ROLLING BEARINGS FOR THE PAPER INDUSTRY - … Bearings for the Paper Industry Products · Service · Design · Dimensioning Publ. No. WL 13 103/2 EA FAG OEM und Handel AG A company

FAG OEM und Handel AG

ROLLING BEARINGS FOR THE PAPER INDUSTRY

Products · Service · Design · Dimensioning

A Partnership in PaperFAG offers a complete Paper Mill Pro-

gram that complements our DistributorNetwork.

FAG is committed to the Pulp & PaperIndustry to assure a total Quality Processfrom start to finish.

Our total 10-point concept from Or-der Entry to Proactive Maintenancebrings cost savings on a continual basis.

1. Innovation and Quality assured2. Global Resources and Support3. Products4. Inventory Review5. Stock Management6. Training Program7. Technical Service8. Proactive Maintenance9. Communication10. Documented Savings

The OEM und Handel company ofthe FAG Kugelfischer Georg Schäfer AGGroup supplies rolling bearings, neces-sary accessories, and services to originalequipment customers in machinery andplant construction as well as to customersin the distribution and spare parts busi-ness. Comprehensive rolling bearingknow-how, competent consultation onapplications, and extensive customer ser-vice for more operational reliability makeFAG an indispensible partner to its cus-tomers. Research and development of ourproducts is based on the requirements of

operation in the field. An ideal outline ofrequirements is best achieved throughcooperation of our application engineerswith the manufacturers and operators of equipment for the paper industry. Itforms the basis for successful solutionsboth technically and economicallyspeaking.

Production locations are found inGermany, Italy, Portugal, South Korea,the USA and India. Sales are conductedby sub-sidiaries and distribution partnersin almost every country in the world.

Preface

Rolling Bearings for the Paper IndustryProducts · Service · Design · Dimensioning

Publ. No. WL 13 103/2 EA

FAG OEM und Handel AGA company of the FAG Kugelfischer Group

Postfach 12 60 · D-97419 SchweinfurtTel. +49-9721 / 91-3689 . Fax +49-9721 / 91-4908E-mail: [email protected]

Contents

FAG 2

1 FAG products and servicesfor the paper industry (outline) . . . . . . . . . . . . . . . . 3

1.1 Standard rolling bearings . . . . . . . . . . . . . . . . . . . . . . 41.2 Special products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51.3 Service range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51.4 Suffixes, technical specifications . . . . . . . . . . . . . . . . 6

2 Requirements on paper machine bearings . . . . . . . . 7

3 Examples of bearing arrangementsfor paper machines . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3.1 Wet end section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83.1.1 Forming roll . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93.1.2 Suction roll . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103.1.3 Center press roll . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123.1.4 Anti-deflection roll . . . . . . . . . . . . . . . . . . . . . . . . . . 133.2 Dryer section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143.2.1 Guide roll . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143.2.2 Dryer roll . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163.3 Calender and finishing group . . . . . . . . . . . . . . . . . . 183.3.1 Calender thermo roll . . . . . . . . . . . . . . . . . . . . . . . . . 183.3.2 Spreader roll . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

4 FAG service for more operational reliability . . . . . . 214.1 Storage of rolling bearings . . . . . . . . . . . . . . . . . . . . . 214.2 Preparations for mounting and dismounting . . . . . . 214.3 Mounting and dismounting with cylindrical

and tapered mating surfaces . . . . . . . . . . . . . . . . . . . . 214.4 Fits and tolerances . . . . . . . . . . . . . . . . . . . . . . . . . . . 234.5 Monitoring and analysing bearings . . . . . . . . . . . . . . 264.6 PC programs for calculating and

designing rolling bearings . . . . . . . . . . . . . . . . . . . . . 284.7 FAG mounting service . . . . . . . . . . . . . . . . . . . . . . . . 284.8 FAG training courses . . . . . . . . . . . . . . . . . . . . . . . . . 284.9 Selection of publications . . . . . . . . . . . . . . . . . . . . . . 29

5 Dimensioning and lubricating rolling bearings . . . . 305.1 Dimensioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305.2 Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325.2.1 Grease lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . . 325.2.2 Oil lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

6 Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 386.1 Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 386.2 Radial clearance, radial clearance reduction . . . . . . . 39

Products and services for the paper industry

1 FAG products and services for the paper industry

FAG has an extensive programme ofproducts and services for the paper indus-try.

The rolling bearing demand in thisfield focusses on standard rolling bear-ings, that is rolling bearings with standar-dised main dimensions.

In pulp preparation, these are, forexample, spherical roller bearings andcylindrical roller bearings. The sphericalroller bearing dominates in paper mak-ing. Deep groove ball bearings, angularcontact ball bearings, and tapered rollerbearings are found in accessory units ofpapermaking machines (motors, gears,fans, pumps). Spherical roller bearings,angular contact ball bearings and cylin-drical roller bearings are typical standardrolling bearings in the field of finishingand converting. FAG also supplies acces-sories and housings suitable for standardrolling bearings.

Spherical roller bearings with an out-side diameter of > 320 mm, which areparticularly popular, are compiled inFAG Paper Scope. It should improveproduct availability especially for the spare parts demand of paper mills. FAGPaper Scope exclusively contains prod-ucts which are important in the paperindustry but which are not required on aregular basis and have widely varying usage levels. They are spherical rollerbearings of the popular series 230, 231,232 and 239 with design variety andcombinations typical to the paper indus-try, e.g.

– cylindrical and tapered bore– increased radial clearance (C3 or C4)– increased running accuracy (T52BW)

with a speed index ofn · dm > 250 000 min–1 · mm

– lubricating holes in inner ring (H140)– case-hardened inner rings (W209B)

for dryer rolls and calender rolls

The industrial trend is towards thedesigns C3/C4, H140, T52BW andW209B for modern machines.

FAG has also drawn up a special pro-gramme with which more complex tech-nical bearing tasks can be handled reli-ably and economically. It includes self-aligning cylindrical roller bearings, splitspherical roller bearings, triple ring bear-ings and special housings.

The FAG offer is completed withproducts for mounting, maintenance,and diagnosis, mounting and dismount-ing service, technical consultation forapplications, training courses and means,PC calculation programs and technicalpublications.

You will find an outline of the FAGproducts and FAG service for the paperindustry in the tables on pages 4 and 5.

The table on page 6 contains the rele-vant suffixes and technical specifications.

3 FAG

Spherical roller bearings for the paperindustry

Self-aligning double row cylindrical roller bearing

Condition monitoring of rolling bearingswith the FAG Bearing Analyser

Products and services for the paper industryStandard rolling bearings, housings and accessories

1.1 Standard rolling bearings, housings and accessories (Catalogue WL 41 520)

Bearing type

Deep groove ball bearings

Angular contact ball bearings

Tapered roller bearings

Cylindrical roller bearings

Spherical roller bearings

Bearing series/design/size Application

618...C3 (d 300...700) rope sheaves619...C3 (d 140...260) spreader rolls62.. (d 60...160)

160.. (d 60...160) motors, gearsagitators/mixers, fans

73.. (d 100...200) pressurized screens72.. (d 100...200) pulpers

pumps, gearswinders, reelers

pressurized screenspulpersintermediate gearspumps, gearsbreast roll – axial bearings

NU30../NU10.. (d 200...350) refiners

NU23.. (d50..140) felt rolls,NUB2../3.. (d 50...140) guide rolls

NU/N30..C5.M17D.T27 (d 180...710) dryer rolls, M. G. cylinders NU/N31..C5.M17D.T27 (d 180...710)NNU49.. (d 50...150) reel-spool bearings

FAG 5... corrugator rolls

gearspulpers

240/241.. (d 120...220) suction rolls, box bearings230..(K).MB.C3.T52BW(.H40AB/H40AC or H140) suction rolls, operator's end(d 360...710)239..(K).MB.C3.T52BW(.H40AB/H40AC or H140)(d 440...950)231..K.MB.C3 (d 440...950) suction rolls, drive end

223/222..EK.C3 (d 50...180) guide rolls232..EA(S)K.M.C3 (d 110...180)

230/231/232..K.MB.C3 (d 200...560) press rolls

230/239/(248)..MB.T52BW(.H40AB/H40AC or H140) anti-deflection rolls230/239/(248)..MB.C3.T52BW(.H40AB/H40AC or H140) (d 200...850)

230/231..MB(.C3)(.C4) (d 150...260) calender rolls

232..K.MB.C4.T52BW soft calender rolls231..K.MB.C4.T52BW (d 420...560)

230/231..K.MB.C4(.W209B) (d 180...300) dryer rolls

230/231..K.MB.C4(.W209B) (d 320...710) M. G. cylinders

231..K.MB (d 50...150) reel-spool bearings

240..SK30.MB.C4.T52BW (d 140...160) corrugator rolls

pulpers, refiners,chippers, grinders, pressurized screens, debarking drums (track rollers)

FAG 4

NU NUB2../3.. NNU 49

E design

Design H140

Products and services for the paper industrySpecial products · Services

5 FAG

1.3 Service range

• Mounting and diagnosis

• Equipment for mounting, mainte-nance and diagnosis

• Technical consultation for applica-tions

• FAG training courses

– basic course on rolling bearings– individual courses for maintenance

personnel– software for learning alone at the

PC (W.L.S.)– videos

• FAG publications and Technical Infor-mation sheets

• PC programs for calculating anddesigning bearings– FAG product catalogue on CD-ROM– Special calculating programs for

bearings and mating parts

• Arcanol rolling bearing greases

1.2 Special products

Bearing type

Self-aligning cylindrical roller bearings (Publ. No. WL 13 111)

Triple ring bearings (TI WL 43-1192)

Split spherical roller bearings (Publ. No. WL 43 165)

Housings

Bearing series/design/size Application

FAG 5.....K.C5 (.W209B) (d 150...300) dryer rolls

FAG 5.....K.C5 (.W209B) (d 320...710) M.G. cylinders

FAG 5..... (d 180...420) driven anti-FAG 5..... (d 100...400) deflection rolls

in press sectionsand calenders

222SM..MA (d 55...200) transmissions,pulpers,agitators/mixers,fans

FAG 5..... (d 170...400) dryer rollwith separate clamping rings conversions

PMD31.. (d 180...300) dryer rollsPMDR31.. (d 180...300)

as plummer blockor rocker blockhousing

PM30..K-- (d 130...710) dryer rollsPM30..H-- (d 130...710) M. G. cylinders

(only forconversions)

SUC30../31.. (d 130...710) individual productas plummer blockor rocker block housing

PMF 23/22/32.. (d 75...180) guide rolls(dryer section)

PM30..H--PM30..K--

PMF (TI WL 13-2)

PMDRPMD (TI WL 13-1)

Products and services for the paper industry Suffixes and technical specifications for rolling bearings in the paper industry

1.4 Suffixes and technical specifications for rolling bearings in the paper industry

Suffix Description

C2 radial clearance smaller than normalC3 radial clearance larger than normalC4 radial clearance larger than C3C5 radial clearance larger than C4

E, ED modified internal construction

H40 no lubricating grooves or holes in outer ringH40AB spherical roller bearing with 6 lubricating holes in inner ringH40AC spherical roller bearing with 6 lubricating holes and lubricating groove in inner ringH40CA bearing with 6 lubricating holes and lubricating groove in outer ringH44S lubricating holes in outer ring closed with aluminium plugsH44SA 3 aluminium plugs for closing lubricating holes in outer ringH44SB 6 aluminium plugs for closing lubricating holes in inner ring (only in combination with H40AC)H88 running accuracy P5 for inner ring, P4 for outer ring + J26C + M15NZ + restricted width tolerance

for outer ringH140 combination of H40AC, H44SA, H44SB and T52BWH157 combination of H40 and H40AC + oil injection nozzles

J26A point of max. radial runout marked on inner ring or sleeveJ26B point of max. radial runout marked on outer ringJ26C point of max. radial runout marked on inner ring and outer ring

M machined brass cage, guided by rolling elementsMB two-piece machined brass cage, guided by inner ringMB1 one-piece machined brass cage, guided by inner ringMB2 modified two-piece machined brass cage, guided by inner ringM15NZ measuring report with Talyrond graph, series numberM17D crack inspection for inner ring

T27 cylindrical rollers with crowned outside diameterT50H restricted tolerance of outside diameter (towards minus-minus)T52BW P5 running accuracy for inner ring and outer ring (+ J26C)

W10A isotemp heat treatment for outer ringW10D isotemp heat treatment for outer ring and inner ringW209B inner ring made of case-hardening steel

Popular combinations:

C3.H40AB.T52BWC3.H40AC.T52BWC3.H140C3.T52BWC5.M17D.T27.W10A.W209BC5.M17D.T27.W10DH40AB.T52BWH40AC.T52BWH44S.T52BW

FAG 6

Requirements on paper machine bearings

2 Requirements on paper machine bearings

The machines used today for the pro-duction of endless paper and cardboardwebs are very large reaching up to 200 min length at times. With a web width of10 m, 1,800 m of paper can be producedper minute. The paper web runs overnumerous rolls which are supported byrolling bearings.

