What ABEC grade bearings for a T&C grinder?

RLamparter · Jul 27, 2010

K.O. Lee B923A head. The parts breakdown says it's a 203KDD but doesn't list an abec grade.

There are some on the net that say a current abec 3 bearing is better than a better grade bearing from 40 years ago because of improvements in bearing manufacture. I don't know whether to believe that or not.

What grade bearings are needed for a tool & cutter grinder? Do you have any favorite vendors who sell quality bearings. I'm hoping only to need one since I think I can hear which bearing is causing the sound.

RWL

RC99 · Jul 27, 2010

I doubt an ABEC 3 from today is better then an ABEC 3 from 40 years ago unless the specs have changed..

If anything an ABEC 3 from today should be a lot lot cheaper then an ABEC 3 from forty years ago due to them being easier to make..

Forrest Addy · Jul 27, 2010

Goes to show just how valuable "some guy tole me" advise is. ABEC class tolerances have remained the same for 40 years so why would a Grade 3 bearing of today be better than a Grade 5 of today? Does not compute.

You have a precision grinder made by a first class machine tool manufacturer. Replace the existing spindle bearings with a comparable class. My experience with precision grinding spindles leads me to suggest you use ABEC Class 7 for replacements. Lo-ball the bearing class at some perceptable detriment in machine performance.

I can see why the average guy would flinch at spending $500 - $800 for a set of ordinary looking bearings. While Grade 7 would be what I would reccommend Grade 5 may do the job if you can live with the lower performance. No lesser Class though. I hate these compromises. Sure as hell the substitution will bite you in the butt at a Murphy moment.

Mike C. · Jul 27, 2010

Just me, but if one bearing is bad, the other is surely soon to follow. It's either at the same point in service life and/or the one that went out has beat it up so bad that it won't last long.

RLamparter · Jul 28, 2010

.RC. said:
I doubt an ABEC 3 from today is better then an ABEC 3 from 40 years ago unless the specs have changed....

My understanding was that the machinery that makes bearings has improved so much that many of the bearings that are certified as abec 3 would actually pass testing for a higher grade, but aren't tested for that. I can't verify the statement, but it's what was said somewhere else.

RLamparter · Jul 28, 2010

Forrest Addy said:
My experience with precision grinding spindles leads me to suggest you use ABEC Class 7 for replacements. Lo-ball the bearing class at some perceptable detriment in machine performance.

While Grade 7 would be what I would reccommend Grade 5 may do the job if you can live with the lower performance. .

Forest, do you (or anybody else) have a favorite supplier that usually sells quality bearings at favorable prices?

RWL

RLamparter · Jul 28, 2010

KO Lee's specification

I called KO Lee for a price and information on the bearings. The current designation for the bearings is 6203 LLB/2A (the original designation was 203 KDD)

They sell them for $15 apiece. The person said he didn't have an abec specification available to him. The price suggests that it's some kind of ordinary bearing. That price doesn't sound like an abec 7 bearing does it? From KO Lee a pair of bearings will cost me roughly $50 with Shipping & Handling. If this is an ordinary bearing, I'd prefer to save a couple of bux.

The LLB stands for two non-contacting rubber seals at NPN. What's the 2A?

RWL

MBensema · Jul 28, 2010

RLamparter said:
My understanding was that the machinery that makes bearings has improved so much that many of the bearings that are certified as abec 3 would actually pass testing for a higher grade, but aren't tested for that. I can't verify the statement, but it's what was said somewhere else.

That is true, standard grade bearings can and quite often do meet ABEC 3 standards, but the important part is there is no guaranty they will. That is the main issue, a bearing is good to ship if it meets the spec and you have no way of knowing if you got one bearing off of manufactuing line 1 that just happened to meet ABEC 3 specs or from manufacturing line 2 that was at the outer limits of ABEC 1 specs that day. Both bearings meet the ABEC 1 spec and will ship.

