969mm bearing is what I will use.

I don't know what else to do if no one else can give me a better idea.

 

[GregLocock]

Cup is stationary, cone is rotating

Using the fits for a ball bearing when you have a taper roller seems a bit odd, particularly when the table I pointed you at is for taper rollers used as hub bearings.

A cursory glance suggest you should be 2 thou interference on the shaft and 1.5 to 3 thou loose on the housing. pages A119 and A120, 3 to 5 inch, rear wheel column.

Those figures are in line with my experience.


Cheers

Greg Locock

I rarely exceed 1.79 x 10^12 furlongs per fortnight

 

[JJPellin]

I did not go back to verify the tables, but I would not expect to have a recommendation of a loose housing fit since it sounds like this application is rotating housing, stationary load. With that arrangement, our tables would indicate tight fit on the housing and loose fit on the shaft. With a loose fit on the housing, I would expect a fretting problem between the outer race and the housing.

Johnny Pellin

 

[GregLocock]

No, it is stationary housing. As I said. As the OP said.

Cheers

Greg Locock

I rarely exceed 1.79 x 10^12 furlongs per fortnight

 

[vwhammer]

Sorry once again I did not give enough info.

It is a two row ball bearing.

http://frugalmechanic.com/auto-part...13180?p=g100&gclid=CJPt7NaltJ8CFVw55QodcEOw1Q

I think the table suggest +0.0000 -0.0003 for the 3.1495 bore which will make it a M7 tight fit.

 

[GregLocock]

Oh, when you mentioned Timken and wheel bearing I assumed taper roller, sorry.

OK, I'd call that a Gen 1 hub unit. If the internal geometry is similar to what I am used to then a press fit is the usual solution.

However the unit I use was designed 20 years later than that one, and may have completely different constraints.

Cheers

Greg Locock

I rarely exceed 1.79 x 10^12 furlongs per fortnight

 

[mrpi]

Have a look at this SKF page that lists recommended fits for various load/bearing situations:

http://www.skf.com/portal/skf/home/products?newlink=1_0_74&lang=en&maincatalogue=1

Beat to fit, paint to match.

 

[flash3780]

Check Harris' "Essential Concepts of Bearing Technology".

 

[cmcbain]

What is the application for this? If I had to bet, I would say that you're machining uprights for a Formula SAE car...

 

[tbuelna]

vwhammer,

Besides the fit on that duplex angular contact ball bearing OD, you must also consider the ID fit. The bearing OD should have a slight interference fit at RT with a steel housing. The inners should also have an interference fit on the shaft, in order to prevent fretting.

However, the interference fits of both the races should not produce a condition where the internal clearances of the installed bearing are reduced below acceptable limits.

Regards,
Terry

 

[vwhammer]

Well I machined my parts so it is what it is now.
we stuck with the +0.0000 -0.0003.
For references sake I believe this is real close to a class M7 fit which is not considered an interference fit but rather a press fit.

I have not actually put the bearings in yet because there is still some more parts that need to be made and welded to my bearing housing which may present it's own set of problems.

The "shaft" that I am using is actually a factory Porsche part
so I won't have to machine any of that stuff.