SKF angular contact ball bearings – your key to longer service life Contents The SKF brand now stands for more than ever before, 1Product information ................................................. 3 and means more to you as a valued customer. Diversity and quality .................................................... 3 Why specify angular contact ball bearings? .............. 3 While SKF maintains its leadership as the hallmark of Why specify SKF angular contact ball bearings? ....... 3 quality bearings throughout the world, new dimensions Advantages by design with in technical advances, product support and services SKF Explorer bearings ................................................ 4 have evolved SKF into a truly solutions-oriented supplier, Technical improvements ............................................. 4 creating greater value for customers. Identification symbols................................................. 5 Advantages for your design: These solutions encompass ways to bring greater higher performance with SKF Explorer bearings ..... 6 productivity to customers, not only with breakthrough Longer service life ...................................................... 6 application-specific products, but also through leading- New designs with smaller bearings ............................ 7 edge design simulation tools and consultancy services, New designs with higher power density..................... 7 plant asset efficiency maintenance programs,and the Efficient in all industrial segments ............................. 8 industry’s most advanced supply management techniques. The SKF brand still stands for the very best in rolling 2Recommendations ...................................................10 bearings, but it now standsfor much more. Selection of bearing size.............................................10 Bearing life ..................................................................10 SKF – The knowledge engineering company Load carrying capacity of paired single row bearings ....................................................11 Equivalent dynamic bearing load ...............................12 Equivalent static bearing load ....................................12 Minimum load .............................................................12 Determining axial force for bearings mounted singly or paired in tandem ...........................13 Design of bearing arrangements ...............................14 Mounting and dismounting .........................................16 Mounting ....................................................................16 Dismounting ...............................................................17 Service for a lasting partnership ................................18 3Product data .............................................................19 Single row angular contact ball bearings ..................19 General bearing data ..................................................19 Assortment .................................................................22 Product table ..............................................................24 Double row angular contact ball bearings ................34 General bearing data ......................................................34 Assortment ..................................................................38 Product tables .............................................................40 Other SKF angular contact ball bearings ..................46 SKF – The knowledge engineering company ............48 2 1Product information 2Recommendations 3Product data Customer benefits Page ............. 10 Page ............. 19 Diversity and quality 1 Why specify angular contact ball bearings offer a completely Universal matching contact ball bearings? new level of performance. With SKF At SKF, universally matchable single angular contact ball bearings, you bene- row angular contact ball bearings are High rotating speeds, combined radial fitin a number of ways: standard. These bearings simplify and axial loads, a high degree of stiff- assembly and can also increase the ness and running accuracy – these are High performance quality of your products. Our selection the application requirements where They have a high load carrying capacity of clearance and preload classes angular contact ball bearings excel. and thus allowing smaller bearings to covers almost all possible application The great variety of applications and be used while still providing long ser- requirements. operating conditions calls for unique vice life. bearing solutions made possible by Integral sealing solutions a wide range of angular contact ball Quieter and cooler running Double row angular contact ball bear- bearings. With their optimal internal geometry, ings are available with integral seals they run quieter and cooler and can and shields. These bearings are sup- provide longer maintenance intervals. plied with grease and do not require Why specify SKF angular maintenance. contact ball bearings? Precise shaft guidance Due to precision manufacturing pro- Standard solutions Because SKF is your reliable, expert cesses, almost all SKF angular con- It will be hard to find an application for source for angular contact ball bear- tacts meet closer tolerances, to enable which there’s no standard SKF bearing ings. Because SKF has a wide range a smoother, truer running shaft with readily available from our vast selection of types and variants unmatched any- less heat and less vibration. and enormous variety. where else. Because when you work with SKF you don’t have to settle for High temperature capability Customer satisfaction any unfavourable compromises. Since They can withstand relatively high Now you can build additional value into the introduction of the BE bearings in operating temperatures without sig- your products with SKF Explorer bear- 1984, SKF single row angular contact nificant loss of dimensional stability. ings. Your customers will definitely be ball bearings have set the standard. impressed by the low operating costs, Since then, time certainly hasn’t stood reliability and long service life of your still, and neither has SKF. machines – no doubt in part to your use The best example: the SKF Explorer of SKF bearings. single row and double row angular 3 1Product information 2Recommendations 3Product data New design Page ............. 