Best options for grinding small rings

jsc · Jun 23, 2015

I do not have much experience with centerless grinders, so I am wondering what my options are for a machine that can do centerless grinding of small quantities of rings up to a diameter of 4 inches and 3 inches high. My understanding is that the size of the machine is mostly dependent on the diameter of the work and has nothing to do with the height/length, is that right? I only need infeed to do rings, no through feed. By small quantities, I mean no more than about 30-50 rings a day.

For internal grinding of the same rings is that a completely different machine, or can the same machine be setup up to do both types of operation?

allloutmx · Jun 23, 2015

KEL-VARIA - Complete machining in ultimate quality - Cylindrical-grinders by Kellenberger & Co AG - Engineering and Production of high accuracy grinding machines, St.Gallen and Biel, Switzerland

This will do just what you want.

Fulcircleny · Jun 23, 2015

Jsc,

In my experience, a centerless will handle your OD, but not your ID. Centerless machines work by feeding the stock, "thru" there would be no way to do the ID, again, in my experience. To me, your parts sound more like tubes, rather than rings( 3" high, does this mean long?). A "Universal" OD, ID grinder would be what I would recommend. grind the ID first, then on an arbor, grind the OD. They are a bit cumbersome, but can be found inexpensively and work really well. For 50 parts a day, you can stack your work, make 100 ID, swivel the head(or however you machine would work)grind 100 OD'S. Best of luck,

Chris

specfab · Jun 23, 2015

What they said ^^^. Centerless grinding is OD only. Good call on Kellenberger machine.

Mechanola · Jun 23, 2015

Not to say anything against Kellenberger but rings can be produced to very fine finish and withing close tolerances with simpler processes. You can hone the ID and lap the rest, I mean lap OD, flat, and perpendicular. Much cheaper than grinding with solid wheels

Have a look in here from 11:44 on. https://www.youtube.com/watch?v=fnoVV-RWIWY

michiganbuck · Jun 23, 2015

Small rings is not very clear. Precision ID, OD, Varying sizes, precision ends and lengthes or not. That matters much for suggesting process.

Hate to critique a fine company I have much respect for but for hand lapping the weight of hands and pressure applied to lapping by the direction and down pressure applied by different parts of ones hands and various surface areas on the part, turning the part after x-number on laps is the desired method.
Perhaps 3 figure8s, turn 1/3 for 3 more, turn 1/3 for last 3.
We would also rotate the lapping block at intervals.
I am really surprised they did not mention those two.

tdmidget · Jun 23, 2015

Maybe that Kellenberger was a joke? 1/2 million buck machine for 50 parts/day? There are centerless ID processes but not on th same machine. It is important to realize that while centerless can prodoce the roundest parts, concentricity is not at all a strong point. You need to consider that concentricity requirement to do both on centerless machines. As Far as the OD, any clapped out centerless can do a good job there with an experienced hand running it.

jsc · Jun 23, 2015

tdmidget said:
Maybe that Kellenberger was a joke? 1/2 million buck machine for 50 parts/day? There are centerless ID processes but not on th same machine. It is important to realize that while centerless can prodoce the roundest parts, concentricity is not at all a strong point. You need to consider that concentricity requirement to do both on centerless machines. As Far as the OD, any clapped out centerless can do a good job there with an experienced hand running it.

Right, I was thinking more like $10,000 used. In reviewing different centerless grinders, they all basically seem to do the same thing. I couldn't tell the difference between them which is why I was asking. So, basically the answer is you need two machines: any old centerless grinder and any old centerless ID grinder?

jsc · Jun 23, 2015

Mechanola said:
Not to say anything against Kellenberger but rings can be produced to very fine finish and withing close tolerances with simpler processes. You can hone the ID and lap the rest, I mean lap OD, flat, and perpendicular. Much cheaper than grinding with solid wheels

Have a look in here from 11:44 on. https://www.youtube.com/watch?v=fnoVV-RWIWY

I thought "hones", meaning fixed inner diameter grinders were for bores. For rings I thought it was much better to use an ID centerless grinder.

sable · Jun 23, 2015

I have read about attachment for grinding the OD of a part on a centerless while on some kind of mandrel which ensures the part remains concentric. I have never seen one .

tdmidget · Jun 23, 2015

What is the concentricity call out? Parts machined on Modern CNC equipment will likely start with a very good concentricity. It may well be acceptable after centerless grinding.

