Timken Bearing - Farrell Bearings
Timken BearingDamage Analysis with LubricationReference ed
IntroductionTimken stands behind its productsand the customers it serves.Whether training a team ofmaintenance personnel on properbearing installation in the PowderRiver Basin area of Wyoming orproviding application engineeringassistance from our technologycenter in Bangalore, India,Timkenfriction management knowledgeand expertise spans the globe,supporting major industries.More than 100 years ofexpertise in material science andtribology — along with our longhistory of being a quality steelmanufacturer — makes Timkenuniquely qualified in bearingdamage analysis. Our sales andservice teams are trained to bothassess bearing damage issueson site, as well as work withcustomers to offer preventivemaintenance techniques toimprove performance.The purpose of this referenceguide is to help maintenance andoperations personnel identifysome of the more common typesof bearing damage, explainpossible causes and discuss corrective actions. In many cases, thebearing damage may be due to acombination of causes.This guidealso contains useful bearing references and lubrication guidelines.For more information onbearing damage analysis, contactyour Timken sales or serviceengineer, or visit www.timken.com.2
Table ofContentsPagePreparation and Approach to Bearing Damage Analysis . . . . . . . . . . . . . . . . . . 4Types of Bearing DamageWear–Foreign Material. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Abrasive Wear. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Pitting and Bruising . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Grooving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Debris Contamination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Etching–Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Inadequate Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Fatigue Spalling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Excessive Preload or Overload . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Misalignment and Inaccurate Machining of Seats and Shoulders . . . . . . . . . . . . . . . 11Handling and Installation Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Damaged Bearing Cages or Retainers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14High Spots and Fitting Practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Improper Fit in Housings or Shafts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Brinell and Impact Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17False Brinelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Burns from Electric Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Cam Fracture-Wide Inner Ring Ball Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Roll Out (Sub Case Yielding, Case Crushing). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Rollers Locked in Place. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Bearing Stamping Lip Fractured Off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Understanding Bearing LifeBearing Fatigue Life. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Bearing Service Life . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Lubrication Reference GuideFactors that Impact Lubrication Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Lubrication Guidelines – Required Grease Quantity. . . . . . . . . . . . . . . . . . . . . . . . . . . . 27Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28Types of Bearings and Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29Tapered Roller Bearing Speed Capability Guidelines . . . . . . . . . . . . . . . . . . . . 30Conversion Equivalents for U.S. and Metric Measurements . . . . . . . . . . . . . . 31Conversion Chart Showing Millimetre, Fractional and Decimal Inch Sizes . . . . . 32Temperature Conversion Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Friction Management Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343
Preparation and Approach to Bearing Damage AnalysisFor an accurate and completeanalysis, the following stepsshould be taken when investigating bearing damage and systembreakdowns. For assistance withbearing damage analysis, contact aTimken sales or service engineer.1. Obtain operating data frombearing monitoring devices;analyze service andmaintenance records andcharts; and secure applicationdiagrams,graphics or blueprints.2. Prepare an inspection sheet tocapture all observations.Takephotographs throughout theprocedure to assist documentation or description ofdamaged components.3. Extract used lubricant samplesfrom bearings, housing andseal areas to determinelubricant conditions. Packageseparately and label properly.44. Secure a sample of new,unused lubricant. Record anyspecification or batchinformation from the container.Obtain technical specificationsand any related materialsafety data (handling, disposal,toxicological) documentationto accompany lubricantshipments.8. Mark and record the mountedposition of bearings andcomponents prior to removal.9. Measure and verify shaft andhousing size, roundness andtaper using certified gauges.10. Following removal — butbefore cleaning — recordobservations of lubricantdistribution and condition.5. Check bearing environmentfor external influences,including other equipmentproblems that preceded orwere occurring at the timebearing damage was reported.11.Clean parts and recordmanufacturers’ informationfrom marking on the bearingrings (part number, serialnumber, date code).6. Disassemble equipment(either partially or completely).Record an assessment of themounted bearing condition.12. Analyze condition of theinternal rolling contact surfaces,load zones and the corresponding external surfaces.7. Inspect other machineelements, in particular theposition and condition ofcomponents adjacent to thebearing, including locknuts,adapters, seals and seal wearrings.13. Apply a preservative oil andrepackage bearings to avoidcorrosion.14. Compile a summary report ofall data for discussion withTimken sales or serviceengineers.
