Rolling Bearings for Rolling Mill Applications

For over 100 years the name FAGhas been synonymous with highquality rolling bearings of all types.FAG started designing and producingroll neck bearings very early and iswell experienced in this field.This publication includes theprinciples of roll neck bearingselection and calculation. Themounting and maintenance of thesebearings are also explained in detail.Other specific questions not coveredin this publication should be referredto experts of Schaeffler GroupIndustrial for advice.The dimensions and technical dataof the rolling bearings for rollingmills are given in Publication WL 41 140. A selection of publi-cations about roll neck bearingarrangements and general topicsconcerning rolling bearingengineering (e.g. dimensioning,mounting and dismounting,lubrication and maintenance) islisted on page 68 of this publication.

Preface

Contents

Roll neck bearings 4Conditions governing design 4Cylindrical roller bearings 5Thrust bearings 6Tapered roller bearings 7Spherical roller bearings 9Tapered roller thrust bearingsfor screw-down mechanisms 9

Calculation of bearing load 10Self-aligning chocks 10

Strip rolling 10Groove rolling 11

Rigid chocks 12Cantilevered stands 13Calculation of roll deflection 14

Dimensioning 18Statically stressed bearings 18Dynamically stressed bearings 18Adjusted rating life calculation 22

Lubrication 29Lubrication of roll neck bearings 29Grease lubrication 29

Load and speed 30Other operating conditions 30

Oil lubrication 31Viscosity requirements 31Other demands on the oil 31Methods of oil lubrication 32

Design of the lubricating system 32Amount of grease 32Relubrication intervals (grease) 32Lubricant flow 33Grease lubrication 33Oil mist lubrication 34Oil-air lubrication 34Circulating oil lubrication, oil injection lubrication 35

Tolerances of roll neck bearings 36

Surrounding parts 37Fits 37

Radial bearings 37Thrust bearings 37

Machining tolerances for cylindrical bearing seats 40

Tolerances for roll necks and chocks 42Conditions required for loose-fitted inner rings 44Chocks 44

Stand windows and chock seats 45Seals 46

Mounting and maintenance 48Preparations for mounting 48

Checking of cylindrical roll necks 48Checking of tapered roll necks 49Checking of the chocks 49Surface finish 50Protection of the bearing seats 51Preparation of bearings for mounting 51

Mounting and dismounting of four-row cylindrical roller bearings 51

Mounting of inner rings 52Mounting of outer rings 53Mounting of thrust bearings 54Mounting of pre-assembled chocks on the roll necks 54Dismounting 55Loose fit of inner rings 55

Mounting and dismounting of four-row tapered roller bearings 56

Mounting 56Dismounting 58Maintenance 58

Mounting and dismounting of spherical roller bearings 58

Mounting of tapered bore spherical roller bearings 58Dismounting of tapered bore spherical roller bearings 58

Methods for the mounting and dismounting of cylindrical roller bearing inner rings (tight fit) 59

Induction heating 59Heating with gas burners 60

Mounting facilities for roll couplingsand labyrinth rings 61

Induction heating of roll couplings 61Induction heating device for labyrinth rings 62

Spares 62Statistical stockkeeping 62Storage 64

Worked example 65

Selection of publications 68

Conditions governing design

Roll neck bearings are very heavilyloaded and subjected to high unitor specific pressure. Also, themounting space particularly in radialdirection is severely restricted ascan be seen in fig. 1.In consequence, a bearing of lowsectional height yet with a verygood load carrying capacity has tobe provided.The radial mounting space of a rollneck bearing is limited in that theoutside diameter of the bearing isdictated by the roll body diameterminus a certain amount of stockallowed for roll regrinding andminus the wall thickness of thechock. Also, the roll neck diameterwhich controls the bearing borediameter has, under high loading,to have adequate bending strength.A compromise will therefore haveto be found between the diameterof the roll neck and its bendingstrength on the one hand and thebearing section height and its loadcarrying capacity on the other.The available mounting space shouldbe primarily used to accommodatethe radial bearings since, comparedto the radial loads, the axial loadsare relatively small.Roller bearings have a higher loadcarrying capacity than ball bearings.Therefore, roller bearings, i.e.cylindrical roller bearings, taperedroller bearings or spherical rollerbearings, become the automaticchoice for carrying the radial loads.These bearings are made ofthrough-hardened rolling bearingsteel or in some cases ofcasehardening steel.The selection of the bearings for aspecific application is influencedby the frequency of roll change.

Usually the chocks have to beremoved when grinding the rollbarrel. When using non-separablebearings such as spherical rollerbearings, whose inner rings aretightly fitted on the roll neck, thistask is made more difficult than isthe case with cylindrical rollerbearings where the chock togetherwith the outer ring and the roller-and-cage assembly can bewithdrawn, leaving the shrink-fittedinner ring on the roll neck.

Roll neck bearingsConditions governing design

4

Four-row tapered roller bearings ora pair of spherical roller bearingsgenerally are loose-fitted on acylindrical roll neck. Thus thechocks can be easily removed; however, the field of application ofthese bearing types is limited dueto the unsuitability of loose fits forhigh-speed rolling.If radial cylindrical roller bearingsare used, the thrust loads have to beaccommodated by a separate bearing.The provision of separate bearings

1: Available mounting space

2: Axial clearance “a” as a function of radial clearance and contact angle α

a2

a2

αα

Chock wallthickness

Sectionalheight

Roll bodydia.

Stock forregrinding

Stock forregrinding

for the individual accommodation ofradial and axial loads is particularlydesirable in mills where close axialcontrol is necessary for holdingspecified stock tolerances as is thecase in shape-section rolling stands.Thrust bearings provide an extremelygood axial guiding accuracy due to

the very small or even zero axialclearance to which these bearingscan be fitted. Radial bearings, onthe other hand, having to performthe dual function of radial and axialguidance, will always have a largeraxial clearance. Fig. 2 (page 4)shows how for a specified radial

Roll neck bearingsConditions governing design · Cylindrical roller bearings

5

clearance the axial clearance “a”depends on the contact angle α.Spherical roller bearings featurethe largest axial/radial clearanceratio. These values are smaller inthe case of four-row tapered rollerbearings. For angular contact ballbearings the ratio is smaller still.

Cylindrical roller bearings

Within a given mounting spacecylindrical roller bearings offer thegreatest load carrying capacity.Consequently, this bearing type issuitable for the highest radialloads and – owing to its lowfriction coefficient – for the highestspeeds.Different types of cylindrical rollerbearings are used for roll necksupport. Which type will be used in specific cases depends on therolling stand design.To accommodate the maximumnumber of rollers, especially inlarger bearings, and hence providean optimum load carrying capacity,the bearings are equipped withthrough-bored rollers and fittedwith pin-type cages (fig. 3). Such a

cage consists of two rings whichretain the rollers laterally and areconnected by the pins which passthrough the centre of the rollers.This cage offers a high strengthwhich is particularly important forroll neck bearings which aresubjected to great acceleration anddeceleration – e.g. in reversingmills.To achieve a particularly goodrunning accuracy, cylindrical rollerbearings with rough-ground innerring raceways are used. The racewaysare finish-ground together with theroll when the ring is mounted onthe roll neck.Fig. 4 shows double-row cylindricalroller bearings of series 49. Theyare used mainly for work rolls. To reduce stress resulting frompossible tilting moments, the

bearing rings are separated byinner and outer spacers. The loadcarrying capacity of these bearingsis of secondary importance. Primarilythey must be suitable for highspeeds.Cylindrical roller bearings as shownin fig. 5 are used generally in fine-section and wire mills. Theyfeature machined brass or steelcages. They are not only suitablefor high speeds (up to 40 m/s), but they can also accommodatehigh loads.The finishing sections of such millsoperating at rolling speeds of up to100 m/s and more handle onesingle strand. Single-row cylindricalroller bearings are usually used forthis application. Their service life isperfectly sufficient.

3: Four-row cylindrical roller bearing withthrough-bored rollers and so-called pin-type cages

4: Double-row cylindrical roller bearings ofdimensional series 49 with inner and outerspacers

5: Four-row cylindrical roller bearing withmachined cage for high rolling speed

Thrust bearings

Normally the chock at the operator’send is axially located in the rollstand to which it transmits theaxial forces. The thrust bearingscan be of different types.For high axial loads and mediumspeeds we recommend to usetapered roller thrust bearings (fig. 6),double-row tapered roller bearingswith a large contact angle (fig. 7) orspherical roller thrust bearings (fig. 8).

The tapered roller thrust bearing(fig. 6) features a spacer ringbetween the housing washerswhose length is machined accordingto the axial clearance required.Tapered roller thrust bearings,double-row tapered roller bearingsand spherical roller thrust bearingsare used principally in bloomingmills, heavy-plate mills and hotstrip mills, i.e. applications involvingconsiderable axial forces combinedwith low to medium speeds. Duringoperation only one roller row ispurely axially loaded. The other rowis not loaded. To make sure thatthe bearing kinematics is notimpaired, the cups of the double-rowtapered roller bearings and thehousing washers of the sphericalroller thrust bearings are on bothsides preloaded with a minimumload by means of springs (figs 7and 8).In strip mills, in fine-section andwire mills the rolling speeds areoften so high that tapered rollerthrust bearings and spherical rollerthrust bearings cannot be used. In these cases the axial load isaccommodated by angular contactball bearings or deep groove ballbearings.For the back-up rolls of large four-high strip and foil mills a deepgroove ball bearing (fig. 9) willoften be sufficient for accommodatingthe axial loads. Generally it has thesame sectional height as theadjacent radial cylindrical rollerbearing.A double-row tapered roller bearingwith a large contact angle can beused instead of the deep grooveball bearing. The required loadratings can thus be obtained with a considerably smaller bearing.These smaller double-row tapered

Roll neck bearingsThrust bearings

6

roller bearings make it possible touse smaller surrounding componentsso that the cost for the overallconstruction can be reduced.Work rolls of four-high strip millsand rolls of two-high fine-sectionand wire mills are generally fittedwith angular contact ball bearings(fig. 10) to carry the axial loads.The chock at the drive end is notaxially located in the stand; it isheld on the roll neck by a deepgroove ball bearing, which issufficient considering that theguiding forces are not very high.This does not considerably increasethe overall width of the wholebearing arrangement. It is advisableto use a deep groove ball bearingof the same sectional height as theradial bearing.Some roll neck bearing arrangementsfeature identical thrust bearingsboth at the drive end and at theoperator’s end. This simplifiesstock-keeping.The deep groove ball bearings andthe angular contact ball bearings inthese applications only serve totransmit axial loads. To positivelyprevent the outer rings fromtransmitting any radial loads, the chocks should be radially relief-turned a few millimeters at theseats provided for the outer rings(see also table 50 on page 39).

6: Double-direction tapered roller thrustbearing with spacer ring

7: Double-row tapered roller bearing with large contact angle and outer rings axiallypreloaded with helical springs

8: Spherical roller thrust bearing pair for thrustaccommodation in both directions

9: Deep groove ball bearing10: Double-row angular contact ball bearing

9 10

Tapered roller bearings

Due to the inclination of theirrollers, tapered roller bearingsaccommodate radial and axialloads at the same time. Four-rowand double-row tapered rollerbearings (figs. 11a and b) are usedin rolling mills.Tapered roller bearings are separable.Despite this fact, however, it is notpossible – as is the case withcylindrical roller bearings – to firstfit the inner rings onto the rollneck, fit the outer rings into thechock and finally slip the chockonto the roll neck. The completebearing has to be mounted into thechock, and then the chock togetherwith the bearing pushed onto theroll neck. This means that the bearinginner ring must have a sliding fit onthe roll neck although technically(because of the circumferential load)it should be a tight fit.The loose fit induces a condition of creep between the bearing bore

and the roll neck, resulting in heat-upand wear. However, wear can beminimized by lubricating thesurfaces of the inner ring and theroll neck well, see also page 44.To provide space for extra grease,and thus improve the lubrication ofthe roll neck, spiral grooves areoccasionally provided in the innerring bore (fig. 12). This groove alsoserves to collect abraded particles.For the same reason radial groovesare also provided in the abuttinginner ring faces.In the case of work rolls supportedby four-row tapered roller bearings,wear is moderate due to the lowloads. Moreover, the allowableregrinding stock on the work rollswill most probably have been usedup – necessitating new rolls – beforeroll neck wear has reached a pointcritical to continued bearingperformance.Large tapered roller bearings – likelarge cylindrical roller bearings – areprovided with through-bored rollers

Roll neck bearingsTapered roller bearings

7

and pin-type cages. This cagedesign is necessary for reversiblestands because of the greatacceleration and decelerationforces.For the aforementioned reasons,four-row tapered roller bearingswith a cylindrical bore cannot beused for all roll neck applications.Especially high speeds and loadscall for a tight-fitted inner ring. In these cases preference is usuallygiven to tapered bore bearingsfitted onto a tapered roll neck(fig. 13), whereby the required tightfit is simply achieved.The inner ring of the design shownin fig. 13a consists of one doublecone and two single cones, the outerring of two double cups. Fig. 13bshows another design with foursingle cups separated by threespacer rings.We manufacture four-row taperedroller bearings both with metric andinch dimensions and tolerances.

11: Tapered roller bearingsa: four-rowb: double-row

12: Four-row tapered roller bearing with spiral-grooved inner ring bore

13: Four-row tapered roller bearing with tapered bore and pin-type cagea: outer ring consisting of two double cupsb: outer ring consisting of four single cups

a

b

a

b

Sealed multi-row tapered roller bearings

Work roll bearing arrangements inhot and cold strip mills must beparticularly efficiently sealedagainst large quantities of water or roll coolant mixed with dirt.Generally, work roll bearingarrangements are lubricated withgrease. To cut grease cost andprotect the environment, users tryto reduce grease consumption.Longer bearing lives can beachieved by improving thelubrication and the cleanliness inthe rolling contact areas.In order to achieve these objectives,we have developed four-row taperedroller bearings with integrated seals

(fig. 14) which have the same main dimensions as the unsealedbearings. High-grade rollingbearing grease is used which doesnot escape from the bearings, thuscutting grease consumption. The housing seals are packed withsimple and cheap sealing grease.Sealed tapered roller bearings, due to the increased cleanlinessin their lubricating gaps, generallyhave a longer life than unsealedones although the integrated sealsreduce the mounting space availablefor the rollers, resulting in a loadrating reduction.

Sealed double-row tapered rollerbearings (fig. 15) are used as thrustbearings for work rolls.

Roll neck bearingsTapered roller bearings

8

14: Sealed four-row tapered roller bearing 15: Sealed double-row tapered roller bearing

Spherical roller bearings

In rolling mills, spherical rollerbearings are mainly used for low-speed roll neck applicationswithout special demands on axialguiding accuracy. As the mountingspace is limited in radial direction,preference is usually given tospherical roller bearings of series240 and 241, both of which have alow sectional height (fig. 16).Spherical roller bearings are self-aligning; they can accommodateradial and axial loads. Since theiraxial clearance is four to six timestheir radial clearance, their axialguiding accuracy is moderate.Spherical roller bearings can beused for low and medium speeds.The rolling speed should notexceed 12 m/s. Owing to their self-aligning properties, the chockcan be secured in the roll standquite easily: Misalignments of theroll stand and roll neck bending arecompensated for within the bearing.This self-aligning property is alsoadvantageous in mills with pre-stressed stands where thechocks are fixed with tie bars andconsequently cannot align freely.For applications where an easy,quick removal of the spherical

roller bearings from the roll neckis required and where the rollingspeed is low, the inner rings areloosely fitted on the roll neck.Just like tapered roller bearings(fig. 12), spherical roller bearingscan be provided with spiral groovesin the inner ring bore to improvelubrication of the surfaces incontact (fig. 17).If the inner rings of spherical rollerbearings are tightly fitted on theroll neck, mounting and dismountingwill be easiest if bearings with atapered bore are used. The hydraulicmethod simplifies mounting.Spherical roller bearings are alsopreferable for cantilever rollmounting since they can compensatefor the considerable roll deflectionswhich have to be expected there. In view of the relatively great axialclearance, profile rolls must beequipped with a supplementarythrust bearing.

