When to use which?

They serve the same purpose - is cost the issue? Assembly?

I have an application for which either will work (speed, load, function), but the lead engineer (at work) looks at me as if I have antlers when I suggest using taper roller bearings.

Any insight would be greatly appreciated!

Scott

Comparing the two bearings, tapered ones will have a larger contact surface area between the race and rollers than angular ones. With this being said, tapered ones will require more of a clamping force to minimize backlash thus requiring more torque to rotate the bearing. Lets not forget the resistance of the grease and because of the physical size there is a larger rotational inertia. They are designed for low speed and heavy loads.
Angular contact bearings are smaller, lighter in weight, less rolling friction and will operate at a higher rotational speed. Yes they do cost more but they are worth it in the long run.

yeppers Tappered roller bearings = heavy loads, lower speeds, usually less accuracy.

angular = high speed, very accurate, and less load.

Which is used more frequently for middle-of-the-road applications? Sounds like angular contact bearings are more popular??

I worked for an Austrian machine builder (GFM) - they liked taper rollers.
Now I work for a Japanese company (Mitsubishi) - they like angular contact.

I know it sounds like it, but I am not hung up on this - it's just one of those things I keep thinking about.

If your application sat right in the middle of the considerations which bearing would you employ?

Scott

well assuming your building a non-commercial hobby sized machine (considered light duty from a commercial standpoint) Angular gives the higher rpm and better tolerance, not to mention easier to design around (IMO of coarse)

I would use angular. Even the heavy duty machines use angular they are just MUCH bigger than what a hobbiest would generaly consider (also more expensive)

This is for a production environment - but I take everything I learn home with me....and they can't stop me :devious:

Scott

So once set on angulars, where do I get them reasonable? Any source of bargain basement closeout prices for 1/2 inch ID angulars?

You never did mention your application or RPM range for these bearings?
If your side load isnt insane (and you are trying to be frugal) you can stack regular "deep-groove" bearings. A deep grove is not specifically meant for side load but the are rated for some. In some cases it works really well to put in 2 or 3 (instead of 1 angular) $5 bearings and just replace when necessary.
Another option would be to design in a thrust bearing and radial bearing combo. This takes alot more physical space and machining but your bearings are still inexpensive ($5) and endplay is adjustable to zero (angular contacts can be difficult to build to zero endplay).
some food for thought - mud for mudpies

So once set on angulars, where do I get them reasonable? Any source of bargain basement closeout prices for 1/2 inch ID angulars?

Tapered rollers can be a lot cheaper than angular contact. But finding tapered rollers with a 1/2" ID might be tough.

So once set on angulars, where do I get them reasonable? Any source of bargain basement closeout prices for 1/2 inch ID angulars?

A good source - http://bearingsdirect.com/products/

They show prices, availability - buy online.

I would suggest you design in MM - lots more options for metric sizes than english!!!

Scott

You never did mention your application or RPM range for these bearings?
....
Another option would be to design in a thrust bearing and radial bearing combo. This takes alot more physical space and machining but your bearings are still inexpensive ($5) and endplay is adjustable to zero (angular contacts can be difficult to build to zero endplay).
some food for thought - mud for mudpies

I did not mention the specs on purpose - I knew someone would ask, but I did not want to contaminate the information pool too early!

The speeds are less than 1500RPM. Loads not to exceed about 300 pounds peak dynamic thrust, 50 pounds or less radially. Precision is a concern, but not super critical, so I find either arrangement to be suitable.

The one thing I like about taper rollers for this application is that they are very stout and can be adjusted to give the desired endplay. I can't really see any reason not to use them.

All of the ideas you mention are excellent options, too!

Scott

Great, bearings direct has some good prices! I know I should have been more specific also, its just a router lead screw that Im working on. I think I'm going to try the double row angular's. They can be had for 8.50 each. Its a trip that you can spend so much money on a single bearing. Some of them are two hundred bucks!

my lathe has tapered rollers; FAG 55mm od 30mm bore; they work very nicely at a steady 3500rpm all day; they are rated to 10,000 in oil
I tried them at that speed; they were fine; the chuck is not LOL

The load carrying capacities plus the rigidy of tapered rollers compared to angular bearings is not even a contest. Even cheap tapers can handle 7500 rpm with grease, up to 10,000 rpm in oil; all for $6.00 U.S. The oil seal is usually the limiting factor for speed for tapers.

Angular bearings are nice for Aerospace where the light weight and low power requirements make them a perfect fit. They are way over their heads on a machine spindle.

So why are the majority of spindles using properly pre-loaded angular contact ball bearings? I've had to purchase Taper roller bearings of "high precision" and they are definitely not inexpensive.

I believe our bearing Guru, NC Cams, has already covered this subject.

It probably is a question of accuracy, speed and rigidity requirements. The old "Speed costs money. How fast do you want to go?"

Here's a pretty concise article on tapers vs angular. The comparison is pretty stark.
http://www.bearings.machinedesign.com/ArticleDraw.aspx?artid=57752
Jim

I believe our bearing Guru, NC Cams, has already covered this subject.

This is a two year old thread. I do not think Mr. Cams was educating us on bearings until just over a year ago. But yes - he has covered it I believe.

Scott

Here's a pretty concise article on tapers vs angular. The comparison is pretty stark.Jim

Not to start a brawl here but this article is comparing a highly specialized taper roller bearing to others and was quite obviously produced to promote a product. I have less faith in these types of articles than I do in NCcams' life of engineering experience which he has graciously shared with us common folk.

Although sometimes brutal, Cam's posts bleed with undisputable knowledge and for that I am most grateful.

