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James.

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Reply with quote  #1 
I have a bearing and it is stamped SKefco, all I can find is in 1973 Skefko changed its name to SKF (U.K.) Limited.

On it is also stamped is XH, I guess this is the year of manufacturing? Does anyone have a list of letters to years of manufacturing?

Thanks
James
John from PA

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Reply with quote  #2 
Any particular reason why you think you need the manufacturing date?

A two-letter date code doesn't match with some old SKF materials I have.  SKF apparently had a system that consisted of three numbers followed by a letter.  186N for instance meant the bearing was made on the 186th day of 1993 or 2016.  By the way 1993 was the first year in the chart I have which skips the letters "I" (probably to avoid confusion with "1", Q and V (often used to indicate thrust direction).

There is a German firm (http://www.ukf.de) that makes a series of spindle bearings that carry the designation XH.

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James.

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Reply with quote  #3 
Quote:
Originally Posted by John from PA
Any particular reason why you think you need the manufacturing date?

A two-letter date code doesn't match with some old SKF materials I have.  SKF apparently had a system that consisted of three numbers followed by a letter.  186N for instance meant the bearing was made on the 186th day of 1993 or 2016.  By the way 1993 was the first year in the chart I have which skips the letters "I" (probably to avoid confusion with "1", Q and V (often used to indicate thrust direction).
  


Hi John,

This bearing was fitted as a new bearing this year and has already failed, I was just suspicious given the Skefko stamp. images attached.

Thanks
James

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RustyCas

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Reply with quote  #4 
James, that could be a counterfeit bearing, with the Skefko name on it to throw folks off.  I would suggest you contact your bearing supplier, and ask them to verify the manufacturing details.  They should be able to provide you with details -- if not, I'd look for another supplier.
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James.

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Reply with quote  #5 
Thanks Rusty,

I didn't even think of that possibility.
I will chase the supplier on the bearing origin.

James
James.

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Reply with quote  #6 
update, the bearing supplier tracked down where the bearings came from. They were ex-stock that was gathered from a very old plant that shut down a while ago. Basically they kept all the old bearings just encase they were needed. This plant goes back to the 60's. So it is believable that this was an original Skefko bearing!! No wonder it only lasted a few months...being that old.

Which begs the question that what would be the difference in quality of a 1970's bearing to a 2017 bearing?
John from PA

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Reply with quote  #7 
Quote:
Originally Posted by James.
Which begs the question that what would be the difference in quality of a 1970's bearing to a 2017 bearing?


Probably improved manufacturing methods and QA. Manufacturing methods might for instance mean better materials (double vacumn degassed alloy steel) and heat treat methods. QA involves measurement to standards. AFBMA requires for a grade 3 ball to be spherical within 3 millionths of an inch and the diameter must be accurate within 30 millionths of an inch. Not sure that could reliably be done in the 60's or 70's. Precision gears had similar tolerances and the machines that did the measuring were extremely expensive.
dnk

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Reply with quote  #8 
Quality issues aside, I don't see a bearing sitting on a shelf that long without false brinelling issues.
John from PA

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Reply with quote  #9 
Quote:
Originally Posted by dnk
Quality issues aside, I don't see a bearing sitting on a shelf that long without false brinelling issues.


Good point.  Bearing manufacturers recommend that bearings be transported and stored in the horizontal position.  Unless it is a sealed bearing the bearing is only coated with a rust inhibiting fluid and generally wrapped in a wax impregnated paper.  There isn't any grease or lubricant applied.

If a bearing is stored vertically then the forces, even though small, may be imposed on only one or two of the elements causing brinelling over time.  I would suspect that the bigger the bearing, and hence heavier, then this may be more likely to occur.
James.

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Reply with quote  #10 
Quote:
Originally Posted by dnk
Quality issues aside, I don't see a bearing sitting on a shelf that long without false brinelling issues.


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png 20170920_045319.png (455.97 KB, 20 views)

RustyCas

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Reply with quote  #11 
Yes, those spalls appear to be at the ball spacing.
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Vibe-Rater

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Reply with quote  #12 
Hi James,

As you know I used to work for SKF but only a few years. (2003 - 2007) How time flies. What John from PA mentions I think is correct. Each SKF bearing shows when it was made and nth day of the year sounds correct as well.

Not sure of this but Skefco was bought by SKF...?

TB Mobius (Ex SKF Australia long time) would know. You will have his email I'm almost sure.  There are other SKF contacts that will know as well. Drop me an email for their addresses if required.  Don't want to spray them around on web.

Hope you are keeping well.  rgds
OLi

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Reply with quote  #13 
IRL the beaarings may be stored long times if done properly. When Swedish airforce used RR Avon they bought a lifetime of bearings as they are special and the few positions that are left now, mostly for land use, they were still used at least some years ago and that would be 40-50 years of storage. If you on the other hand treat or store them bad they will fail just like a brand new treated the same. I argue, the thing is steel, it will not fall apart in 100 years if stored properly.
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