Roll neck bearingsSpherical roller bearings · Tapered roller thrust bearings for screw-down mechanisms

9

Tapered roller thrustbearings for screw-downmechanisms

Single-direction tapered rollerthrust bearings are frequentlymounted between the pressurespindle and the upper chock(fig. 18). Due to their low friction,these bearings reduce the screw-down forces. This is particularlyadvantageous in large standsand in stands where the thicknessof the rolled material changesfrequently.

16: Spherical roller bearing 17: Spherical roller bearing with spiral groovein the inner ring bore

18: Tapered roller thrust bearings for screw-down mechanismsa: design without pressure washerb: design with pressure washer

a

b

The magnitude of the rolling loadtoday is generally determined withcomputer calculation programs.Major influences are the rolledstock, the rolling type (strip orgroove rolling) and the proposedrolling schedule. The actual rollingloads sometimes differ considerablyfrom the calculated values if therolling schedule is not identicalwith the proposed one. Moreover,the shock loads at the entry of thematerial between the rolls escapecalculation. The rolling load at theinitial pass may be more than twicethe constant load. The magnitudeof the initial pass peak loaddepends on the configuration ofthe product entering the rolls andthe temperature of the leadingedge of the product. The initialpass peak load is of short durationand in most cases therefore doesnot enter into life calculation.However, it should not be overlookedthat such stresses may occasionallydrastically affect the service life ofrolling bearings.The distribution of the rolling loadacross the two bearing locationsdepends on the rolling standdesign and the rolled stock.

Self-aligning chocks

The chocks are supported separatelyin the stands. The rolling loads aretransmitted to the stands throughpressure bearings (tapered rollerthrust bearings) with crownedsupport surfaces.This enables the chocks to adapt tothe position of the roll neck in caseof roll deflection, poor screw-downconditions etc. This ensures that allroller rows of the multi-row bearingsare evenly loaded (fig. 19).

The material passes symmetricallybetween the two bearing locations,

Calculation of bearing loadSelf-aligning chocks

10

each roll neck bearing being loadedby 1

/2 ~ Pw.

Fr = 1/2 ~ Pw

19: Self-aligning chock

20: Self-aligning chocks for strip rolling

Pw

Fr

Groove rolling

It is necessary to distinguishbetween rolls with different grooves(e.g. in blooming mills) and rollswith identical grooves (e.g. in wiremills).When rolling with different grooves(fig. 21), a rolling schedule shouldbe established indicating the timepercentages and rolling loads ofthe individual grooves in order todetermine the load acting on thetwo necks. The fatigue life is basedon the average load acting on thehighest loaded neck.

For rolls with identical grooves(fig. 22), the different neck loadscan be calculated from the rollingschedule.

Alternatively, the following indicativevalues can be assumed for themaximum neck load:

Single-strand rolling: maximum neck load Fr = 0,67 ~ Pw

Two-strand rolling: maximum neck load Fr = 1,1 ~ Pw

Calculation of bearing loadSelf-aligning chocks

11

Four-strand rolling:maximum neck load Fr = 2,0 ~ Pw

Pw = Rolling load, relative to onestrand

The calculation of the bearing loadfor variable speeds and roll loadsis described on page 22.

21: Self-aligning chocks: Rolls with different grooves 22: Self-aligning chocks: Rolls with identical grooves

Pw

Fr

Pw

Fr

Rigid chocks

Both bearings are mounted intohousings that are rigidly connectedto each other. Roll deflections,neck offsets or misalignmentscause mutual tilting of the twobearing rings. This has no influenceon the bearing operation andcalculation as long as the rollsare supported by spherical rollerbearings.When using double-row or multi-rowcylindrical roller bearings, an

uneven loading of the roller rowsmust be expected. We havedeveloped a computerised methodof calculating the roll deflection inorder to determine the loads actingon the individual roller rows.Then it has to be checked if thehigher loaded roller row offers asatisfactory fatigue life.Rigid chock guidance is preferablychosen for groove rolling. Thedistribution of the rolling load onthe two roll necks can be calculatedas shown on page 11.

Calculation of bearing loadRigid chocks

12

The upper and lower chocks arepreloaded against each other sothat they cannot adjust to anymisalignment. This can cause bothroll deflection and an offset of thetwo chocks relative to the roll axis.The majority of these stands areequipped with spherical rollerbearings (figs. 23 and 24). If noseparate thrust bearing is provided,the locating bearing mustaccommodate the axial load as well.

23: Rigid chock guidance 24: Pre-stressed stands

Pw

Fr

Pw

Fr

Cantilevered stands

Rolling stands for small-sectionprofile and wire rolling are providedwith rolls with as a small a diameteras possible. In some cases,cantilevered rolls are used (fig. 25).When using multi-row bearings, theloads acting on them should becalculated from the roll deflectioncurve. In this way the fatigue lifefor the highest loaded roller rowcan be assessed.The rolling load is distributed onthe two supports as follows:

FrB = FrA } Pw

Calculation of bearing loadCantilevered stands

13

26: Load scheme to fig. 25

25: Cantilevered rolls

Pw

FrA

FrB

Pw

FrA FrB

a b

FrA = Pw ~

a + b b

Calculation ofroll deflection and of theload conditions within the rolling bearings

The calculation program Bearinx®

can be used to calculate the bendingbehaviour of differently loaded,elastically supported elastic rolls.The support reactions, the internalbearing stresses, the equivalentstresses in the shafts and otherimportant data are printed out(values) and drawn by a plotter.

The following influences can beanalysed:

• Elasticity of plain and steppedsolid or hollow shafts made ofdifferent materials, deformationdue to shear loads.

• Shaft loads from rolling loads,from bending moments or fromexternal forces acting on thebearings.

• Shaft support in the form ofbearings with non-linear elasticity;the bearing geometry, the bearingclearance, the rolling elementand raceway profiles as wellas special load-transmittingconditions are taken into account.

• Any number of load cases(load/speed combinations) canbe created and calculated.

The following calculation resultsare printed out:

The deflection and inclination ofthe roll axis at any point, theshearing forces and bendingmoments, the stresses, the bearingreaction forces, the bearingelasticity, the load conditionswithin the rolling bearings and thepressure distribution in the individualrolling elements’ rolling contactareas. Based on the calculatedstressing of the individual rollingcontact areas, Bearinx® determinesthe life of the bearings with greaterprecision.

Calculation of bearing loadCalculation of roll deflection and of the load conditions within the rolling bearings

14

Calculating the roll deflection and load conditions within the rolling bearings (example)

Subjects of calculation are the workroll and the back-up roll of a four-high cold rolling mill.

Load:Rolling load Pw = 8 000 kN

The input data describes theoutline of the roll. The rolling loadcan either be input as a line load or split up into separate componentloads which, arbitrarily distributedover the whole width of the rolledmaterial, act on the roll barrel. The chocks are being considered assystems that are exposed to loadsand/or moments. The self-aligningproperties of the chocks will betaken into account. Roll bearingswill be cylindrical roller bearingsand tapered roller bearings. Theirspring characteristics are non-linear.

Calculation of bearing loadCalculation of roll deflection

15

27a: Work roll and back-up roll bearing arrangement

27b: Resultant back-up roll deflection in YZ direction

Calculation of bearing loadCalculating the load conditions and pressures (pressure distribution)

16

28a: Visualisation of the pressures acting on the four-row cylindrical roller bearing on the back-up roll

28b: Load distribution within the four-row cylindrical roller bearing on the back-up roll

Calculation of bearing loadCalculating the load conditions and pressures (pressure distribution)

17

29a: Visualisation of the pressures acting on the four-row tapered roller bearing on the work roll

29b: Load distribution within the four-row tapered roller bearing on the work roll

Dimensioning calculation involvesthe comparison of a bearing’s loadwith its load carrying capacity. A differentiation is made betweendynamic and static stress. Staticstress implies that the loadedbearing is stationary (no relativemovement between the rings) or isturning slowly. For these conditionsthe safety against excessive plasticdeformations of the raceways androlling elements is checked.Most bearings are dynamicallystressed. The rings turn relative toeach other. The dimensioningcalculation checks the safetyagainst premature material fatigueof the raceways and rolling elements.

Statically stressed bearings

The calculation of the static loadsafety factor S0 serves to ascertainthat a bearing with adequate loadrating has been selected.

whereS0 Static load safety factorC0 Static load rating [kN]P0 Equivalent static load [kN]

The static load safety factor S0 is asafety factor against permanentdeformations of the contact areasof the rolling elements. Roll neckbearings are usually not checkedfor static safety. The factor S0 isdetermined, however, for the bearingsof the screw down mechanisms.A value ofS0 = 1,8...2is recommended for this application.The static load rating C0 [kN] isindicated for every bearing in thetables of our catalogues. This load

(a radial one for radial bearings, an axial and centric one for thrustbearings) causes a theoreticalcontact pressure at the centre ofthe most heavily loaded contactarea between rolling element andraceway ofp0 = 4 200 N/mm2 for ball bearings

except self-aligning ballbearings

p0 = 4 000 N/mm2 for all rollerbearings

Under the C0 load (equivalent to S0 = 1) a plastic total deformationof rolling element and raceway ofabout 1/10 000 of the rollingelement diameter develops at themost heavily loaded contact area.The equivalent static load P0 [kN] isa theoretical value. It is a radialload for radial bearings and an axialand centric load for thrust bearings.P0 causes the same stress at thecentre of the most heavily loadedcontact area between rollingelement and raceway as the actualload combination. For the calculationof P0, see our catalogues.

Dynamically stressedbearings

The standardized calculation method(DIN ISO 281) for dynamicallystressed rolling bearings is basedon material fatigue (formation ofpitting) as the cause of failure. The life formula is:

[106 revolutions]

whereL10 = L Basic rating life

[106 revolutions] C Dynamic load rating [kN]P Equivalent dynamic load [kN]p Life exponent

DimensioningStatically stressed bearings · Dynamically stressed bearings

18

L10 is the basic rating life inmillions of revolutions which isreached or exceeded by at least90 % of a large group of identicalbearings.The dynamic load rating C [kN] isindicated for every bearing in thetables of our catalogues. With this load an L10 rating life of106 revolutions is reached.The equivalent dynamic load P [kN]is a theoretical value. It is a radialload for radial bearings and anaxial load for axial bearings whichis constant in size and direction. P yields the same life as the actualload combination.

P = X ~ Fr + Y ~ Fa [kN]

whereP Equivalent dynamic load [kN]Fr Radial load [kN]Fa Axial load [kN]X Radial factorY Thrust factorThe values for X and Y as well asinformation on the calculation ofthe equivalent dynamic load for thevarious bearing types can be foundin our catalogues and in PublicationWL 41 140 “FAG Rolling Bearingsfor Rolling Mills”.While the radial loads acting on rollneck bearings can be determinedwith sufficient accuracy, little isknown about the axial loads, whichhave to be estimated. In practice, ithas been found satisfactory toassume the following values whichare sufficiently safe:for plain rolls (in two-high and four-high strip mills)

Axial load = 1 to 2 % of therolling load

for grooved rollsAxial load = 5 to 10 % of therolling load

S0 =C0

P0

L10 = L = � C �p

P

P = Fr for radial bearings whichaccommodate only radial loads.

For tapered roller thrust bearingswhich for design reasons canaccommodate only axial loads,P = Fa.

P = Fr (for one row) applies to purelyradial loads or to Fa/Fr � eIf Fa/Fr � e, P = 0,4 ~ Fr + Y ~ Fa (for one row).e is an auxiliary value, cp. ourcatalogues.

Different life exponents p are usedfor ball bearings and rollerbearings.p = 3 for ball bearings

for roller bearings

If the bearing speed is constant,the life can be expressed in hours

whereLh10 = Lh Basic rating life [h]L Basic rating life

[106 revolutions]n Speed

(revolutions per minute) [min-1].On converting the equation weobtain

or

where

Index of dynamic stressing,

i.e. fL = 1 for a life of 500 hours,

Speed factor,

i.e. fn = 1 for a speed of 331/3 min-1.

The table shown in fig. 32 lists thefn values for ball bearings, thetable in fig. 34 lists the fn valuesfor roller bearings.

The life equation is therefore giventhe simplified form

wherefL Index of dynamic stressingC Dynamic rating load [kN]P Equivalent dynamic load [kN]fn Speed factor

DimensioningDynamically stressed bearings

19

Index of dynamic stressing fL

The fL value that is to be obtainedfor a correctly dimensioned bearingmounting is an empirical valueobtained from field-proven identicalor similar bearing mountings.For comparisons with a field-provenbearing mounting the calculation ofstressing must, of course, be basedon the same former method. Theusual data for the calculation andthe fL values are listed in the tablein fig. 30.

For the conversion of fL into thebasic rating life Lh, see table 31 forball bearings and table 33 for rollerbearings.

Application Recommended Stress conditionsindex ofdynamic stressing fL

Roll stands 1...3 mean rolling load; rolling speed(fL value determined by roll stand androlling programme)

Rolling 3...4 nominal moment; nominal speedmill gears

Roller tables 2,5...3,5 weight of material, shocks;rolling speed

30: Recommended fL values and general stress conditions

p =10 3

Lh10 = Lh =L ~ 106

[h]n ~ 60

Lh = � C �p

~

331/3

500 P n

p� Lh = p� 331/3

~

C

500 n P

fL = p� Lh

500

fn = p� 331/3

n

fL =C

~ fnP

Lh =L ~ 500 ~ 331

/3 ~ 60 n ~ 60

DimensioningIndex of dynamic stressing fL and speed factor fn for ball bearings

20

31: fL values for ball bearings

Lh fL Lh fL Lh fL Lh fL Lh fL

h h h h h

100 0,585 420 0,944 1 700 1,5 6 500 2,35 28 000 3,83110 0,604 440 0,958 1 800 1,53 7 000 2,41 30 000 3,91120 0,621 460 0,973 1 900 1,56 7 500 2,47 32 000 4130 0,638 480 0,986 2 000 1,59 8 000 2,52 34 000 4,08140 0,654 500 1 2 200 1,64 8 500 2,57 36 000 4,16

150 0,669 550 1,03 2 400 1,69 9 000 2,62 38 000 4,24160 0,684 600 1,06 2 600 1,73 9 500 2,67 40 000 4,31170 0,698 650 1,09 2 800 1,78 10 000 2,71 42 000 4,38180 0,711 700 1,12 3 000 1,82 11 000 2,8 44 000 4,45190 0,724 750 1,14 3 200 1,86 12 000 2,88 46 000 4,51

200 0,737 800 1,17 3 400 1,89 13 000 2,96 48 000 4,58220 0,761 850 1,19 3 600 1,93 14 000 3,04 50 000 4,64240 0,783 900 1,22 3 800 1,97 15 000 3,11 55 000 4,79260 0,804 950 1,24 4 000 2 16 000 3,17 60 000 4,93280 0,824 1 000 1,26 4 200 2,03 17 000 3,24 65 000 5,07

300 0,843 1 100 1,3 4 400 2,06 18 000 3,3 70 000 5,19320 0,862 1 200 1,34 4 600 2,1 19 000 3,36 75 000 5,31340 0,879 1 300 1,38 4 800 2,13 20 000 3,42 80 000 5,43360 0,896 1 400 1,41 5 000 2,15 22 000 3,53 85 000 5,54380 0,913 1 500 1,44 5 500 2,22 24 000 3,63 90 000 5,65

400 0,928 1 600 1,47 6 000 2,29 26 000 3,73 100 000 5,85

32: fn values for ball bearings

n fn n fn n fn n fn n fn

min-1 min-1 min-1 min-1 min-1

10 1,49 55 0,846 340 0,461 1 800 0,265 9 500 0,15211 1,45 60 0,822 360 0,452 1 900 0,26 10 000 0,14912 1,41 65 0,8 380 0,444 2 000 0,255 11 000 0,14513 1,37 70 0,781 400 0,437 2 200 0,247 12 000 0,14114 1,34 75 0,763 420 0,43 2 400 0,24 13 000 0,137