Wear – Foreign MaterialOne of the most common sources of trouble in anti-friction bearings is wear and damage caused by foreignparticles. Foreign particle contamination can cause abrasive wear, bruising and grooving, circumferentiallining or debris contamination.Types of Bearing DamageBearing damage can occur as a result of a number of different operatingconditions.Those listed in this section are the most commonly found foranti-friction bearings, including cylindrical, spherical, needle, taperedand ball designs. It is important to remember that proper bearingmaintenance and handling practices are critical.Abrasive WearFine foreign material in the bearingcan cause excessive abrasive wear.Sand, fine metal from grinding ormachining, and fine metal or carbides from gears will wear or lapthe rolling elements and races. Intapered bearings, the roller endsand cone rib will wear to a greaterdegree than the races.This wearwill result in increased end playor internal clearance which canreduce fatigue life and result inmisalignment in the bearing.Abrasive wear can also affect otherparts of the machine in whichthe bearings are used.The foreignparticles may get in through badlyworn or defective seals. Improperinitial cleaning of housings and parts,ineffective filtration or improperfilter maintenance can allowabrasive particles to accumulate.Fig. 1: Fine particle contamination enteredthis spherical roller bearing and generatedwear between the cage surfaces, rollersand races.Fig. 2: The roller end wear on thisspherical bearing was also caused byfine particle contamination.Fig. 3: Fine particle contaminationcaused abrasive wear on this taperedroller bearing.Fig. 4: Exposure to abrasives and water ina severe environment caused extremewear on this pillow block bearing.5
Wear – Foreign MaterialPitting and BruisingHard particles rolling through the bearing may cause pitting andbruising of the rolling elements and races. Metal chips or largeparticles of dirt remaining in improperly cleaned housings caninitiate early fatigue damage.Fig. 5: Contamination bruising on thisneedle outer ring race resulted from aharsh environment.GroovingGrooving is caused by extremely heavy wear from chips or metalparticles.These contaminants become wedged in the soft cage materialand cause cut grooves in the rolling elements. This condition results inimproper rolling contact geometry and can reduce service life.Fig. 6: Large particle contaminationimbedded into the soft cage material canresult in grooving, as shown here.Debris ContaminationCommon causes of external debris contamination include dirt, sand and environmental particles. Commoncauses of internal debris contamination include wear from gears, splines, seals, clutches, brakes, joints,housings not properly cleaned, and failed or spalled components.These hard particles travel within thelubrication, through the bearing, and eventually bruise (dent) the internal surfaces.The dents formshoulders that act as surface-stress risers, causing premature surface damage and reduced bearing life.Fig. 7: A tapered roller bearing innerrace (cone) with spalling from debriscontamination bruises is shown here.Fig. 8: Hard particles causedcontamination bruising on this sphericalroller bearing.Fig. 10: Debris from otherfatigued parts, inadequatesealing or poor maintenancecaused bruising on thistapered roller bearing race.6Fig. 9: This photo, taken with a microscope,shows a debris contamination bruise on abearing race. A corresponding surfacemap of the dent is shown below in Fig. 11.Fig. 11
Etching – CorrosionEtching – CorrosionEtching or corrosion is one of the most serious problems encountered in anti-friction bearings.The high degreeof finish on races and rolling elements makes them susceptible to corrosion damage from moisture and water.Etching is most often caused by condensate collecting in the bearing housing due to temperature changes.The moisture or water oftentimes gets in through damaged, worn or inadequate seals. Improper washing anddrying of bearings when they are removed for inspection can also cause considerable damage. After cleaningand drying or whenever bearings are put into storage, they should be coated with oil or another preservativeand wrapped in a protective paper. Bearings, new or used, should always be stored in a dry area and kept inoriginal packaging to reduce risk of static corrosion appearing before mounting.Fig. 12: This cylindrical bearing inner ringhas etching and corrosion.Fig. 13: Advanced corrosion and pittingon the cone race and rollers makes thisbearing unsuitable for further service.Fig. 15: This cup has heavy corrosion onthe race. This type of corrosion may onlybe a surface stain without pitting. If thestaining can be cleaned with a fine emerycloth or crocus cloth, the bearing may bereused. If there are pits that cannot becleaned with light polishing, the bearingshould either be discarded or if practical,refurbished.Fig. 16: This ball bearing outer race alsodepicts etching and corrosion.Fig. 14: Heavy water damage is shown onthis ball bearing inner ring and cage.7
