Roller vs Ball thrust bearing

[Black_Moons]

Hi, Today Im placing an order at VXB bearings for some bearings.. And well, ordering one bearing seemed very sad after looking at the $12 shiping cost so I thought id pad my order with some junk for my parts bins.
I allready have a small assortment of regular ball bearings, so I thought today maybe id order a couple thrust bearings

They seem to have 3 main types:
Balls in grooved washers, expensive, about $10+
Balls on flat washers, Cheap, starts at $3
Rollers on flat washers, Cheap, starts at about $3

What are the diffrences beween small ball and roller bearings if they are on flat washers as races?

Are thrust bearings using ball bearings in grooves better at some applications?

Im just buying 2 of 3 diffrent sizes to have some kinda stock on hand for prototypeing, Should I get rollers or balls?

[John Stevenson]

Roller races tend to be thinner and go into places ball races can't.

I fit shed loads to rotary table conversions and wouldn't be able to get ball thrust in without a lot of excess bulk.

.

[motorworks]

Hi
Did you check with your local Kinecor
www.kinecor.com
I am sure that they can supply whatever your want at as good as or better $$
then anything from the US.
Been there and done that
i.e. Order from the US only to find when I factored everything in,it was cheaper here.

just a though
eddie
ps

Prince George
Tel: (250) 562-1334
Fax: (250) 562-1058

Surrey
Tel: (604) 513-0351
Fax: (604) 513-0361

[Black_Moons]

motorworks: I really dislike companys that can't be bothered to put all the information/prices online when im just ordering random stuff...
kinecor seems to only have a 'line of business' brochure of who they can order from, I hate those.

[motorworks]

B-M
Still one day give them a try
I have been buying from them since 1989 and could not ask for better service.
all the best :)
eddie

[bjmh46]

[QUOTE=.....

What are the diffrences beween small ball and roller bearings if they are on flat washers as races?

Are thrust bearings using ball bearings in grooves better at some applications?

Im just buying 2 of 3 diffrent sizes to have some kinda stock on hand for prototypeing, Should I get rollers or balls?[/QUOTE]


Based on your questions above:
-Rollers on flat washers will have more capacity than balls on flat washers because of the shape of the contact patch. (assumes about the same design envelope, hardness, etc.) However the advantage goes away at higher speed because a cylindrical roller, as it is constrained to roll in a thrust bearing, has to "scuff".

-Ball bearings in grooves offer higher load carrying capacity than balls on flats because the shape of the groove allows for a larger contact patch as the load increases. It is true that the balls will also "scuff" at higher loads because the contact patch exists over inner and outer radius extremes. (not as much as the cylindrical roller above) So this would be my preferred thrust bearing for the broadest range of applications.

IMHO:
If you're looking for load capacity, tiny space requirements, and low cost, it's hard to beat needle thrust bearings and hardened washers. Used to be a Torrington product, but I'm not sure who all is making them now. If you're looking for extreme capacity at moderate speeds, at substantially higher cost, tapered roller thrust bearings are the "go-to" piece of hardware. So as far as your ordering dilemma goes, I've not given you a darn bit of help! Only trying to answer your questions and hoping I didn't confuse!

Regards
Bob

[Black_Moons]

bjmh46: Very helpful!
Low speed = roller
High speed = ball

rollers are stronger then balls except at higher rpms.. exact point depending on how much load there is and bearing size and a billion other factors nodoubt. But load/rpm is a good factor to look at simply.

Would the grooved race ball bearings be weaker then flat race ball bearings at very high RPM? Or are they allways better?

[darryl]

A flat race ball bearing is going to put a lot of radial force on the ball retainer at high rpm. The grooved model has the grooves keeping the balls in place, with the retainer simply keeping them spaced apart. That would definitely be something to consider.

I would have said pretty much what Bob did. If there was anything else to consider, it might be the lubrication requirement.

[Evan]

Rollers on flat races will carry tremendous loads but are only good for a few hundred rpm at most. Balls on flat races have almost no load capacity and are for controlling end float. Balls on grooves are for load at speed. Needles on flat are my last choice unless nothing else will fit. Needles are completely intolerant of contamination.

[Black_Moons]

ahh few hundred rpm thats helpful about rollers, I woulda assumed like 1k rpm.

Just how much load could a say 1" OD flat race ball bearing support?

[AiR_GuNNeR]

Check the size of the roller bearings in your vise, might as well get a replacement set for those while you are at it.
Eric

[Black_Moons]

Do kurt vise roller bearings even need replacement?

[JoeLee]

I wouldn't go stocking up on bearings to justify a shipping price unless you know what you future needs may be.

JL.............

[lazlo]

Like someone mentioned earlier, roller thrust bearings only work at low speeds, because the rollers have to skid to traverse the circumference of the thrust washer. A tapered roller thrust bearing doesn't skid.

[MuellerNick]

An axial needle bearing with 26mm OD has a limit of 13000 RPM (with oil).
An axial roller bearing (shorter than needles) mit 28 mm OD has 12000 RPM oiled.

That much for "a few hundred".


Nick

[Black_Moons]

MuellerNick: Under what load?
As I understand it load greatly reduces peak RPM.

[japcas]

Do kurt vise roller bearings even need replacement?

If the vise is used in a home shop environment they will probably last forever. If you use coolant on your mill they are more likely to be ruined by rust than anything. We keep several sets of the vise bearings at the shop where I work because we use a lot of these vises on our vmc's with coolant and sometimes the coolant gets low and allows the bearings to rust. We've probably got 30 to 40 different Kurt vises in the shop though so they see a lot of use.

[MuellerNick]

Static / dynamic load for the first bearing is 8.3 / 12.9 kN.

Certainly, live expectancy goes down with increased load and/or increased RPM. But that's true for any bearing.
You'd always have to do the calculations according to the manufacturer's data sheet and formulae. Load, RPM, temperature, shock, lubrication, cooling, quality of alignment, ...


Nick

[interrupted_cut]

My experience goes along with Nick's numbers for needle thrust bearings. They are routinely used as camshaft thrust bearings at half engine speed for pushrod engines. So ~5000 bearing RPM isn't uncommon. Hard to say what the load is, as it is caused by tracking errors of the roller cam followers.

[lazlo]

Like someone mentioned earlier, roller thrust bearings only work at low speeds, because the rollers have to skid to traverse the circumference of the thrust washer. A tapered roller thrust bearing doesn't skid.

Just to point out that I think we're mixing up needle thrust bearings, like used on Kurt vises, which skid, with needle roller bearings, like often used on lathe carriage feeds, which don't.

[MuellerNick]

Just to point out that I think we're mixing up needle thrust bearings,

At least not me. I was talking about axial needle bearings. Axial means, they can take axial loads.


Nick

[Evan]

An axial roller bearing (shorter than needles) mit 28 mm OD has 12000 RPM oiled.


We aren't talking about axial bearings but about radial roller bearings for thrust loads axially.

Like these:

http://metalshopborealis.ca/pics/hgrinder3.jpg

[MuellerNick]

but about radial roller bearings for thrust loads axially.


The bearing in the picture is called axial roller/needle bearing (http://www.directindustry.com/prod/schaeffler-technologies-gmbh-co-kg-ina/axial-needle-roller-bearings-169-54671.html).


Nick