Frequent Bearing Failures, Within 24 Hrs

Change from grease lubrication to oil lubrication (static or circulating) is one of the remedy; please refer to the following or similar links at www.google.com

http://www.machinerylubrication.com/Read/262/grease-to-oil-lubricated

Look into the possibility of larger sized bearings to be installed in place of smaller ones or to support the original smaller ones.

Have you tried hybrid bearings. They can handle higher loads. The ceramic balls are not effected by heat as much as the steel balls. They also are not effected as much by changing conditions of the lubricant.

I would also look at some of the settings on the robotics. You may have them exceeding the load the tool was designed for.

When you say "you know they are failing because of heat" this suggests that you've done the basic speed and load calculations for bearing life. As you may know bearing life goes down as the cube of actual over reference load capacity, and inversely as speed.

The other main possible causes could include "dust" (unlikely if bearings are sealed) and "inappropriate loads". For example, high thrust loads on a bearing that is intended for radial loads.

Bearing technology is one of the more mature technologies in engineering and it is unlikely that your problem is more complicated than operating outside the specified limits for the bearing your are using.

So to that end - what temperature are your bearings operating at ?

3 options.

1. Bearing ratings....

2. Upgrades.

3. Workarounds.

SOLUTION:

You must inform the manufacturer of "sander". If he doesn't want to help you or the cost is prohibitory or there are not manufacturer please try to upload the drawing of application or sketch with bearing placement. I think in this site there are many experts which can help you. All the rests follow.

High temperature bearings are an on going discussion and all things being taken into consideration to give the final synopsis of a "bearing issue". If this is assured what the problem is a ceramic bearing will hold to great heat expectations, then yet, the adjoining shafts that the bearings ride on, or interlocking pieces must have the appropriate characteristics of needed strength, temperature, force and all things involved with the rotation.

Have a great Day!!!

If the problem is caused by either heat or abrasive it would be assisted by a compressed air feed supplied locally to the bearing. The large particulates released by the grinding process are not going to be the problem, it is only the fines that will get into the bearing. Creating a high pressure zone adjacent to the bearing should keep these away and carry away any excess heat. If a vacuum removal system is fitted, upgrading this should also help.

This is on a robot so you have to keep the weight of any solution as low as possible. Use polypropylene pipe for flexibility, high pressure air to reduce the bore. jet nozzles to direct the air flow. Positioning of the nozzles is critical, find a way of using temporary clamps until you have a configuration that works. Don't abandon if at first the problem gets worse. If you can change the characteristics at all, you must be on the correct track, you just have the nozzles incorrectly positioned.

Tips

Nozzles that produce a wide flat blade of air flow will probably work better.

A full size plastic plate mounted 0.5mm to 1.5mm away from the face of the bearings and fed at the centre with air would create a 360 degree nozzle.

James

Here is a link to some good info on types of bearings.Perhaps this will help you decide if you have the right type for your application.

Off hand, without more info on your application and conditions, it sounds like you may need a sealed and shielded bearing,which excludes contaminates and keeps grease in.

http://www.wwdmag.com/how-grease-lubricated-bearings-function-article4043

HTRN

Pop the bearing apart. Your failure mode is suggesting something obvious. Either a lack of lubricant or the presence of abrasive material, it's impossible for me to say at the moment. If you don't think you can get the bearing apart using simple hand tools take a cutting wheel to it. Don't try to use a hacksaw or other implement as you'll only succeed in dulling the blade. Bearings destroyed in 24 hours is very unusual. I'm guessing you will find the culprit inside the bearing. Are you using roller bearings or ball bearings? In this application I would think you need ball bearings to handle the varying load vectors and high speeds. If you're using roller bearings that would also be a clue as to the failure timescale and mode. Typical roller bearings are very good with radial loads, not so much with axial and transient moment loads, which i think your sander would see. So just double check you didn't make a mistake installing them. If you want more help i am available free of charge. I work as a bearing engineer for the aerospace industry. I thought of one more thing, I doubt it would cause such an immediate failure, but check to see if you're getting any static or electric discharge of any kind. Current will cause spot welding as the bearing rotates (even a small amount of current) and will cause the bearing to fail. The damage is called fluting and it's easily identifiable if you can catch it before the bearing fails. I doubt this is causing your problem, but who knows. If you want more help we can certainly narrow this down. It's a simple enough problem if they're failing so quickly. I noticed a lot of good replies. Good luck and you need more help I will be checking this forum as i'm sure others will be.

Thank you very much for your help ful comments , this bearing is a small bearing 6002 , speed is not very high , we use air motor to operate this grinder , this bearing goes in that air grinder , if you can give me direct email ,my email add is iamajit@gmail.com i can send you some photo graphs , but i know temp goes very high because of grinding (sanding ) sanding means we use sand paper pad to to finish our products , this sand paper pads rotates , and goes around the product

Check the fit of the bearing. If it's a press fit which I assume it is, it my be to tight and the bearing is in an overloaded condition before you even start the sander.

Try an ExAir spot cooler. www.exair.com I may also look at static build upon the belt/bearing. I have seen bearings fail because a charge was being discharged through them to ground, You could also look at using a high end lubricant like Krytox.

Good luck

Ken

Have you contacted the bearing manufacturer?

Try http://www.skf.com/portal/skf/home.

Here is a contact for you.

CR4 Admin: Email removed.

From the Site FAQ: Do not post phone numbers or email addresses.

http://www.vxb.com/page/bearings/PROD/Kit7782

it depends the kind of bearin you are using. Open bearing or seal bearing. it shuld use seal bearings for the appropiate speed. If these parameter are used then another way to void this problem is to see if case where tese bearing seat can be modified so it can be cold by water.

goyo