As shown in the diagram below, papermachines are essentially made up of thesame components: wet end section con-sisting of forming section and press sec-tion; dryer section; finishing group withcalender and paper reeling.

The typical requirements placed onbearing arrangements in paper machinesare:

• utmost operational reliability• easy mounting• compensation for misalignment• avoidance of corrosion in the wet sec-

tion

• suitability for high temperatures indryer section

• high speed suitability• high bearing quality and precision

A paper machine should operate ifpossible without any interruption andshould only have to be shut down forscheduled maintenance and repair work.As a result, the demand for utmost opera-tional safety and reliability must be giventop priority when designing all bearingarrangements and selecting the bearingsthemselves. Lubrication and maintenanceplay just as important a role as correctbearing selection whereby maintenanceincludes diagnosing rolling bearings dur-ing operation.

Mounting and dismounting should be facilitated in order to save time and money when bearing changes are re-quired.

Due to the dimensions of papermachines and the distances between bear-ings as a result, the bearings must be ableto accommodate misalignment andlength variations.

There is a high degree of moisture inthe environment of the wet end section.Sealing must be designed so that watercannot penetrate and corrosion can beavoided. Moisture can severely impairlubrication and thus affect the bearing'slife considerably.

In addition, high operating tempera-tures and bearing temperatures in thedryer section make requirements on thelubrication and bearing design evengreater.

Finally, speeds arising due to the highpaper speed must be taken into consider-ation when arranging and selecting thebearings.

Paper machines are stand-alone plantswhich are tailored to customers' specificrequirements. They are not produced inseries, which is quite common in otherfields. Experience with similar compo-nents and operating conditions can nev-ertheless be useful when designing bear-ing arrangements.

7 FAG

Wet end section

large extent of waterenvironmental temperature < 50°C

Suction roll

Anti-deflection roll

Press section

Guide roll

Dryerroll

Thermo roll

high humidityenvironmental temperature > 100°C( ) ( )

Dryer section

Paper guide roll

Finishing group

Forming section

DuoStabilizerroll

Anti-deflectionroll

Spreader roll

Formingroll

Spreaderroll

Spreader roll

A modern paper machine

Requirements on paper machine bearingsExamples of bearing arrangements for paper machines

Today the spherical roller bearing isthe dominating bearing type particularlyamong medium-sized and large-sizedbearings. Larger cylindrical roller bear-ings are frequently adapted to specialoperating conditions and roll designs.

Other bearing types are found in aux-iliary equipment in paper plants (motors,gears, fans, debarking drums, grinders,chippers, refiners, agitators/mixers, coat-ing machines, rewinders and cuttingequipment). See lists on pages 4 and 5.

In the paper industry bearings aredesigned for a far longer life than in otherindustrial equipment, see section 5.1.

Lubrication considerably influencesthe life of the bearings. All roll bearingsin modern paper machines are connectedto an oil circulation system for operation-al reliability and maintenance reasons.Grease lubrication is found in the wetend section (with lower environmentaltemperatures) of older paper machines.

In the dryer section, bearings for ropesheaves, spreader rolls and sometimesguide rolls are lubricated with grease, seesection 5.2.

A high degree of cleanliness in thebearings during the entire operation peri-od is also decisive for a long service life.This requires utmost sealing reliability,especially against moisture, and diversedesigns depending on the type of roll inquestion, see examples in section 3.

FAG 8

3 Examples of bearing arrangements for paper machines

3.1 Wet end section

Examples of bearing arrangements for paper machinesWet end section

3.1.1 Forming roll

In modern high-speed paper machinesthe forming roll is the first roll overwhich the paper, still pulp, is guided. Itdiverts a large amount of water andshapes the remaining paper mass intoform. The forming roll consists of a non-corroding special steel cylinder up to 10 m in length. The water is removedthrough small holes located around thesurface of the cylinder. It first gathers in alatticework like a honeycomb at the outerside of the roll and is thrown into a tubafter about half a rotation. The paper fibre from which more water has beenremoved between two synthetic wirebelts, is conveyed to the press section viathe suction rolls.

Technical data

Roll length 7,120 mm; roll diameter1,150 mm; rotation 276 min–1 (speed1,000 m/min); roll weight 200 kN; wiretension 5 kN/m.

Bearing selection, dimensioning

The suction box diameter is decisivefor the size of the main bearing at theoperator's end. We recommend bearingswith a dynamic load rating as low as pos-sible in order to reduce the danger of slip-page (cf. example 3.1.2). Self-aligningbearings are necessary as misalignmentcould arise.

Roll weight, wire tension and rotationare the main criteria for dimensioning thebearings.

FAG spherical roller bearings aremounted: 22326ED.C3 as support bear-ing for the suction box, as main bearing (operator's end) 23996K.MB and asmain bearing (drive end) 23068K.MB.The main bearings mounted on thetapered shaft seats can be hydraulicallymounted and dismounted.

The locating bearing (drive end) pro-vides axial guidance for the rolls while thefloating bearing compensates for anylength variations by outer ring displace-ment in the housing bore.

Machining tolerances

Main bearing: circumferential loaddemands a tight fit for the inner rings;roundness tolerance IT5/2 (DIN ISO1101); taper angle tolerance AT7 (DIN7178). Housing bore according to G7,due to point load at the outer ring.

Suction box bearing: housing boreaccording to N7 (circumferential load atthe outer ring), shaft according to f6(point load for inner ring).

Lubrication

Circulation lubrication with a mineraloil with sufficient viscosity and EP addi-tives as well as additives with good anti-corrosive properties and water separationability. Minimum oil quantity, see section5.2.2.

Sealing

Main bearing: A multiple labyrinthprotects against water penetration fromoutside particularly at the roll side.

Suction box bearing: Labyrinth as pro-tection against penetration of water (suc-tion box side).

9 FAG


3.1.2 Suction roll

Suction rolls are found in the wire orpress section of a paper machine. Theyare hollow cylinders up to 10 m in lengthwhich have several small holes all aroundtheir circumference. Some water contentis removed from the web due to the rotat-ing roll shell and the vacuum inside theroll. The suction box, as interior axle, isstationary. The roll shell is driven byplanet wheels in modern paper machines.

Technical data

Roll length 7,800 mm; roll diameter1,600 mm; rotation 278 min–1 (speed1,400 m/min); roll weight 270 kN; wiretension 5 kN/m.


The diameter of the suction box isdecisive for the size of the bearing. Werecommend bearings with a dynamicload rating as low as possible; the higherspecific bearing load reduces the dangerof slippage (too low a load and starvedlubrication can cause the rolling elementsto slide on the raceway).

Self-aligning bearings are necessary asmisalignment could arise.

Roll weight, wire tension and rotationare the main criteria for dimensioning thebearings.

FAG spherical roller bearings FAG239/850K.MB.C3 with tapered bore (K 1:12) and increased radial clearanceare used. The bearings are mounteddirectly on the tapered shaft seats for run-ning accuracy reasons. The hydraulicmethod is applied to facilitate mounting.

The locating bearing provides axialguidance for the rolls while the floatingbearing compensates for any length varia-tions by displacement of the outer ring inthe housing bore.

The nominal life for both bearings isLh > 100 000 h. The adjusted rating lifecalculation reaches over 200 000 h whenthe operating temperature is 60 °C andthe oil ISO VG 68 (viscosity ratio κ > 2;factor a23 = 2.2).


The inner ring has circumferentialload and is attached to the tapered bear-ing seat of the shaft.

Roundness tolerance IT5/2 (DIN ISO1101); taper angle tolerance AT7 (DIN7178).

Housing bores according to G7 due topoint load at the outer ring.

Lubrication

The spherical roller bearings are sup-plied by circulation lubrication with aminimum oil quantity of 8 l/min. A min-eral oil with sufficient viscosity and EPadditives is selected. Additives with goodanti-corrosive properties and water separ-ation ability are also required. An effec-tive lubrication is achieved with an oilsupply to the centre of the bearing.

Sealing

Any oil which escapes is thrown off viasplash grooves into oil collecting cham-bers and directed back. At the roll side abaffle plate and multiple grease-filled lab-yrinth with integrated V ring prevent water penetrating from the outside.

FAG 10

Courtesy of Valmet


11 FAG

11 FAG


3.1.3 Center press roll

The paper web runs through the pressrolls on a felted cloth and a large amountof water is pressed out of it. One or more(suction) press rolls are pressed againstthe center press roll in modern press sec-tions. The center press roll is solid, madeof granite/steel or steel with a protectivecover.

Technical data

Roll length 8,800 mm; roll diameter1,500 mm; speed 1,450 m/min; rollweight 750 kN. Pressure by 3 rolls at 30°,180° and 210°; bearing temperature about60 °C. Direct drive.


Self-aligning spherical roller bearingsof the series 231 or 232 with a very highload carrying capacity are chosen due tothe high radial load and the misalign-ment which is possible between the bear-ing locations.

A low bearing height is also importantfor these bearings since the height of thehousing is restricted by the roll diameter.

The roll weight and the load compo-nents of the pressure rolls yield a resultingbearing load Fr = 300 kN.

A spherical roller bearing FAG231/600K.MB.C3 is mounted at both sides. The bearings with tapered bore (taper 1:12) are pressed directly onto thetapered shaft seat by means of thehydraulic method.

The floating bearing arrangement atthe operator's end permits temperature-depending length variations of the roll byshifting the outer ring in the housing.The locating bearing is at the drive end.

The nominal life calculated is Lh > 100,000 h with a rotation of 308 min–1. With good lubrication (vis-cosity ratio κ ≈ 3, basic factor a23II = 3)and improved cleanliness (contaminationfactor V = 0.5) in the lubricating gap Lhna >> 100,000 h according to theadjusted rating life calculation.


The inner ring has circumferentialload and is attached to the tapered bear-

ing seat. Roundness tolerance IT5/2(DIN ISO 1101); taper angle toleranceAT7 (DIN 7178).

Housing bores according to G7 sincethere is point load at the outer ring.

Lubrication

Circulation lubrication (minimum oilquantity 7 l/min) with a mineral oil (ISOVG 100), which contains EP additivesand additives with good anti-corrosiveproperties and water separation ability.

An effective lubrication is achievedwith an oil supply to the centre of thebearing. Oil return on both sides of bear-ing via oil collecting pockets and con-necting holes.

Sealing

Oil splash grooves in the roll journalprevents oil escaping at the cover passage.Non-rubbing and maintenance free gap-type sealing protect the bearings fromenvironmental influences.

FAG 12

13 FAG


3.1.4 Anti-deflection roll

In the press sections and calenders,anti-deflection rolls provide for an evenpaper thickness across the web and a con-sistently high paper surface quality. Thedrive is found at the locating bearing end.Its power is transmitted via gearing andthe curved teeth coupling to the rollshell.

