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O/T - Cerbec ceramic balls, distribution?

I've never heard of Coorstek but I've had success purchasing grade 5 SiN balls from Spheric Trafalgar:

Spheric Trafalgar LTD

Prices were about 1/10 of the price from Bal-Tec, and they had balls in .0001" increments around common nominal sizes (spheric trafalgar supplies balls for precision bearings, my impression was bal-tec is more interested in measuring tools and standards so their prices were higher and variety more limited). Definitely easier to purchase from Bal-Tec, but Spheric Trafalgar was the only place I found that could supply the sizes/grades I needed.
 
Thanks much for the info, did you buy directly from them? Order through a distributor?

Cerbec replied to my inquiry, it's getting complicated:


Hi Terry,

Thank you for contacting CoorsTek. We appreciate your inquiry. CoorsTek strives to be the partner of choice for technology and manufacturing companies worldwide.

CoorsTek is a technical ceramics manufacturer that makes custom engineered parts to our customer’s specifications. Before we connect you with a sales representative, we would like to see what additional information you could provide. Could you please describe the following:

Please provide your complete company contact information

Once we are able to obtain enough information we will then forward to a CoorsTek representative who can discuss in more detail.

Regards,

Katie Arpin
Customer Engagement Center Rep



Edit: I called STL, the first guy hung up on me, the second call went to a full mailbox. Called Bal-tec, talked to someone that could check stock but nothing else...
 
Milland said:
I'm going to hate myself for this, but: (100 PCS) (4.763mm) (3/16") Ceramic Bearing Ball Silicon Nitride (Si3N4) G5 | eBay

Yes, they're suspect if you're working on a satellite or similar critical item, but if you can chance it, the pricing is ridiculously lower than other options. You can buy 10 sets and sieve them, test to destruction, shoot them at squirrels, etc. and still have enough for the job.
Click to expand...


Ya, thanks. Cheap China crap is all over the place, usually about 1/10th the price of the "real deal". I wouldn't trust their specs with a 10' pole, if they even give specs.

All kinds of stories of cheap balls coming apart, makes a complete mess.

Got a quote from Bal-Tec at least, $3.57 ea.

Bal-tec - Products Catalog
 
I purchased direct thru Spheric Trafalgar; they have a warehouse in Georgia where they stock balls. It still required an annoying number of emails however for what should've been as easy as ordering on ebay. Also, I don't remember the exact details of why, but I believe the actual balls were manufactured by Tsubaki-Nakashima, aka TN Uk, LTD: Precision Ball (Bearings) | PRODUCTS | TSUBAKI NAKASHIMA CO.,LTD. . Or at least when I ordered it was their company URL on the email address.

Prices were ~10-50cents/ball from memory, for balls that were smaller than what you're looking for (sorry project requires that I be vague). I had the option of choosing Toshiba SiN since it's apparently considered a higher quality base material. Bal-tec quoted similar balls without control of the base material at $5 each, for comparison.

It sounds like Coorstek is a material manufacturer rather than ball manufacturer? I know that TN didn't make the base material for their ceramic balls.

My impression was ST's Georgia warehouse is mostly distribution, so probably worth emailing their UK office. Their prices will smoke Bal-tec, and their quality was as good as I can measure. Of the thousands of balls I've purchased from them, they've all been within 5uin of eachother on every ball I've measured (I've measured a few hundred of them over a year or two). Note however that the G5 tolerance allows a surprising amount of variation in batch size; it's just that balls within each batch be well matched and spherical within tight tols. This has been true in my experience; the balls I ordered were up to 30uin off nominal, but very well matched to eachother within batches (and actually between batches). I know ordering from these places is a pain, sorry I don't have any tricks to make that any easier.

Are you using these to rebuild a precision ball bearing? If so note that the bearing balls are often not the nominal size, since manufacturers will adjust ball size to set preload based on batch-to-batch race gage diameter variations.
 
Terry Keeley said:
Ya, thanks. Cheap China crap is all over the place, usually about 1/10th the price of the "real deal". I wouldn't trust their specs with a 10' pole, if they even give specs.
Click to expand...
Just about all the Famous Name bearing manufacturers have many many plants in Ningbo, bearing capital of the world. If you've got ball bearings in anything, good chance you have a lot of "crap" Chinese bearings in your stuff.