10 Page ............. 19 Advantages by design with SKF Explorer bearings At SKF we’re continuously working to Diagram 1 improve the performance and durabil- m ity of our products. And with the new m 0,015 SKF Explorer angular contact ball e, SKF Explorer 7307 BECB set bearings, we think you’ll notice the nc 0,010 SKF previous standard 7307 BECB set a difference immediately. These bear- ar 0,005 e ings can provide: Cl 0 m SKF Explorer 3310 A/C3 • Even longer service life, m -0,005 SKF previous standard 3310 A/C3 • Even higher reliability, ad, -0,010 SKF Explorer 7307 BEGA set • Even more performance. elo SKF previous standard 7307 BEGA set Pr -0,015 The following pages will describe the -0,020 improvements we have made to our 10 100 1000 10000 angular contact ball bearings in the Operating hours 72 B and 73 B series and in the 32 A and 33 A series, of course also for the bearings in the 52 A and 53 A series, Examples:7307 BE set, Fa/Fr= 1,23, C/P = 29, operating temperature 110 °C (230 °F) 3310 A/C3, Fa/Fr= 1,23, C/P = 19, operating temperature 80 °C (175 °F) which are identical to the correspond- ing 32 A and 33 A bearings. Change of the residual axial bearing clearance/preload during operation Technical improvements Improved materials SKF Explorer angular contact ball angular contact ball bearings are less bearings are manufactured from an sensitive to potential axial overloading. extremely high quality bearing steel with a very low oxygen content and More precise shaft guidance a minimum number of impurities. The SKF Explorer single row bearings are rings are manufactured from forged or manufactured to P5 running accuracy. cold rolled blanks. SKF Explorer double row bearings are All rings are heat treated to provide manufactured to P6 running accuracy. dimensional stability up to 150 °C (300 °F). The advantage: SKF single Better ball quality row angular contact ball bearing sets The balls used in SKF Explorer hold their original built-in clearances angular contact ball bearings and preloads for extended operating are one ISO grade better than times (➔diagram 1 ). before. The more uniform ball diameter helps to improve run- Improved inner geometry ning accuracy even at high Computer-aided design and manufac- speeds, while reducing noise and turing programs permit almost unde- operating temperature. tectable geometrical changes in the bearing. These small but effective New cages changes in the bearing’s geometry SKF Explorer single row angular con- lead to measurable improvements in tact ball bearings have solid cages performance and service life. One made from polyamide or brass. effect of this fine tuning: SKF Explorer Polyamide cages have been improved 4 1Product information 2Recommendations 3Product data New design Page ............. 10 Page ............. 19 Fig 1 to better withstand high accelerations. SKF Explorer angular contact Machined brass cages are manufac- 1 ball bearings tured to closer tolerances and have been improved to provide better ball • Improved materials guidance and maximize the effects of • Optimized internal geometry the lubricant under all operating condi- • Higher precision tions. • Higher ball quality SKF Explorer double row angular • Improved cages contact ball bearings are available as • For universal matching in standard with a newly-developed bearing sets crown cage made of sheet steel. • New shields for double row bearings Effective seals Double row angular contact ball bear- ings are available with seals or shields. Shielded SKF Explorer double row Shielded SKF Explorer bearings (➔fig angular contact ball bearing 1 ) use a new shield design. A new simple labyrinth keeps contaminants out and retains grease in the bearing cavity. their part numbers remain the same. Nevertheless, SKF Explorer bearings Identification symbols can be recognised easily. SKF Explorer angular contact ball Packaging bearings are not an extension of the SKF Explorer bearings come in a assortment. They replace final variants unique package, so that they can be of the previous types. And because it recognised immediately as SKF is easier for inventory management, Explorer bearings. Laser inscription A new feature of the SKF Explorer bearings is their laser inscription. It is not only more legible, but also more environmentally friendly because acids are no longer required for etch- ing. It also permits individual mark- ings. Depending on the requirements in Quality Assurance, the bearings can be traced precisely. 5 1Product information 2Recommendations 3Product data New performance class Page ............. 10 Page ............. 19 Advantages for your design: higher performance with SKF Explorer bearings The technical improvements incorpor- life and decreased maintenance costs tact ball bearings (➔fig 1 ). With the ated in SKF Explorer angular contact for your application. existing design, the axial bearing of ball bearings can provide one of four the drive shaft is the critical point. The general design benefits. For existing calculated life of this bearing arrange- Longer service life designs, you can either increase ser- ment, consisting of three 7308 BEGAP vice life or increase power output. For bearings amounts to 50 900 hours; new designs, you can maintain power The extended life of SKF Explorer calculated in accordance with the SKF output or increase power density. The angular contact ball bearings can be Life Method. With the new SKF option you chose depends on the cus- demonstrated best with the use of an Explorer bearings, the calculated life tomer and the application’s require- example. The shafts of a