The adjustment roll is pressed againstthe mating roll (calender roll) under veryhigh pressure. As a result the mating rollis bent and the form of the roll shellchanged. The shell of the adjustment rollmust adjust to this form.

The anti-deflection roll consists of astationary axle and a rotating roll shell.Control elements which can be pressure-balanced separately are provided on theaxle. They support the roll shell hydro-statically and effect its adjustment. Theroll shell is formed like the bent matingroll by the changing pressure giving thepaper an even thickness.

Technical data

Roll length 9,300 mm; roll diameter1,025 mm; roll weight 610 kN; shell

weight 210 kN; pressure 700 kN; cir-cumferential velocity 1,500 m/min (n = 470 min–1); bearing temperature 55 °C.


Spherical roller bearings FAG23096MB.H140 (dynamic load rating C = 3,800 kN) are used. Required life: > 100,000 h. The bearing only has aguidance function when in operation(with pressure and closed gap).

Due to the danger of slippage bearingsof the series 239 with a low load ratingshould be selected.

The bearings have a reduced radialrunout (specification T52BW as part ofH140), since running inaccuracy of therotating roll shell influences the quality ofthe paper web.


Bearing seats on the axle according tof6 due to point load for the inner rings.

Tight fit (housing bore according toP6) due to circumferential load for theouter rings. The outer ring lubricationholes are closed because of hydraulic dis-mounting.

Lubrication

When dynamic misalignment and/orslippage may occur, a very good lubricantmust always provide a load-carryinglubricating film. The bearings are lubri-cated with the lubricating oil used for thehydraulic system (ISO VG 150 with EPadditives).

In new designs and particularly withheated rolls, the oil is fed via lubricatingholes in the inner ring into the bearingsdirectly at the contact areas.

Separate oil circuit for the deep grooveball bearings in the transmission.

Sealing

The bearings are sealed to the outsidewith a shaft seal. To the inside a baffleplate provides for an oil resevoir in thebearing area.

FAG 14

Examples of bearing arrangements for paper machinesDryer section

3.2 Dryer section

3.2.1 Guide roll

Guide rolls guide, as the name indi-cates, and turn the wire and felt cloth inthe wet end and dryer sections of a papermachine. The same bearings are used forthe guide rolls in both areas. Lubricationand sealing differ, however, depending onthe place of application.

In old machines the wet end section isusually lubricated with grease, and thedryer section with oil.

In new machines both areas have oilcirculation lubrication. Due to differentoperating conditions separate oil circuitsare necessary for the wet end and dryersection.

The larger the machine the more oftenit is found to be faster. For this reason the

bearing inner rings are mounted with atapered bore directly on the tapered rolljournal.

Wet end section

Depending on the positions of thebearings in the machine they are subjectto a small or large degree of moisture.Water must not penetrate the housing,particularly when machines are beinghigh-pressure cleaned.

Dryer section

Environmental temperatures of about95 °C lead to great changes in length andplace high demands on lubrication. Theoperating temperature of the bearings canbe up to 115 °C.

Technical data

Working width 8,800 mm; roll diame-ter 700 mm; paper speed 1,650 m/min (n = 750 min–1); roll weight FG ≈ 80 kN;web tension 1 kNm (tensile strength Fz ≈ 9 kN); wrap angle 180°; bearingtemperature approx. 105 °C.


The bearings must be able to accom-modate loads and compensate for mis-alignment at the same time (misalign-ment, deflection). An increased radialclearance according to C3 is necessarydue to temperature differences.

Spherical roller bearings FAG22330EDK.C3 are mounted.

Courtesy of Beloit

15 FAG


Bearing load:

P = (FG + Fz)/2 = (80 + 9)/2 = 44.5 kN

The diameter of the roll journal isdetermined by the roll rigidity required.As a result there is a high index ofdynamic stressing fL corresponding to anominal life Lh of well over 200,000hours. The attainable life is even higherfor the given lubrication conditions.

The housings can be in standing orsuspended position or can be laterallyscrewed on. They are designed for oil cir-culation lubrication.


The inner rings have circumferentialload and are directly fitted to the taperedroll journal. The roll journals have oil

grooves so the bearings can be mountedand dismounted with the hydraulicmethod.

Roundness tolerance IT5/2 (DIN ISO1101); taper angle tolerance AT7 (DIN7178).

Bearing seats in the housing boreaccording to G7.

Lubrication

In the dryer section: see example 3.2.2(dryer roll) since the bearings are con-nected to the oil circuit of the dryer rolls.Minimum flow rate 0.9 l/min.

In the wet end section: see examples3.1.2 (suction roll) and 3.1.3 (centerpress roll), since the bearings are connect-ed to the oil circuit of the wet end sectionrolls. Minimum flow rate 0.5 l/min.

Sealing

Gap-type seals, which are non-rub-bing and maintenance-free, prevent oilfrom escaping through the cover passagesbores in the dryer section.

The bearings in the wet end sectionmust have refillable labyrinth seals to pre-vent water from penetrating. Remainingoil is thrown off via splash grooves intocollecting chambers and directed back.Cover sealings (O-rings) make the hous-ing oilproof.

FAG 16


3.2.2 Dryer roll

The remaining water is evaporated inthe dryer section. The paper runs overnumerous heated dryer rolls guided byendless dryer wires (formerly dryer felts).The dryer rolls are steam heated (temper-ature depends on the type of paper, itsthickness and speed, and on the numberof dryer rolls). The high temperatures ofthe heating steam transfer to the bearingseats stressing the rolling bearings accord-ingly. Today, the journal through whichthe steam flows is insulated in order tokeep the bearing temperatures low.

Technical data

Working width 5,700 mm; roll diame-ter 1,800 mm; paper speed 1,400 m/min(rotation 248 min–1); heating tempera-ture 165 °C (7 bar); roll weight 90 kN.

Felt pull 4.5 kN/m; wrap angle 180°;environmental temperature below thedryer section hood approx. 95 °C; insu-lated journal bores.

Bearing selection

The bearing load is calculated fromthe roll weight, felt pull and temporarywater fill. The floating bearing is loadedwith 75 kN, the locating bearing with 83 kN taking into account the drive force. Heating the dryer roll leads to heatexpansion which in turn leads to consid-erably great changes in length with suchlong rolls. Self-aligning rolling bearingsare necessary due to the misalignmentarising between both bearing locations.

A double-row cylindrical roller bear-ing of the dimension series 31 is provided

as floating bearing at the operator's end.It easily compensates for length variationsin the bearing between the rollers and theinner ring raceway. With its sphericalsliding surface a plain spherical bearing'sseating ring accommodates any align-ment inaccuracy of the journal. A double-row self-aligning cylindrical rollerbearing FAG 566487K.C5 with thedimensions 200x340x112 mm is mount-ed.

A spherical roller bearing FAG23140BK.MB.C4 is mounted as locatingbearing on the drive end.

Both bearings have about the sameoperating clearance in order to avoid anydetrimental preload during the heating-up stage which may lead to a maximumtemperature difference of 50 °C. Thespherical roller bearing has an increasedradial clearance according to C4(260...340 µm), the cylindrical rollerbearing an increased radial clearanceaccording to C5 (275...330 µm).

Both bearings have a tapered bore (K 1:12) and are mounted by the hydrau-lic method directly onto the tapered jour-nals.

Since the cylindrical roller bearing andthe spherical roller bearing have the samedimensions unsplit PMD plummer blockhousings (FAG PMD3140AF or BF) areapplied both at the drive end and at theoperator's end.

Due to increased operating tempera-ture, both bearings are given special heattreatment (isotemp) and are thus dimen-sionally stable up to 200 °C.

Bearing dimensioning

An attainable life Lhna ≥ 250 000hours is requested for dryer roll bearings.

Lubrication decisively influences theadjusted rating life.

Under an average operating tempera-ture of 100 °C the operating viscosity ν ≈ 16 mm2/s for a mineral oil with anominal viscosity of 220 mm2/s (ISO VG220).

The rated viscosity is determined fromthe speed and the mean bearing diameterdm = (200 + 340)/2 = 270 mm to ν1 = 25 mm2/s.

The viscosity ratio is then:κ = ν/ν1 = 16/25 = 0.64.

With the value K = 1 a basic factora23II = 1.1 is obtained for the sphericalroller bearing.

The values K = 0 and a23II = 1.4 applyto the cylindrical roller bearing.

With normal cleanliness (cleanlinessfactor s = 1) the factor a23 = a23II · s is 1.1 for the spherical roller bearing and 1.4 for the cylindrical roller bearing.

The attainable life Lhna = a1 · a23 · Lh istherefore well over 250,000 h for bothbearings.


The inner rings have circumferentialload and have a tight fit on the taperedroll journal. The journals have oil groovesso the bearings can be mounted and dis-mounted by means of the hydraulicmethod. Roundness tolerance IT5/2(DIN ISO 1101), taper angle toleranceAT7 (DIN 7178). Bearing seats in thehousing bore according to G7.

17 FAG

Lubrication

The bearing housings are connected toa central oil circulation lubricationsystem so that heat is constantly with-drawn from the bearing. High-grademineral oils ISO VG 220 or 320 are usedwhich must have a high operating viscos-ity, thermal stability, good protectionagainst wear, good water separation abil-ity and a high degree of cleanliness. Aminimum oil quantity of 1.6 l/min is

guided directly to the centre of the bear-ing via a lubricating groove and lubricat-ing holes in the outer ring.

The oil can be carried off at both sidesof the bearing due to the center feed oilsupply. The danger of oil retention andleakage thus is minimized considerably.Any contaminants or wear particleswhich might penetrate the bearing areimmediately washed out of it with thismethod of lubrication.

Sealing

Gap-type seals, which are non-rub-bing and maintenance-free, are providedas sealing for the journal passages. The oilis thrown off via splash grooves and oilcollecting chambers and flows backthrough return holes to the two oil cav-ities on the housing floor. Cover seals (O-rings) make the housing of the papermachine oilproof.


FAG 18

3.3.1 Calender thermo roll

The paper passes through the so-calledcalender stack after leaving the dryer sec-tion. Soft calenders smooth the surface ofthe paper thus improving its printability.The calender consists of two pairs ofrolls. One calender roll (steel) lies above acounter roll, another below one. Thecounter roll is the so-called anti-deflec-tion roll (elastic material). Soft calenderrolls can be heated by water, steam, or oil.The gap or the "nip" pressure depends onthe type of paper.

Technical data

Working width approx. 7 m; rotation350 min–1 (speed 1,100 m/min); heatedby oil at 200...250 °C; insulated roll jour-nal; operating temperature at bearing inner ring 130 °C.


The radial bearing load depends onthe application of the calender roll as lower or upper roll, on the weight FG andthe variable pressure load with percentageof time.

P1 = FG + Fnip min = 600 kNP2 = FG + Fnip med = 990 kNP3 = FG + Fnip max = 1260 kNP4 = FG – Fnip min = 60 kNP5 = FG – Fnip med = 390 kNP6 = FG – Fnip max = 720 kNPercentages of time: P1, P4 : 10% eachP2, P3, P5, P6 : 20% each

The sum of the roll weight and the nipload acts for the application as bottomroll whereas only their difference actsdecisive for the application as top roll.

Taking the maximum load for design-ing the bearing would lead to overdimen-

sioning (equivalent dynamic load P < 0.02 · dynamic load rating C) in the case of application in the top roll.Slippage may occur with such a low loadwhich in turn can lead to bearing damagewhen lubrication is inadequate. In orderto avoid this problem, smaller bearingswith a smaller dynamic load rating Cshould be selected so that P/C > 0.02.The risk of breaking through the lubri-cating film drops with the smaller rollingelement mass. In critical cases it is recom-mended to use bearings with coated rol-lers.

Requirements with respect to load car-rying capacity and self-alignment are metby spherical roller bearings.

