One Ball fatigue failure at Deep Groove Ball bearing

In summary, the conversation is centered around finding a solution for a gear box field failure. The failure is described as a premature fatigue failure of one rolling element in a deep groove ball bearing, while the rest of the balls are in good condition. The failure is attributed to spalling, which is the fracture of running surfaces and removal of small particles of material. The poster recommends that the failure could be due to variations in manufacturing tolerances or a defective bearing, or potentially due to excessive loading beyond the bearing's design parameters. It is also suggested that the failure could be due to corrosion caused by contaminants in the lubrication. The application is an automotive gear box with 5 liters of specialized oil, and the bearing was installed according to recommendations. The
  • #1
Ranganath Nagaraju
I am working on finding a solution for a gear box field failure.

Failure description:
In the deep groove ball bearing only one rolling element has a pre-mature fatigue failure (Image-6.jpg) and rest of the all ball is in good condition (image-05.jpg).

Do anyone has seen the same kind of failure mode in the gear box.
 

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  • #2
:welcome:

How much research did you do before posting?
The picture of the ball you showed very clearly shows spalling.

It took my only 10 seconds with Google to find this.

http://www.schaeffler.com/remotemedien/media/_shared_media/08_media_library/01_publications/barden/brochure_2/downloads_24/barden_bearing_failures_us_en.pdf said:
Fatigue failure-usually referred to as spalling-is the fracture of the running surfaces and subsequent removal of small. discrete particles of material. Spalling can occur on the inner ring, outer ring, or balls

Why only one ball rather than all is more difficult, and I'm not sure relevant. Failures of the balls must always start with one ball first.
 
  • #3
anorlunda said:
:welcome:

How much research did you do before posting?
The picture of the ball you showed very clearly shows spalling.

It took my only 10 seconds with Google to find this.
Why only one ball rather than all is more difficult, and I'm not sure relevant. Failures of the balls must always start with one ball first.
I know that's spalling. You need not to google it, if you know about bearing.
Spalling do happen due do many criteria and each way or kind of spalling will have a different cause.

<< Mentor Note -- post edited to fix text speak and to remove mild insult >>
 
Last edited by a moderator:
  • #4
Within any set of "identical" items there are going to be variations that result from tolerance variations along the manufacturing of those items (material, dimensional, heat treating, plating, etc) that will result in one of those items being more susceptible damage than all of the rest but still within the manufacturer's design specifications; or, one item could actually just be defective. Alternatively, in the case of a bearing set, the passage of a contaminating particle can also result in initiating the failure of one of balls.
In your case, if this is an isolated case of this type of failure, then either of these factors can explain what you have seen. On the other hand, if this is a new design, it might be considered that this could be evidence that the bearing is being subjected to a loading in excess of it design parameters that has caused it weakest ball element to fail.
 
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  • #5
JBA said:
Within any set of "identical" items there are going to be variations that result from tolerance variations along the manufacturing of those items (material, dimensional, heat treating, plating, etc) that will result in one of those items being more susceptible damage than all of the rest but still within the manufacturer's design specifications; or, one item could actually just be defective. Alternatively, in the case of a bearing set, the passage of a contaminating particle can also result in initiating the failure of one of balls.
In your case, if this is an isolated case of this type of failure, then either of these factors can explain what you have seen. On the other hand, if this is a new design, it might be considered that this could be evidence that the bearing is being subjected to a loading in excess of it design parameters that has caused it weakest ball element to fail.

Hello JBA

Thanks for the advice. I have taken the sample to the metallurgy lab to check the hardness, chemical composition and the micro structure.
I checked the dimension in a passometer and the variation between the rolling elements are OK. I need to wait for the metallurgy lab report
 
  • #6
That doesn't look like spalling to me but more like corrosion.

A single drop of water sitting at the lowest part of the outer race will cause erosion of the ball and possibly a corresponding spot in the race...but not always.
 
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  • #7
HowlerMonkey said:
That doesn't look like spalling to me but more like corrosion.

A single drop of water sitting at the lowest part of the outer race will cause erosion of the ball and possibly a corresponding spot in the race...but not always.
There is hardly any damage on the raceways. Just some smearing pits, formed due to over rolling on the contaminants.
 
  • #8
Ranganath Nagaraju said:
Thanks for the your reply. There is hardly any damage on the raceways. Just some smearing pits, formed due to over rolling on the contaminants.
 
  • #9
The corroded metal bits don't evaporate into nothing so they take a few trips around the race.

What is the application, lubrication type, and conditions of installation?
 
  • #10
HowlerMonkey said:
The corroded metal bits don't evaporate into nothing so they take a few trips around the race.

What is the application, lubrication type, and conditions of installation?

Thanks for the suggestions, its an automotive gear box and which has 5 liters of oil. There is no signs of lubrication failure.
Its the oil specialized for the CVT gear box.
The deep groove ball bearing is installed as per the recommendation , pushing inner ring on shaft and pushing outer on the housing,
 
  • #11
Spalling is a relatively specific bearing failure and usually caused by over-loading the bearing at or near its fatigue strength. It sounds like you might be over-loading the bearing, in which case you should consider increasing the specification of the bearing used in this application.

See here:
http://www.reliableplant.com/Read/30255/reasons-bearings-fail
8. Fatigue (Spalling)
Spalling is often the result of overloading, an excessive preload, tight inner-ring fits and using the bearing beyond its calculated fatigue life.

What to Look for
Fatigue can be indicated by the fracture of running surfaces and subsequent removal of small, discrete particles of material from the inner ring, outer ring or rolling elements. Spalling is progressive and will spread with continued operation. It is always accompanied by a noticeable increase in vibration and noise.

How to Fix it
Replace the bearing and/or consider a redesign that uses a bearing with greater calculated fatigue life, internal clearances, and proper shaft and housing recommendations.
 
  • #12
Isn't the outer ring clamped by a bearing plate (fixed position)?

Your comment: "The deep groove ball bearing is installed as per the recommendation , pushing inner ring on shaft and pushing outer on the housing," sounds like you have a press-fit on inner and outer ring, which is not usual due to the assembly.
 

1. What is a "One Ball fatigue failure" at a Deep Groove Ball bearing?

A "One Ball fatigue failure" at a Deep Groove Ball bearing refers to when one of the balls in the bearing experiences excessive stress and ultimately breaks due to repeated loading and unloading. This type of failure is common in bearings that are under high loads or have been in use for a long period of time.

2. What causes a "One Ball fatigue failure" at a Deep Groove Ball bearing?

The primary cause of a "One Ball fatigue failure" is the repeated loading and unloading of the bearing, which causes stress on the ball. This can be due to high loads, improper installation or alignment, lack of lubrication, or contamination of the bearing.

3. How can "One Ball fatigue failure" be prevented?

To prevent "One Ball fatigue failure" at a Deep Groove Ball bearing, it is important to properly install and align the bearing, ensure it is well-lubricated, and regularly monitor for any signs of contamination or wear. It is also important to use bearings that are designed to handle the load and operating conditions of the specific application.

4. What are the consequences of a "One Ball fatigue failure" at a Deep Groove Ball bearing?

A "One Ball fatigue failure" can lead to increased vibration and noise, decreased performance and efficiency, and ultimately, bearing failure. This can result in costly downtime and repairs, as well as potential damage to other components of the machinery.

5. Can a "One Ball fatigue failure" be repaired?

In most cases, a "One Ball fatigue failure" at a Deep Groove Ball bearing cannot be repaired and the bearing will need to be replaced. It is important to address any signs of wear or damage early on to prevent further damage and potential failure.

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