Pressing bearings help please

[Kev In]

I have only pressed a few bearings in the past with a borrowed cheap arbour press. I now have 200 bearings to put on and I am looking for advice and recommendations on what I should use for equipment/tools and how I should do this properly.

The bearings are R6-2RS and are .375 dia bore, .875 dia, and .281 wide. I am pressing them on 1018 steel. That is 3.25” long. The shaft has a small shoulder to stop the bearing on each end of the shaft.

Appreciate the advice and guidance.
Kevin

 

[PCustoms]

Is this a production job? What is the fit on the shaft?

Put the shafts in a freezer, warm the bearings to about 150F in an oven. Should fit on, although your surface finish doesn't look that great.

 

[Copymutt]

That's a lot of pressing. It's going to go slow. I'm assuming you'll use the arbor press. A hydraulic might be in order depending on the fit.
In any case a little lube really helps. Looks like you need to watch that you don't press on the synthetic walls of those bearings. Press only on the inner hub.
You could get lucky with the time proven correct fitting socket. Many times the solution to a problem lies within the problem as in this case you might be able to use a second bearing to press one on, at least till it's flush. Another thought is to use a correct diameter section of steel pipe that clears your shaft and sits flush on that inner hub.
Another tip is if it won't hurt the shaft receiving your bearing, a quick file job around the top end will help locate the bearing squarely.
Good luck.
Jim

 

[BillK]

Kevin,
Do you know anyone with an Automotive Machine shop ?? If so ask if you can rent some time on their Sunnen connecting rod and piston press. It would probably take about 10 seconds per shaft once you had it set up. I would do both bearings at once.

 

[BillK]

Give these guys a shout http://www.cepauto.com/

 

[chrispyny]

Agreed with others. Freeze the shafts. You can buy 20 or so lbs of dry ice if you really want to bring the temps down. Use large coolers, dry ice below and above the shafts.

Then heat the bearings in an oven. I’d go higher than 150. Water boiling is 100°C. I would go as high as boiling water, no problem.

They should go on by hand at that point. All 200 in a half hour tops.

 

[PCustoms]

Agreed with others. Freeze the shafts. You can buy 20 or so lbs of dry ice if you really want to bring the temps down. Use large coolers, dry ice below and above the shafts.

Then heat the bearings in an oven. I’d go higher than 150. Water boiling is 100°C. I would go as high as boiling water, no problem.

They should go on by hand at that point. All 200 in a half hour tops.

Skf says 80 to 90 celcius, which is about 150F. If they don't just slip on that point your fit is out of whack. Don't go above 125 C, or you risk messing with the proPettis of steel.

Sorry on phone or would provide links

 

[chrispyny]

I stand corrected on the temps. And appreciate the heads up. Good to know moving forward. Thanks


Edited to add below, still good to know. I’d still keep it below boiling, like pccustoms says.

Per SKF website.


Mounting bearings using heat
The force needed to mount a bearing increases rapidly with bearing size. Because of the mounting force required, larger bearings cannot easily be pressed onto a shaft or into a housing. Therefore the bearing, or the housing, is heated before mounting.

The temperature difference between the bearing and seating depends on the magnitude of the interference fit and the bearing size. Normally a bearing temperature of 80 to 90 °C (144 to 162 °F) above that of the shaft is sufficient for mounting. Never heat a bearing to a temperature greater than 125 °C (257 °F), unless otherwise specified. Extreme heat can cause the material to change metallurgically and produce alterations in diameter or hardness. Local overheating must be avoided and in particular never heat a bearing using an open flame.

http://www.lubsys.com/knowledge/knw_heatmnt.htm


Seems boiling temperatures are still good to go.

 

[APEowner]

It really depends on the fit and if the shaft is properly designed and machined it shouldn't be very tight. I'd setup some tooling so I could do both ends at one time in an arbor press at room temperature. Once you got rolling you should be able to do two a minute and knock the whole job out in under an hour. Remember you need to be pushing on the inner race.

 

[Kev In]

The machine shop said they would be 1000ths tolerance on the shafts, so they should be fairly easy to go on, hopefully. If they are tight, I may cool the shafts in the freezer and warm the bearings to around 150 F. And use an arbour press.

Any suggestions for tooling, socket, etc., so that I can push both bearings on at once, but only pushing on the inner race on both ends?
Kevin

 

[BillK]

Kevin,
See if the automotive machine shop I gave you a link to has some old piston pins in their scrap bin. That's what I would use. Find a pin that just slides over the shaft. Use one pin to support the bottom and the other one to press on from the top.