Don't take me the wrong way - I have always been a proponent of taper roller bearings because of their cost to performance ratio but there are many cases where they simply do not fit the bill.

Keep in mind that this thread did not specifically identify a use for said bearing types....

Scott

That article is for a highly specialized bearing/application...ceramic tapered rollers are not exactly run-of-mill. But it did have a comment that I think is applicable; "...Tapered rollers are a better choice when spindle stiffness and load-carrying capacity are key design considerations..."

Back in the Dark Ages pre CNC I had several big turret lathes with tapered rollers; these could take incredible abuse and spin big parts completely off balance with no problem, but the maximum spindle rpm was around 1200. Actually one was around 600 rpm max with bearings that had an ID of about 6inches. I modified it to run at around 1500 rpm and we used to get the bearing so hot they would smoke; used it for about 12 years on a daily basis.

This is typical of truly Precision bearings. I had Timken quote replacement bearings for an older Barber Coleman gear hobber. I could have replaced the machine for the price of those taper roller bearings. (exageration of course)

I'm not disputing the usefullness of taper roller bearings. When the shoe fits etc. When equal accuracy is obtainable at lower cost and the speed, loads etc allow, use 'em. Usually I'm space restricted for bearings. For that reason I look first at AC bearings, usually sealed.

From what I have seen there is NO SOURCE for bargain 1/2" ID Angular Contact Bearings ! I have asked if anyone knew of any, all links that were provided ended up with Metric sized bearings. I hope you have better luck I resigned myself to banded thrust bearing/radial bearing combo:devious:
hopefully someone will make me eat these words ?

Paragraph 3 in the link posted in post #16 above says MOST of the difference but not the "why".

Simply put:

A/C's absorb axial and radial loads into two vectors via pure ROLLING friction.

Tapers, take the radial loads in line contact ROLLING friction but they absorbe SOME of the axial thrust via RUBBING friction of the roller ends against the flanges.

This is why there is typically less friction and heat generated in A/C's than tapers, especially when/if you run them in a highly preloaded state.

If you want stiff bearings, you need high preloads - this takes any internal deflection out or the bearing as loading is applied. You can preload tapers BUT you''ll pay dearly with high friction.

Want poof? Check the rotating torque of a 500 lb preloeaded ball screw support bearings versus that of a comparably sized and preloaded rear axle pinion bearing - you can turn the AC with your hand but you'll need a pry bar to turn the pinioin.

Otherwise, the article in post 16 gives an adequate layman's explanation as to why tapers are used in place of A/C's and vice versa.

From an accuracy and speed standpoint, A/C's have pretty much universally usurped tapers in the machine tool industry. Why? They've learned that you can cut faster/better with a light fast spindle cuts as opposed to deep heavy ones - the more cutting edges you can put across/thru the material the faster you can remove it, pretty much regardless of all else.

When you start to run bearings at high speeds, simple internal friction of tapers ultimately detracts from the bearing's ability to run/survive at speed.

Why no small sizes? You need a angled raceway to run the ball againts and it is phyically possible to make an A/C only so small. Besides, when you need to absorb that much thrust at so small a size, needle bearings package even easier and cheaper or there isn't enought deman to warrant the creation of something that small/special.

....From an accuracy and speed standpoint, A/C's have pretty much universally usurped tapers in the machine tool industry. Why? They've learned that you can cut faster/better with a light fast spindle cuts as opposed to deep heavy ones - the more cutting edges you can put across/thru the material the faster you can remove it, pretty much regardless of all else....

It was really the development of carbides (and ceramics) that can be run very fast taking small cuts that removed the need for spindles that could handle the brute force of driving a large HSS tool at a slow speed with a very deep cut at a heavy feed.

technomage, I suppose you already know or have now discovered antifriction bearings are almost all metric with a few exceptions. I looked thru every catalog I have and couldn't find any 1/2" AC bearings either. I did find some 1/8", 3/16" & 1/4" in a Barden catalog (C-20) in the instrument bearing (angular contact) section p.26/27 if that helps any.

For the spindle for my mill I am using a .56" ID (15mm) thrust bearing, ushing against a 1"OD x .5"ID shaft. The shaft has a through-bolt going through it to hold the chuck in place. The top of the through-bolt is centered in a 1/2"ID bearing. The shaft that the through-bolt goes through is pressed into a 1"ID bearing.

Here is a diagram I made when I first came up with the idea. That is not the final design, but it is pretty close (some dimensions and materials changed). I did is so I wouldnt forget, heh.

http://www.lindenwoodracing.com/mill_spindle.jpg

*edit*

Arg, saving the images in paint really screws up their alignment for some reason!

This thread does as much to demonstrate the creativity that exists in the hobby as much as any.

The thread also shows that tapers will clearly "WORK" as axial thrust bearings. And for the cost, they are perhaps the most affordable and most wide range as far as size and capacity.

They are NOT necessarily the optimum for low friction under axial thrust, however, and this is due to the way thrust is absorbed. Some of the thrust is clearly absorbed via sliding/rubbing of the ends of the rollers against the flanges. Yes, some thrust is taken via rolling of the rollers but some is taken via thrust/rubbing.

THis is where A/C balls prove superior - at least in regard to friction. Rolling friction is ALWAYS lower than sliding friction. Hence for a given package size, a ball A/C will/should have less friction, especially under high or give preload, than a taper. The tape would have more capacity and be stiffer buy you'd pay for it in size, friction and probably save in cost.

As is the case, it pretty much works down to a packaging versus cost issue. Package what you can find or fit, buy what you can afford, live with what compromises you choose.

Take a look at
http://www.airbearingtechnology.com