bearing size

All af course depends on the type of application you want to install the bearing on. The bearing choice and design depends of course on the loads the bearing has to be able to take. Have a look as the SKF website: www.skf.com

Look for the detailed catalogue where you can find the specs of all their bearings.

If you go to any bearing manufacturers WEB site and type in the 6203 ZZc3 bearing that you gave as an example which looks like a good number manufacturer will list the design specs on the bearing.

You will need to decide which one that has the bore you need and the load and RPM requirements.

Check out this site http://www.bocabearings.com it has a lot of good info on bearings.

Refer Mechanical engg Design data book which will directly give the meaning. You mayrefer PSG design data book which is very useful

Dear Suresh,

Normaly, last two digits in a metric system bearings multiplied by 5 gives the bore size of the bearing in mm. First two or three digits of the Bearing Number indicates the type of bearings like Deep Groove ball Bearing, Taper Roller Bearing, Spherical Tapper Roller Bearing etc. For details, one can go to the Bearing Catalogue or the website of the Bearing manufacturer.

ZZ is meaning both sides of bearing are shielded. Only Z is meant for one side shielded. Without Z meaning both sides of the bearing are not shielded.

c3 or c4 or c5 meaning the internal clearances between Ball and race are more and more as the number increases. These are required for special application like used in Oven/Furnaces/ High temperature where bearing have to work smoothly considering thermal expansion.

As someone suggested, selection of bearings depends lot on the application and it is a vast engineering subject. The tolerances on the Shaft and housings are also equally important.

Hope I did not confuse you.