The construction height of the bearingis limited by the diameter of the roll jour-nal and roll outside shell. The relativelywide spherical roller bearings FAG231/560AK.MB.C4.T52BW are mounted.

The nominal life Lh = 83,000 h withgiven loads and percentages of time.

With a lubricating oil ISO VG 220the viscosity ratio is κ = 0.71 at an oper-ating temperature of 130 °C. An attain-able life Lhna > 100,000 h is obtained withthe adjusted rating life calculation (wherefs* > 12; a23II = 1.2; V = 0.5; s = 1.6).

The increased radial clearance C4 isrequired due to the danger of detrimentalradial preload in the bearing during theheating up phase when the temperaturedifference is great. With a speed index n · dm = 224,000 min–1 · mm we recom-mend bearings with increased runningaccuracy according to specificationT52BW.


The inner rings have circumferentialload and are directly fitted on the taperedroll journal. The roll journals have oilgrooves so that the hydraulic method canbe applied for mounting and dismount-ing the bearings.

Examples of bearing arrangements for paper machinesCalender and finishing group

3.3 Calender and finishing group Courtesy of Valmet

19 FAG


Roundness toleranceIT5/2 (DIN ISO 1101),

taper angle toleranceAT7 (DIN 7178).

Bearing seats in the housing bore according to F7.

Lubrication

Oil circulation lubrication with a syn-thetic oil ISO VG 220, suitable in qual-ity, which has stood dynamic testing onthe FAG test rig FE8.

By supplying a large amount of oil tothe centre of the bearing (minimum oilflow rate 12 l/min) heat dissipation isachieved as well as a low thermal stress ofthe oil. Any contaminants or wear parti-cles are washed out of the bearing. Oilreturns to both sides of the bearing via oilcollecting pockets and connecting holes.

Sealing

Angle rings at the roll side preventdirect oil escape at the cover holes. Re-maining oil is thrown off via splashgrooves into collecting chambers anddirected back. Cover sealings (O-rings)make the housing oilproof.

Courtesy of Voith

3.3.2 Spreader roll

Paper webs which are transported inlengthwise direction tend to developcreases. Spreader rolls stretch or expandin cross direction the webs running overthem. They flatten creases and any mid-dle or end parts of the web. Spreader rollsconsist of a stationary axle which is bentsymmetric to its longitudinal axis, andaround which the roll shell rotates. Tube-shaped sections make up the roll shelland are arranged to rotate freely and haveangular freedom. The sections adjust toone another in such a way that the bend-ing form of the axle is reflected on theshell surface. Depending on the case ofapplication – wet end section, dryer sec-tion, or finishing/converting – the sec-tions are made of stainless steel or provid-ed with a flexible cover (e. g. rubber).

Technical data

Roll length 8,300 mm, consisting of22 sections; weight/section plus wire orpaper web tension at 30° wrap angle 2 kN; a radial load of just 0.5 kN perbearing results therefrom. Rotation ofroll shell 1,160 min–1.

Operating temperature in the wet endsection 40 °C; in the dryer section and in

finishing with infrared drying tempera-tures can reach up to 120 °C.


With rotating outer ring, extremelysmooth running is required from thebearings since the sections in the wet endsection and in the dryer section or finish-ing/converting are only driven by thewire tension and the paper web respec-tively.

High operational reliability is also nec-essary since the failure of one bearing alone means that the whole spreader rollhas to be dismounted.

FAG 61936.C3 deep groove ball bear-ings are mounted. For new high-speedapplications (n · dm values 0.6 to 1 · 106

min-1 · mm) deep groove ball bearingswith ceramic balls (hybrid bearings) areselected. The increased radial clearanceC3 permits easy alignment of the sec-tions. With the low load, the bearingshave a nominal life Lh of well over100,000 hours.


As the outer ring of the bearing rotateswith the roll shell it is given a tight fit

with M6 tolerance and is secured axiallyby a snap ring.

The inner ring has point load and isfitted to the shaft sleeve with h6. Due tothe bent roll axle and for assembly rea-sons the sleeve is loosely fitted and axiallypositioned with a bolt.

Lubrication

The bearings are greased for life, i.e.no relubrication is provided for. Theselection and filling quantity of lubricat-ing grease is determined by the demandfor smooth running as well as a servicelife of up to five years (8,000 operatinghours per year). Low-friction greases (e.g. FAG grease Arcanol L75) are ad-vantageous with high speeds and low loads.

Sealing

Non-rubbing dust shields are used forsealing due to the smooth runningrequired. They are stuck to the bearingouter ring on both sides so the base oilcentrifuged from the lubricating greasecannot escape. O-rings also provide foroil tightness.

FAG 20


FAG service for more operational reliabilityStorage of rolling bearings · Preparation · Mounting and Dismounting

4 FAG service for more operational reliability

FAG has a complete package of serviceequipment and services. Working withbearings is facilitated by FAG measuringand mounting devices such as the diagno-sis device which monitors the conditionof the bearings plus the FAG mountingand diagnosis service on site when mount-ing and monitoring jobs prove difficult.

Application engineering at FAG pro-vides advice and training in relation to allaspects of rolling bearing technology.

4.1 Storage of rolling bearings

Rolling bearings should be left in theiroriginal packaging until directly beforemounting so as to prevent contaminationand rust. Large bearings such as those found in paper machines are stored in aseparate dry room in horizontal positionwith a support around the entire circum-ference.

Rolling bearing packing including theanti-corrosion agent are such that thebearing's properties can be preserved for along period. It is ensured that the anti-corrosion agent is compatible with thelubricants popular in the paper industryand it is not required to be washed outprior to mounting.

During storage, bearings must not besubject to any agressive media such as gases, mist, or aerosols of acids, causticsolutions and salts. Direct sunlight mustalso be avoided as large fluctuations intemperature may arise in the packaging.

Under standard preservation condi-tions the permissible storage period is upto 5 years. FAG provides upon requestinformation on special preservation andthe usability of older bearings.

Please refer to the catalogue WL 41 520 "FAG Rolling Bearings" formore detailed information on the storageof FAG rolling bearings and greases.

4.2 Preparations for mounting and dismounting

The necessary preparation for mount-ing and dismounting rolling bearings ispresented in detail in the FAG publica-

tion WL 80 100 "Mounting and Dis-mounting of Rolling Bearings".

Prior to unpacking the bearings allmating parts required should be checkedfor their dimensional and form accuracy.

An outside micrometer is generallyused to check the shaft seats of largerbearings.

An inside micrometer or bore measur-ing devices are used to check the housingbores.

Checking a housing bore with an inside micrometer

4.3 Mounting and dismounting with cylindrical and tapered mating surfaces

General information on mountingand dismounting rolling bearings is pro-vided in the FAG publication WL 80 100"Mounting and Dismounting of RollingBearings".

Thermal and hydraulic methods areusually used for mounting bearings in thepaper industry.

4.3.1 Mounting and dismounting with cylindrical mating surfaces

Mounting: Bearings which require atight fit on a cylindrical shaft are heatedup and then shrunk on. For the mostcommmon fits (cf. section 4.4) a temper-ature of 80 to 100 °C suffices for heatingup. The permissible maximum mountingtemperature of 120 °C must not beexceeded in order to avoid changes indimensions and a reduction in hardness.

Induction heating devices allowspeedy, clean and safe heating. The FAGheating device AWG 3,5 (compare alsoTI No. WL 80-47) is suitable for rollingbearings with 20 mm bore or more andweighing up to 40 kg.

FAG induction heating deviceAWG 3,5

Rolling bearings of all sizes and typescan also be heated in oil baths. Disadvan-tage: accident hazard, pollution of theenvironment by oil vapours, inflam-mability of hot oil, danger of bearingcontamination, expensive disposal ofused oil. The heated bearing parts aremoved to the stop quickly and withouttilting. After pushed on, the inner ring isclamped on and held until cold.

Large bearings are usually transportedby crane. The bearing is then suspendedin a mounting tongs.

Dismounting: Mechanical extractorsor hydraulic presses are suitable for with-drawing smaller bearings.

During dismounting, inner ringsshould only be heated up with the ringburner in emergency cases when there areno oil grooves and holes for the hydraulicmethod. Utmost care must be given asthe rings are sensitive to non-uniformheating and local overheating.

Bearings can also be pressed off cylin-drical seats by means of the hydraulicmethod (see section 4.3.2).

21 FAG

FAG service for more operational reliabilityMounting and dismounting

4.3.2 Mounting and dismounting with tapered mating surfaces

Mounting: Rolling bearings in papermachines are nowadays mostly mounteddirectly on tapered journals. Large andwide machines with a high paper speedrequire high running accuracy. The directseat is advantageous since there are onlytwo mating surfaces.

When running accuracy requirementsare not so high adapter or withdrawalsleeves are used whereby four mating sur-faces are involved.

The required tight fit is achieved bypressing on the inner ring or pressing inthe withdrawal sleeve between inner ringand shaft. The reduction in radial clear-ance due to expansion of the inner ringindicates whether a suitable tight fit hasbeen reached.

The radial clearance is first measuredprior to mounting. While pressing on,the clearance is checked constantly untilthe required value is achieved. It is alsopossible to measure axial displacement inplace of measuring the reduction in radialclearance.

Feeler gauges are used to measure theradial clearance. It must be ensured thatthe radial clearance is measured over bothrows of rollers at the same time in thecase of spherical roller bearings. Onlywhen the clearance values at both rowsare the same can it be certain that the inner ring is not laterally displaced inrelation to the outer ring.

The radial clearance of large sphericalroller bearings (d > 500 mm) is measuredat three points because of the ring defor-mation, see scheme.

Hydraulic nuts are used for pressinglarge-size bearings onto the tapered seator for pressing in the withdrawal sleeves.Please see also publ. no. WL 80 103"FAG Hydraulic Nuts". The nut isscrewed onto the shaft thread or sleevethread. While pressing in oil, the annularpiston presses the bearing onto thetapered seat or sleeve between bearingbore and shaft.

If the radial clearance cannot be mea-sured with feeler gauges, the FAG displa-cement measuring instrument RKP.MGcan be used. It is screwed to the face ofthe hydraulic nut.

Hydraulic nuts

The hydraulic method greatly facili-tates the mounting and particularly thedismounting of bearings with a bore ofabout 160 mm or more. Oil grooves andholes as well as connection threads forpressure generators must, however, beprovided. Please refer to FAG publ. no.WL 80 102 "How to Mount and Dismo-unt Rolling Bearings Hydraulically" formore information.

Oil with a viscosity of ≈ 75 mm2/s at20 °C (nominal viscosity 32 mm2/s at 40 °C) is recommended for mounting.Only a little oil is required when thebearing seat is directly on the taperedjournal. Simple oil injectors with low vol-ume suffice.

Large-size adapter or withdrawalsleeves (designs HG or H, see catalogueWL 41 520) have oil inlet holes and oilgrooves for the hydraulic method. The oilloss arising at the edges of the mating sur-faces make a greater oil supply necessaryand a pump must be used.

The hydraulic method is particularlyadvantageous when dismounting large-size bearings. As soon as a continuous oilfilm has formed between the mating sur-faces the bearing ring is released abruptlyfrom the shaft due to the resulting axialforce. An axial stop should be provided inorder to prevent accidents.

Simple oil injectors with low volumesuffice for dismounting bearings whichare directly on the tapered journal where-as a pump is required when the sleeves arefastened on.

Oil with a viscosity of ≈ 150 mm2/s at20 °C (nominal viscosity 46 mm2/s at 40 °C) is recommended for dismounting.If the mating surfaces are damaged a gearoil with high viscosity with≈ 1,150 mm2/s at 20 °C (nominal viscos-ity 320 mm2/s at 40 °C) can be used.Fretting corrosion can be dissolved byadding rust-removing additives to the oil.

