Grade 10 bearings

[nfmisso]

(01-11-2015, 02:23 PM)joseph wolf man Wrote:  nigel you lost me again seriously

Sorry, about that, bottom line, either trust the expert, or go get the required education to be the expert.

If you want to understand how the material of a ball in a bearing system responds, you need to have an Engineering background (Bachelor's degree in Mechanical Engineering or Materials Science are good starting places) to be able to understand the PhD level papers published on the subject.

I am more than happy to suggest topics to read, but you (the global you) are responsible for determining if those topics are beyond your educational background. If you (again the global you) state your educational background, I can suggest a series of subjects that after completion, you will understand the high level papers.

[joseph wolf man]

im trying to learn all i can just the reference u made ive never heard thats what i mean can you explain since you know it

[nfmisso]

(01-11-2015, 02:42 PM)joseph wolf man Wrote:  im trying to learn all i can just the reference u made ive never heard thats what i mean can you explain since you know it

I need to know what you know, so that I can start with what you know.

[Sam]

(01-11-2015, 02:19 PM)nfmisso Wrote:  

(01-10-2015, 09:47 PM)Sam Wrote:  Nigel; you don't actually address any of my questions. Just telling me I'm wrong because you're better qualified than me isn't particularly helpful.

Sam; a proper response would be several hundred pages of detailed technical information that is way beyond the scope of this forum. You have given no information as regards to your educational and experience back ground, so I have no idea where to start. If you are really interested, start by reading some papers on Hertzian contact stress, and R.E. Chinn's paper: "Hardness, Bearings, and the Rockwells," published in : Advanced Materials & Processes, Vol 167 #10, October 2009, p 29-31.

I read R.E. Chinn's paper: Hardness, Bearings, and the Rockwells, and found that, although historically interesting, it didn't really tell me anything I needed to know.

I did some searching to refresh my 35 year break since A-Level Engineering Science, and realised that the practical experience I've had since of tool hardening etc. has somewhat lead me astray.

As I'm not looking for a complete understanding of the stresses within a bicycle wheel bearing, just a good idea of what materials will best survive them, I really don't need a PhD in Contact Mechanics, or even your several hundred pages of technical info., just a simple reminder that Toughness relies on Plastic deformation to avoid fracture, and thus would replace Spalling with Denting which would be as bad or worse, and that in standard Engineering terminology Hardness is a measure of resistance to Plastic deformation. not Elastic deformation (as in common usage).
Simple (or just Simplified ;¬)

You were (of course) right that there is no disadvantage in Harder ball bearings, but can you, from your obviously advanced understanding of the stresses involved, tell me if there's any advantage in Case hardening as opposed to through hardening ?

[nfmisso]

(01-11-2015, 07:33 PM)Sam Wrote:  You were (of course) right that there is no disadvantage in Harder ball bearings, but can you, from your obviously advanced understanding of the stresses involved, tell me if there's any advantage in Case hardening as opposed to through hardening ?

Hi Sam;

All of the ball bearings I have experience with are hardened all the way thru. Hardening does not change the stiffness of steel ( force divided by deflection), so there is no disadvantage to hardening all the way thru. In addition, the last thing you want on a bearing is a transition to a lower strength in a zone that is at high stress - that could lead to delamination like failure of the ball (or raceway); like a layer of an onion peeling off. The stress is highest at the contact point and drop from there.

The bearing I have worked with have been either 52100 or 440C; hardened to Rc 50 to Rc 60 range. 52100 is generally preferred for bearing balls because it can achieve a few points harder (Rc scale).

Case hardening is used in situations where it difficult to harden all the way through, or where it is desirable to have a more resilient core to handle shock loads - machine tools being a prime example. One the machine tool front, in the past few decades Titanium Nitride and similar coatings have resulted in very inexpensive and durable tools with a relatively low grade core. On the downside, my experience is they never have the sharp edge of a top quality tool steel, resulting in slower cutting and more heat.

Sam, most of the people on this list do not have a great deal of education. It is very hard to explain things without knowing what the other person knows. Your technical education and experience is far beyond most here.

My bearing experience is with hard disk drives. The actuator arm in a disc drive during track follow is moving a few micro inches back and forth as the disc rotates at 3000 to 15000 rpm (3000 rpm was decades ago). The balls in the actuator bearing barely move during track follow, which can result in fretting failure. A mode that is highly unlikely to occur on bicycle.