If they are selling a bearing for $15, is is certainly an ABEC 1 bearing. A higher spec bearing will be much more expensive then that.

engrx2 · Apr 23, 2011

Kind of new to this forum, but I thought that the ABEC rating had to do with TIR. But using sensitive gauges, I cannot seem to tell the difference between an ABEC1 (stock) and ABEC7 (super precision). As far as I can tell, they both run dead true (less than 50 millionths) if they come from a good manufacturer (meaning usually USA). There is one other aspect. Most super precision bearings use a phenolic retainer that runs cooler than a metal or plastic retainer. They are also open so that you can put the right type of grease in them that keeps them cool. Finally, most super precision bearings do a face grind on them so you preload them correctly ---too much preload and you'll burn them up. ---Not sure what would happen if you preload a non-face ground ABEC1.

Metalcutter · Apr 23, 2011

RLamparter;

Every one bitches about Chinese workmanship, but then turn right around and try to emulate what they bitched about by going cheap! Sheesh!

These are MACHINE TOOLS! For building machines and precision products. Rebuild them back as best as you can to original or better.

Of course if you REALLY want to be a real flake, pop off the cages and just change the balls.

Please try very hard to have a bit of pride in what you do. Do it as best as you can.

My RANT! Other than that,

Best regards,

Stanley Dornfeld

Ed P · Apr 23, 2011

Keep in mind folks that ABEC standards are NOT all inclusive. They do not cover such parameters as materials, lubricants, ball complements, (number, size and precision), radial play, to name just a few. I would be extremely surprised if bearings sold today are not better than those sold just a decade ago. My source of information is a bearing basics publication from Barden bearings. Furthermore, where is the evidence that the ABEC standards themselves have not been changed over the years?

Ed P

WizardOfBoz · Apr 23, 2011

Ed P said:
Keep in mind folks that ABEC standards are NOT all inclusive. ... Furthermore, where is the evidence that the ABEC standards themselves have not been changed over the years?
Ed P

Point 1, Agree, there are other important design parameters./
Point 2, Because Forrest tells us it's so, and Forrest has been around and (I infer) has been paying attention for those 40 years:

Forrest Addy said:
ABEC class tolerances have remained the same for 40 years

One thing I would guess, depending upon the variability in manufacture, would be that average bearing quality in any class might have gone DOWN. Bear with me and see if this makes sense.
1. Mfrs want minimum scrap and minimum number of off-spec bearings that they have to derate and sell more cheaply.
2. Consistency in mfr has gone UP. Therefore, the variability in bearings has gone done.
3. If you want to maintain a certain success rate in product testing, and you have high variability, you set your machines up so that the average spec is high enough to account for most variability.
4. If we can improve manufacturing so that the variability is lower, I can set my machines up so that the average spec is a bit lower, too.

If I need to beat 0.0004" TIR runout, and my variability is +/- 0.00015, I have to shoot for 0.0025, on average. If I improve my process and reduce variability to 0.0005, then I can let my average slip up to 0.00035". Now, bearings that passed back in the day still passed. As do bearing today. But what you should expect today is less margin.

Right?

J

RussZHC · Apr 23, 2011

The person said he didn't have an abec specification available to him.

I don't doubt you called KO Lee but gotta say, I would find it tough to accept the above statement from someone who is wanting to supply replacement bearings. Even if it is not the standard the world over, there are, as far as I know, equivalency tables.

HelicalCut · Apr 23, 2011

Better is a word open to interpretation, Better for what? a modern bearing of any grade from a reputable manufacturer will probably have better load capacity and fatigue resistance than one 40 years ago but a grinder is more affected by TIR which is determined by specification not date of manufacture.

@ engrx2 50 millionths is not a sensitive indicator when it comes to measuring runout I have the test sheets for a couple of P4 (abec7) bearings in front of me runout both radial and axial on the inner ring is 1 micron (25 millionths). P2 bearings would be half that.

Measuring the runout of precision spindles is capacitance or lvdt gauge territory. The runout of rolling element bearings is not simple eccentricity there are lobes on both the rolling elements and the races which make for a complex ever changing runout. On a grinder this shows up as increased time to sparkout.