15 1,3 80 0,747 440 0,423 2 600 0,234 14 000 0,13416 1,28 85 0,732 460 0,417 2 800 0,228 15 000 0,13117 1,25 90 0,718 480 0,411 3 000 0,223 16 000 0,12818 1,23 95 0,705 500 0,405 3 200 0,218 17 000 0,12519 1,21 100 0,693 550 0,393 3 400 0,214 18 000 0,123

20 1,19 110 0,672 600 0,382 3 600 0,21 19 000 0,12122 1,15 120 0,652 650 0,372 3 800 0,206 20 000 0,11924 1,12 130 0,635 700 0,362 4 000 0,203 22 000 0,11526 1,09 140 0,62 750 0,354 4 200 0,199 24 000 0,11228 1,06 150 0,606 800 0,347 4 400 0,196 26 000 0,109

30 1,04 160 0,593 850 0,34 4 600 0,194 28 000 0,10632 1,01 170 0,581 900 0,333 4 800 0,191 30 000 0,10434 0,993 180 0,57 950 0,327 5 000 0,188 32 000 0,10136 0,975 190 0,56 1 000 0,322 5 500 0,182 34 000 0,099338 0,957 200 0,55 1 100 0,312 6 000 0,177 36 000 0,0975

40 0,941 220 0,533 1 200 0,303 6 500 0,172 38 000 0,095742 0,926 240 0,518 1 300 0,295 7 000 0,168 40 000 0,094144 0,912 260 0,504 1 400 0,288 7 500 0,164 42 000 0,092646 0,898 280 0,492 1 500 0,281 8 000 0,161 44 000 0,091248 0,886 300 0,481 1 600 0,275 8 500 0,158 46 000 0,0898

50 0,874 320 0,471 1 700 0,27 9 000 0,155 50 000 0,0874

DimensioningIndex of dynamic stressing fL and speed factor fn for roller bearings

21

33: fL values for roller bearings

Lh fL Lh fL Lh fL Lh fL Lh fL

h h h h h

100 0,617 420 0,949 1 700 1,44 6 500 2,16 28 000 3,35110 0,635 440 0,962 1 800 1,47 7 000 2,21 30 000 3,42120 0,652 460 0,975 1 900 1,49 7 500 2,25 32 000 3,48130 0,668 480 0,988 2 000 1,52 8 000 2,3 34 000 3,55140 0,683 500 1 2 200 1,56 8 500 2,34 36 000 3,61

150 0,697 550 1,03 2 400 1,6 9 000 2,38 38 000 3,67160 0,71 600 1,06 2 600 1,64 9 500 2,42 40 000 3,72170 0,724 650 1,08 2 800 1,68 10 000 2,46 42 000 3,78180 0,736 700 1,11 3 000 1,71 11 000 2,53 44 000 3,83190 0,748 750 1,13 3 200 1,75 12 000 2,59 46 000 3,88

200 0,76 800 1,15 3 400 1,78 13 000 2,66 48 000 3,93220 0,782 850 1,17 3 600 1,81 14 000 2,72 50 000 3,98240 0,802 900 1,19 3 800 1,84 15 000 2,77 55 000 4,1260 0,822 950 1,21 4 000 1,87 16 000 2,83 60 000 4,2280 0,84 1 000 1,23 4 200 1,89 17 000 2,88 65 000 4,31

300 0,858 1 100 1,27 4 400 1,92 18 000 2,93 70 000 4,4320 0,875 1 200 1,3 4 600 1,95 19 000 2,98 80 000 4,58340 0,891 1 300 1,33 4 800 1,97 20 000 3,02 90 000 4,75360 0,906 1 400 1,36 5 000 2 22 000 3,11 100 000 4,9380 0,921 1 500 1,39 5 500 2,05 24 000 3,19 150 000 5,54

400 0,935 1 600 1,42 6 000 2,11 26 000 3,27 200 000 6,03

34: fn values for roller bearings

n fn n fn n fn n fn n fn

min-1 min-1 min-1 min-1 min-1

10 1,44 55 0,861 340 0,498 1 800 0,302 9 500 0,18311 1,39 60 0,838 360 0,49 1 900 0,297 10 000 0,18112 1,36 65 0,818 380 0,482 2 000 0,293 11 000 0,17613 1,33 70 0,8 400 0,475 2 200 0,285 12 000 0,17114 1,3 75 0,784 420 0,468 2 400 0,277 13 000 0,167

15 1,27 80 0,769 440 0,461 2 600 0,270 14 000 0,16316 1,25 85 0,755 460 0,455 2 800 0,265 15 000 0,1617 1,22 90 0,742 480 0,449 3 000 0,259 16 000 0,15718 1,2 95 0,73 500 0,444 3 200 0,254 17 000 0,15419 1,18 100 0,719 550 0,431 3 400 0,25 18 000 0,151

20 1,17 110 0,699 600 0,42 3 600 0,245 19 000 0,14922 1,13 120 0,681 650 0,41 3 800 0,242 20 000 0,14724 1,1 130 0,665 700 0,401 4 000 0,238 22 000 0,14326 1,08 140 0,65 750 0,393 4 200 0,234 24 000 0,13928 1,05 150 0,637 800 0,385 4 400 0,231 26 000 0,136

30 1,03 160 0,625 850 0,378 4 600 0,228 28 000 0,13332 1,01 170 0,613 900 0,372 4 800 0,225 30 000 0,1334 0,994 180 0,603 950 0,366 5 000 0,222 32 000 0,12736 0,977 190 0,593 1 000 0,36 5 500 0,216 34 000 0,12538 0,961 200 0,584 1 100 0,35 6 000 0,211 36 000 0,123

40 0,947 220 0,568 1 200 0,341 6 500 0,206 38 000 0,12142 0,933 240 0,553 1 300 0,333 7 000 0,201 40 000 0,11944 0,92 260 0,54 1 400 0,326 7 500 0,197 42 000 0,11746 0,908 280 0,528 1 500 0,319 8 000 0,193 44 000 0,11648 0,896 300 0,517 1 600 0,313 8 500 0,19 46 000 0,114

50 0,885 320 0,507 1 700 0,307 9 000 0,186 50 000 0,111

Variable load and speed

If the load and speed fordynamically stressed bearingschange over time, this fact must betaken into account when calculatingthe equivalent load. The curve isapproximated by a series ofindividual loads and speeds of acertain duration q [%]. Then theequivalent dynamic load P isobtained from:

and the mean rotational speed nm

is obtained from:

For the sake of simplicity, exponent3 is indicated in the formulae forball bearings and roller bearings.If the load is variable, but thespeed constant:

If the load grows linearly from aminimum value Pmin to a maximumvalue Pmax at a constant speed:

The mean value of the equivalentdynamic load may not be used forthe calculation of the modifiedrating life (see page 23). Theperiods during which the same loadtype acts on a bearing must besummed up and the individualsubsums entered in the Lhnm

calculation. The modified rating lifecan then be calculated using theformula on page 28.

Adjusted rating lifecalculation

The basic rating life L or Lh more orless deviates from the actuallyattainable life of the rolling bearings.The equation L = (C/P)p takes intoaccount only one of the operatingconditions: the load. But theattainable life actually alsodepends on a number of other

DimensioningAdjusted rating life calculation

22

influences, e.g. the lubricating filmthickness, the cleanliness in thelubricating gap, the lubricantdoping and the bearing type.Therefore the standard DIN ISO281:1993-01 has introduced, inaddition to the basic rating life, the“adjusted rating life”, but so farthere are no values for the factorwhich takes into account theoperating conditions.

P

[ kN ]

load

PPmax

Pmin

PP1

P2

P3

P4

n4

n3

n2

n1

nm

q1 q2 q3 q4

100%

P

n

[ kN ]

[ min-1 ]

load

speed

time

percentagetime qP =

3�P13

~

n1~

q1 + P23

~

n2~

q2 ...[kN]nm 100 nm 100

nm = n1 ~

q1 + n2 ~

q2 + ...[ min-1 ]100 100

P = 3�P1

3~

q1 + P23

~

q2 + ... [ kN ]100 100

P =Pmin + 2Pmax [ kN ]

3

Adjusted rating life

The adjusted rating life Lna iscalculated using the followingformula in accordance with DIN ISO 281:

Lna = a1 ~ a2 ~ a3 ~ L[106 revolutions]

or when expressed in hours:

Lhna = a1 ~ a2 ~ a3 ~ Lh [h]

whereLna Adjusted rating life

[106 revolutions]Lhna Adjusted rating life [h]a1 Life adjustment factor

for reliabilitya2 Life adjustment factor

for material characteristicsa3 Life adjustment factor

for operating conditions, in particular lubrication

L Basic rating life [106 revolutions]

Lh Basic rating life [h]

Life adjustment factor a1

for requisite reliability

Rolling bearing failures due tofatigue are subject to statisticallaws which is why the requisitereliability must be taken intoaccount when calculating thefatigue life. Generally a 90%requisite reliability is assumed(corresponding to a failureprobability of 10%). The L10 life isthe basic rating life. The factor a1 isused to express requisite reliabilitiesbetween 90 % and 99 %, see table 35.

Life adjustment factor a2

for special material characteristics

Factor a2 takes into considerationthe characteristics of the materialand its heat treatment. The standardpermits factors of a2 � 1 for bearingsmade of steel of particularly goodcleanliness.

Life adjustment factor a3

for special operating conditions

Factor a3 takes into considerationthe operating conditions, especiallythe lubrication condition underoperating speed and operatingtemperature. DIN ISO 281:1993-01does not yet include figures for thisfactor.

DimensioningAdjusted rating life calculation

23

Expanded adjusted rating life

Diverse and systematic laboratoryinvestigations and the feedbackfrom practical experience enable us today to quantify the effect ofvarious operating conditions on theattainable life of rolling bearings.The life adjustment factors a2 anda3 that take into account theinfluences of special materialcharacteristics and lubricatingconditions and were introducedinto DIN ISO 281 in 1977 were notquantified. For this reason severalrolling bearing manufacturers havedeveloped their own methods forcalculating the adjusted rating life.These methods take into accountthe fact that the influences ofmaterial characteristics andlubrication are interdependent.DIN ISO 281, Appendix 1, describesthe manual calculation of theexpanded adjusted rating life Lnm

at the catalogue level. Computer-aided calculation is standardisedin DIN ISO 281, Appendix 4.

Requisitereliability % 90 95 96 97 98 99

Factor a1 1 0,62 0,53 0,44 0,33 0,21

35: Factor a1

Calculation of the expanded adjusted rating life

The calculation method describedin DIN ISO 281, Appendix 1, fordetermining the expanded adjustedrating life was derived from themethods developed by severalrolling bearing manufacturers. The expanded adjusted rating lifeis obtained from

Lnm = a1 ~ aDIN ~ L [106 revolutions]

and

Lhnm = a1 ~ aDIN ~ Lh [h]

wherea1 Life adjustment factor

for reliability (see page 23)aDIN Life adjustment factor

for operating conditionsL Basic rating life

[106 revolutions]Lh Basic rating life [h]

If influences vary during operation,the value of Lhnm has to bedetermined for each individualperiod of operation under constantconditions. Then the total expandedadjusted rating life has to bedetermined on the basis of thesevalues using the formula on page 28.

Life adjustment factor aDIN

The standardised method forcalculating aDIN takes into accountthe following influences: • the bearing load• the lubrication condition

(lubricant type and viscosity,additives, speed, bearing size)

• the fatigue limit of the material• the bearing type• the ambient conditions

(contamination of the lubricant)

aDIN = f (eC ~ Cu/P, κ)

DimensioningExpanded adjusted rating life calculation

24

The fatigue limit load Cu takes intoaccount the fatigue limit of theraceway material; the contaminationfactor eC describes the increasedstresses caused by contaminants inthe bearing. P is the equivalentdynamic load.

P = X ~ Fr + Y ~ Fa [kN]

whereFr Radial load [kN]Fa Axial load [kN]X Radial factorY Thrust factorThe viscosity ratio κ is a measure ofthe lubricating film formation, seepage 26.

36: Graph for determining aDIN

eCP κ = ν / ν1

aDIN

n

dmν40

ν1

ν

t

Cu

t Operating temperatureν40 Nominal viscosityν Operating viscosityn Operating speeddm Mean diameterν1 Reference viscosityκ Viscosity ratioP Equivalent dynamic loadeC Life adjustment factor for contaminationCu Fatigue limit load

Fatigue limit load Cu

The fatigue limit load Cu is definedas the load below which – underlaboratory conditions – no fatigueoccurs in the material.Values for the fatigue limit load Cu

are indicated in the catalogues ofSchaeffler Group Industrial.

Life adjustment factor eC

for contamination

If the lubricant is contaminatedwith particles, cycling of theseparticles can generate permanentindentations in the raceways. Localincreased stresses are generated atthese indentations that reduce thelife of the rolling bearing. This factis taken into account by using thelife adjustment factor eC forcontamination.Guide values for the factor eC areindicated in table 37. The reduction of the rating lifecaused by solid particles in the

DimensioningExpanded adjusted rating life calculation

25

lubrication gap is dependent on• the type, size, hardness and

number of particles• the lubricant film thickness

(viscosity ratio κ)• the bearing size

The values indicated apply forcontamination by solid particles.Other types of contamination suchas contamination by water or otherfluids cannot be taken intoconsideration here. If heavycontamination occurs (eC → 0) the bearings fail due to wear. Theoperating life is then considerablyshorter than the calculated rating life.

Degree of contamination Factor eC

Dpw < 100 mm Dpw ≥ 100 mm

Extreme cleanliness 1 1Particle size within lubricant film thicknessLaboratory conditions

High cleanliness 0,8 to 0,6 0,9 to 0,8Oil filtered through extremely fine filterSealed, greased bearings

Normal cleanliness 0,6 to 0,5 0,8 to 0,6Oil filtered through fine filterGreased, shielded bearings

Slight contamination 0,5 to 0,3 0,6 to 0,4Slight contamination of the lubricating oil

Typical contamination 0,3 to 0,1 0,4 to 0,2Bearing is contaminated with wear debrisfrom other machine elements

Heavy contamination 0,1 to 0 0,1 to 0Bearing environment is heavily contaminatedBearing arrangement is insufficiently sealed

Severe contamination 0 0

Dpw pitch circle diameter; instead of Dpw the approximate mean bearing diameter dm = (D + d)/2 can be used.

37: Factor eC

Viscosity ratio κ

The viscosity ratio κ is used as ameasure of the quality of thelubrication film. κ is the ratio ofthe kinematic viscosity ν of thelubricant at operating temperatureto the reference viscosity ν1.κ = ν/ν1

The reference viscosity ν1 isdetermined from diagram 38 as afunction of the mean bearingdiameter dm = (D + d)/2 and theoperating speed n.The operating viscosity ν of alubricating oil is obtained from theV-T diagram (fig. 39) as a functionof the operating temperature t andthe (nominal) viscosity of the oil at40 °C. In the case of lubricating greases, ν is the operating viscosity of thebase oil.Recommendations on oil viscosityand oil selection are given on page 31.

In heavily loaded bearings with ahigh percentage of sliding thetemperature in the contact area ofthe rolling elements is up to 20 Khigher than the temperaturemeasurable at the stationary ring(without the influence of externalheating).

Taking into account the effectof EP additives

With a viscosity ratio of κ < 1 and acontamination factor eC ≥ 0,2, iflubricants with EP additives ofproven effectiveness are used, thevalue κ = 1 can be used for thecalculation. With a heavilycontaminated lubricant(contamination factor eC < 0,2) the effectiveness of the additivesunder the given contaminationconditions must be proved. Proof ofthe effectiveness of the EP additivescan be provided in field operation

DimensioningExpanded adjusted rating life calculation

26

or in a rolling bearing test rig (FE 8)in accordance with DIN 51819-1.If EP additives of proveneffectiveness are used, i.e. if κ = 1,the life adjustment factor has to be limited to aDIN ≤ 3. If the value ofaDIN (κ) calculated for the actual κis higher than 3, this value can beused for the calculation.