On a part that small I don't think freezing the shaft will make any difference.

I use this stuff for press fit lube: http://www.jegs.com/i/Dart/301/LUBE/10002/-1 Not sure if you will find it locally. Mc Master Carr has it too.

 

[yaidunno]

The machine shop said they would be 1000ths tolerance on the shafts, so they should be fairly easy to go on, hopefully. If they are tight, I may cool the shafts in the freezer and warm the bearings to around 150 F. And use an arbour press.

Any suggestions for tooling, socket, etc., so that I can push both bearings on at once, but only pushing on the inner race on both ends?
Kevin

A little background on bearing fits:

There are 3 main types of fits. Slip fit, transition fit, and interference fit. Under each of these 3 classes are subclasses of fits. Part sizing and tolerance (2 very different things) are determined by what class of fit is called out.

I'm guessing the shop meant that the ends would be held to .001", but if that is over or under nominal is anybody's guess. Most all bearing fits go down to .000X" diameter call outs. The only thing we know at this point is that they are not a slip fit. Most transition fits can be put together with no heat/cooling. A copy of the print, or the fit call out would end the debate quickly.

Tooling would be a cup that each bearing slips in with a small ring in the bottom that contacts the inner race. That's what I'd do anyhow.

 

[rbgearz]

Used to put pretty large bearings on shafts just by leaving the shafts in dry ice overnight. If the fit was a little tight, would heat the bearings. Are the bearings sealed and pre lubed?

 

[rbgearz]

I see now that the bearings are sealed. Wouldn't heat them up too much.

 

[Whitworth]

You’d have to be at 1/3 of a thousandth for a consistent press fit on that size bearing. If the machine shop provides a decent product it should be no problem. Saying a thousandth tolerance seems to tell me they don’t know what their doing or don’t know what you expect. You’ll have some loose, some tight, and some perfect with that tolerance.

That aside, I agree with set up some tooling with a manual arbor press and you’ll fly right through the job. The next step up is a pneumatic press. And you’ll probably want some Loctite on hand as well.

 

[buildyourown]

To much press on that bearing and it will expand the inner race enough that the bearing will be notchy and fail very early. You certainly dont want to use a hydraulic press. Anythig more than about .001" interference is too much.

I nice arbor press or a bench vise with smooth jaws will do the job well. An rare earth magnet on the arbor press can be used to hold the shaft straight while starting.

 

[TheEquineFencer]

My first inclination would be to heat the bearing, cool the shaft and use a BFH made out of brass and drive it on.

I'd be inclined to heat the bearing, cool the shaft and use a vice with smooth copper plating over the jaws.

Try the simple stuff first, then pull out the big guns....

 

[racingtadpole]

Dry ice and heat for what are effectively skateboard bearings? Put some soft jaws in the vice, make a v block out of some timber then find a socket the right size... put on your favourite tunes and get after it. Doesn’t matter which way you do it, 200 of them will take you a couple of hours regardless.

 

[matt_i]

This is months out of date, but I'm surprised nobody mentioned a micrometer + telescoping gage to measure the ID and OD and establish the "fit".

More than .0005" of interference is a no-go as mentioned above. You can try it but its going to kill the small bearing. Even a 3T arbor press is going to be enough to destroy the inner race.

I would take a piece of round stock, lets just say .625" OD and drill a 3/8 + 1/64" dia hole on the axis in the lathe. Face both ends, 3 jaw chuck is fine. Now you have a press-tool to press only on the inner race of the bearing.

Alternatively could take a larger piece, lets just say 1" OD and drill the same hole but then make a "pilot" on the end that's .625" oD and say .062" back from the face. Make this piece short in total length, let's say 3/4" long or less, and face the back. This design should sit on a piece of flat stock on the press body that spans the clearance slot in the pressframe. Its a little easier to set the bearing on the pilot, align it, and then press down on the end of the shaft.

With the right set of tolerance on the shaft it should go very fast. 20 seconds per bearing is generous even handling the parts. x 200 bearings = 4000 sec/3600 is a little more than an hour's work going slow.

 

[racingtadpole]

Lol.. one of those rare moments where I never bothered to check how old the thread was..

 

[theoldwizard1]

My first inclination would be to heat the bearing, cool the shaft and use a BFH made out of brass and drive it on.

Dry ice for the shafts and a hot (200F) oil bath for the bearings and you won't need a hammer. You will need gloves !

 

[matt_i]

Trying to learn here...what is the best way to maintain a 200F oil bath, and how does one handle the bearings without making a large mess of oil dripping all over the press?