FAQ

Following are the answers to some of the most frequently asked questions in the field of bearings and its allied industry.

Q. 1. What is the difference between a seal and a shield on ball bearing? Why can't we just use all seals instead of stocking both shields and seals?
Ans : The shield is attached to the outer race and it is a clearance between the outer and inner race. On the other hand the seal is attached to the outer with the inner race. The main reasons of not using seals in all applications instead of shields, are:

Speed

Heat

Starting Torque

The seal could cause problem in these areas due to its rubbing against the inner race and in the case of shield, there is a clearance between outer and inner race and then there is no such kind of problem.

Q. 2. On single row deep groove type bearings' after they are mounted, a perceptible end shake is grabbed and moved. Are these bearings loose internally?
Ans : No, everything is fine. Look at the picture below. the bearing must have a slight amount of movement. This is necessary for running clearance, so it does not bind. And say, before for doing this, remember to take a second to wipe off your fingers.

Q. 3. Can burrs on the shaft create a problem?
Ans: Sure, They are. If a shaft due to any reason gets bumped hard then it is enough to produce a burr, but you can't see it, you can be sure that the bearing which it was meant for, no longer would slip over a bumped end. Checking and removing burrs is certainly a time consuming activity.

Q. 4. As we listen to all the things that are told about correct storage, installation, handling, lubrication, maintenance, etc., we can't help but wonder. "Isn't help this lot of nice theory, most of which isn't done?" Ho~ many plantscan do all this as perfectly as desired?
Ans : Honestly, very few, but not all. It is a cruel dirty world out there, where bearings have to be installed and handled ,is a far from perfect environment. But, we never predict immediate and catastrophic failure, did we? No, both you and i know that bearings operate reasonably well in spite of all those horrible things that happen to them. The point we always try to make is that you do the best as you can in all these areas, with talking into consideration the bearing life and improve performance.

Q. 5. Is selectingthe right lubricant vital? It seemsthat bearingsfail for other reasons~not from picking the wrong oil or grease?
Ans : Bearingsdo fail for many reasons,but improper lubrication is there at the top of the list. And rest are the following:

43% due to improper lubrication

27% due to improper mounting

21 % due to other causesand

9% due to reachingthe fatigue limit of the metal

Reasonsfor lubrication failure are following:

Incorrect selection of the greasebasefor a particular application.

use of static or circulating oil in a improper manner.

Insufficient lubrication either in quantity or in required viscosity.

Deteriorationof prolongedservicewithout proper intervals.

Contaminationof the lubricant and the bearing with foreign materials.

Q. 6. Is there any right or wrong way to store bearings? Can we put them on a shelf until we need them?
Ans : Yes, there is a right and wrong way to store bearings. You should store bearings in a clean and dry place. Always use the oldest bearing first. Bearings are the precision components and should be treated gently. Never drop them or handle them roughly. In fact, the less you handle them the better since finger printers can lead to rusting. It is necessary to measure temperature changes in your bearing storage area regularly because condition like condensed moisture forms could be harmful for bearings.

Q. 7. Our bearings operating at high speeds seem to get unusually hot. What is cause? We are sure about the proper lubrication of bearings at the time of operating to avoid this problem.
Ans : Over lubrication might be your problem. As unlikely as it may seem, over lubrication as well as insufficient lubrication of bearings used in high application, both are equally harmful. Over lubrication creates action of oil or grease, which increases the friction, and the torque characteristics of the bearings. and the reason is that, to operate the bearing and lubricant at a high temperature. The fact that your bearings are "well lubricated" is probably the source of your trouble.

Q. 8. So we take good care of the bearing during storage and then we install it in a dirty, nasty environment. Dies that make sense?
Ans : No, it doesn't make such sense, but there are some things which should be kept in mind at the time of working in an such kind of environment. Start it by cleaning the workbench area ,then the tools which will be used by you on the new bearing. You should also get rid of all the linty clothes. At the time of working on the bearing, you should wrapped it by its original wrapper or on some other type of clean paper. Never let a bearing rest on a dirty surface even for a short time; cover it with a clean, lint-free cloth. Bearings should not be washed unless it is for an oil mist or circulating oil system. these comments are pretty basic, but they should be repeated.

Q. 9. What is the main function of a bearing lubricant?
Ans : Bearing lubricant should establish and maintain a micro thickness separating film of oil between rotating and static members. The forming of the elastic hydrodynamic film is the result of a build-up wedging action of the lubricant between rolling elements and raceways.

Q. 10. Why does some new equipment come in with bad bearings? Often they are noisy or rough on first startup and often they fail in the first few hundred hours of operation?
Ans : This is not too much surprising, really, when one thinks of all that might have, happened in assembly, in transits, in setting up, etc. First, the subassembly might have been dropped or bumped hard or pressure might have been applied to the wrong ring during assembly which would have resulted inbrine, litagm a ball denting the raceway. Second, perhaps the jolting, jostling in shipment or the unit setting idle where there was extreme external vibration, resulted in metal to false brine ling. These are just samples of some of the more obvious and common problems. On the above, simply replacing the bearings should solve the shaft and housing dimensions must be checked.