Diagrams for determining the lifeadjustment factor aDIN

The life adjustment factor aDIN canbe taken from diagrams 40a to d onpage 27 forradial ball bearings (top left),radial roller bearings (top right),thrust ball bearings (bottom left),roller thrust bearings (bottom right).For κ > 4, the curve for κ = 4 shallbe used.If κ < 0,1 this calculation method isnot applicable.

38: Reference viscosity ν1 39: V-T diagram for mineral oils

10 20 50 100 200 500 1 000

Mean bearing diameter dm =

100 000

50 000

20 000

10 000

5 000

2 00010

5

3

D+d2

mm

1 000

500

200

100

50

20

10

5

2

500

200

100

50

20

n [m

in-1 ]

1 000

Refe

renc

e vi

scos

ity

νs

1m

m2

Viscosity [mm2/s]at 40 °C

Ope

rating

tem

pera

ture

t [°C]

Operating viscosity ν [mm2/s]

12011010090

80

70

60

50

40

30

20

104 6 8 10 20 3040 60 100 200 300

1500100068046032022015010068

4632

22

15 10

DimensioningExpanded adjusted rating life calculation

27

c: aDIN for thrust ball bearings40: Life adjustment factor aDIN

0,005 0,01 0,02 0,05 0,1 0,2 0,5 1 2 5

0,1

0,2

0,5

1

2

5

10

20

50

aDIN

4κ = 2 1 0,8 0,6

0,5

0,4

0,3

0,2

0,15

0,1

eC · Cu

P

a: aDIN for radial ball bearings

0,005 0,01 0,02 0,05 0,1 0,2 0,5 1 2 5

0,1

0,2

0,5

1

2

5

10

20

50

aDIN

0,5

0,4

0,3

0,2

0,1

0,60,8124κ =

0,15

eC · Cu

P

d: aDIN for roller thrust bearings

0,005 0,01 0,02 0,05 0,1 0,2 0,5 1 2 5

0,1

0,2

0,5

2

5

10

20

50

0,1

0,15

0,2

0,30,4

0,5

0,6

0,8

1

24κ =

aDIN

eC · Cu

P

b: aDIN for radial roller bearings

0,005 0,01 0,02 0,05 0,1 0,2 0,5 1 2 5

0,1

0,2

0,5

1

2

5

10

20

50

aDIN

0,4

0,3

0,2

0,15

0,1

0,8124κ =

0,5

0,6

eC · Cu

P

Expanded adjusted rating lifeunder variable operating conditions

For applications where the load andthe other life influencing parametersvary, the expanded adjusted ratinglife (Lhnm1, Lhnm2,...) must becalculated separately for eachindividual period of operation q [%]when the bearing operates underconstant conditions. The expandedadjusted rating life is calculatedfor the total operating time bymeans of the formula

Limits of life calculation

Like the former life calculationmethod, the expanded adjustedrating life calculation takes onlymaterial fatigue into account as acause of failure. The expandedadjusted rating life obtained canonly correspond to the actualservice life if the lubricant life, theservice life of the other components(e.g. the seal) or the life limited bywear are at least as long as thefatigue life of the bearing.

DimensioningExpanded adjusted rating life calculation

28

Bearing calculation on a PC

The BEARINX® calculation programcombines extensive new calculationoptions with a user-friendlyWINDOWS interface. It is particularlyuseful due to fast parametricanalysis and automatic data importbetween individual calculationmodules as well as an extensivebearing database. BEARINX® makesuse of the higher precision of thecalculation options available todaythat are described, for example, inDIN ISO 281, Appendix 4. The program takes into accountthe influences of misalignment,operating clearance and loadsacting on the bearing.

Lhnm =100

q1 +q2 +

q3 + ...Lhnm1 Lhnm2 Lhnm3

In roll neck bearings the lubricant– as in other rolling bearings –must form a load carrying filmwhich prevents metal-to-metalcontact between the bearing partswhich would damage their surfaces.The thickness and load carryingcapacity of the lubricant filmdepend on the viscosity of the oil,on the bearing speed and size, andon the lubricant properties. Also,the lubricant has to protect thebearing parts from corrosion,lubricate the lips of the seals(collar seals etc.) and fill the gapsof labyrinth seals.Since the function of the lubricantin the sealing is different from itsfunction in the bearing, it isadvisable to lubricate bearings and

seals separately and choose thebest lubricant for each purpose. Inmany cases, however, this solutioncannot be put into practice becauseof the hazard of mistaking onegrease for the other (harmfulmixture), complicated stockkeepingetc.

Grease lubrication

Where operating conditions permit,grease is the lubricant of choice forroll neck bearings due to thesimplicity of sealing and greasereplenishment. Mineral oil companiesproduce a large number of specialrolling bearing greases; however,these greases differ considerably in

LubricationGrease lubrication

29

their composition and properties,making the selection of anappropriate grease for specificapplications difficult. We offer avariety of particularly suitablebearing greases under the tradename Arcanol.

Table 41 lists a selection of rollingbearing greases and their properties.For specific applications, werecommend customers to ask theirgrease supplier for exact data. The suitability of the rolling bearinggreases Arcanol for the variousbearing types is known. But thesupplier has to prove the suitabilityof unfamiliar greases. Wherenecessary, we can carry outperformance tests for a customer.

41: A selection of rolling bearing greases and their properties

Grease type, Con- Remarks, typical Arcanol Temperature Base oil Speed Load Water Anti-thickener sistency applications range viscosity resist- corrosive

(NLGI at 40 °C ance propertiesclass) °C mm2/s

Lithium soap 3 universal rolling bearing MULTI3 }30...+140 80 medium medium stable very goodgrease, long lubrication (L71V) up to 90°Cintervals, e.g. in electricmotors; good sealinggrease

Lithium/calcium 2 rather difficult operating LOAD220 }20...+140 ISO VG high high stable very goodsoap; conditions, e.g. in back-up (L215V) 220 up to 90 °CEP additives rolls and work rolls, esp.

in sealed tapered rollerbearings

Lithium soap; 2 rather difficult operating MULTITOP }40...+150 85 very high high stable very goodEP additives conditions, especially (L135V) up to 90 °C

high speeds, esp. insealed tapered rollerbearings

Lithium/calcium 2 very difficult operating LOAD400 }20...+140 400 medium very high stable very goodsoap; conditions, esp. high (L186V) up to 90 °CEP additives impact loads

Lithium-calcium 2 extremely difficult LOAD1000 }20...+140 ISO VG low very high stable very goodsoap; operating conditions, (L223V) 1000 up to 90 °CEP additives very high impact loads,

e.g. in lifting tables

Load and speed

Load and speed are of majorimportance when selecting anappropriate grease for a specificapplication. The stress due tospeed can be estimated from thespeed index ka ~ n ~ dm

whereka Factor for the bearing type

(see diagram 42)n Operating speed [min-1] dm Mean bearing diameter;

dm = (D+d)/2d Bearing bore [mm]D Bearing O.D. [mm]

The load ratio P/C is a measure ofthe specific loadingP Equivalent dynamic load [kN]

(see catalogues)C Dynamic load rating [kN]

(see catalogues)The table (fig. 42) can be used todetermine which type of grease issuitable for specific operatingconditions. For applications

involving high speeds as well ashigh loads, the temperatures mayincrease, requiring a particularlytemperature-resistant grease orspecial cooling measures. Theupper speed and load limits ofthe lubricating greases must beobserved; this information can be obtained from the mineral oilcompany or from Schaeffler GroupIndustrial.

Other operating conditions

The position of the roll axis mustalso be taken into account in thegrease selection. Vertical orinclined rolls may cause the greaseto escape from the bearing andchock (effect of gravity). Thereforewe recommend to provide baffleplates beneath the bearing and tochoose a grease which is particularlyadhesive and resistant to working(consistency class 3 or, whereadvisable, class 2).

LubricationGrease lubrication

30

Relubrication is another criterionfor grease selection. If largequantities of grease are needed forbearings or seals, or if there arelong lubricating ducts (e.g. centrallubricating system), greases whichcan be pumped without problems,i.e. greases of consistency class 1or 2, must be selected.In damp environments and withlonger idle times, roll neck bearingsare exposed to a risk of corrosiondue to condensation. Therefore, thegreases used for these applicationsmust have special anti-corrosiveproperties.Bearing locations exposed to splashwater must be protected by a seal.Seals and bearings should berelubricated at short intervals.The table in fig. 43 shows anoverview of the above criteria andpermits users to select a suitablelubricating grease based on therequired grease properties.

42: Grease selection from the load ratio P/C and the relevant bearing speed index ka ~ n ~ dm

ka · n · dm [min-1 · mm]

HL

N

HN

0,9

0,6

0,3

0,15

0,09

0,06

0,03

0,0250 000 100 000 200 000 400 000 1 000 000

0,6

0,4

0,2

0,1

0,06

0,04

0,02

0,013

P/C

fo

r ra

dial

ly loa

ded

bear

ings

P/C

fo

r ax

ially

loa

ded

bear

ings

Range NNormal operating conditions.Rolling bearing greases K according to DIN 51825

Range HLHeavy loads.Rolling bearing greases KP according to DIN 51825 or other suitable greases

Range HNHigh speed rangeGreases for high-speed bearings.For bearing types with ka > 1, greases KP according to DIN 51825 or other suitable greases.

ka values

ka = 1 deep groove ball bearings, angular contact ballbearings, four-point bearings, radially loadedcylindrical roller bearings

ka = 2 spherical roller bearings, tapered roller bearingska = 3 axially loaded cylindrical roller bearings,

full-complement cylindrical roller bearings, tapered roller thrust bearings

Oil lubrication

Viscosity requirements

Depending on the bearing speedand size, the oil must have a certainviscosity at operating temperaturein order to form a load-carryinglubricant film and reach its ratedlife. This reference viscosity ν1 isdetermined with the help of thediagram in fig. 38.For a normal service life, bearingswith a small amount of slidingmotion should be lubricated withan oil whose operating viscosity νat least equals the referenceviscosity ν1. Rolling bearing typeswith unfavourable kinematics(axially loaded roller bearings, low-speed and highly loaded large sizebearings) always require effectiveadditives. If the lubricant film

formed in the bearing is not adequate,these additives create a separatingboundary film in the raceway/rollingelement, rolling element/cage androlling element/guiding lip contactareas. This boundary film preventswear and premature fatigue.

Other demands on the oil

Most rolling bearing lubricating oils are mineral oils which containadditives that improve theirproperties.These additives provide, for instance,a better oxidation stability, improvethe oils’ anticorrosive properties orreduce foaming. Dispersion agentskeep finely distributed insolublecontaminants in suspension. EP additives are important whereP/C > 0,15 and the operating

LubricationGrease lubrication · Oil lubrication

31

viscosity ν is lower than thereference viscosity ν1.High-temperature oils with superiornon-deterioration properties areavailable for applications wherethe bearings are subjected to greatthermal stressing. Some oils featurea favourable V-T behaviour, i.e.their viscosity varies less withtemperature than the viscosity ofnormal oils; they are primarily usedfor applications where temperaturesvary to some degree. For extremelyhigh temperatures, synthetic oilsoils (e.g. polyglycols orpolyalphaolefins) are preferred tomineral oils because they are muchmore resistant to aging.The suitability of oils for specificapplications either has to be knownfrom experience or determined intests.

43: Criteria for grease selection

Criteria for grease selection Grease characteristics

Bearing stressing Speed index Grease selection according to diagram 42 and table 41Load ratio

Operating conditions Position of roll axis Grease of consistency class 3; softer greases require frequent relubrication

Frequent relubrication Good pumping capability, consistency class 1 or 2 for central lubricating systems

For-life lubrication Grease resistant to working whose service life and lubricating properties are known.

Environmental Extreme temperatures Grease whose service life is suitable for the operatingconditions temperature; with constant relubrication, greases that

resist the operating temperatures at least for a shortperiod may be chosen too, but they must not solidify.

Contamination by foreign matter Stiff grease, consistency class 3

Corrosion by condensed water Emulsifying grease (e.g. lithium grease, lithium/calcium grease)

Corrosion by splash water Water-repellent grease (e.g. calcium complex grease, lithium/calcium grease)

Methods of oil lubrication

Circulating oil lubrication is thelubricating method which enables– for the usual speed range of theroll neck bearings – not only safelubrication but also providescooling of the bearings and carriesaway contaminants and water fromthe bearing locations. In roll neckmountings it is provided as acooling lubrication system forapplications with• energy losses within the bearing

itself, i.e. with high loads andhigh speeds

• heating of the roll neck journalsthrough external heat sources

• insufficient heat dissipation.Oil injection lubrication, where thelubricant is injected directly intothe bearing through lateral nozzles,is required where a circulating oillubrication system is not sufficientto cool the bearing and the rollneck. Oil injection lubricationpermits extremely high speeds.Circulating oil lubrication and oilinjection lubrication require someexpenditure for inlets, outlets,pumps, oil reservoirs and, possibly,oil recoolers.With oil sump lubrication, thesmall lateral spaces in the chockscan accommodate only a smallamount of oil which, due to heavystressing, deteriorates rapidly.Therefore the oil has to be changedfrequently, or possibly non-agingsynthetic oils have to be used.Throwaway lubrication is frequentlyused for rolling mill bearings.With oil mist lubrication, compressedair carries the atomized oil to thenozzle at the bearing where the oilparticles form larger drops whichare injected into the bearing. Thissmall amount of oil adds to the oil

sump which contributes to thebearing lubrication. It also ensuresthat during start-up of the bearingand during short malfunctions ofthe lubricating system all functionalareas are adequately supplied withoil. With a horizontal shaft, theposition of the oil drain holes inthe chock is chosen such that thebottom rolling element is halfimmersed in the oil sump.The constant overpressure createdby the air current in the chock andthe air escaping at the sealsincrease the effectiveness of thesealing. The escaping air usuallycontains some of the atomized oilwhich is harmful to the environment.With oil-air lubrication the oil isintermittently fed to the lubricatingpipe of the bearing via a meteringunit and carried into the bearing bythe air current. This oil is notatomized. Therefore high-viscositytransmission oils with EP additivescan be used. As with oil mistlubrication, the air current increasesthe effectiveness of the sealing.The volume of air can be selectedwithin wide limits. For oil-airlubrication, an oil sump is alsorequired.

Design of the lubricating system

Amount of grease

The bearings and housings shouldbe greased as follows:• The bearings should be packed to

capacity with grease to make surethat all functional areas aresupplied with grease.

• The housing space beside thebearings should be filled withgrease to such an extent that the

LubricationOil lubrication · Design of the lubricating system

32

grease escaping from the bearingscan be easily accommodated. Inthis way no excessive amount ofgrease will circulate through thebearing. Usually the free spacesin the chocks beside the bearingsare just large enough toaccommodate the grease escapingfrom the bearings; thereforethese spaces do not have to befilled with grease if the bearingsrun at high speeds.

• Low-speed bearings(n ~ dm < 50 000 min-1

~ mm) andtheir housings should be packedwith grease to capacity. Thelubricant friction due to workingis negligible.

Relubrication intervals (grease)

The exact relubrication or greaserenewal intervals depend on theextent to which the grease hasbeen stressed by bearing frictionand speed. Bearing friction is afunction of load and the result ofthe different kinematic conditionsencountered in the various bearingtypes. Moreover – especially in rollneck applications – special thoughtshould be given to the environmentalconditions and the effectiveness ofthe sealing used. If the sealing isinadequate, moisture, splash waterand mill scale would demanddrastically reduced relubricationintervals.Recommendations for relubricationintervals can be obtained byperiodically examining the conditionof grease and seals – preferably onthe occasion of roll changes – to findout if contaminants have penetratedinto the bearing.

