Super-Precision Angular Contact Ball Bearings: High-Capacity 72
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Super-precision angular contact ball bearings: High-capacity 72 .. D (E 200) series Contents A Product information C Product data SKF high-capacity super-precision Bearing data – general ............ 18 angular contact ball bearings ...... 3 Boundary dimensions ............. 18 Chamfer dimensions. 18 An extended range – a growing Tolerances ...................... 18 assortment ..................... 4 Bearing preload .................. 18 Bearing design ................... 5 Bearing axial stiffness. 22 Bearing series ................... 6 Fitting and clamping of bearing rings .. 24 Bearing variants .................. 6 Load carrying capacity of bearing sets . 25 Single bearings and matched Equivalent bearing loads ........... 26 bearing sets ..................... 7 Attainable speeds ................. 26 Cages .......................... 26 Applications .................... 8 Seals .......................... 27 Materials ....................... 27 Heat treatment ................... 27 B Recommendations Marking of bearings and bearing sets .. 28 Packaging ....................... 29 Bearing arrangement design ....... 10 Designation system ............... 29 Single bearings. 10 Bearing sets ..................... 10 Product tables .................. 32 Type of arrangement .............. 11 Application examples .............. 12 D Additional information Lubrication ..................... 14 Grease lubrication for open bearings .. 14 Setting the highest standard for Sealed bearings .................. 15 precision bearings ............... 42 Running-in of open and sealed, Super-precision angular contact ball grease lubricated bearings .......... 15 bearings ........................ 42 Oil lubrication for open bearings ...... 16 Super-precision cylindrical roller bearings ........................ 43 Super-precision double direction angular contact thrust ball bearings ......... 43 Super-precision angular contact thrust ball bearings for screw drives ........ 43 Super-precision axial-radial cylindrical roller bearings ................... 43 SKF – the knowledge engineering company ....................... 46 2 SKF high-capacity A super-precision angular contact ball bearings Machine tools and other precision applica- SKF bearings in the 72 .. D (E 200) series tions require superior bearing performance. are characterized by: In these applications, high system rigidity is one of the main performance challenges, as • high load carrying capacity the magnitude of elastic deformation under • high degree of stiffness load determines the productivity and accur- • extended bearing service life acy of the equipment. Parallel Kinematic • low heat generation Machines (PKM), for example, are known for • low noise and vibration levels their ability to provide high structural rigidity and high dynamic capacities. But this is only The bearings provide high reliability and possible when the bearings inside these superior accuracy for applications such as machines step up to the challenge. SKF has Parallel Kinematic Machines (PKM), lathe developed a new generation of super-preci- spindles, grinding and boring machines, sion angular contact ball bearings that can high-speed dynamometers and meet these ever-increasing performance turbochargers. requirements. The ability of the new design super-precision angular contact ball bear- ings in the 72 .. D (E 200)1) series to accom- modate heavy loads, and still provide a high degree of rigidity, makes them an excellent solution for these and similar applications. 1) Where applicable, designations in parentheses and italics refer to the corresponding SNFA equivalent. 3 An extended range – a growing assortment The growing SKF assortment of super- To accommodate the diverse operating Bearings in the 72 .. D (E 200) series, like precision bearings is now complemented by requirements of precision applications, all angular contact ball bearings, are nearly angular contact ball bearings in the 72 .. D bearings in the 72 .. D (E 200) series are always adjusted against a second bearing to (E 200) series. The extended range of bear- manufactured to two tolerance classes and balance the counterforces. To accommodate ings in this series now accommodates shaft with two contact angles. Those suitable for heavier loads and axial loads in both direc- diameters ranging from 7 to 140 mm. And, universal matching or mounting in sets are tions, the bearings are used in sets consist- there is also a relubrication-free, sealed produced to four preload classes, to meet ing typically of up to four bearings. bearing series, available on request. almost all application requirements in terms of speed and rigidity. Matched bearing sets with a special preload can be supplied