FAG 22

Measuring the radial clearance of large spherical roller bearings

a

b c

ebec

eaeceb

eaa

b c

a

b c

ea

ec=ea

2

eb= ea

2

Messung ohne Prisma

Welle

Messung mit Prisma

Radialluft e =ea + eb + ec

2

measuring with V block measuring without V block

Shaft

radial clearance e =ea + eb + ec

2

FAG service for more operational reliabilityFits and tolerances

4.4 Fits and tolerances

General guidelines on selecting thecorrect fit can be found in the FAG Cata-logue WL 41 520.

The G7 tolerance is commonly usedfor the housing bore; paper machinehousings of the series PM30, PMD,PMDR and PMF are machined accord-ing to G7, for example.

In the case of tapered journals the ta-per diameter must be determined so thatthe bearing is at the right spot on theshaft once pressed on. When determiningthe taper diameter – the reference dimen-sion is the small diameter – the expansionnecessary to obtain a tight inner ring fitmust be taken into consideration. Thisradial expansion of the inner ring de-creases the radial clearance of the bearing.It must be borne in mind that even withsolid steel shafts, the radial clearance isnot reduced by the entire amount ofinterference of the tapered seat. Evensmaller amounts of expansion result withhollow shafts and shafts made of castiron. In such cases the taper diametermust be accordingly larger. The dimen-sional tolerances of the bearings and themachining tolerances of the shaft mustalso be taken into account. The axial dis-placement is appropriately based on thechanges in distance between the face ofthe taper at the small diameter and theinner ring. The following tables indicatethe recommended dimensional and formtolerances.

Tolerances of tapered shaft seats

23 FAG

Nominal dimension Dia Roundness tolerance Straightnessof shaft tolerance (IT5)/2 tolerance

k6 DIN ISO 1101 IT3over to min maxmm µm µm µm

80 120 +3 +25 7.5 6120 180 +3 +28 9 8180 250 +4 +33 10 10250 315 +4 +36 11.5 12315 400 +4 +40 12.5 13400 500 +5 +45 13.5 15500 630 0 +44 14.5 (17)630 800 0 +50 16 (19)800 1000 0 +56 18 (21)

(values in brackets according to FAG)

Tolerances of taper angle

Nominal dimension Taper angle tolerance acc. AT7 (DIN 7178)of bearing width Bover to ATα ATDmm angular seconds µm

40 63 +65 0/+12.5...0/+2063 100 +52 0/+16...0/+25100 160 +41 0/+20...0/+32160 250 +33 0/+25...0/+40250 400 +26 0/+32...0/+50

ATD/2ATDAT

�

t1

t5t6

The stop area for the taper measuringdevice and the taper OD must bemachined in one setting

A

t1

t5

t6

A

d'

B

L

�

�2

Taper 1:12

Taper 1:30

ATD/2

dd1


Calculation of small taper diameter with roll journals

d' = d + ∆R · 1/(dm/h) · 1/fi · w + G'+ ∆dmp/2+ L · 1/k [mm]

d' Small taper diameter of journal [mm]d Nominal bearing bore diameter [mm]∆R Mean value of radial clearance reduction (table 1) [mm]dm/h Wall thickness ratio of inner ring (table 2)1/fi Correction factor for steel hollow journals (diagram 3)

= 1 for solid shaftsw Correction factor for different journal materials

(diagram 4)G' Smoothing value in relation to diameter = 2 · 0.6 · Rz (table 5) [mm]∆dmp Tolerance of nominal bearing bore diameter (table 6) [mm]L Distance between face of mounted bearing and of journal [mm]

(standard case: face of mounted bearing abuts with face of journal, e. g. L = 0)

1/k Taper ratio (= 0.0833 for taper 1:12/ = 0.0333 for taper 1:30)

Table 1: Radial clearance reduction ∆R

Nominal bore diameter Radial clearance reductiond spherical roller bearings cylindrical roller bearingsover to min max min maxmm mm mm

50 65 0.03 0.04 0.03 0.03565 80 0.04 0.05 0.035 0.0480 100 0.045 0.06 0.04 0.045100 120 0.05 0.07 0.045 0.055120 140 0.065 0.09 0.055 0.065

140 160 0.075 0.1 0.06 0.075160 180 0.08 0.11 0.065 0.085180 200 0.09 0.13 0.075 0.095200 225 0.1 0.14 0.085 0.105225 250 0.11 0.15 0.095 0.115

250 280 0.12 0.17 0.105 0.125280 315 0.13 0.19 0.115 0.14315 355 0.15 0.21 0.13 0.16355 400 0.17 0.23 0.14 0.17400 450 0.2 0.26 0.15 0.185

450 500 0.21 0.28 0.16 0.195500 560 0.24 0.32 0.17 0.215560 630 0.26 0.35 0.185 0.24630 710 0.3 0.4 0.2 0.26710 800 0.34 0.45 0.22 0.28

800 900 0.37 0.5 0.24 0.31900 1000 0.41 0.55 0.26 0.34

Table 2: Wall thickness ratiofor inner rings where d > 50 mm

Bearing series dm/h

Spherical roller bearings

239 0.91230 0.88231 0.85

232 0.83240 0.88241 0.87

222 0.84223 0.78

Cylindrical roller bearings

NU10 0.87NU2 0.85NU3 0.78

NU4 0.73NU30 0.89

FAG 24

L

d' dmh di


Diagram 3: Correction factor 1/fi for hollow journals (steel)

Diagram 4: Correction factor w for different materialsGG = grey cast iron; GGG = spheroidal graphite cast iron; St = steel

Table 5: Smoothing value G' in relation to diameter

Machining SmoothingG'mm

polished 0

very finely ground 0.001

ground 0.0025

very finely turned 0.005

finely turned 0.007

Table 6: Tolerance ∆dmpof bearing bore

Nominal bore Tolerancediameterover tomm µm

50 80 0/+30

80 120 0/+35

120 180 0/+40

180 250 0/+46

250 315 0/+52

315 400 0/+57

400 500 0/+63

500 630 0/+70

630 800 0/+80

800 1000 0/+90

25 FAG

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.9

1.0

1.2

1.4

1.6

1.8

2.0

dm/h=0.7

0.8 0.9

di/dm

1/fi

0.8

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.9

1.0

1.05

1.10

1.15

1.20

1.25

1.30

1.35

St

GGG

GG

w

0.8

di/dm

FAG service for more operational reliabilityMonitoring and analysing bearings

4.5 Monitoring and analysing bearings

Rolling bearings in paper machinesmust be monitored in order to avoid highrepair costs and lost production. The ser-vice life of the bearings and the availabil-ity of the machine can be optimally usedonly when the bearings are maintained inrelation to their condition. This presup-poses, however, recognition of bearingdamage on time, evaluation of the extentof damage and development of theprogress in damage. Condition-relatedmaintenance means that the bearing canbe replaced during a scheduled stop ofthe machine, thus avoiding unnecessarydowntime.

4.5.1 FAG Detector 2000

The FAG Detector is mainly of inter-est for bearings in the peripherals of paper machines where hardly any dis-turbing influences by other machineparts are expected.

The handy, cost-effective measuringdevice, is easy to use with just eight keys.First the acceleration sensor is attached tothe bearing location to be monitored.

First, the acceleration sensor has to beattached to the bearing location to bemonitored. After a round of taking mea-surements, the measured values that areused to evaluate the condition of machineor component are transferred to a com-

puter where they are interpreted, analysedand displayed graphically by the software”FAG 2000”.

For every measuring point the softwarecompares the newly measured values withthe alarm-triggering limiting values speci-fied for this measuring point. If one ofthese threshold values is exceeded this isindicated by the software.

Newly added values can be displayedgraphically versus the measuring time.

Trend analyses help users to assesswhen an alarm is likely to be triggered.

More detailed information on the De-tector 2000 will be provided on request.

4.5.2 FAG Bearing Analyser 2000

An efficient damage diagnosis systembased on envelope detection has been oneof the numerous FAG services for manyyears. Operators have the opportunity ofpurchasing the Bearing Analyser diagno-sis device from FAG with which they canpermanently monitor the condition oftheir plants themselves.

The first hint of bearing damage isgenerally given by changes in vibration.They are registered and evaluated by theFAG Bearing Analyser. The handy anduser-friendly vibration analyser functionsaccording to the long-proven envelope

detection method. It diagnoses all dam-age which causes noise, e.g. cracks, pit-tings, indentations or dirt. The accelera-tion sensor connected to the portabledevice measures vibrations up to 20 kHz.

Once current speed and bearing datahave been entered, the expert system eval-uates them and displays to the user with ahigh degree of reliability whether or notthe bearing is damaged. The higher theprogress of damage, which can be deter-mined by means of trend measurements,the more frequent the monitoring beforebearing exchange is a must.

More detailed information on the”FAG Bearing Analyser” will be providedon request.

4.5.3 VibroCheck system

FAG's online monitoring system “VibroCheck” allows a large number ofmeasuring locations to be monitoredcontinuously with the PC. Vibrationsensors at the bearing location conductsignals to monitoring modules (VCmodules). The signals are transferred viaPC to the control station of a paper millor per modem to an FAG service stationif required. When a warning limit hasbeen reached, an expert system makes an automatic diagnosis with the samedegree of reliability as the analyser (sec-tion 4.5.2).

FAG 26

FAG VibroCheck

FAG Bearing Analyser 2000FAG Detector 2000

FAG service for more operational reliabilityMonitoring and analysing bearings

4.5.4 Bearing analysis

The cause of damage and the possibil-ity of avoiding more failures in the futuremust be clarified when a damaged bear-ing is dismounted from a machine. Thebearing must be sent for inspection to

FAG if the cause of failure cannot bedetermined by either the operator of thepaper machine or an FAG representativeon the spot.

The following data must be providedwhen returning damaged bearings:

Pressure polished raceway and first stagesof wear in the outer ring of a sphericalroller bearing; mounted at the operator'send of a dryer roll. Cause: amount ofwater in lubricating oil too high.

Slippage damage on a barrel roller of aspherical roller bearing; mounted in asuction roll. Cause: too low load andunsuitable lubricating grease

Static corrosion in the outer ring race-way of a spherical roller bearing. Cause:amount of water in lubricating greasetoo high

27 FAG

1. Company Name, Address, Dept.

2. Application

2.1 Machine

2.2 Exact mounting location (e.g. guide roll, dryer section,locating or floating bearing)

2.3 Machine manufacturer

2.4 Service period

2.5 Machine data (product, length, width)

2.6 Number of previous bearing failures at this location/section

3. Operating conditions - roll diameter- paper speed- roll length- rotation- radial (axial) load- daily running period- lubrication (type, oil type,grease type, quantity, relubrication interval)

- drawing of bearing location(fits, sealing etc.)

4. Bearing - code (with all suffixes)- life until failure (mounted when?)- mounted by whom?- appearance of damaged bearing (inner ring, outer ring, rollers, cage) photos and sketches if available

- how was the damage recognised?

Detailed information on failure analysis and inspection of used bearings can be foundin FAG publ. no. WL 82 102 "Rolling Bearing Damage"

FAG service for more operational reliabilityPC programs · Mounting service · Training

4.6 PC programs for calculating and designing rolling bearings

The strive towards more operationalreliability commences long before bear-ings are mounted. The selection of thecorrect bearing is always the first step.

The FAG catalogue on CD ROM is afar more efficient means of selecting andcalculating rolling bearings than the actual printed book itself. The user has acomplete consulting system which leadshim or her – with Windows user guid-ance – to the list of FAG standard bear-ings ready for order. Both the nominallife and the adjusted life can be calculatedas well as permissible speed, cycling fre-quences (important for bearing diagno-sis), heat balance and required oil vol-ume.

With the version 2.0 of the catalogueon CD ROM a DXF file of the selectedbearing can be generated and importedinto CAD drafting programs. Completepages with bearing tables can be printed,also the performance data, the dimensionplan and the abutment dimensions of sin-gle bearings.