Lubricant flow

For effective lubrication, the greaseor oil must safely reach the rollingand sliding surfaces. If grease isused, the excessive amount ofgrease must be able to escape.Overlubrication would cause anundesirable increase in churningaction, creating a temperature risewith a resulting loss in greaselubricity. The seals must beeffectively lubricated as well.

Grease Lubrication

Four-row roller bearings thatsupport horizontal rolls should besupplied with lubricant at twopoints (fig. 44). Ball bearings thataccommodate the thrust loads(fig. 44a, right) can be integratedinto the general lubricating systembut may also be lubricatedseparately. Tapered roller thrustbearings (fig. 44a, left) must belubricated separately as theirlubrication requirements are moredemanding. Double-row angularcontact ball bearings should alsobe lubricated separately. If the

LubricationDesign of the lubricating system

33

chocks are not removed forregrinding of the roll body (loose fit of the inner rings), the bearingsmust be regreased through thejournal.Sealed multi-row tapered rollerbearings are packed at themanufacturing plant with thegrease best suited for a specificapplication. The right amount anddistribution of grease within thebearing promise very long servicelives. We recommend to providedrain holes on both sides of thebearing so that the bearing sealsare exposed to moisture as little aspossible.

b) Roll neck bearing arrangement with four-row tapered roller bearings44: Layout of lubrication system for four-row roller bearings (grease lubrication)

a) Roll neck bearing arrangement with four-row cylindrical roller bearings and thrust bearings

Oil mist lubrication, oil-air lubrication

LubricationDesign of the lubricating system

34

45: Oil mist or oil-air lubrication system for chocks with four-row cylindrical roller bearings and thrust bearings

46: Oil mist or oil-air lubrication for a chock with a four-row tapered roller bearing

Oil level 

Air vent  Oil-air or oilmist inlets 

Oil-air or oil mist inlets 

Air vent  

Oil-air or oil mist inlets 

Oil level 

Air vent  Oil-air or oilmist inlets 

Oil level 

Oil-air or oil mist inlets 

Air vent  

LubricationDesign of the lubricating system

35

Circulating oil lubrication, oil injection lubrication

47: Oil inlet and oil outlet for circulating lubrication

48: Oil inlet and oil outlet for injection lubrication

Tolerances of roll neck bearings

Tolerances of roll neck bearings

36

Tolerances of metric radial and thrust bearings (normal tolerance)

Nominal dimensions Tolerancesmm μm

Inner ring Outer ring Inner and outer ringΔdmp ΔDmp ΔBs = ΔCs

Radial bearings Thrust bearings

over 50 to 80 0 –15 0 –13 0 –19 0 –150over 80 to 120 0 –20 0 –15 0 –22 0 –200over 120 to 150 0 –25 0 –18 0 –25 0 –250

over 150 to 180 0 –25 0 –25 0 –25 0 –250over 180 to 250 0 –30 0 –30 0 –30 0 –300over 250 to 315 0 –35 0 –35 0 –35 0 –350

over 315 to 400 0 –40 0 –40 0 –40 0 –400over 400 to 500 0 –45 0 –45 0 –45 0 –450over 500 to 630 0 –50 0 –50 0 –50 0 –500

over 630 to 800 0 –75 0 –75 0 –75 0 –750over 800 to 1 000 0 –100 0 –100 0 –100 0 –1 000over 1 000 to 1 250 0 –125 0 –125 0 –125 0 –1 250

over 1 250 to 1 600 0 –160 0 –160 0 –160 0 –1 600over 1 600 to 2 000 0 –200 0 –200 0 –200 0 –2 000

Tolerances of inch four-row tapered roller bearings (normal tolerance)

Nominal dimensions Tolerancesmm μm

Cone Cup Cup and coneΔdmp ΔDmp ΔBs = ΔCs

over 76,2 to 304,8 0 +25 0 +25 ±1 524over 304,8 to 609,6 0 +51 0 +51 ±1 524over 609,6 to 914,4 0 +76 0 +76 ±1 524over 914,4 to 1 219,2 0 +102 0 +102 ±1 524over 1 219,2 0 +127 0 +127 ±1 524

Tolerance symbolsDIN ISO 1132, DIN 620

Bore diameter

d Nominal bore diameterds Single bore diameter

Single plane mean bore diameter

dpsmax Single plane maximum bore diameter

dpsmin Single plane minimum bore diameter

Δdmp = dmp – dSingle plane mean bore diameter deviation

Outside diameter

D Nominal outside diameterDs Single outside diameter

Single plane mean outside diameter

Dpsmax Single plane maximum outside diameter

Dpsmin Single plane minimum outside diameter

ΔDmp= Dmp – DSingle plane mean outside diameter deviation

Tolerances of roll neck bearings · Surrounding partsFits

37

Width

Bs, Cs Single ring width (inner and outer ring)

ΔBs = Bs – B, ΔCs = Cs – CDeviation of one single ringwidth (inner ring and outerring) from the nominal value

Fits

Radial bearings

The inner rings of radial roll neckbearings are subjected tocircumferential load duringoperation. They should therefore be tightly fitted on the roll neck.Due to mounting reasons, this isnot possible with four-row taperedroller bearings with a cylindricalbore. Therefore a slide fit must beprovided. The inner rings ofspherical roller bearings andcylindrical roller bearings are slide-fitted if the rolling speed is

low, and quick and easy extractionfrom the roll neck is desired.The outer rings of radial bearingsare subjected to point load. In thiscase no tight fit is required so thatthe rings may be slide-fitted in thechock. Axial location of the outerrings is provided by the end coversof the chocks.

Thrust bearings

Bearings intended for axial locationof the roll and location of thechocks are subjected to axial loadsonly so that the inner rings can be

slide-fitted on the roll necks.In some roll neck applications thethrust bearings are mounted on asleeve for easier assembly. In thiscase a slightly tighter fit isadvisable.The housing washers of taperedroller thrust bearings are looselyfitted in the chocks. The outer ringsof all other bearings serving toprovide axial location must beradially relieved. Therefore, thehousing bore must be significantlylarger than the outside diameter ofthe outer rings.

dmp =dpsmax + dpsmin

2

Dmp =Dpsmax + Dpsmin

2

Surrounding partsFits

38

49: Tolerance fields for roll necks and sleeves (bearing tolerances see page 36)

Nominal diameter Tolerance1)

mm mm

Cylindrical roller bearings d < 200 n6and d = 200...400 p6/r6spherical roller bearings d > 400...630 +0,200...+0,260(tight fit) > 630...800 +0,250...+0,330

> 800...1 250 +0,320...+0,420> 1 250...1 400 +0,400...+0,550> 1 400...1 600 +0,520...+0,650

Cylindrical roller bearings d e7andspherical roller bearings(slide fit)Metric d < 315 –0,180...–0,230tapered roller bearings d = 315...630 –0,240...–0,300(slide fit) > 630...800 –0,325...–0,410

> 800 –0,350...–0,450Inch d = 101,6...127,0 –0,100...–0,125tapered roller bearings > 127,0...152,4 –0,130...–0,155(slide fit) > 152,4...203,2 –0,150...–0,175

> 203,2...304,8 –0,180...–0,205> 304,8...609,6 –0,200...–0,249> 609,6...914,4 –0,250...–0,334> 914,4 –0,300...–0,400

Angular contact ball bearings d e7and deep groove ball bearingsmounted on the roll neck

Angular contact ball bearings d k6and deep groove ball bearingsmounted on a sleeve d1 e9/H7

Tapered roller thrust bearings, d e7double-row tapered roller bearings (thrust bearings), and spherical roller thrustbearings mounted on theroll neckTapered roller thrust bearings, d k6spherical roller thrust bearingsmounted on a sleeve d1 e9/H7

1) For high speeds and bearings with a tapered bore, please contact Schaeffler Group Industrial to determine thenecessary tolerances of the surrounding parts.

d d1d d1

d d d

d d

d d

d d d

d d

d1d d1d

ddd

Surrounding partsFits

39

50: Tolerance fields for chocks

Radial bearings Nominal diameter Tolerance1)

mm mm

Metric cylindrical roller D ≤ 800 H6 (G6)bearings, spherical rollerbearings and tapered rollerbearings

D > 800 H7 (G7)

Inch tapered roller D ≤ 304,8 +0,055...+0,080bearings > 304,8...609,6 +0,101...+0,150

> 609,6...914,4 +0,156...+0,230> 914,4...1219,2 +0,202...+0,300

> 1 219,2 +0,257...+0,380

D D D

DD

Thrust bearings Nominal diameter Tolerance2)

mm mm

Tapered roller bearings, D ≤ 500 +0,6...+0,8double-row (thrust bearings), > 500...800 +0,8...+1,1spherical roller thrust > 800 +1,2...+1,5bearings, angular contactball bearings and deepgroove ball bearings

Tapered roller thrust D ≤ 800 H6 (G6)bearings

D > 800 H7 (G7)

1) For bearings with a tapered bore, please contact Schaeffler Group Industrial to determine the necessary tolerances ofthe surrounding parts.

2) For high axial loads, please contact Schaeffler Group Industrial to determine the necessary tolerances of thesurrounding parts.

D D D D

D

Machining tolerances for cylindrical bearing seats (DIN ISO 1101 and ISO 286)

Surrounding partsTolerances for cylindrical bearing seats

40

Recommendations for machining shafts, housing bores and surrounding parts (sleeves, covers etc.)

Bearing Bearing Diameter Roundness Parallelism Abutmenttolerance seating tolerance tolerance tolerance shoulderclass surface runout

tolerancet1 t2 t3

PN Shaft IT6 (IT5) Circumferential IT4 IT4P6X load IT4/2

Point load IT5IT5/2

Housing IT7 (IT6) Circumferential IT5 IT5load IT5/2Point load IT6IT6/2

P5 Shaft IT5 Circumferential IT2 IT2load IT2/2Point load IT3IT3/2

Housing IT6 Circumferential IT3 IT3load IT3/2Point load IT4IT4/2

No values are indicated for ISO qualities IT4 and better where the nominal diameter is > 500 mm. In these cases half the machining tolerance is used.

d1 d2D1 D2

CA

A-B

D B

t3 A-Bt3

A

t1

2t C D

t1

2t

B

DA-Bt3t3

CA-B

A-Bt1�

D2t

t1

C

t1

2tA-Bt1�

t1 = roundnesst2 = parallelismt3 = runout of abutment shoulders

Surrounding partsRoughness of the bearing seats

41

Tolerance Roughness Nominal shaft diameter Nominal housing boreclass of mm mmbearings over 50 120 250 500 50 120 250 500

to 50 120 250 500 50 120 250 500

Roughness valuesμm

Normal1) Roughness class N5 N6 N7 N7 N7 N6 N7 N7 N8 N8Average roughness 0,4 0,8 1,6 1,6 1,6 0,8 1,6 1,6 3,2 3,2value Ra

CLA, AA2)

Roughness depth 2,5 4 6,3 6,3 6,3 4; 6,3*) 6,3; 8*) 6,3; 10*) 10; 16*) 10; 16*)

Rt ≈ Rz

P6 Roughness class N4 N5 N5 N6 N6 N5 N5 N6 N7 N7Average roughness 0,2 0,4 0,4 0,8 0,8 0,4 0,4 0,8 1,6 1,6value Ra

CLA, AA2)

Roughness depth 1,6 2,5 2,5 6,3 6,3 2,5 2,5 6,3 6,3 6,3Rt ≈ Rz

*) Roughness depths for grey-cast iron housings with turned fitting surfaces.1) For more stringent requirements on running accuracy, the next higher surface quality must be selected.2) GB: CLA (Centre Line Average Value); USA: AA (Arithmetic Average)

Recommendations for the surface roughness of rolling bearing seats(the roughness values apply only to ground surfaces)

Roughness classes according to DIN ISO 1302

Roughness class N1 N2 N3 N4 N5 N6 N7 N8 N9 N10 N11 N12

Roughness value Ra in μm 0,025 0,05 0,1 0,2 0,4 0,8 1,6 3,2 6,3 12,5 25 50

in μinches 1 2 4 8 16 32 63 125 250 500 1 000 2 000

Surrounding partsTolerances for roll necks and chocks

42

Tolerances for roll necks and chocks

Nominal shaft diametermm

over 50 65 80 100 120 140 160 180 200 225 250 280 315to 65 80 100 120 140 160 180 200 225 250 280 315 355

Roll neck tolerancesμm

e7 –60 –60 –72 –72 –85 –85 –85 –100 –100 –100 –110 –110 –125–90 –90 –107 –107 –125 –125 –125 –146 –146 –146 –162 –162 –182

e9 –60 –60 –72 –72 –85 –85 –85 –100 –100 –100 –110 –110 –125–134 –134 –159 –159 –185 –185 –185 –215 –215 –215 –240 –240 –265

f6 –30 –30 –36 –36 –43 –43 –43 –50 –50 –50 –56 –56 –62–49 –49 –58 –58 –68 –68 –68 –79 –79 –79 –88 –88 –98

g6 –10 –10 –12 –12 –14 –14 –14 –15 –15 –15 –17 –17 –18–29 –29 –34 –34 –39 –39 –39 –44 –44 –44 –49 –49 –54

k6 +21 +21 +25 +25 +25 +28 +28 +33 +33 +33 +36 +36 +40+2 +2 +3 +3 +3 +3 +3 +4 +4 +4 +4 +4 +4

n6 +39 +39 +45 +45 +52 +52 +52 +60 +60 +60 +66 +66 +73+20 +20 +23 +23 +27 +27 +27 +31 +31 +31 +34 +34 +37

p6 +51 +51 +59 +59 +68 +68 +68 +79 +79 +79 +88 +88 +98+32 +32 +37 +37 +43 +43 +43 +50 +50 +50 +56 +56 +62

r6 +60 +62 +73 +76 +88 +90 +93 +106 +109 +113 +126 +130 +144+41 +43 +51 +54 +63 +65 +68 +77 +80 +84 +94 +98 +108

Nominal chock diametermm

over 80 100 120 140 160 180 200 225 250 280 315 355 400to 100 120 140 160 180 200 225 250 280 315 355 400 450

Chock bore tolerancesμm

G6 +12 +12 +14 +14 +14 +15 +15 +15 +17 +17 +18 +18 +20+34 +34 +39 +39 +39 +44 +44 +44 +49 +49 +54 +54 +60

G7 +12 +12 +14 +14 +14 +15 15 15 +17 +17 +18 +18 +20+47 +47 +54 +54 +54 +61 +61 +61 +69 +69 +75 +75 +83

H6 0 0 0 0 0 0 0 0 0 0 0 0 0+22 +22 +25 +25 +25 +29 +29 +29 +32 +32 +36 +36 +40

H7 0 0 0 0 0 0 0 0 0 0 0 0 0+35 +35 +40 +40 +40 +46 +46 +46 +52 +52 +57 +57 +63

Surrounding partsTolerances for roll necks and chocks

43

Tolerances for roll necks and chocks

Nominal shaft diametermm

over 355 400 450 500 560 630 710 800 900 1 000 1 120 1 250 1 400to 400 450 500 560 630 710 800 900 1 000 1 120 1 250 1 400 1 600

