axial cracks running longitudinal along raceway ball track in 52100 inner ring

[gma301221]

a pattern of axial cracks with pre spall shape around the centre axial crack observed in inner ring of 52100 ball bearing. Surface surrounding the area of axial crack shows dents. one inner ring showed spall and multiple axial cracks at several intervals. what can be the cause? bearing ran for only 1year. if it was inclusion then we should not see these axial crackings at multiple intervals. Can it be lubrication issue? or grinding burn. Raceway microstructure did not show untempered martensite to decode it as grinding burn. WHat is hidden grinding burn?


05-28-21 SEM analysis I performed showed presence of remnant Aluminum oxide at the spall site, sodium oxide embedded in the matrix. There are bunch of axial cracking. If lubrication is containing contaminants than it would lead to fan shaped initiation point into spall. due to overolling of ball over the spall site, the initiation appears to be removed. SUpplier says hidden grinding burn. Microstructure did not any grinding burn at the raceway. Is it worth sending sample for residual stress analysis at surface and subsurface.

 

[MintJulep]

A Google search for "timken bearing failure" will provide you with many good reference documents about identifying bearing failures.

 

[mfgenggear]

Gma

Grinding issues are on the surface can be the following
over temper
over hardening
some companies allow slight over temper
and never over hardening.
and is very evident with temper etch solutions , and the solution depending on the material and heat treat process.

first step is to take photographic of the failed components.
then submit the failed parts to met lap for failure analysis
investigate if there was adequate lubrication and the proper lube was used.
verify if there are chips in the oil. contamination, a sample of the lube analysis is required.
then look at the manufacturing steps of the bearings. was it the correct diameters, and clearance,
was the assembly assembled properly, was there debris or contamination during assembly, was the correct steps taken during assembly.
a complete failure analysis is required,

 

[EdStainless]

You also need to think about mechanical issues, alignment, vibration, pre-load, and such.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[TugboatEng]

And tolerance issues such as interference and such.

 

[mfgenggear]

then after all that a body diagram of shafts and bearings needs to be re analyzed.

 

I concur with MintJulep's advice:
there are some good illustrated guides and handbooks for identifying damage modes in bearings to be found on the interweb.

Tribological failures are a very unique and specialized area of investigation, so you might also wish to engage the vendor's technical support.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

Try Barden

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."