Unfortunate but true.
 
Halcohead said:
I purchased direct thru Spheric Trafalgar; they have a warehouse in Georgia where they stock balls. It still required an annoying number of emails however for what should've been as easy as ordering on ebay. Also, I don't remember the exact details of why, but I believe the actual balls were manufactured by Tsubaki-Nakashima, aka TN Uk, LTD: Precision Ball (Bearings) | PRODUCTS | TSUBAKI NAKASHIMA CO.,LTD. . Or at least when I ordered it was their company URL on the email address.

Prices were ~10-50cents/ball from memory, for balls that were smaller than what you're looking for (sorry project requires that I be vague). I had the option of choosing Toshiba SiN since it's apparently considered a higher quality base material. Bal-tec quoted similar balls without control of the base material at $5 each, for comparison.

It sounds like Coorstek is a material manufacturer rather than ball manufacturer? I know that TN didn't make the base material for their ceramic balls.

My impression was ST's Georgia warehouse is mostly distribution, so probably worth emailing their UK office. Their prices will smoke Bal-tec, and their quality was as good as I can measure. Of the thousands of balls I've purchased from them, they've all been within 5uin of eachother on every ball I've measured (I've measured a few hundred of them over a year or two). Note however that the G5 tolerance allows a surprising amount of variation in batch size; it's just that balls within each batch be well matched and spherical within tight tols. This has been true in my experience; the balls I ordered were up to 30uin off nominal, but very well matched to eachother within batches (and actually between batches). I know ordering from these places is a pain, sorry I don't have any tricks to make that any easier.

Are you using these to rebuild a precision ball bearing? If so note that the bearing balls are often not the nominal size, since manufacturers will adjust ball size to set preload based on batch-to-batch race gage diameter variations.
Click to expand...


Again, thanks for your time with this.

I got a quote from Cerbec, $1.19 ea with a $500 minimum. Want 300 3/16" balls? Not sure if they make the balls or not, that division was aquired from Saint-Gobain about ten years ago.

It's for bearings for my high end R/C boat engines, 6000 and 6002 sizes, up to 30K rpm.

I've found a few companies that offer built up bearings with Cerbec balls but I have quite a few sets of WIB (Swiss) bearings and figured I could re-ball them myself. I've pulled a few apart, checked the balls and they're right on nominal size for the C3 fit. If I find one with odd size balls I won't use it.

Looks like you're right about Spheric Trafalgar in Georgia, Tsubaki-Nakashima list them as a "Group Company" as well as a few others in the US:

Offices and Group Companies | COMPANY | TSUBAKI NAKASHIMA CO.,LTD.

I'll try emailing them, maybe I just need to be more patient. Did you have minimums to deals with?

Thanks again.




edit: Looks like TN acquired Spheric Trafalgar in 2013: Corporate History | COMPANY | TSUBAKI NAKASHIMA CO.,LTD.
 
EmanuelGoldstein said:
Just about all the Famous Name bearing manufacturers have many many plants in Ningbo, bearing capital of the world. If you've got ball bearings in anything, good chance you have a lot of "crap" Chinese bearings in your stuff.

Unfortunate but true.
Click to expand...


I hear that.

For sure lots of quality, high end stuff is made in China as well but trying to separate the good from the bad is tough for an end user when low numbers are involved.
 
I can't comment on minimums, I was buying in quantities of 500-5000. I will say for the high-end angular contact bearings I was working, if you ignored labor it turned out significantly cheaper to re-ball all steel bearings than to buy factory hybrid bearings. I had to re-ball the bearings either way though for this particular application.

Personally I would go with an off-the-shelf bearing rather than trying to re-ball bearings if the only reason is to save money by converting current stock to hybrids. Maybe deep groove radial ball bearings don't vary the ball size as much. Angular contacts I've dealt with had pretty large lot-to-lot variation in ball size (as much as 10um).
 
Halcohead said:
I can't comment on minimums, I was buying in quantities of 500-5000. I will say for the high-end angular contact bearings I was working, if you ignored labor it turned out significantly cheaper to re-ball all steel bearings than to buy factory hybrid bearings. I had to re-ball the bearings either way though for this particular application.
Click to expand...