Roll neck tolerancesμm

e7 –125 –135 –135 –145 –145 –160 –160 –170 –170 –195 –195 –220 –220–182 –198 –198 –215 –215 –240 –240 –260 –260 –300 –300 –345 –345

e9 –125 –135 –135 –145 –145 –160 –160 –170 –170 –195 –195 –220 –220–265 –290 –290 –320 –320 –360 –360 –400 –400 –455 –455 –530 –530

f6 –62 –68 –68 –76 –76 –80 –80 –86 –86 –98 –98 –110 –110–98 –108 –108 –120 –120 –130 –130 –142 –142 –164 –164 –188 –188

g6 –18 –20 –20 –22 –22 –24 –24 –26 –26 –28 –28 –30 –30–54 –60 –60 –66 –66 –74 –74 –82 –82 –94 –94 –108 –108

k6 +40 +45 +45 +44 +44 +50 +50 +56 +56 +66 +66 +78 +78+4 +5 +5 0 0 0 0 0 0 0 0 0 0

n6 +73 +80 +80 +88 +88 +100 +100 +112 +112 +132 +132 +156 +156+37 +40 +40 +44 +44 +50 +50 +56 +56 +66 +66 +78 +78

p6 +98 +108 +108 +122 +122 +138 +138 +156 +156 +186 +186 +218 +218+62 +68 +68 +78 +78 +88 +88 +100 +100 +120 +120 +140 +140

r6 +150 +166 +172 +184 +199 +225 +235 +266 +276 +316 +326 +378 +378+114 +126 +132 +150 +155 +175 +185 +210 +220 +250 +260 +300 +300

Nominal chock diametermm

over 450 500 560 630 710 800 900 1 000 1 120 1 250 1 400 1 600 1 800to 500 560 630 710 800 900 1 000 1 120 1 250 1 400 1 600 1 800 2 000

Chock bore tolerancesμm

G6 +20 +22 +22 +24 +24 +26 +26 +28 +28 +30 +30 +32 +32+60 +66 +66 +74 +74 +82 +82 +94 +94 +108 +108 +124 +124

G7 +20 +22 +22 +24 +24 +26 +26 +28 +28 +30 +30 +32 +32+83 +92 +92 +104 +104 +116 +116 +133 +133 +155 +155 +182 +182

H6 0 0 0 0 0 0 0 0 0 0 0 0 0+40 +44 +44 +50 +50 +56 +56 +66 +66 +78 +78 +92 +92

H7 0 0 0 0 0 0 0 0 0 0 0 0 0+63 +70 +70 +80 +80 +90 +90 +105 +105 +125 +125 +150 +150

Conditions required forloose-fitted inner rings

A loose fit of the inner ringsrequires a certain minimum rollneck hardness to limit wear of theroll necks. Roll neck wear is alsoconsiderably influenced by thelubricant film between inner ringbore and roll neck surface. Ifadequate lubrication of the rollneck is ensured over the entireperiod of operation, a roll neckhardness of 35 to 40 Shore C issufficient.If, for instance, the chocks are not,as usual, removed for the grindingof the rolls, the gap between theinner rings and the roll neck willnot be repeatedly supplied withfresh grease. In such cases aseparate roll neck lubricating systemis provided, fig 51. Schaeffler GroupIndustrial also urgently recommendssuch a roll neck lubricating systemfor sealed four-row tapered rollerbearings if the bearings remain onthe roll necks for a long time (drainholes must be provided in the under-side of the chocks).

Grooves have to be provided in theabutment surfaces of parts adjacentto the inner ring. Through thesegrooves, grease will be supplied tothis area and into the gap betweeninner ring and roll neck. Somebearing series are produced withsuch lubricating grooves in the innerring faces so that no lubricatinggrooves have to be provided in thesurrounding parts.

Chocks

The rings of roll neck bearings arenearly always thin-walled. Theymust, therefore, be well supported;otherwise they would be unable toaccommodate the high operatingloads.For efficient support of the bearingouter rings the chocks must besufficiently rigid. Chocks made ofcast steel with a minimum tensilestrength of 450 N/mm2 generallyoffer sufficient rigidity if their designis based on the following formulae:

Surrounding partsConditions required for loose-fitted inner rings · Chocks

44

where hA represents the upper, hB

the lateral and hC the lower wallthickness of the chock in mm. d represents the bearing bore inmm and D the bearing O.D. in mm(fig. 52). If the chock design isbased on these formulae, and if theoperating loads are not too high,the influence of chock deformationon the bearing stressing will usuallyremain within acceptable limits. Forextreme loads and new designs itwould be advisable to check thedeformation of the chock and itseffect on the bearing by calculation.This calculation can be effectedquickly by means of a computerprogram developed by us.

51: Bearing arrangement with lubricating holesin the roll neck

52: Wall thicknesses of a chock

D d

D

hA

hC

hB hB

hA = (1,5 ... 2,0)D } d

2

hB = (0,7 ... 1,2)D } d

2

hC = (0,15 ... 0,25)D } d

2

The deformation of the chock isdetermined by means of the strain-energy method, with thechock being regarded as a heavilycurved closed beam with a variablecross section. The result of such acalculation is shown in fig. 53.To ensure accurate running of therolls and close gauge control of therolled product, the chock clearancein the stand window should besmall. On the other hand, thereshould be sufficient clearance toavoid jamming of the chocks atoperating temperature. This appliesnot only to the chock located in thestand but also to the floating one.When specifying the clearance, thetemperature gradient betweenchock and roll stand should be

taken into account. At low rollingspeeds, it is approx. 30 K, and athigh rolling speeds approx. 50 K.

Stand windows and chock seats

A reasonable clearance for thechocks is obtained by adding upthe tolerance field H9 and the heatexpansion differential betweenchock and roll stand. Sometimes,however, mounting requirementsnecessitate a larger clearance.The chock seats in the standwindows and on the screw-downmechanism must be crowned; inthis way the bore of the chock canalign itself parallel to the roll neck,and the bearing can carry loads

Surrounding PartsChocks

45

over its entire width even if it isnot exactly adjusted and if rolldeflections occur. The supportingareas should be hardened to resistflattening under these high loads.With multi-row bearings, the milldesigner should make sure thatthe position of the screw-downmechanisms is dead in line withthe centre of the radial bearing, asotherwise the roller rows would beunevenly loaded.

Coupling design, too, has aninfluence on the running behaviourof the rolls. Smooth running is, forinstance, achieved by usingcouplings which are shrunk ontothe drive-end neck of the roll.

53: Graphic representation of the calculation results

2500

2500

1050

1800

FR

FR FR

b ca

a) idealized form of thechock

b) chock deformation(exaggerated)

c) load distribution withinthe bearing

Seals

The seals serve to prevent thepenetration of cooling liquid, millscale and other contaminants intothe bearings; also, they preventlubricant from escaping from thebearings.The type of seal chosen for specificapplications depends on the rollingspeed, the required sealingefficiency, the lubricant and theoperating temperature. The followingillustrations show several typesof seals used in rolling millconstruction.In hot-rolling stands, the bearingsmust be sealed against the ingressof water and mill scale. Fig. 54

shows an effective sealing for smallroll stands. An axial sealing ringflings off any water coming near thebearing. A grease-filled labyrinthand two collar seals complete thesealing. During operation, grease isperiodically replenished betweenthe collar seals so that water andmill scale cannot penetrate into thebearing.Additional collars further increasethe efficiency of this sealing system.Additional protection against wateris provided by grooves on theoutside of the rotating labyrinthring. The water collects in thegroove provided in the stationaryhousing cover and is dischargedthrough a hole in the bottom

Surrounding partsSeals

46

(fig. 55). The distance “a” betweenbearing and roll body is usuallyvery short to keep the bendingstresses in the roll neck as small aspossible. The lateral space availablefor the sealing is then very limitedso that the individual seals ofcombined sealing units must bepositioned one above the other.Often, collar seals cannot be usedfor the bearings in rolling stands offine-section and wire mills due tothe high speeds. In such casesseals built of piston rings (fig. 56)or face seals (fig. 57) are used. At high speeds, the lip of the faceseals lifts off its contacting surface,thus preventing seal wear andfrictional heat.

54: Sealing for small hot-rolling stands 55: Sealing for large hot-rolling stands exposed to heavy contamination

a

As already mentioned, in certainapplications the bearing inner ring,and possibly the inner labyrinthring as well, are slide-fitted on theroll neck (fig. 58). In this case notonly the entrance to the bearingitself must be sealed – in fig. 58 bylabyrinth and collar seal – but alsothe gap between the labyrinth ringand the roll neck. This gap issealed by a face seal, fig. 58.In hot-rolling mills with horizontalrolls, the seals at the drive end andat the operator’s end are alwaysidentical. This is not possible withvertical rolls: since the openings ofthe labyrinth rings must be directeddownwards so that the water can

drain off, the labyrinth rings cannotbe identical.In hot-rolling stands, lubricantleaking from the bearings has nonegative effect on the rolled material.In cold-rolling stands, however, anyleakage from the bearings must beavoided since the lubricant mightcontaminate the material surface as well as the rolling fluid. Therefore the inner collar seal isfitted with the lip directed towardsthe bearing (figs. 59 and 60 onpage 48).The surfaces on which the collarseal lips slide must be superfinished. To avoid damage to thesealing lips during mounting, the

Surrounding partsSeals

47

sliding surfaces must be chamfered.The sealing lip must be lubricatedregularly.At the end not facing the roll,sealing is usually less difficultespecially if a closed cover isprovided. As a rule, one collar sealwith the lip directed toward thebearing is sufficient. Where no endcover is provided, a second collarseal with its lip directed outward isoften fitted.The dimensions of the collar seals,face seals and piston ring typeseals as well as the attainablesliding speed and the permissibleambient temperatures are indicatedin the manufacturers’ catalogues.

56: Sealing in a small rolling stand consistingof a piston ring and a labyrinth

57: Sealing system for a high-speed roll neckbearing consisting of a face seal and alabyrinth

58: A face seal seals the gap between innerlabyrinth ring and roll neck

Surrounding parts · Mounting and maintenancePreparations for mounting

48

Detailed mounting and dismountinginstructions are contained in ourPublication WL 80 100 “Mountingand Dismounting of RollingBearings”. In addition to theinformation given there, we will inthe following explain a number ofprocesses of importance for rollingmill operation.

Preparations for mounting

Prior to mounting the bearings, thesurrounding parts – roll necks,chocks, sleeves, covers etc. – haveto be checked for dimensional andgeometrical accuracy against thedesign drawings.

Likewise, the specified surfacefinish of the roll necks, chocks andlateral abutting surfaces have to bechecked. All sharp edges and burrsfrom machining must be removed.

Checking of cylindrical roll necks

An exact check of the dimensionaland geometrical accuracy ofcylindrical roll necks necessitatesfour diameter readings to be taken(1-2-3-4) at each of the threepositions (c-d-e) for the radialbearing seats and at each of thetwo positions (a-b) for the thrustbearing seats (fig. 61). The valuesmeasured are recorded in ameasuring report.

59: In cold-rolling stands the sealing lip of the inner collar seal must be directed towardsthe bearing (back-up roll)

60: Symmetrically arranged collar seals for the work rolls of a cold-rolling stand

61: Measuring points for checking roll necks

123 4

a1 b1 d1 e1c1 f1 f2 d2e2 c2 a2b2

Checking of tapered roll necks

For checking tapered roll necks(taper 1:12 or 1:30), we recommendto use our taper measuringinstrument MGK9205. Tapered roll necks with a largediameter can be measured with astraight edge whose upper edgeand lower edge form an angle, thetaper angle of the journal = 2 α. If the upper edge of the straightedge is parallel to the generatrixof the roll neck, which is situateddiametrically opposite to thestraight edge, i.e. if M has thesame magnitude at two measuringpoints, the taper angle of the rollneck is o.k. Moreover, the tapermust have a certain ratio to areference face, e.g. to the side faceof the roll body. Taper measuring instrumentsMGK9205 (fig. 63) are available inseveral sizes and designs, see TI No. WL 80-70.

A tolerance according to IT6 ispermitted for the taper diameter.The permissible deviation of thetaper angle from nominal is shownin table 65.

Mounting and maintenancePreparations for mounting

49

Checking of the chocks

The chocks should be measuredacross four diameters (1-2-3-4) infour lateral positions (a-b-c-d), fig. 64. Also, the position of thechock bore relative to the chockface (A1 and A2) has to be checked,if necessary with the locking ledgesscrewed on (for tolerances of formand position, see page 40).The deviations from nominal shouldbe recorded in a measuring reportin the same way as those measuredfor the roll neck.The surrounding parts also have to be checked, especially alldimensions leading to an axialpreload. The surfaces of thesurrounding parts must be squareto the roll axis (for position andform tolerances, see page 40).The lubricating holes have to becleaned and subsequently checkedby blowing compressed air throughthem.

62: Checking the roll neck of a small rollwith a dial indicator snap gauge.

63a: Straight edge of the Taper MeasuringInstrument MGK9205

63b: Measuring a tapered roll neck with a TaperMeasuring Instrument MGK9205; the stoptouches the front datum surface.

64: Measuring points for checking the chock

2α

R

M

123

4

a b c d

A1 A2

A

Surface finishThe bearing seats must not be toorough so that a positive contact

between mating parts and asatisfactory transmission of thehigh loads are ensured.

Mounting and maintenancePreparations for mounting

50

The bearing seat roughness ofroll bearings should not exceed thevalues specified on page 41.

66: Measuring the bore of a large chock with an internal micrometer 67: Checking the surface roughness

65: Permissible deviation of the taper angle

Dimensionsmm

Bearing width B > 16...25 > 25...40 > 40...63 > 63...100 > 100...160 > 160...250 > 250...400 > 400...630

Tolerancesμm

Taper angle tolerance ATD +8 +12,5 +10 +16 +12,5 +20 +16 +25 +20 +32 +25 +40 +32 +50 +40 +63to AT7 (DIN 7178) (2·t6) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

The taper angle tolerance ATD is measured perpendicular to the axis and is defined as the difference between thetwo diameters. When using FAG taper measuring instruments, the ATD values must be halved (tolerance of angleinclination).For bearings with nominal width values between two values indicated in the table, the taper angle tolerance ATD

must be determined by interpolation.

Example: Bearing with B = 90 mm

ATD =Δ ~ ATD

~ B =25 } 16

~ 90 =9

~ 90 � 22 μm ( ATD / 2 = t6 amounts 0...+11 μm )ΔB 100 } 63 37

Protection of the bearing seats

The formation of fretting corrosionin all seating areas where rollingbearings are fitted with a sliding fit(chock) or with a tight fit (roll neck)can be reduced by coating themwith a lubricating paste with ananti-corrosion additive, e.g. withour ARCANOL-MOUNTINGPASTE.Prior to applying the coating, theseats have to be cleaned thoroughly.Such a thin layer of the pasteshould be applied that the normallybright surface is just dulled.

Preparation of bearings for mounting

The bearings should not be removedfrom their original packing untilafter the chocks and rolls and allaccessories are ready for themounting process. Normally theanti-corrosion oil does not have tobe washed out as it does not react

with any of the commonly usedrolling bearing oils and greases.The performance, load carryingcapacity and service life of abearing depend not only on itsquality but also on correct mounting.Therefore, the mounting should bedone only by experienced fitters.Our fitters are at the disposal ofcustomers for initial mounting, forbriefing the fitters at a customer’splant and for any other eventuality.In the following paragraphs we willexplain how four-row cylindricalroller bearings, four-row taperedroller bearings and spherical rollerbearings are to be mounted anddismounted in roll neck applications.

Mounting of four-rowcylindrical roller bearings

Four-row cylindrical roller bearingsdiffer by their design (fig. 68).

Mounting and maintenancePreparations for mounting · Mounting of four-row cylindrical roller bearings

51

Design I: Outer ring + roller set: two outer rings, three loose lips,rollers and cagesInner ring: two inner ringsDesign II: Outer ring + roller set: two outerrings with integral lips, rollers andcagesInner ring: two inner ringsCustomers can order either acomplete bearing (e.g. Z-524678.ZL)or the single components, e.g. outer ring with roller set(Z-R524678.ZL) and inner ring (Z-L524678.ZL). Each inner ring and outer ring ismarked with the bearing code (e.g. Z-524678.ZL) and the serialnumber (e.g. 5), fig. 69. The innerrings at each bearing location musthave the same serial number; thesame applies to the outer rings(e.g. 5.. and 5..A). Inner rings ofone serial number can, however, bematched with outer rings and rollersets with a different serial number.