Check out a polar plot from a spindle to see what runout actually looks like. Makers of P4 grade bearings are likely to load them with class 10 rather than class 25 balls which makes it easier to hit runout targets, the races may be lapped more as well, the smoother balls and races make for a quieter bearing at high speed, P4 bearings usually have a higher speed rating than standard bearings.

gmatov · Apr 23, 2011

All bearings are MADE to the highest standard, then tested to see if they pass ABEC 7. If they do not, but pass ABEC 5, they ship. If not they are tested to ABEC 3, and if they pass, they are shipped. If not, they are sold as ABEC 1.

Similar to CPU's. ALL of them are 100 GHz Processors, until they are tested, and they go down to where they still pass as functional 2 GHz Processors. They don't like to scrap what could be 500 buck product, that costs 5 bucks to make. 20 buck return makes for zero scrap, and good for the bottom line.

Better steel is not all that big in bearings. Some of the best steels ever made are more than 50 years old. Stellites, for example. 9 on the Mohs scale, just under diamond. Possibly TOO hard for bearings.

If Lee says their bearings are 15 bucks, I would not try to gild the rose with better than OE. THEY should know if ABEC 7 would be better, since they could charge you 500 more to buy their Factory Replacement,IF they said you HAD to go ABEC 7.

They say no, why would you want to outguess them? They are simply radial bearings. There should be no pre-load. Your wheels turn, they don't take thrust, and you don't have to worry about how much "pre-load" you put on them. None.

Cheers,

George

Ed P · Apr 23, 2011

RLamparter said:
Forest, do you (or anybody else) have a favorite supplier that usually sells quality bearings at favorable prices?

RWL

Ball Bearings, Roller Bearings, Mounted Units, Oil Seals, Roller Chains, Cam Followers: Emerson Bearing Co: Boston, MA

MBensema · Apr 24, 2011

gmatov said:
All bearings are MADE to the highest standard, then tested to see if they pass ABEC 7. If they do not, but pass ABEC 5, they ship. If not they are tested to ABEC 3, and if they pass, they are shipped. If not, they are sold as ABEC 1.

Not even close. The process to make ABEC 7 and 9 bearings is different then the lower grade bearings. Barden only makes ABEC 7 and 9 bearings, anything else is scrap, and there is not much scrap in their process. Their process is setup to produce the quality they require, which costs significantly more to do. Standard grade bearings are made on a production line that optimizes speed in manufacture to enable the cheap prices you see on those bearings. These production lines to not have the labor intensive gaging stations required to test for ABEC 7 and 9 specs since most of those specs are not required in the lower grade bearings.

lane · Apr 24, 2011

According to my KO Lee book that is not a precision bearing .Just a standard motor bearing. I thank that is a Fafnir Bearing. The spindle bearing is a Precision bearing.2MM9305wocrdum Duplux

HelicalCut · Apr 24, 2011

gmatov said:
All bearings are MADE to the highest standard, then tested to see if they pass ABEC 7. If they do not, but pass ABEC 5, they ship. If not they are tested to ABEC 3, and if they pass, they are shipped. If not, they are sold as ABEC 1.

Interesting theory, I wonder how those dynamic tolerances would stack up?

For example you are trying to hit 25 millionths TIR using balls which are 25 millionths out of round (class 25) in races which might have 10 millionths ripples and be 20 millionths eccentric with the bore. For a small extra cost class 10 balls can be used and grading components before assembly is really going to improve the chances of hitting tolerance.

Rolling element bearings are not like CPU's, a CPU is static and the variables which affect the performance of the device are static so they can be managed like static tolerances.

JST · Apr 24, 2011

gmatov said:
All bearings are MADE to the highest standard, then tested to see if they pass ABEC 7. If they do not, but pass ABEC 5, they ship. If not they are tested to ABEC 3, and if they pass, they are shipped. If not, they are sold as ABEC 1.

Cheers,

George

Beans....

The better grades have selected-for-size balls and different cages, plus the races are made to tighter tolerances for race runout.

What ABEC grade bearings for a T&C grinder?

Hot Rolled

Attachments

Diamond

Diamond

Diamond

Hot Rolled

Hot Rolled

Hot Rolled

Hot Rolled

Plastic

Titanium

Aluminum

Diamond

Plastic

Stainless

Diamond

Aluminum

Hot Rolled

Cast Iron

Stainless

Diamond

Similar threads