 Hello friends, I am Mr. Sanjeev B. Nai, Assistant Professor in Mechanical Engineering Department, Walter Nistudov Technology, Sallapur. In this video, I am explaining the procedure of selection of bearing from manufacturers catalog. At the end of this session, learners will be able to select the bearing from standard manufacturers catalog. The various steps involved in the procedure are, first one has to calculate the radial force FR and axial force FA acting on the bearing, which is essentially coming out of shaft design. But if the bearing is mounted with the shaft, whatever forces acting on shaft, its reactive actions are taken on the bearing and those are radial forces and axial forces considered acting on the bearing. One has to select the type of bearing according to the application and here are few guidelines to select the particular type of bearing. If low and medium radial loads are acting, then the ball bearings are suitable. But if the radial load is heavy, then roller bearings can be used. If it is expected to have some misalignment between the shafts during working conditions, then self-aligning ball bearings or self-aligning roller bearings can be used. In case of thrust load is considered, then low and medium thrust load thrust ball bearings can be used, whereas for heavy thrust load, cylindrical roller or thrust bearings can be used. If the bearing is subjected to both, that is radial and axial loads, then to certain extent deep group ball bearing can be used, where radial load is comparatively high, but limited thrust load is acting on that, then deep group ball bearings are the best suitable. If thrust load is very high along with high radial load, then angular contact ball bearings can be used. But if a further heavy duty construction is required for the bearing, then spherical roller bearings or taper roller bearings can be used for very high combined load. As for the speed concern, high speed applications, the permissible speed of the shaft depends upon the temperature rise in the bearing. So, if the speed goes on increasing particularly for high speed application, then the temperature rise is one of the major concern. And this temperature rise is outcome of the friction between the bearing elements and that is why ball bearings are having comparatively less friction than the roller bearings. Deep group ball bearings become the better application in such case, whereas combined load if it is comparatively heavier, then angular contact ball bearing can be used for high speed application. The another important requirement of the design in some of the cases is rigidity requirements, particularly in case of machine tool spindles. Because machine tool spindles are subjected to work on the workpiece with the help of tool forces, cutting tool forces, which act in radial as well as axial dimension directions. And deflection of the spindle is expected to be very less as far as the accuracy of the machining is concerned. One can select double row cylindrical roller bearings or many applications they refer taper roller bearings. The noise consideration particularly in household appliances or for high speed applications once again, drip group ball bearings are suitable. Now recall why we use X and Y factors in design and selection of bearings. The values X and Y are determined from the catalog. So, manufacturer provides the catalog of X and Y values to be referred according to particular type of bearing. For example, here I have shown you a drip group ball bearing a standard chart of X and Y factors, which refers X and Y like this one that is E value which is FA by FR is the E value. So, it is the reference E value of 0.22 and whatever actual value of E that is FA by FR I am going to get for particular application is referred either greater than E or less or equally. And accordingly we can select X and Y factors from this chart. With the help of this X and Y what we can do is we calculate equivalent radial load acting on the bearing. Because basically bearing is subjected to both radial and axial load whereas if I want to compare this with the dynamic capacity which is radial load considered in the catalog as a value, we have to convert this combined load into equivalent radial load and that equivalence is obtained as P is equal to X VFR plus YFA in which X and Y factors we just see that we got get it from table FR and FA these are actual values of load acting on the shaft and bearing. And V is a rotational factor that is one if the inner race is rotating that is if the bearing inner race is mounted on the shaft V is one and if it is mounted on the axle some of the cases is 1.2. Then decide the expected life of the bearing in million revolutions because the life and load capacity they have got relationship. So if I want to decide a particular requirement of the dynamic capacity of the bearing I should connect it with expected life that is I should first decide what is expected life of bearing that used in particular application. It has been provided some guidelines once again for that for overall economy of system as a whole if automobile cars, trucks, trolleys etc there we find that life is expressed as 50 million revolutions or hundred and like that one. So one can select some guideline values from the different charts as per applications and one can expect that life for the bearing. With the help of the life expected and equivalent load calculated one can calculate the required dynamic capacity C once again by load life relationship you can recall it and that is what L is equal to C by P raised to K million revolutions. So here I know L in million revolutions P in value and the value K is depending as a ball bearing 3 or roller bearing 10 by 3 and this way I can make use of this equation to know the value of C this is the way I required calculated dynamic capacity. Further depending upon the application is a type of drive whether I am using these bearings for gear drives or bale drives or chain drives I multiply this C value with a load factor because many uncertainties are there and shocks are there other factors are involved vibrations or something like that. So we have to enhance that load C with some load factor 1.2 something. So this is another guideline where we can implement this required dynamic capacity further as a modified value for application. Now the data I collect so far is a type of bearing decided the shaft diameter is very fourth step that we should know where I calculate the bearing reactions. So diameter of the shaft is known and dynamic capacity required just we have seen in previous step we calculate the value of C. By knowing these three I can select the bearing from standard catalog. So bearing being a standard mechanical element it is designated by a number either 4 digit or 5 digit. The last two digits of that 4 digit or 5 digit number specifies the bore or shaft size, third digit from right refers the specify the series, fourth and fifth digit they specify the type of bearing. So I consider here one example where it is a deep group ball bearing of a SKF manufacturer. So bearing number is 4 digit jigs 005 where the bore or shaft size is 25 how we just see the last two digits multiplied by 5 gives the bore size. So 04 onwards if you multiply by 5 we get corresponding value of bore size. So below that 03 it is a 17 mm 0 to 80 is 15 mm 0 0 it is 10 mm so 10 12 15 17 these are the steps we depend upon last two digits from 00 to 03 whereas 04 onwards we just multiplied by 5 you get the bore size or shaft size this is the way last two digits are referred whereas the third digit is here with 0 that specifies the series so it is a 0 series called the extra light series what it refers is the dynamic load capacity bearing. So lowest dynamic load capacity is been there for this bearing 0 series so as I improve this number from 0 onwards up to 4 if I take 2 it is a medium it is a light series so where it is 14000 so likewise if I go on increasing the series number I get higher and higher value of dynamic load carrying capacity so according to the required dynamic capacity I decide this number so for example if I want to select a bearing for 25 mm shaft having 12000 dynamic capacity requirement then I can select this bearing as a 6205 so this is the way one can select the type of the bearing and select the number of the bearing from particular catalog of that type and that is the way we can decide and we can select the particular bearing from the manufacturer's catalog this is our reference thank you.