[Sam]

(01-11-2015, 09:29 PM)nfmisso Wrote:  . . . . . . . . . In addition, the last thing you want on a bearing is a transition to a lower strength in a zone that is at high stress - that could lead to delamination like failure of the ball (or raceway); like a layer of an onion peeling off. The stress is highest at the contact point and drop from there.

Case hardening is used in situations where it difficult to harden all the way through, or where it is desirable to have a more resilient core to handle shock loads - machine tools being a prime example.

My bearing experience is with hard disk drives. The actuator arm in a disc drive during track follow is moving a few micro inches back and forth as the disc rotates at 3000 to 15000 rpm (3000 rpm was decades ago). The balls in the actuator bearing barely move during track follow, which can result in fretting failure. A mode that is highly unlikely to occur on bicycle.

Hi Nigel,

The resilience to shock loads was exactly the reason I was interested in case hardening, as unlike hard drives (I assume) bicycle wheel bearings experience considerable shock, both from potholes/jumps etc. and from grit/ fragments in the bearing.

I would think delamination of case hardening to be unlikely as the hardening will be a gradual reduction rather than a defined layer, and may possibly fit quite well with the stress distribution, but I'm just guessing.
I know that some carbon steel ball bearings sold specifically to the cycle market are promoted as Case hardened, but I have also only come across Through hardened in 52100 or 440C, probably because these come to us from general bearings, most of which are designed for the higher speed lower shock environments; I think most slow, high load bearings will be roller these days. I'll have to see what I can find about ball bearings in car hubs.

I suspect your experience with the actuator bearings may overlap with headsets to some extent, but again, the shocks and stresses will be quite different.

[joseph wolf man]

I know how to bulid mountain bikes and repair them and some of the technical information

[nfmisso]

(01-12-2015, 12:13 PM)joseph wolf man Wrote:  I know how to bulid mountain bikes and repair them and some of the technical information

You are making false claims. Based on the information you have posted and questions you have asked, you do not know how to assembly a bike, nor how to repair them.

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(01-11-2015, 10:46 PM)Sam Wrote:  .....I suspect your experience with the actuator bearings may overlap with headsets to some extent, but again, the shocks and stresses will be quite different.

Hi Sam;

Actually bicycle bearings experience much lower shock loads than HDD (hard disk drive). Tires and wheels protect bicycle bearings. HDD's are designed for 1000G 2ms duration shock loads. It would take hammering on the BB axle with the bike very rigidly clamped at the BB to approach that sort of shock. Just clamping the frame halfway up the seat post would reduce the shock load and increase the duration by an order of magnitude or more.

Another probably reason for through hardening of balls and smaller bearing components is costs. Given the dimensions involved, it is easy to control the process so that they are always hardened through, while to case harden, the timing would have to be much more precise. That would hard to do on million piece batches.

[joseph wolf man]

ik some of it that ive learned from either home taught or others teaching me and it wasn't a false claim because one I want to make sure I do it right that's why ive been asking for help I hate messing up that's why im willing to learn by every way possible not just by experience

[cny-man]

If you learned to write properly at some point in school it would be much easier on all of us if you could use punctuation. We make the effort to be clear not only in the info we give but in the manner we communicate it. It's only respectful for those asking for help to do the same.

Also, just so you know - the info discussed above about grade 10 bearings, hardness, stress, etc. is not worth spending your time on. It will add absolutely nothing to your ability to fix bikes.

[joseph wolf man]

(01-12-2015, 03:58 PM)cny-man Wrote:  If you learned to write properly at some point in school it would be much easier on all of us if you could use punctuation. We make the effort to be clear not only in the info we give but in the manner we communicate it. It's only respectful for those asking for help to do the same.

Also, just so you know - the info discussed above about grade 10 bearings, hardness, stress, etc. is not worth spending your time on. It will add absolutely nothing to your ability to fix bikes.

dude I know how to write. im just always trying to get what im saying out as fast as I can, so if you dont mind, please trying to say im retarded when im not, I swear im not retarded or stupid. I just don`t go and check what I write my aplogizes. I will try to make more sense now on ok?

[cny-man]

I did not say nor did I imply you are retarded, only inconsiderate. In your haste to get things out fast you make everyone reading it take more time to decode it. It's quite easy to look over what you entered and hit Edit to make it clearer. I use punctuation and capitalize sentences even when on a smartphone, and almost always edit my entries.

[joseph wolf man]

ok then I will