I've looked into this myself, and have read at least one reference to there being a slight inner/outer race ball path geometry difference between A/C bearing designed for steel balls, and those with ceramic balls.

This is due to the modulus of elasticity differences between 52100 steel and silicon nitride, which among other things means the Si3N4 balls will stress the rings more (as the rings absorb more distortion that was otherwise shared with the steel ball), and can change preload when using universal bearings.

Did you notice any difference in these areas when you did your own reballing?
 
Milland said:
I've looked into this myself, and have read at least one reference to there being a slight inner/outer race ball path geometry difference between A/C bearing designed for steel balls, and those with ceramic balls.

This is due to the modulus of elasticity differences between 52100 steel and silicon nitride, which among other things means the Si3N4 balls will stress the rings more (as the rings absorb more distortion that was otherwise shared with the steel ball), and can change preload when using universal bearings.

Did you notice any difference in these areas when you did your own reballing?
Click to expand...

I can't share details about my application. However in a general sense, yes the load rating of hybrid ceramic SiN bearings is lower than the load rating of straight steel bearings due to increased contact stresses in the races. The lower density of SiN also allows higher speeds (Dn) by reducing centrifugal loading against the outer races and reducing adhesion between the balls and races.

I'm sure there are manufacturers who customize their race geometry for SiN balls vs steel balls, but no manufacturer/engineer I ever spoke to suggested they did this. In terms of swapping ball material changing preload, yes this is an effect but doesn't necessarily require different race geometry to compensate. Re-sizing the balls or changing the face relief could both achieve similar performance.

Example: For a 1/4" ball under 22 lbf of load between two flat 52100 plates (bearing races aren't flat plates, but this example is an approximation), you'd see the plates be ~45uin (1.1um) closer together for 52100 balls vs SiN balls (https://www.tribology-abc.com/calculators/e2_1.htm). At 2.2 lbf/ball you'd see 9uin difference in deflection. So maybe with re-balling a steel bearing to SiN you would want to run /slightly/ smaller balls (I calculate for a 7205 light preload AC bearing you might run SiN balls 10-20uin smaller to match preload, which is a smaller increment than I can purchase G5 balls in). Presumably though anyone reballing a bearing would also be prepared for this and running appropriate calculations.

In general, bearings are sensitive to ball size, but I wouldn't stress 10 or 20uin on a 1/4" ball set, so long as all the balls are high quality and well matched in size. Any minor preload variation from reballing should likely be repairable by adjusting the width of the bearing spacers (if necessary at all).
 
Out of curiosity, what are you using to measure them, TK ? I remember Jeff Bratton had his temp-controlled clean room and used a Pratt & Whitney Supermike, then spaced the balls/rollers around the bearing according to size ...
 
EmanuelGoldstein said:
Out of curiosity, what are you using to measure them, TK ? I remember Jeff Bratton had his temp-controlled clean room and used a Pratt & Whitney Supermike, then spaced the balls/rollers around the bearing according to size ...
Click to expand...

If you're careful with cleaning/handling, you can set up "slip gauges" using stacks of good gage blocks with overhangs to allow balls through or reject them. While you won't get sphericity, with some care you can grade the sizes to better than a micron. Just watch body heat and dirt contamination.
 
dian said:
https://www.tribology-abc.com/calculators/e2_1.htm

what does "indentation" mean? is it assumed the ball doesnt deform? and if you have two balls?
Click to expand...

Yes, of course balls (and races) will deform, but the amount for each is dependent on the materials used. When you take a traditional 52100 steel ball/race bearing, and trade the balls for silicon nitride replacements, if you use the exact same ball diameter you will chance the stress distribution in the "system", as well as load and speed characteristics.

It's not a "one for one" procedure...
 
Took nearly two weeks but I got a reply from STI, they are in fact a part of the Tsubaki Nakashima group.

100pcs 3/16” OK Grade 5

Silicon Nitride

Toshiba TSN-03NH

Price: $1.35 each

Delivery: 7-10 days from GA

Prices: FOB GA


This place is awsome, thanks Halco!
 
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