FAG also supplies numerous specialcalculation programs. The following canbe calculated for example:– changes in bearing clearance– bearing elasticity and rigidity – shaft bending.Please refer to TI no. WL 49-41 for moreinformation on these PC programs.

4.7 FAG mounting service

Upon request, FAG fitters/Service Engineers mount all bearings in the paperindustry, check mating parts (roll jour-nals, housings), search for faults whenbearings are not running perfectly, dis-mount bearings, train maintenance staff

and provide advice on rationalisationmeasures for mounting procedures. Fit-ters/Service Engineers also assist whenselecting suitable tools and show users theequipment and processes involved.

4.8 FAG training courses

A good standard of technical knowl-edge helps to increase the service life ofbearings and to avoid failures.

For years now, FAG has provided prac-tical training, courses and seminars onthe theme of rolling bearings. They areheld at FAG, at FAG distributingpartners', and directly in the paper mills.Seminars on the spot are advantageous inthat the participants save both travellingexpenses and the time getting there andback.

Training modules for paper mills are:- Basic bearing seminars- Mounting and dismounting training- Lubrication guidelines- Damage analysis seminars- Tailor-made in-house seminars

FAG training

FAG developed the Software W.L.S.with interactive program guidance forlearning alone at the computer. Thislearning program conveys solid basicknowledge on the properties of thediverse bearing types, the system of cod-ing, on mounting bearings and avoidingbearing damage. The dialogue-orientedlearning program takes more and moreindividual training and further trainingin companies into consideration. Thecomplete software package is suitable forall those involved with rolling bearingswhether in Purchasing or Materials Management, Designing and Develop-ment or in Maintenance.

FAG rolling bearing learning systemW.L.S.

Several FAG video films are availablefor training, instruction, and service,such as:– mounting and dismounting rolling

bearings– hydraulic method for mounting and

dismounting large rolling bearings– induction heating device for mount-

ing large rolling bearings– bearing replacement with FAG split

spherical roller bearings 222SM.

Please see TI no. WL 00-11 for more films.

FAG 28

FAG service for more operational reliabilityA selection of publications

4.9 A selection of other FAG publications

CatalogueWL 41520 FAG Rolling Bearings

Publ. No.WL 13 111 Self-aligning Cylindrical Roller Bearings for Dryer Rolls/M.G. Cylinders and Guide Rolls of Paper MachinesWL 13 112 A Partnership in PaperWL 13 501 Bearing arrangement of an M.G. cylinder of a papermaking machineWL 13 502 FAG Spherical Roller Bearings in a Wood GrinderWL 13 503 FAG E spherical roller bearings in felt guide rolls in the dryer section of papermaking machinesWL 13 504 Increased capacity of a Finnish papermaking machineWL 13 505 Refiner Bearings Arrangement with FAG Cylindrical Roller BearingsWL 13 506 Creping cylinder bearings in a tissue paper making machineWL 13 507 Increasing the Output of Papermaking Machines by Converting the Dryer Section to FAG Rolling BearingsWL 13 508 FAG split spherical roller bearings in dryer rollers of papermaking machines reduce downtimes for bearing

replacementWL 13 509 FAG deep groove ball bearings for spreader rolls in papermaking machinesWL 13 510 Considerable energy reduction by conversion of dryer rolls in papermaking machines from sliding bearings to

rolling bearingsWL 13 511 Dryer Roll Bearings have worked reliably in a Finnish Cardboard Mill for more than 10 yearsWL 13 512 FAG Split Spherical Roller Bearings in Paper Mill Agitators Reduce DowntimeWL 13 513 FAG Hybrid Bearings for Spreader RollsWL 13 514 FAG Self-Aligning Ball Bearings for Fly Rolls in CalendersWL 43 165 FAG Split Spherical Roller BearingsWL 80 100 Mounting and Dismounting of Rolling BearingsWL 80 102 How to Mount and Dismount Rolling Bearings HydraulicallyWL 80 103 FAG Hydraulic NutsWL 80 137 Rolling bearing diagnosis with the FAG bearing detectorWL 80 141 Rolling bearing diagnosis with the FAG bearing analyserWL 80 151 Repair service for large rolling bearingsWL 81 115 Rolling Bearing Lubrication WL 82 102 Rolling Bearing Damage

TI No.WL 13-1 Housings for Dryer Rolls in Paper-Making MachinesWL 13-2 PMF Housings for Guide Rolls in Paper MachinesWL 43-1192 FAG Triple Ring Bearings for the Paper-Making IndustryWL 49-41 PC Calculation ProgrammesWL 62-1 “Doping” for the SurfaceWL 80-14 Mounting and Dismounting of Spherical Roller Bearings with Tapered BoreWL 80-46 FAG Hand Pump Sets WL 80-47 FAG Induction Heating DevicesWL 80-48 FAG Mechanical Extractors

29 FAG

Dimensioning and lubricating rolling bearingsDimensioning

5 Dimensioning and lubricating rolling bearings

5.1 Dimensioning

Rolling bearings are checked for meet-ing demands on life and cost-efficiencyby means of the dimensioning calcula-tion. Bearings in paper machines aredynamically stressed as a rule. The ringsof such bearings rotate relative to oneanother.

The calculation of the nominal life Lhfor dynamically stressed bearings is pro-vided in detail in the catalogue WL 41 520 "FAG Rolling Bearings". Ofthe operating conditions only the loadand the speed are taken into account withthis process. The attainable life reallydepends, however, on a number of otherinfluences.

Based on the adjusted life calculationaccording to DIN ISO 281, FAG devel-oped a refined process to determine theattainable life Lhna with which the operat-ing conditions, particularly the cleanli-ness effect in the lubricating gap, can beexpressed in figures. The process for cal-culating the attainable life is described inthe catalogue WL 41 520.

Recommended values for dimensioning

Reccommended values for the attain-able life Lhna are indicated in the follow-ing table for the various mounting loca-tions in machines and equipment used inthe production of paper. The Lh life val-ues reached so far are also provided forreasons of comparison. They largely cor-respond to the recommendations madeby TAPPI (Technical Association of thePulp and Paper Industry, USA). As anexample a recommended value for Lh of285,000 hours is indicated for dryer rolls.For old non-insulated journal bearingarrangements an attainable life Lhna of about 100,000 hours results where factora23 = 0.35. In modern machines withstandard journal insulation an Lhna value

of more than 250,000 hours is expected,an unusually high service life.

In contrast, the service life expectationfor bearings in the wet end section is wellbelow 15 years as changes and modern-izations are common within this time.

Enormous differences in operatingspeeds as in the case of dryer rolls forexample, play an important role whendesigning. They are less than 800 m/minfor board machines and up to 1,800 m/min for dryer rolls for news-paper machines.

Recommended values for dimensioning rolling bearings found in paper production

Application AttainablelifeLhna*)h years**)

Wet section

forming rolls,suction rolls,guide rolls, > 100 000 > 12press rolls

Dryer section (basic demand: Lh > 100 000 h)

guide rolls > 120 000 > 15

dryer rolls > 250 000 > 30

M.G. Yankee cylinders > 350 000 > 45

Other parts

calenders,glazing rolls, > 80 000 > 10reel spool bearings

anti-deflection rolls > 80 000 > 10

refiners,pulpers > 80 000 > 10

*) calculated with a23 = a23II, i.e. s = 1 for normal cleanliness**) at 8,000 operating hours per year

We recommend determining first Lhfor the roll with the highest load takingthe design speed (nD) into considerationand the equivalent dynamic load P (seepage 31).

The real operating speed and thus thelowest viscosity ratio κ should be takeninto consideration for calculating the Lhnavalue.

Please see reference values in diagramon the page 31 for the operating tempera-ture of dryer roll bearings (inner ring).

FAG 30

Dimensioning and lubricating rolling bearingsDimensioning

Equivalent dynamic load P of bearingsin paper machines

G weight of roll/cylinder [kN]

Fz felt pull/wire pull [kN]at 180° wrap angle

f1 = 1.055 for temporary filling of dryer and M.G./Yankee cylinders with condensation water

f2 = 1.1 for axial forces acting on locating bearing(drive, pull of oblique felt or wire), when values are not available

Dryer / M.G./Yankee cylinder,operator's end:

P = (G/2 + Fz) · f1additionally: axial displacement forcewith spherical roller bearing as floatingbearing and force from steam joint,with M.G./Yankee cylinder relief bymeans of pressure rolls

Dryer / M.G./Yankee cylinder, driveend:

P = (G/2 + Fz) · f1 · f2additionally: radial force from driveand force from steam joint and axialdisplacement force of floating bearing

Guide rollP = (G/2 + Fz) · f2

Suction roll:P = (G/2 + Fz) · f2additionally: force direction as well asrelief or load due to negative pressurein suction box

Press roll/pressure roll:P = (G/2 + Fz) · f2additionally: force direction as well asrelief or load due to other rolls/cylin-ders

Calender roll:P = G/2 + FNip/2additionally: position of application,time and load shares (cf. also section3.3.1)

Correction factor for reduction in hardness

Under operating temperatures > 100 °Cthe dynamic load rating C must be multi-plied by fH for bearings in paper ma-chines which are heat-treated to S1 inaccordance with standard.

Correction factor fH for consideration ofoperating temperature effect on the loadrating of bearings made of chromiumsteel

Reference values for the temperature of bearings in dryer rolls, valid for popularspherical roller bearing sizes lubricated with minimum oil flow rates (section 5.2.2),depending on steam temperature and insulation (correlation steam tempera-ture/steam pressure see 6.1.3 and 6.1.4)

31 FAG

0 100 200

1.1

1.0

0.9

temperature°C

fH

0.8

meantemperaturebearinginner ring

70

80

90

100

110

120

130

140

150

°C

140 150 160 170 180

roll journal insulated

roll journal not insulated

steam temperature

ºC

Dimensioning and lubricating rolling bearingsLubrication

5.2 Lubrication of rolling bearings

The operating conditions and the con-sequent demands on lubrication can dif-fer greatly from one bearing location toanother in paper machines. For this rea-son lubrication is dealt with in section 3under bearing examples. Here, just gener-al views on the lubrication of rollingbearings in paper machines are presented.Rolling bearing lubrication is presentedin detail in the FAG publication WL 81 115 "Rolling Bearing Lubrication".

Load, speed and operating tempera-ture of the bearing as well as environmen-tal conditions and operational reliabilityare decisive for the choice of lubricationsystem. As a result oil circulation lubrica-tion is generally selected for bearings inmodern paper machines whereas greaselubrication is seldom considered.

Heat balance calculations are some-times of use in order to calculate the lossin bearing efficiency (see publ. no. WL81 115). How correct such a calculationis depends on previous knowledge ofoperating data and corresponding valuesfor heat flow conditions.

5.2.1 Grease lubrication

Grease lubrication is possible for smalland middle-size bearings if speed andtemperatures are not too high. Greaselubrication is advantageous in that theconstruction is not complex and thegrease also provides for sealing. Mainten-ance is also simple. The remaining servicelife can be longer when there is a break-down in lubricant supply. In the case ofbearings in paper machines grease lubri-cation is mainly used for those in the wetend section as temperatures are low andsealing against water and contaminationmust be kept in mind.

Grease-lubricated bearings in the dryersection where temperatures are high andbearing locations are under great stressare an exception.

Selection of grease

You will find criteria for selectinggrease in the FAG publication numberWL 81 115, for example.

Along with the data on grease proper-ties provided by the grease manufacturer,experience in the field of grease applica-

General recommendations for the grease lubrication of bearings in paper machines(wet end section and dryer section)

• Greases according to FAG's outline of requirements (see pg. 33)

• Direct grease supply (for example with spherical roller bearingsvia lubricating groove and holes in the outer or inner ring)

• Weekly – monthly relubrication depending on environmental effects

• Relubrication quantity according to FAG publ. no. WL 81115/4, pg. 38m1 = 0.002 · D · B [g] with manual grease supplym2 = 1 · [π/4 · B · (D2 – d2) · 10–9 – G/7800] [kg/h] with

automatic grease supply systems

with D bearing outside diameter [mm]B bearing width [mm]d bearing bore [mm]G bearing weight [kg]

• Grease removal at both sides

• Plenty of relubrication prior to and following downtime

• Avoid mixing different greases if possible, even if compatibility is indicated

• Install short supply pipes

• Protect supply pipes from heat

tion are of particular importance. As aresult, FAG drew up an outline of re-quirements and specifications for thedryer section and the wet end section sep-arately. You can receive upon request anupdated list of greases recommended byFAG for the wet end section and thedryer section.