on request. For many sizes, the bearings are available, standard, with a choice of two ball materials. The most common sizes have a polyetheretherketone (PEEK) cage to accommodate extended operating temperatures. SKF super-precision angular contact ball bearings: 72 .. D (E 200) series Features Benefits • High number of large balls • High load carrying capacity, high degree of rigidity • Optimized chamfer design • Facilitated mounting • ISO dimension series 02 • Large cross section, robust • Asymmetrical outer ring • Accommodates radial loads, and axial loads in one direction • Lightweight cage (phenolic resin or PEEK) • Low friction, good lubricant supply to ball/raceway contact areas • High-temperature PEEK cage, for most common sizes • Accommodates operating temperatures up to 150 °C • High-speed grease, for sealed variant • High-speed capability, relubrication-free, good thermal stability • Non-contact seals, for sealed variant • High-speed capability, prevents entry of contaminants, extended bearing service life 4 Bearing design The design of the symmetrical inner ring and asymmetrical outer ring enables the A SKF super-precision single row angular bearings to accommodate radial loads, and contact ball bearings in the 72 .. D (E 200) axial loads in one direction. When compared series are designed to accommodate heavy to other precision angular contact ball bear- loads at relatively high speeds under low to ings, D design bearings have a high number moderate operating temperatures. of large balls to provide the highest possible Features of D design bearings include, load carrying capacity. The bearings have an among others: outer ring shoulder-guided cage made of either fabric reinforced phenolic resin or • a symmetrical inner ring carbon fibre reinforced polyetherether- • an asymmetrical outer ring ketone (PEEK). Both cage types are • a high number of large balls designed to enable good lubricant supply to • a lightweight cage, outer ring the ball/raceway contact areas. The shape of shoulder-guided the chamfers of the inner and outer rings is D design bearings have a high number of large • an optimized chamfer design optimized for improved mounting accuracy. balls to accommodate heavy loads. As a result, mounting is not only facilitated, but there is also less risk of damage to asso- ciated components. a° r1, r3 b° r2, r4 Optimized design of bearing ring chamfers to facilitate mounting. 5 Bearing series Bearing variants Contact angles Standard bearings are manufactured with Bearings in the 72 .. D (E 200) series are The many variants of SKF bearings in the the following contact angles: based on the ISO diameter series 2 and 72 .. D (E 200) series are well suited to width series 0. Bearings in the 72 series are accommodate various operating conditions • a 15° contact angle, designation suffix CD (1) more robust and have the largest cross sec- with regard to load, speed and rigidity. • a 25° contact angle, designation suffix tion for a given bore diameter, compared to ACD (3) bearings in the 718, 719 and 70 series. With two contact angles to choose from, designers can optimize their application based on axial load, speed and rigidity requirements. A larger contact angle pro- vides a higher degree of axial stiffness and a higher axial load carrying capacity. Speed capability is subsequently reduced. Bearings in the 72 series are more robust and have the largest cross section for a given bore Two contact angles to accommodate different diameter, compared to bearings in other series. axial load, speed and rigidity requirements. 15° 25° 72 70 719 718 6 Ball materials Sealed bearings Single bearings and Bearings with a bore diameter up to 85 mm Bearings with a bore diameter ranging from A are available, standard, with: 10 to 80 mm can be supplied with an inte- matched bearing sets gral seal fitted on both sides and filled with Bearings in the 72 .. D (E 200) series are • steel balls, no designation suffix premium grease. The seal forms an available, standard, as: • ceramic (bearing grade silicon nitride) extremely narrow gap with the cylindrical balls, designation suffix HC (/NS) surface of the inner ring shoulder. • single bearings When compared to bearing arrangements • single, universally matchable bearings Larger bearings are available, standard, with with open bearings and external seals, those • matched bearing sets steel balls and can be supplied with ceramic with sealed bearings provide a number of • sets of universally matchable bearings balls on request. advantages including: As ceramic balls are considerably lighter and harder than steel balls, hybrid bearings • extended bearing service life can provide a higher degree of rigidity and • reduced need for maintenance run considerably faster than comparably • reduced inventory sized all-steel bearings. The lower