68: Different designs I and II of four-row cylindrical roller bearings

69: Marking and assembly of the components of four-row cylindrical roller bearings

Design I

Design II

5..

5..

5..

5..

5..

5..A

5..A

5..B

5..B

5..B

5..A

5..A

5..C

5..C

Design I

Design II

First, the labyrinth ring or backingring – depending on the interference – is heated to 150 to170 °C and shrunk onto the rollneck. While the ring cools down, itmust be axially clamped so that itabuts the roll body without a gap.

Mounting of the inner rings

The inner rings of cylindrical rollerbearings with a cylindrical bore,which are tightly fitted on the rollneck, have to be heated to 80 to100 °C prior to mounting. This isusually done in an oil bath (fig. 70)which ensures uniform heating. An

excessively high heating temperaturecan be avoided by using athermostat. After the rings are takenout of the oil bath, the oil in thebores and on the faces of the ringsmust be wiped off.Frequently, the inner rings aredismounted by means of aninduction heating device (see page 59). If such a device isavailable, it can also be used toheat the inner rings for mounting.After the heating process, smallerbearing rings are manually placedon the roll neck (fig. 71). For largerbearings, we recommend to usemounting tools, e.g. a pair ofmounting grippers (fig. 70). The

Mounting and maintenanceMounting of four-row cylindrical roller bearings

52

grippers always carry the ring withits axis in a horizontal position. If arope is used to suspend the innerring, it must, as a rule, be carefullyadjusted in a horizontal position.After cooling down, the rollingbearing rings should abut thelabyrinth ring without a gap. Neithershould there be a gap between twoadjacent labyrinth rings. Thereforethe rings have to be axiallyclamped while they cool down.Smaller inner rings can also bemounted without a gap betweenthem by pushing a so-calledmounting sleeve against the ringface while the rings cool down.

71: Fitting a small cylindrical roller bearing inner ring manually70: The inner ring of a cylindrical roller bearing is heated in an oil bathand then lifted out by means of a pair of grippers.

Mounting of outer rings

The outer rings of cylindrical rollerbearings are slide-fitted in thechocks. Smaller outer rings can beinserted into the chock manually.The outer rings or cages of largerbearings are usually provided withthreaded holes for eye bolts sothey can be inserted into the chockmore easily (fig. 72).If very large bearings have to bemounted with their axis in ahorizontal position, the rings can,for instance, be inserted into thechock on a beam suspended inropes (fig. 73).The outer ring faces are dividedinto four zones which are marked I,II, III and IV (fig. 74). On initialmounting the outer rings arepositioned such that the load isacting on zone I. The load zones ofall outer rings should be positionedin the same direction.We recommend to check the bearingsthoroughly after 1 000 to 1 200 hoursin operation. Then the outer ringsshould be rotated inside the chockby 180° to load zone III and, thenext times, to load zone II and then IV.

Mounting and maintenanceMounting of four-row cylindrical roller bearings

53

72: Mounting of a cylindrical roller bearing outer ring by means of a crane

73: Mounting of a cylindrical roller bearing outer ring by means of a beam

74: The load zones of a four-row cylindrical roller bearing are marked on the outer ring.

508

75

0

FAG . .

5087

50

FAG

Made

in

Gemany

IV II

III

I . .

Mounting of thrust bearings

Angular contact ball bearings anddeep groove ball bearings used asthrust bearings must not be loadedradially. Therefore the chock bore isusually 0,6...1,5 mm larger thanthe bearing outside diameter. This may produce a radialdisplacement of the outer ring so that only the upper balls carrythe thrust load. To prevent this, the fitter should bring the rolls,complete with chocks and radialbearings, into working position. In this position, the center lines ofthe radial bearing inner rings areoffset radially in relation to theouter ring centre line by half theradial clearance. The thrust bearingsare then installed in this position.To enable the outer ring to radiallyalign under axial load, the coverbolts are tightened only slightlyand then locked in this position.Spherical roller thrust bearings areaxially preloaded by means ofsprings; they are used primarily inwork rolls. There must be sufficientradial and axial clearance betweenouter ring and housing (fig. 75).The cups of double-row taperedroller bearings with a large contactangle are also axially adjusted bymeans of springs (fig. 76).

Mounting of pre-assembled chockson the roll necks

Once the labyrinth ring and theinner rings have been shrink-fittedonto the roll neck, the pre-assembledchock can be pushed onto the rollneck (fig. 77).

Mounting and maintenanceMounting of four-row cylindrical roller bearings

54

75: Mounting of thrust bearing components in the housing

76: The cups of double-row tapered roller bearings are adjusted by means of springs.

77: The pre-assembled chock is pushed onto the roll neck. The loose lip of the cylindrical roller bearing outer ring is temporarily retained by angle pieces.

If the inner rings are to be fittedloosely on the roll neck, their boreshave to be greased or oiled beforemounting.The chocks, complete with outerrings and thrust bearings, areusually carried to the roll neck bymeans of a crane and aligned asclosely as possible with the rollneck so that the chocks can bepushed easily onto the neck. In theprocess, no score marks must beproduced on the rollers and innerrings.The inner rings or the sleeves onwhich the thrust bearings aremounted must be clamped bymeans of a locknut so that theycannot creep during operation,causing wear. The locknut must besecured.

Dismounting

After removing the parts holdingthe thrust bearings on the roll, thechocks can be withdrawn from theroll neck as complete units.When the rolls are replaced, thechock can be mounted onto thenew roll after the inner rings havebeen mounted.Dismounting of the differentbearing components for inspectionis effected in the reverse order of mounting, using the sameequipment.Withdrawal of the tightly fittedinner rings from the roll neckrequires special equipment. Induction heating devices (seepage 59) have proved suitable forthis purpose. In some casesthe inner rings are extractedhydraulically. But there may beproblems, especially with largebearings, if the fitting surfaces

are damaged by cold welding orfretting corrosion. In exceptionalcases the inner rings can also beheated with a gas burner (page 60).

Mounting and maintenanceMounting of four-row cylindrical roller bearings

55

Loose fit of the inner rings

In section or light-section millswith a frequently changing rollingprogramme, the inner rings aresometimes slide-fitted onto the rollnecks. The cover facing the rollbody is designed such that on itsremoval the bearing rings areremoved as well. Thus the compo-nents of the bearing arrangementare held together as a unit (fig. 79).

78: Completely assembled chock

79: When changing the chock, the complete unit is replaced.

Mounting of four-rowtapered roller bearings

The components of four-rowtapered roller bearings are markedas follows: bearing code, FAG logo,serial number and letters to ensurethe correct mounting order. Fig. 80shows how the sides of the bearingrings are marked.The widths of the spacer rings B, Dand C have been machined suchthat the correct axial clearance isobtained. The ring width and axialclearance are indicated on thespacers.Like the outer rings of four-rowcylindrical roller bearings, the cupsare divided into four zones markedI, II, III and IV (fig. 74).

Mounting

Four-row tapered roller bearings aremounted vertically. First, the narrowcup marked AB is inserted into thechock with its load zone I in thedirection of the load. Then the othercomponents are inserted in theorder shown in fig. 80. The loadzones I of all cups must be turnedin the direction of the load.The cages of large four-row taperedroller bearings feature threadedholes for eye bolts (only designedfor transport purposes). Theyfacilitate the handling andmounting of the bearing components(figs. 81 and 82).After all bearing components havebeen mounted, the cover bolts aretightened slightly, the seal not yetbeing in place (fig. 83).

Mounting and maintenanceMounting of four-row tapered roller bearings

56

81 and 82: The bearing components are inserted into the chock

80: Sequence of assembly of the bearing components

A BB

A

B

Ca

DC

Ce E

DED

81 82

Then the chock is turned over sothat the bearing axis is horizontal.Centering pieces are attached tothe cone’s outer faces and clampedwith tie rods (fig. 84).While constantly turning the innerrings, the nuts at the tie rods andthe cover bolts are tightened evenly.A feeler gauge is used to check if

cones and spacers abut each otherwithout a gap. Then the gap Sbetween chock and cover ismeasured, and a seal of therequired width (S + x) inserted. The magnitude of x required for asafe preload depends on the typeof seal used and is determined bythe rolling mill manufacturer. Oncethe cups and the cover have beenclamped tightly, the centeringpieces and tie rods can be removed.Experienced fitters can do withoutcentering pieces and tie rods.While inserting the cones into thevertical chock, they constantlyrotate the cones until the taperedrollers positively contact theguiding lips. Then they insert theradial seals into the cover.The cone bores are greased oroiled. After the labyrinth ring hasbeen shrunk on, the chock ismounted onto the roll neck.The bearing is axially clamped withthe locknut until it abuts thelabyrinth ring without a gap. Whiletightening the nut, the chock

Mounting and maintenanceMounting of four-row tapered roller bearings

57

should be turned several times tothe left and right. Then the nut isloosened again until there is a gapof 0,2 to 0,4 mm between cone andnut. With a thread pitch of 3 mm,this distance corresponds to onetenth of a nut turn.It is advisable to grease the bearingonly after mounting to avoidcontamination of the grease. Thisis best done by means of a greasegun. If no grease gun is available,the roller-and-cage assemblieshave to be greased manually priorto mounting.Where rolling speeds are very high,the chocks must not be completelyfilled with grease. Please askSchaeffler Group Industrial forinformation on the appropriateamount of grease for specificapplications.

83: The cover bolts of the chock are tightenedslightly, and the chock is turned into ahorizontal position.

84: The cups are clamped together while the cones are constantly rotated.85: The mounted chock

S84 85

Dismounting

If the chock is to be mounted ontoa different roll on the occasion ofroll replacement, all the fitterneeds to do is remove the nut,withdraw the complete chock fromthe neck and mount it onto the newroll. If the bearings have to bedismounted for maintenance andinspection, dismounting is effectedin the reverse order of mounting.Double-row tapered roller bearingscan be dismounted in the sameway.

Maintenance

After some time in operation, theaxial clearance of the four-rowtapered roller bearings increasesdue to wear of the running surfaces.It is therefore necessary to checkthe axial clearance from time totime.If the axial clearance is too largethe spacers must be reground. Thecorrected axial clearance should besomewhat larger than the originalaxial clearance. More details aregiven in our “Mounting andmaintenance instructions for four-row tapered roller bearings”.

Mounting of sphericalroller bearings

Spherical roller bearing inner ringsare installed in rolling stands witha tight or loose fit. If the inner ring may have a loosefit, mounting is easy. First, thebearings are inserted into thechock and the lateral covers arescrewed on. Prior to mounting thechocks with the bearings onto the

roll necks, the inner ring boresshould be greased. The mountingprocess is made easier by using amounting sleeve.Since the inner rings revolve on the roll neck, a small amount ofclearance must be providedbetween the lateral abutmentsurfaces. This axial clearance isbest obtained by first tighteningthe nut and then loosening it againas with tapered roller bearings. Inthis position the nut is secured.If a tight fit of the spherical rollerbearing inner rings is required,bearings with a tapered bore arecommonly used.On the occasion of roll replacement,the bearing can be mounted ontothe new roll provided that thetapered roll necks and the width ofthe labyrinth rings have very closetolerances.

Mounting of tapered-bore spherical roller bearings

The greased spherical roller bearingis inserted into the chock andclamped. The chock with thespherical roller bearing is pushedonto the roll neck until it abuts theroll neck. Then the chock is pushed

Mounting and maintenanceMounting of four-row tapered roller bearings · Mounting of spherical roller bearings

58

even further onto the roll neckusing the hydraulic method. Forthis purpose the roll necks musthave oil grooves and oil ducts. Thechock is best pressed up onto theroll neck by means of a hydraulicnut. Details on hydraulic mountingand hydraulic nuts are given in thePublication WL 80 102 and inTPI WL 80-57.The spherical roller bearing ispushed onto the roll neck until itabuts the labyrinth ring (fig. 86). Toensure that the specified drive-updistance is observed, the width ofthe labyrinth ring must be exactlyadapted to the actual diameter ofthe tapered roll neck.Then the hydraulic nut is removedand the locknut placed on the rollneck, tightened and secured.

Dismounting of tapered-borespherical roller bearings

The locknut is loosened by a fewturns, the distance correspondingat least to the drive-up distance. If now oil is pressed between thefitting surfaces, the bearing willsuddenly come off as soon as anuninterrupted oil film has formed.After removing the locknut, thechock with the spherical rollerbearing can be removed from theroll neck and mounted onto anotherroll neck.

86: Mounting of a spherical roller bearing bymeans of a hydraulic nut.

Methods for the mountingand dismounting of cylindrical roller bearinginner rings (tight fit)

Induction heating

To release the tight fit of cylindricalroller bearing inner rings, theymust be quickly heated up to 60 to80 K above ambient temperature,that is to 80 to 100 °C for a rolltemperature of 20 °C. During thisprocess the roll neck should heatup as little as possible to obtainsufficient clearance between theinner ring and the roll neck toremove the inner ring.Induction heating equipmentoperating at 50 Hz (A.C.) hasproved suitable for mounting anddismounting medium-sized andlarge cylindrical roller bearing innerrings. With the usual wall thicknessof the inner rings, the roll necktemperature increases – dependingon the roll neck volume – by only5 to 10 K while the inner rings reach

temperatures of 80 to 100 °C. Thistemperature must be reached – andis reached by our equipment – within0,5 to 1,5 minutes for small andmedium-sized bearings and within2,5 to 5 minutes for larger bearings.

Induction coils for 400 Vand low-voltage induction coils

Mounting equipment should not betoo complex and expensive since itis used only rarely. For the occasionalmounting and dismounting of smalland medium-sized cylindrical rollerbearing inner rings with diametersof up to ca. 200 mm, a 400 Vdevice is the best solution (fig. 87).

Mounting and maintenanceMethods for the mounting and dismounting of cylindrical roller bearing inner rings

59

For large bearing rings, an inductioncoil which is connected directly tothe 400 V mains is too impractical;it weighs several times as much asthe parts to be mounted. For regularmounting of large and medium-sizedrings it is advisable to operateinduction heating equipment onlow voltage (fig. 88). A transformeris connected between two phasesof the 400 V mains and the inductioncoil; the secondary circuit of thetransformer must be adjustablebetween 20 and 40 V.

87: Diagrammatic view of a pedal switch induction coil (400 V) for cylindrical roller bearing inner rings with a bore diameter of 130 mm

88: Low-voltage induction coil with transformer

Ring mass 7,2 kgCoil mass ca. 15 kgCurrent ca. 60 AHeatup time 40 sCoil body made of laminatedfabric

Using low-voltage equipment offerstechnical and economic advantages.The electric coil can be cooled withwater so that it does not heat up.Thus the copper winding can behigher loaded. The device is lighterand, due to the improved electriccoupling of the single or doublelayer coil, it offers an increasedefficiency. The devices can be used to heatinner rings for mounting anddismounting.When shrink-fitting the inner ringsonto the roll neck, it is advisable tofirst put them onto the neck end,heat them up to mountingtemperature and then push themonto their seat together with theinduction coil (fig. 89). If the rollneck end is not shaped to guidethe rings, we recommend to use amounting sleeve (fig. 90).The bearing rings and roll necksare magnetized by the inductionheating process; they must bedemagnetized after mounting. Thiscan also be done by means of theinduction coil. The induction coil ispulled over the mounted part withthe current switched on and thenslowly removed to a distance of1 to 2 meters from the parts. As thedistance increases, the effect ofthe magnetic field decreases untilits influence is so feeble that theparts are sufficiently demagnetized.

Heating with gas burners

In cases where the rings cannot bedismounted by means of inductioncoils or the hydraulic method, onlyone possibility is left: heating byflame. This method should only beemployed as an emergency measure.Ring burners (fig. 91) have proved

to be an acceptable solution. The burner should be positionedca. 50 mm from the ring surface.For the usual gas pressure thediameter of the burner jets is 2 mm.