Richard King · Jun 23, 2015

I have seen Cincinnati Centerless that have a in-feed grind that doesn't use thru grinding. I found this Royal Oak on You tube, It's smaller, but the same idea. This was done for years by hand and not the CNC control types. https://www.youtube.com/watch?v=zuS0X9yvMkA

Then you could 2nd op it on a Heald ID grinder with the ring mounted on a magnetic chuck. https://www.youtube.com/watch?v=4VDPNvL0kU0 I saw them grinding Timken bearing Races (rings) this way. You don't tell us your spec or OD, ID size and surface finish requirements so it's a big guess but as TD says you might be able to do this on a CNC Lathe.

Used Grinders like this can be purchased fairly cheap if your willng to do some repairs or buy a reconditioned one from one of several rebuilders out there. PM me for some info if you need some. Also i know a company with open time and reasonable prices who could do the job for you. They also have several Studer combo OD / ID grinders if you need super precision. Rich

allloutmx · Jun 24, 2015

tdmidget said:
Maybe that Kellenberger was a joke? 1/2 million buck machine for 50 parts/day? There are centerless ID processes but not on th same machine. It is important to realize that while centerless can prodoce the roundest parts, concentricity is not at all a strong point. You need to consider that concentricity requirement to do both on centerless machines. As Far as the OD, any clapped out centerless can do a good job there with an experienced hand running it.

I wasn't making a joke this time

. He was looking for options and at my day job the work that comes through the grinding dept. isn't cheap, so 30-50 pcs a day would probably a good paying job.

To the OP- you might also want to look into used jig grinders for your application and budget.

tdmidget · Jun 24, 2015

If you can give us an idea of the required concentricity we can probably be of more help. Also what are the previous ops done on?

jscpm · Jun 27, 2015

These are forged rings which are being provided to different customers with different requirements. Normally, I am just providing the ring as-milled, but being able to grind it as an added services would be advantages in some cases which is why I am interested in learning about the grinding options. A typical concentricity someone might want would be 0.001" maximum variation between inner and outer diameter on a 4" inch ring, 1" high with a nominal wall thickness of 0.25".

tdmidget · Jun 28, 2015

If you start with workpieces with both ID and OD done in the same operation you will not lose much in centerless of the OD, maybe .0002-.0003. Honing the ID will not change it so you would be good on your concentricity.

npok · Jul 4, 2015

MBB-1660 - Sunnen

A hone like this can finish your IDs quickly, accurately and slick as you like.

You just need to have your IDs roughed out.

EM2 · Aug 30, 2016

I'm newbie here & centerless grinding. I wanna ask what is the best centerless grinder for small diameter wire, 1.5 mm to .01 mm . We have been using Royal Masters Centerless Grinders (TG-12X4 & GENX-R). The machines are good but Royal Master service is bad. I been searching on the web for other brands but I haven't found a decent answer. I hope you guys can help. Thanks...

thall · Aug 31, 2016

EM2 said:
I'm newbie here & centerless grinding. I wanna ask what is the best centerless grinder for small diameter wire, 1.5 mm to .01 mm . We have been using Royal Masters Centerless Grinders (TG-12X4 & GENX-R). The machines are good but Royal Master service is bad. I been searching on the web for other brands but I haven't found a decent answer. I hope you guys can help. Thanks...

Maybe Glebar?

Precision Centerless Grinders |GLEBAR - Innovation Manufactured - Precision Centerless Grinders | Glebar

michiganbuck · Aug 31, 2016

Rings might be considered a narrow part, rolls might be a wider part.

The ded true is usually for parts yo to 1 1/2 but can grind up to 5" yes just for OD.

http://unisonemail.com/pdf/DT Price Book.pdf

It is a centerless unit that is used with a surface grinder.

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