FAG 32


Requirements on greases for bearings in the wet end section:

– very good water resistance– good sealing effect– very good anti-corrosive properties– good lubricating film formation properties– good compatability with elastomers and plastics– multi-metal compatibility– good oxidation stability– excellent lubricity also in bearings with complex kinematics by means of a selected

thickener and EP additives which are effective in the most diverse bearing types– high degree of cleanliness– good conveyance in central lubricating systems

(no separation of oil and thickener under pressure, good decompression character-istics, good pumpability behaviour in storage containers)

Requirements on greases for bearings in the dryer section:

– excellent oxidation stability– very good suitability to high temperatures– no development of residues/deposits in bearings and housings– very good anti-corrosive properties– multi-metal compatibility– good lubricating film formation properties– excellent lubricity also in bearings with complex kinematics by means of an effi-

cient thickener and effective additives in bearings at most diverse temperatures– good sealing effect – good compatibility with elastomers and plastics– high degree of cleanliness– easy conveyance in central lubricating systems

(no separation of oil and thickener under pressure, good decompression character-istics, good flowing behaviour in storage containers, no coking in pipes)

– good grease escape from the housing– very long service life

Overall reduction factors q

Bearing location Overall reduction factor q

Wet end sectionpartially very moist environment 0.1 – 0.3

Dryer sectionwhere grease lubricated 0.3 – 0.4(e.g. dryer felt guide rolls)

Grease supply

The appropriate grease quantity, relu-brication intervals based on grease servicelife, correct designing of bearing lubrica-tion and the suitable mode of lubricationare decisive for an adequate lubricantsupply. The fundamental aspects are dealtwith in detail in the publication no. WL 81 115.

The diagram with lubrication intervalstf shown there is only valid for favourableenvironmental conditions and standardlithium soap base greases. The effect oftemperature and the environment is ofparticular importance in the case of papermachines.

The reduced lubrication interval tfqwith the overall reduction factor q (see table, below left) is derived from

tfq = q · tf

which takes into account all adverse oper-ational and environmental conditions.

The relubrication interval of 0.5 to 0.7 · tfq should be taken. Experience hasshown that relubrication intervals of ≤ 2weeks and of about 4 weeks suffice forbearings in the wet end section (extreme-ly wet locations) and for grease-lubricatedbearings in the dryer section respectively.

In the case of spherical roller bearingsthe fresh grease should always be suppliedvia the lubricating groove and the lubri-cating holes in the outer ring to expell theused grease and ensure optimal greaseexchange. A completely even distributionon both roller rows is achieved wherebythe used grease is expelled from the bear-ing. This is of particular importance forbearings in danger of corroding in thewet end section. It is not possible toreplenish bearings during operation witha rotating outer ring.

Therefore bearings with lubricatingholes in the inner ring should be usedhere in order to supply grease directly tothe centre of the bearing. Bearing designswith lubricating groove and holes are rec-ommended; with this design a circumfe-rential lubricating groove on the bearingjournal is not necessary.

33 FAG


The effect of such measures is fre-quently underestimated. As experiencehas shown, the most damage arises in thegrease-lubricated bearings of the wet endsection due to poor lubricant supply ordilution of the lubricant with water (reduced lubricating effect) and directcorrosion at the functional areas.

Since corrosion can occur during bear-ing downtime also (due to penetration ofwater during cleaning or development ofcondensation) it is advantageous to re-plenish the bearings thoroughly directlybefore shutting down the machine orwhen rolls are put in reserve.

A mixture of different greases shouldbe avoided if possible. Greases with dif-ferent soap bases should not be mixed.Thorough cleaning with flushing is amust if a different grease type is to beapplied.

When a new bearing has been mount-ed relubrication should be undertakenrelatively soon in order to eliminatemounting contamination and running-inwear.

5.2.2 Oil lubrication

Oil lubrication is necessary when bear-ings are expected to heat up very highdue to load and speed and/or due to theirenvironment.

Oil circulation lubrication preferablyused in new paper machinery has the fol-lowing advantages:

Contaminants do not compile whenthe oil supply drainage is correctlydesigned; they are transported to the cor-responding oil maintenance equipment(filters, separators, sedimentation pit etc.)

and removed from circulation. Oil stressis reduced with a large total oil volume.Besides, heat dissipates with oil coolingand the bearing temperature drops.

General recommendations for the lubrication of bearings in paper machines withcirculating oils:

• Oils according to the outline of FAG requirements• Direct oil supply, via lubricating groove and lubricating holes in the rings of spheri-

cal roller bearings and self-aligning cylindrical roller bearings • Oil exit on both sides with sufficiently dimensioned drain pipes cross section• Avoidance of residual oil sump• Minimum flow rates according to FAG recommendations• Lubrication monitoring of each individual bearing location• Protection of supply pipes from heat• Oil supply temperature of max. 50 – 60 °C by means of oil cooling for the dryer

section• Separate oil supply systems for the different sections of paper machines• Effective journal insulation in the case of dryer rolls and thermo rolls

Note: With the insulation of hollow journals and an adequate oil flow rate as wellas recooling, a low bearing temperature can be achieved today and thus sufficientoperating viscosity of the lubricating oil. A viscosity ratio κ < 0.4 can be anticipatedwith non-insulated journal bores and low speed and therefore a life factor a23 of0.35 at a max.

• Settle-down zones and air release facilities in the tank• Oil maintenance measures:

– Rinsing and fine-mesh filtering prior to starting up, afterbig repair work, bearing damage or complete oil exchange

– Filtering in main stream with 12 µm, better 6 µm, with a filtration ratio of βx ≥ 75. Additional by-pass filtering with 6 µm and βx ≥ 75 increases effectivity with high flow rates considerably.

– Oil cleanliness class 15/12 according to ISO 4406– Water content < 0.03 % weight (300 ppm)– Exchange oil on time depending on oil condition

(responsibility of the oil supplier)

In the case of highly doped mineraloils and synthetic oils compatibility withsealing and cage materials should be keptin mind.

FAG 34


Oil selection

Mineral oils and synthetic oils are suit-able for lubricating rolling bearings. Theselection of the oil depends on the oper-ating conditions present at the bearinglocation.

FAG specifies the oil requirement intwo separate lists for paper machines –one for the wet end section and one forthe dryer section.

Requirements on circulating oils for bear-ings in the wet end section:

– high oxidation stability– good demulsifying ability– good anti-corrosive properties– multi-metal compatibility– hydrolysis stability– high viscosity index– high pressure-viscosity coefficient– effective boundary layer forming addi-

tives in rolling bearing– good compatibility with elastomers

and plastics– keep clean performance– good filterability– good compatibility with preservatives– particularly good long-term suitability

Requirements on circulating oils for bear-ings in the dryer section:

– best oxidation stability– good demulsifying ability– good anti-corrosive properties– multi-metal compatibility– hydrolysis stability– high viscosity index– high pressure-viscosity coefficient– effective boundary layer forming addi-

tives in rolling bearing– good compatibility with elastomers

and plastics

– keep clean performance– good filterability– anti-foam properties– no residue/deposit development and

cloudiness of the oil– particularly good long-term suitability.

You can receive upon request anupdated FAG recommendation list of oilsfor both sections.

Oil supply

The volume of oil to be supplied ineach case depends essentially on the con-ditions regarding heat elimination andheat supply. With a high speed index (n · dm > 300,000 min–1 · mm, e.g. withsuction rolls) heat balance calculations asin accordance with FAG publ. no. WL 81 115/4 are recommended.

Only a very small oil volume is actual-ly required to lubricate the bearing itselfbut far greater volumes are selected forsafety reasons and to insure that all con-tact areas have sufficient oil. The volumeincreases even more if heat dissipation isrequired.

The advantage of direct lubricant sup-ply via lubricating groove and holes inthe rings should be availed of for oil-lubricated bearings as well.

Rolling bearings must be lubricatedbefore going into operation. With circu-lating oil lubrication, this is achieved bystarting the oil pump before the machineis put into operation. Please refer to thediagrams on pages 36 and 37 for oil flowrates recommended by FAG for each ofthe bearing locations in a paper machine.

Pressure drop with oil circulation lubrication

As already described, the oil shouldreach the bearing as directly as possible.As a result the cool oil, with no previousheating, is directed to the contact areas tobe lubricated where it heats up and car-ries off heat. The oil has a higher viscositydue to the low temperature and a betterload-carrying lubricating film can buildup.

Due to the lubricating grooves in theFAG spherical roller bearings and doublerow cylindrical roller bearings there is adrop in pressure when the oil volume islarge. With a large number of bearings asis the case in paper machines, this mustbe taken into consideration by providingmore pumping capacity when designingthe circulation system. The dimensions ofthe lubricating grooves are decisive forthe drop in pressure. The lubricating holes have a negligible effect. By approxi-mation the pressure drop is calculatedwith the formula

∆p = 44 · 10–5 H2 · D · Q · ν [bar][(H – t) · t]3

where

Q oil flow rate [l/min]ν oil viscosity [mm2/s]H groove width [mm]t groove depth [mm]D bearing outside diameter [mm]

It is advisable to provide a circumfe-rential groove in the housing in order toreduce the drop in pressure with a largevolume of oil. This is also recommendedfor floating bearings with big axial dis-placement distances to ensure oil supply.

35 FAG


Minimum oil flow rates for circulation lubrication

for bearings in guide rolls for bearings in dryer rolls and M.G./Yankee cylinders

for bearings in wet presses for bearings in suction rolls

FAG 36

5

1

l/min

min

imum

oil

flow

rat

e Q

bearing outside diameter D

0.5

0.2

0.1

0.05

0.02

Spherical roller bearing series 223..K.C3 dryer section wet end section

50 200100 500mm

20

10

5

2

1

l/min

min

imum

oil

flow

rat

e Q


Spherical roller bearing series 231..K.C4Spherical roller bearing series 230..K.C4

gauge pressure of saturated steam = 3.0 bar = T = 142 °C(lower half of area)gauge pressure of saturated steam = 10.5 bar = T = 185 °C(upper half of area)

^

^

0.5

0.2

200 500 1000mm

20

5

2

1

l/min

min

imum

oil

flow

rat

e Q


n · dm ≤ 200 000 min-1 · mm lower half of arean · dm > 200 000 min-1 · mm upper half of area

Spherical roller bearing series 232..KSpherical roller bearing series 231..K

0.5

0.2

0.1

100 200 500 1000mm

1

3

2

5

10

20

0.5500400 1000

Spherical roller bearing series 230..KSpherical roller bearing series 239..K

n · dm < 200 000 min-1 · mm lower half of arean · dm = 200 000 - 300 000 min-1 · mm upper half of arean · dm > 300 000 min-1 · mm upper limit of area

min

imum

oil

flow

rat

e Q

l/min

bearing outside diameter D700 mm

7

0.7

1.5


Minimum oil flow rates for circulation lubrication

for bearings in soft calenders

Oil removal

The design of the oil drainage systemis of particular importance in the case ofrelatively high oil flow rates and reducedbearing temperatures as a result of insula-tion and cooling.

Oil drains which are not adequatelydimensioned and high-viscosity oils cancause an oil leak at the housing especiallywhen the paper machine starts in a coldcondition.

In addition to large drain cross sec-tions on both sides of the bearing withadequately dimensioned levelling holes atthe lowest point of the housing, the

drainage pipes should be provided withthe largest possible slope.