Mounting and maintenanceMethods for the mounting and dismounting of cylindrical roller bearing inner rings

60

The jets are spaced over thecircumference 25 mm apart. Thetemperature and length of theflames are adjusted by the additionof air. Guiding pieces ensure a

89: Mounting of two inner rings by means of an induction coil. The device is also used fordismounting.

90: The rings are guided on a mounting sleeve.

91: Gas ring burner

Gas Air

concentric position of the ringburner and an even heating of thebearing rings. The ring burner mustbe moved back and forth across thering in axial direction to ensureeven heating of the rings.In rare cases a welding torch isused, which renders the bearingrings unserviceable as temperaturesof more than 300 °C are reached.Then fluorinated materials, e.g.Viton® seals, can release gases andvapours which are detrimental tohealth. Please observe the relevantsafety data sheet.

Mounting facilitiesfor roll couplings andlabyrinth rings

Induction heating of roll couplings

Apart from the inner rings, in somecases the couplings are also tightlyfitted on the roll necks of high-speedwire and light-section trains.During each roll change the rollcouplings must be removed andmounted onto other rolls. With theformerly used hydraulic methodthis procedure took much time and,particularly after repeated mountingand dismounting, it becamedifficult. Therefore FAG hasdeveloped induction heatingequipment similar to that used for inner rings. In this way themounting times have been reducedconsiderably.As a rule, the couplings aremounted onto the roll necks withan interference of 1,5 to 1,8 ‰. A mounting temperature of 170 to200 °C is required to release theinterference fit. This temperature isreached within 70 to 360 seconds,depending on the coupling size.

To date, induction coils for couplingsweighing up to 485 kg are available.For several years these deviceshave proved their worth in a numberof rolling mills.The design of such an inductioncoil is shown in fig. 92. Thereplaceable tapered sleeve betweenroll neck and coupling which wasrequired for the hydraulic mountingmethod was split and retained as awearing part. Couplings with acylindrical seat and without sleeveare also induction-heated.For dismounting a coupling shrunkonto a cylindrical seat, it isadvisable to suspend the rollvertically such that the couplingcomes off by its deadweight oncethe required temperature aboveambient is reached. Couplingsseated on a tapered sleeve arepulled from the roll neck by meansof an extractor with the roll in ahorizontal position.

Mounting and maintenanceMethods for the mounting and dismounting of cylindrical roller bearing inner rings ·Mounting facilities for roll couplings and labyrinth rings

61

The induction coils for couplingsuse the same transformers as theinduction coils for cylindrical rollerbearing inner rings. Of course theacquisition cost of an inductioncoil is higher than that of hydraulictools. But since many roll necksmust be provided with oil groovesand oil holes for the hydraulicmounting method, and since theexpense for drilling long co-axialholes in large rolls is high, inductioncoils pay after a short time.Moreover, mounting with aninduction coil is cleaner and faster.

Induction coils for labyrinth rings

We also offer induction coils(operated with mains voltage) andlow-voltage coils for heatinglabyrinth rings.

92: Design of the induction coil for couplings. The extractor makes removal of the coupling easier.

Labyrinth rings (fig. 93) are usuallyshrunk onto the roll neck with alarge interference to prevent themfrom working loose if they are heatedin operation by the rubbing seal.It is often difficult to remove tightlyfitted labyrinth rings. By means ofan induction coil they can be heatedto 150 to 200 °C within a fewminutes, and the shrink fit isreleased. The devices are inexpensiveif a factory already has theswitching unit or the transformerfor an induction coil for inner rings.

Spares

To prevent costly downtimes it isadvisable to always have three anda half complete sets of bearings foreach stand. One of these sets ismounted on the rolls actually inoperation. A second set is mountedon the rolls being reground. A thirdset of rolls with bearings shouldalways be readily available. Anadditional half set of bearingsshould be kept in stock in order to

complete the bearing sets in theevent of a bearing failure.For cylindrical roller bearings withtightly fitted inner rings it isadvisable to procure additionalinner rings and mount them ontothe roll necks. If the rolls have tobe changed frequently, e.g. insection rolling mills, frequentmounting and dismounting of theinner rings is then not necessary.

Statistical stockkeeping

Upon arrival at the mill, a recordcard should be prepared for eachroll neck bearing (page 63) onwhich all important data arerecorded. It should be completedby operating data, e.g. temperaturesand rolling loads measured duringoperation. Such constantly updatedrecords ensure a more realisticevaluation of operating conditionsand bearing performance thanwould be possible by basing thecalculation on assumed loads.

Mounting and maintenanceMounting facilities for roll couplings and labyrinth rings · Statistical stockkeeping

62

93: Labyrinth ring of a work roll of a 4,2 mheavy-plate stand

Mounting and maintenanceStatistical stockkeeping

63

94

Mill Back-up roll O

Bearing type Bearing No. Serial No.

Bore dia.

Date of order Date of delivery1 st installation Hrs. total Total (tons)

O. D.Double row Radial Clearance Lubricant

Four-row Axial Clearance Lubr. Intervals WidthInstallNo.

1

2

345

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

∞ i a ∞ i a

22

23

24

25

26

27

28

29

30

31

32

33

34

35

For Inspection of Four Row Tapered Roller Bearings

B

C

D

B

C

D

B

C

D

B

C

D

B

C

D

B

C

D

Mounted Dism. StandNo.

Chock No.

Roll No. Loaded zone Drive Side

Inner OuterWith. Side

Inner Outer

Top Roll Bot. Running(hours)

Total run(hrs.)

Production(tons)

Totalproduction

(tons)Remarks

InstallNo.

Mounted Dism. StandNo.

Chock No.

Roll No. Loaded zone Drive Side

Inner OuterWith. Side

Inner Outer

Top Roll Bot. Running(hours)

Total run(hrs.)

Production(tons)

Totalproduction

(tons)Remarks

Date DateGap GapSpacerwidth Clearance Ground

toNew

clearance DateSpacerwidth Clearance Ground

toNew

clearance Gap Spacerwidth Clearance Ground

toNew

clearance

Rolling Bearing Check Card Train Work roll O

Storage

The bearings should be stored intheir original packaging. Theyshould be unpacked only when they are actually needed. In thisway contamination and corrosioncan best be avoided. Large bearingswith relatively thin-walled ringsshould not be stored standingupright but laid flat, supportedover their entire circumference.During transport, care must be takennot to damage the direct wrappingwhich, for large bearings, usuallyconsists of plastic foil.Our rolling bearings are immersedinto anti-corrosion oil and thusprotected from environmentalinfluences as long as they are keptinside their wrapping. Thisprotection is effective for a longtime but only if the bearings arestored in a dry and frost-proofroom. Of course, no corrosivechemicals such as acids, ammonia

or chloride of lime must be storedin the same room.Bearings dismounted for temporarystorage must be washed andimmediately afterwards preservedand wrapped. It is advisable towash them with kerosene.Smaller bearings are preserved bydipping them into anti-corrosionoil. Larger bearings are sprayedcarefully with anti-corrosion oil.Instead of wrapping the bearings,they can be stored immersed in anoil tank.If chocks, complete with bearings,are not to be used for some time,they must be checked to make surethat no water has penetrated intothe chocks. If there is any water,the bearings must of course befilled with fresh grease or – in thecase of oil mist lubrication – cleanedand preserved. For storage, thechocks are closed with covers onboth sides.

Mounting and maintenanceStorage

64

Roll neck mountingsof a wire mill

Builder:SMS Schloemann-Siemag AG,Düsseldorf and Hilchenbach

The wire mill is designed for a finalspeed of 50 m/s. A close finaltolerance is specified for the rolledwire.The line is made up of threesections:• Roughing section (six stands)• Intermediate section

(eight stands)• Finishing section

80~80 mm billets are reducedcontinuously down to wire withdiameters of 12 to 5,5 mm.The roughing and intermediatesections handle two strands. Leavingthe intermediate section, the twostrands are fed to the separatesingle-strand finishing sections.The first stand of the roughingsection comprises rolls with a bodydiameter of 450 mm, the secondstand has rolls with a body diameterof 420 mm. Both roll sizes aresupported by identical bearings.The body diameter of the remainingstands of the roughing section is380 mm.

Worked example

65

In the intermediate section, thefirst two stands are also equippedwith rolls having a body diameterof 380 mm. On the remaining standsof the intermediate section, the rollbody has a diameter of 320 mm.The roll necks of the roughing andintermediate sections are radiallysupported in four-row cylindricalroller bearings. Double-row angularcontact ball bearings are providedfor transmitting the axial forces.Location of the drive end chocks isprovided by deep groove ball bearings.The dimensions and load ratings ofthe different bearings are listed inthe table below.

95: Bearing dimensions and load ratings

Stand Roll Radial bearings Thrust bearingsbody Dimensions dyn. Locating Dimensions dyn. Floating bearing Dimensionsdiam- load bearing end load endeter rating ratingmm mm kN mm kN mm

1 450 Cylindrical roller Angular contact ball Deep groovebearing, four-row bearing, double-row ball bearingZ-507336.03.ZL 260~370~220 2200 Z-508731.01.SKL 260~369,5~92 390 Z-507338.01.KL 260~369,5~46

2 420 Cylindrical roller Angular contact ball Deep groovebearing, four-row bearing, double-row ball bearingZ-507336.03.ZL 260~370~220 2200 Z-508731.01.SKL 260~369,5~92 390 Z-507338.01.KL 260~369,5~46

3-8 380 Cylindrical roller Angular contact ball Deep groovebearing, four-row bearing, double-row ball bearingZ-508727.02.ZL 230~330~206 2080 Z-508732.01.SKL 230~329,5~80 320 Z-508729.KL 230~329,5~40

9-14 320 Cylindrical roller Angular contact ball Deep groovebearing, four-row bearing, double-row ball bearingZ-508657.ZL 190~270~200 1660 Z-508658.01.SKL 190~269,5~66 224 Z-502288.KL 190~269,5~33

Roll neck bearing arrangement of the intermediate section

Fatigue life

When determining the bearingloads the fact has to be taken intoaccount that the rolling stands ofthe roughing and intermediatesections handle two strands. Theroll neck loads are calculatedaccording to the indicative valuesgiven on page 11. 5 % of theindividual maximum rolling load is assumed as axial load (see alsopage 18).The calculation of the fatigue lifefor the cylindrical roller bearingsand angular contact ball bearings issummarized in the table above.The theoretical fatigue life of nearlyall bearings exceeds 60 000 hours.

However, these values are not likelyto be reached in practice. Theservice life will be shorter due to wear.

Machining tolerances, bearing clearance

All cylindrical roller bearings in this line are fitted tightly. The roll necks of the roughing andintermediate sections are machinedto r6.The outer ring seats in the roughingand finishing sections are machinedto J7. To simplify mounting anddismounting, the inner ringsof angular contact ball bearings

Worked example

66

serving as thrust bearings aremounted on sleeves.Since it must be possible todisplace the rolls laterally relativeto each other for groove aligningpurposes, the double-row angularcontact ball bearing of one roll ineach stand is mounted on a threadedbushing. The roll can be axiallyadjusted in the chock by means ofthis bushing. The thrust bearingshave a very small axial clearance.

Lubrication

The bearings of the roughing andintermediate section are lubricatedwith grease.

96: Calculation of fatigue life

Stand Radial bearings Thrust bearingsor pass Radial Speed Speed Dynamic Index of Fatigue Axial Equivalent Speed Dynamic Index of Fatigueno. load coefficient load dynamic life load bearing coefficient load dynamic life

rating stressing load rating stressingn fn C fL Lh fn C fL Lh

kN min–1 kN h kN kN kN h

1 1 080 9,08 1,477 2 200 3,01 19 700 99 92 1,543 390 6,54 >60 000 2 530 13,47 1,312 2 200 5,45 >60 000 48 44 1,353 390 12 >60 0003 680 19,77 1,170 2 080 3,58 35 100 61 57 1,19 320 6,68 >60 0004 340 26,45 1,072 2 080 6,56 >60 000 31 29 1,08 320 11,9 >60 0005 530 36,75 0,971 2 080 3,81 43 200 49 45 0,968 320 6,88 >60 0006 360 51,9 0,876 2 080 5,06 >60 000 33 31 0,863 320 8,91 >60 000

7 330 71,5 0,795 2 080 5,01 >60 000 30 28 0,775 320 8,86 >60 0008 210 99,2 0,721 2 080 7,14 >60 000 19 17 0,695 320 13,1 >60 0009 200 156,1 0,629 1 660 5,22 >60 000 18 17 0,598 224 7,88 >60 00010 140 207,3 0,578 1 660 6,85 >60 000 13 12 0,544 224 10,2 >60 00011 180 264,2 0,537 1 660 4,95 >60 000 16 15 0,502 224 7,5 >60 00012 120 364,8 0,488 1 660 6,75 >60 000 11 10 0,45 224 10,1 >60 00013 250 411,2 0,471 1 660 3,13 22 400 23 21 0,433 224 4,62 >60 00014 100 485,8 0,448 1 660 7,44 >60 000 9,3 8,7 0,409 224 10,5 >60 000

Notes

67

The following list gives a selection of publications available. For further information please contact Schaeffler Group Industrial.

Catalogue WL 41 700 Rolling BearingsPubl. WL 41 140 FAG Rolling Bearings for Rolling Mills – Bearing Tables

Publ. WL 17 109 FAG Rolling Bearings in Rolling MillsPubl. WL 17 114 Sealed FAG Spherical Roller BearingsPubl. WL 80 100 Mounting and Dismounting of Rolling BearingsPubl. WL 80 102 How to Mount and Dismount Rolling Bearings HydraulicallyPubl. WL 80 107 FAG Induction Heating EquipmentPubl. WL 80 110 Radial Clearance Reduction of FAG Spherical Roller Bearings with Tapered BorePubl. WL 80 134 FAG Video: Mounting and Dismounting Rolling BearingsPubl. WL 80 135 FAG Video: Hydraulic Methods for the Mounting and Dismounting of Rolling BearingsPubl. WL 80 151 FAG Repair Service for Large Rolling BearingsPubl. WL 80 154 Mounting Instructions – Four-Row Tapered Roller BearingsPubl. WL 80 250 FAG Mounting and Maintenance Equipment and Services for Rolling BearingsPubl. WL 81 115 Rolling Bearing LubricationPubl. WL 81 116 Arcanol · Rolling-Bearing Tested GreasePubl. WL 81 122 Motion Guard – Automatic LubricatorsPubl. WL 82 102 Rolling Bearing Damage

TI WL 17-7 Split Cylindrical Roller Bearings for Rolling Mill Drive ShaftsTI WL 80-14 Mounting and Dismounting of Spherical Roller Bearings with Tapered BoreTPI WL 80-50 FAG Pressure GeneratorsTI WL 80-53 Rolling Bearing Mounting Cabinet and Mounting Sets - A Basic Course for Vocational TrainingTPI WL 80-54 FAG heating devicesTPI WL 80-55 FAG alignment toolsTPI WL 80-56 FAG tools for mechanical mounting and dismounting of rolling bearingsTPI WL 80-57 FAG hydraulic nutsTPI WL 80-60 Condition Monitoring with FAG ProductsTI WL 80-63 Rolling Bearing Diagnosis with the FAG Bearing Analyser IIITPI WL 80-64 FAG Detector III – The solution for monitoring and balancingTI WL 80-67 FAG VibroCheck online monitoring system for heavy industryTI WL 80-70 Measuring tapered journals with an FAG Taper Measuring Instrument of Series MGK9205

Selection of publications

68

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correctness of the information contained

in this publication but no liability can be

accepted for any errors or omissions.

We reserve the right to make technical

changes.

© Schaeffler Technologies GmbH & Co. KG

Issued: 2011, August

This publication or parts thereof may not

be reproduced without our permission.

WL 17 200/5 EA

Schaeffler Technologies

GmbH & Co. KG

Postfach 1260

97419 Schweinfurt

Germany

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97421 Schweinfurt

Germany

Phone +49 9721 91-3167

Fax +49 9721 91-3100

E-Mail herbert.roth@schaeffler.com

Internet www.fag.com