twin screw amounts to 96 200 hours. This means ments. Whichever option you chose, compressor are supported radially a life 1,9 times longer under otherwise new SKF Explorer angular contact ball with cylindrical roller bearings and axial- identical conditions and without any bearings will provide increased service lywith a matched set of angular con- changes in the design. Increase service life Maintain power output of existing designs of new designs Don’t need to increase power output? Use an Use a smaller SKF Explorer bearing to: SKF Explorer bearing of equal size to: • Reduce overall dimensions to save • Increase the reliability on material cost and weight • Reduce vibration • Reduce heat generation • Reduce heat generation • Increase speeds • Increase service intervals • Increase machine uptime Increase Increase power output power density of existing designs of new designs Avoid costly redesign by using an Use a lower cross section SKF Explorer bearing of equal size to: SKF Explorer bearing with the same outside diameter to: • Increase power density (output) • Increase speeds • Increase shaft size • Increase loads • Achieve a stiffer design • Operate at the same or higher speeds 6 1Product information 2Recommendations 3Product data New performance class Page ............. 10 Page ............. 19 New designs with Table 1 smaller bearings Previous SKF Explorer Cross section Life increase 1 standard bearing A L bearing AExpl ×100 L10m,Expl In many cases where 73 B series prev 10m,prev bearings are used, it will be possible to use 72 B series bearings in the Same bore 7306 BE 7206 BE 64 % 1 future. Even with a smaller bearing, a diameter longer bearing service life will be pos- sible. Table 1 shows some suitable examples. 7308 BE 7208 BE 63 % 1,2 Without changes to the shaft, bearing arrangements can also be designed more compactly. SKF 7319 BE 7219 BE 51 % 1,1 Explorer bearings permit lighter structures with the same capacity. New designs with higher Same outer 7304 BE 7205 BE 84 % 1,7 power density diameter If the outside diameter of the bearing 7308 BE 7210 BE 70 % 1,6 remains unchanged, the transition from 73 B series bearings to 72 B series bearings will permit the use of stronger shafts (➔table 1 ). 7313 BE 7216 BE 63 % 1,5 With otherwise unchanged parts, more rigid designs with higher power density are possible. And the service life of the bearing will be increased significantly. Comparison of SKF Explorer and previous standard bearings – possible downsizing Twin-screw compressor bearing arrangement Fig 1 7 1Product information 2Recommendations 3Product data Application examples Page ............. 10 Page ............. 19 Efficient in all industrial segments Lower friction, quieter running and, used in both pumps and compressors above all, improved reliability in com- must be able to accommodate com- plex applications with combined loads bined axial and radial loads, high make SKF angular contact ball bear- speeds, poor lubrication and con- ings indispensable in many areas. taminated conditions. Long service life and reliable perform- The improvements made to the new ance have earned SKF angular con- SKF Explorer bearings were aimed tact ball bearings an excellent reputa- primarily at the demanding require- tion in a variety of industries ranging ments of both pumps and compres- from gearboxes to turbines. sors. For these applications a recom- Nevertheless, the most common mended product range is available. applications for angular contact ball bearings are pumps and compressors. These applications are not just the most common, they are also the most demanding. For example, the bearings Industrial segments Requirements Solution •Fluid machinery: •Long service life Pumps, compressors, blowers, •High load-carrying capacity and ventilators, turbines high speeds •Automotive engineering: •High degree of stiffness Drives, clutches, gearboxes, •High degree of running accuracy wheel bearings, components •Low heat generation •Industrial drives and drive •Quiet running motors •Technical support •Printing machines •Textile machines •Material handling 1Product information 2Recommendations 3Product data Application examples Page ............. 10 Page ............. 19 1 1Product information 2Recommendations 3Product data Page ............. 3 Bearing size Page ............. 19 Selection of bearing size Bearing life Diagram 1 The life-extending improvements, 50 embodied in SKF Explorer bearings a can best be understood using the SKF SKF Life Method. This life calculation 20 method constitutes an extension of the fatigue life theory developed by 10 Lundberg and Palmgren and is better able to predict bearing life. The life 4 method, first presented by SKF in 5 = 2 1989 is standardized today in ISO κ 10,8 6 281:1990/Amd 2:2000. The modified 0,5 0, rating life for angular contact ball bear- 2 4 0, ings can be calculated from 1 3 L = a a L 0, nm 1 SKF 10 0,5 or 0,2 Lnm= a1aSKF (C)3 0,2 0,15 P 0,1 0,1 With a constant rotational speed, the life in operating hours can be calcu- Other SKF standard lated from the following formula: 0,0050,010,02 0,050,1 0,2 0,5 1 2 5 bearings ηcPP––u SKF Explorer 1 000 000 (C)3 bearings L = a a 0,005 0,010,02 0,05 0,1 0,2 0,5 1 2 nmh 1 SKF 60 n P ηcPP––u where If κ> 4, use curve for κ= 4 As the value of ηc(Pu/P) tends to zero, aSKFtends to 0,1 for all values of κ L = SKF rating life (at 100 – n % nm reliability), millions of revolu- tions Life modification factor aSKFfor Table 1 angular contact ball bearings L = SKF rating life (at 100 – n % nmh Reliability L a nm 1 reliability), operating hours % L = basic rating life (at 90 % reli- 10 ability), millions of revolutions 90 L 1 10m a1 = life adjustment factor for 95 L5m 0,62 reliability (➔table 1 ) 96 L4m 0,53 97 L 0,44 3m aSKF = SKF life modification factor 98 L2m 0,33 (➔diagram 1 ) 99 L1m 0,21 C = basic dynamic load rating, kN P = equivalent dynamic bearing load, kN n = rotational speed, r/min Values for life adjustment factor a 1 10