It is also important that the junctionwhere drain pipes later meet is continuedwith a correspondingly large diameter inorder to avoid jamming. The formula

da = 11.7 · 4√Q · ν/G [mm]

whereda diameter of drain pipe [mm]Q oil flow rate [l/min]ν oil viscosity [mm2/s]G slope [%]

is used for more accurate dimensioningin the slope area of the drain pipes from 1to 5 %.

37 FAG

Calculated for: P/C = 0.05 ... 0.15n · dm = 300,000 min-1 · mmoperating temperature = 125 °Coil viscosity VG220heat dissipation 30% via housing surfacetinl. - toutl. = 20 °C

1 500 mm

P/C = 0.15

P/C = 0.05

Spherical roller bearing series 232.. series 231..


min

imum

oil

flow

rat

e Q

500 600 700 800 1 000 1 200

50

20

10

8

543

2

l/min

TablesConversion

6 Tables

6.1 Conversion6.1.1 Flow rate

6.1.2 Speed

6.1.3 Temperature

6.1.4 Saturated steam pressure

FAG 38

0 1

0 2 4 6

2

8

3

10

4

12

5

14 16 18

6

20 22

7

24 26 28

8 9 10

4030

US gallons/min

l/min

0

0

1 000

500

2 000

1 000

3 000

1 500

4 000 5 000

2 000

6 000 7 000

2 500

8 000

3 000

9 000 10 000 fpm

m/min

150

75

200

100

250

125

300

150

350

175

400

200

1

5 10

2

20

3

30

4

50

5

70

7

100

10

150

15

200

°F

°C

bar

psi

1 US Gallon = 3.7854 l

1 fpm = 0.3048 m/min

x °C = (x·9/5 + 32) °F

1 psi = 0.0689 bar

32 34 36 38

TablesRadial clearance

6.2 Radial clearance

6.2.1 Radial clearance of FAG cylindrical roller bearings

6.2.2 Radial clearance reductionfor FAG cylindrical roller bearings with tapered bore

39 FAG

Dimensions in mm

Nominal over 50 65 80 100 120 140 160 180 200 225 250 280 315 355 400 450 500 560 630bore diameter to 65 80 100 120 140 160 180 200 225 250 280 315 355 400 450 500 560 630 710

with cylindrical bore

Bearing clearance in µm

Clearance group min 40 40 50 50 60 70 75 90 105 110 125 130 145 190 210 220 240 260 285CN (normal) max 70 75 85 90 105 120 125 145 165 175 195 205 225 280 310 330 360 380 425

Clearance group min 60 65 75 85 100 115 120 140 160 170 190 200 225 280 310 330 360 380 425C3 max 90 100 110 125 145 165 170 195 220 235 260 275 305 370 410 440 480 500 565



with tapered bore


Clearance group min 50 60 70 90 100 110 125 140 155 170 185 205 225 255 285 315 350 380 435CN (normal) max 80 95 105 130 145 160 175 195 215 235 255 280 305 345 385 425 470 500 575




*) Please observe deviating values when using the dis-placement measuring instrument RKP.MG.

1) The following applies: Bearings, whose radial clear-ance is in the upper half of the tolerance range prior tomounting, are mounted with the larger value of theradial clearance reduction or of the axial drive up,bearings in the lower half of the tolerance range withthe smaller value of the radial clearance reduction or ofthe axial drive up.

2) Applies only to solid steel shafts and hollow shafts,whose bore is not larger than half the shaft diameter.The drive-up values have to be multiplied for journalswith di/dm > 0.5 by 1/fi for steel journals (see diagram3, page 25) and in case of grey cast iron or spheroidalgraphite cast iron additionally with the factor w (seediagram 4, page 25).

Nominal Reduction of Drive up*) Check value of smallest radialbore dia radial clearance1) on taper 1:122) clearance after mounting

d shaft sleeve CN C3 C4 C5over to min max min max min max min min min minmm mm mm mm

50 65 0.03 0.035 0.45 0.55 0.5 0.65 0.02 0.035 0.05 0.08565 80 0.035 0.04 0.55 0.6 0.65 0.7 0.025 0.04 0.07 0.10580 100 0.04 0.045 0.6 0.7 0.65 0.8 0.03 0.05 0.075 0.11

100 120 0.045 0.055 0.7 0.85 0.8 0.95 0.045 0.065 0.085 0.125120 140 0.055 0.065 0.85 1 0.95 1.1 0.045 0.07 0.095 0.14140 160 0.06 0.075 0.9 1.2 1 1.3 0.05 0.075 0.105 0.155

160 180 0.065 0.085 1 1.3 1.1 1.5 0.06 0.08 0.11 0.16180 200 0.075 0.095 1.2 1.5 1.3 1.7 0.065 0.09 0.125 0.18200 225 0.085 0.105 1.3 1.6 1.4 1.8 0.07 0.1 0.14 0.2

225 250 0.095 0.115 1.5 1.8 1.6 2 0.075 0.105 0.155 0.22250 280 0.105 0.125 1.6 2 1.7 2.3 0.08 0.125 0.17 0.24280 315 0.115 0.14 1.8 2.2 1.9 2.4 0.09 0.13 0.185 0.26

315 355 0.13 0.16 2 2.5 2.2 2.7 0.095 0.14 0.195 0.275355 400 0.14 0.17 2.2 2.6 2.5 2.9 0.115 0.165 0.235 0.325400 450 0.15 0.185 2.3 2.8 2.6 3.1 0.135 0.19 0.27 0.37

450 500 0.16 0.195 2.5 3 2.8 3.4 0.155 0.215 0.31 0.42500 560 0.17 0.215 2.7 3.4 3.1 3.8 0.18 0.24 0.345 0.465560 630 0.185 0.24 2.9 3.7 3.5 4.2 0.195 0.26 0.38 0.5

630 710 0.2 0.26 3.1 4.1 3.6 4.7 0.235 0.305 0.435 0.575

TablesRadial clearance

6.2.3 Radial clearance of FAG spherical roller bearings

6.2.4 Radial clearance reductionfor FAG spherical roller bearings with tapered bore

FAG 40

Dimensions in mm

Nominal over 50 65 80 100 120 140 160 180 200 225 250 280 315 355 400 450 500 560 630 710 800 900bore diameter to 65 80 100 120 140 160 180 200 225 250 280 315 355 400 450 500 560 630 710 800 900 1000

with cylindrical bore


Clearance group min 40 50 60 75 95 110 120 130 140 150 170 190 200 220 240 260 280 310 350 390 430 480CN (normal) max 65 80 100 120 145 170 180 200 220 240 260 280 310 340 370 410 440 480 530 580 650 710

Clearance group min 65 80 100 120 145 170 180 200 220 240 260 280 310 340 370 410 440 480 530 580 650 710C3 max 90 110 135 160 190 220 240 260 290 320 350 370 410 450 500 550 600 650 700 770 860 930



with tapered bore


Clearance group min 55 70 80 100 120 130 140 160 180 200 220 240 270 300 330 370 410 460 510 570 640 710CN (normal) max 75 95 110 135 160 180 200 220 250 270 300 330 360 400 440 490 540 600 670 750 840 930




*) Please observe deviating values when using the dis-placement measuring instrument RKP.MG.

1) The following applies: Bearings, whose radial clear-ance is in the upper half of the tolerance range prior tomounting, are mounted with the larger value of theradial clearance reduction or of the axial drive up,bearings in the lower half of the tolerance range withthe smaller value of the radial clearance reduction or ofthe axial drive up.

2) Applies only to solid steel shafts and hollow shafts,whose bore is not larger than half the shaft diameter.The drive-up values have to be multiplied for journalswith di/dm > 0.5 by 1/fi for steel journals (see diagram 3,page 25) and in case of grey cast iron or spheroidalgraphite cast iron additionally with the factor w (seediagram 4, page 25).

Nominal Reduction of Drive up*) Drive up*) Check value of smallestbore diameter radial on taper 1:122) on taper 1:302) radial clearance

clearance1) after mountingd shaft sleeve shaft sleeve CN C3 C4 C5over to min max min max min max min max min max min min min minmm mm mm mm mm

50 65 0.03 0.04 0.45 0.6 0.5 0.7 – – – – 0.025 0.035 0.055 0.0865 80 0.04 0.05 0.6 0.75 0.7 0.85 – – – – 0.025 0.04 0.07 0.180 100 0.045 0.06 0.7 0.9 0.75 1 1.7 2.2 1.8 2.4 0.035 0.05 0.08 0.12

100 120 0.05 0.07 0.7 1.1 0.8 1.2 1.9 2.7 2 2.8 0.05 0.065 0.1 0.15120 140 0.065 0.09 1.1 1.4 1.2 1.5 2.7 3.5 2.8 3.6 0.055 0.08 0.11 0.17140 160 0.075 0.1 1.2 1.6 1.3 1.7 3 4 3.1 4.2 0.055 0.09 0.13 0.2

160 180 0.08 0.11 1.3 1.7 1.4 1.9 3.2 4.2 3.3 4.6 0.06 0.1 0.15 0.23180 200 0.09 0.13 1.4 2 1.5 2.2 3.5 4.5 3.6 5 0.07 0.1 0.16 0.24200 225 0.1 0.14 1.6 2.2 1.7 2.4 4 5.5 4.2 5.7 0.08 0.12 0.18 0.27

225 250 0.11 0.15 1.7 2.4 1.8 2.6 4.2 6 4.6 6.2 0.09 0.13 0.2 0.3250 280 0.12 0.17 1.9 2.6 2 2.9 4.7 6.7 4.8 6.9 0.1 0.14 0.22 0.32280 315 0.13 0.19 2 3 2.2 3.2 5 7.5 5.2 7.7 0.11 0.15 0.24 0.35

315 355 0.15 0.21 2.4 3.4 2.6 3.6 6 8.2 6.2 8.4 0.12 0.17 0.26 0.38355 400 0.17 0.23 2.6 3.6 2.9 3.9 6.5 9 6.8 9.2 0.13 0.19 0.29 0.42400 450 0.2 0.26 3.1 4.1 3.4 4.4 7.7 10 8 10.4 0.13 0.2 0.31 0.46

450 500 0.21 0.28 3.3 4.4 3.6 4.8 8.2 11 8.4 11.2 0.16 0.23 0.35 0.51500 560 0.24 0.32 3.7 5 4.1 5.4 9.2 12.5 9.6 12.8 0.17 0.25 0.36 0.55560 630 0.26 0.35 4 5.4 4.4 5.9 10 13.5 10.4 14 0.2 0.29 0.41 0.63

630 710 0.3 0.4 4.6 6.2 5.1 6.8 11.5 15.5 12 16 0.21 0.31 0.45 0.69710 800 0.34 0.45 5.3 7 5.8 7.6 13.3 17.5 13.6 18 0.23 0.35 0.51 0.77800 900 0.37 0.5 5.7 7.8 6.3 8.5 14.3 19.5 14.8 20 0.27 0.39 0.57 0.87

900 1000 0.41 0.55 6.3 8.5 7 9.4 15.8 21 16.4 22 0.3 0.43 0.64 0.97

FAG OEM und Handel Aktiengesellschaft

Postfach 1260D-97419 SchweinfurtGeorg-Schäfer-Strasse 30D-97421 SchweinfurtTel. +49-97 21 / 91-36 89Fax +49-97 21 / 91-49 08E-mail: [email protected]

Every care has been taken to ensure thecorrectness of the information contained inthis publication but no liability can beaccepted for any errors or omissions.We reserve the right to make changes inthe interest of technical progress.© by FAG 2000. This publication or partsthereof may not be reproduced withoutour permission.

WL 13 103/2 EA/97/12/00

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ROLLING BEARINGS FOR THE PAPER INDUSTRY - … Bearings for the Paper Industry Products · Service · Design · Dimensioning Publ. No. WL 13 103/2 EA FAG OEM und Handel AG A company