Inadequate LubricationInadequate LubricationBearing damage from inadequatelubrication varies greatly in appearance, ranging from very light heatdiscoloration with roller large endscoring (Figure 17), to total bearinglockup with extreme metal flow(Figure 18). It is not uncommon tofind a bearing that has experienceda dry start-up in an application tohave considerable metal flow, yetstill have shiny and polishedsurfaces.This is because the bearingwill quickly experience heat damagefrom metal-to-metal contact atstart-up, then eventually cool offonce the lubricant makes its wayto the bearings.The bearings maythen attempt to “heal” themselvesby masking the initial metal flowand heat discoloration.A second, more pronouncedlevel of damage can occur, whichoften covers up the initial problemand resultant bearing damage.Thisbearing damage typically causeshigh localized heat and metal flowin bearings, thus altering theoriginal bearing geometry and thebearing’s material.Any visible signsof metal tearing, scoring, heat,distortion or geometry alteration(Figures 19 and 20) render bearingsas scrap and they should never beused again.Careful inspection of all bearings,gears, seals, lubricants and surrounding parts often sheds lighton the primary cause of damage.See the Lubrication ReferenceGuide on page 24 to learn moreabout how lubrication conditionsimpact bearing performance.Fig. 17: Heat damage on these taperedrollers was caused by metal-to-metalcontact.Fig. 18: Total bearing lockup is depictedhere.Fig. 19: A misshaped inner ring and torncage from inadequate lubrication areshown here.Fig. 20: Excessive heat generationcaused metal flow in this ball bearinginner ring.Fig. 21: Peeling on the race of thisspherical plain bearing was caused bythin lubricant film.Fig. 22: Micro-spalling or peeling was theresult of thin lubricant film from highloads/low RPM or elevated temperatures.Inadequate lubrication is a termused to describe a broad array ofpossible damage conditions, inwhich the lubricant intended forthe bearings was not sufficient toseparate the bearing’s rolling andsliding contact surfaces duringservice. It is very important thatthe proper lubricant amount, type,grade, supply system, viscosity andadditives be properly engineeredfor each bearing system basedupon history, loading, speeds,sealing systems, service conditionsand expected life.Without properconsideration of these factors,less than adequate bearing andapplication performance maybe expected.8
Fatigue SpallingFatigue SpallingSpalling is simply defined as thepitting or flaking away of bearingmaterial. Spalling primarily occurson the races and the rolling elements. It is important to realizethat there are many types of“primary” bearing damage shownthroughout this reference guide,and they will eventually deteriorateinto a secondary damage mode ofspalling.Timken classifies threedistinct spalling damage modes:Fig. 23: High loads resulted in fatiguespalling on this cylindrical roller bearing.Fig. 24: Heavy spalling and fracturing fromhigh loads on this spherical roller bearingare shown here.Fig. 25: Misalignment, deflections orheavy loading on this tapered rollerbearing caused GSC spalling.Fig. 26: This ball bearing inner ringdepicts fatigue spalling. The fracture is asecondary damage mode. Geometric StressConcentration (GSC) SpallingThis mode is the result ofmisalignment, deflection, or edgeloading that initiates high stress atlocalized regions of the bearing.The damage occurs at the extremeedges of the race/roller paths. It isusually the end result of machiningproblems with the shaft or thehousing, or from high loads. Point Surface Origin (PSO)SpallingThis mode is the result of very highand localized stress causing thebearing to prematurely fatigue.Thespalling damage is typically fromnicks, dents, debris, etching and hardparticle contamination in the bearing.PSO spalling is the most commonspalling damage, and it oftenappears as arrowhead shaped spalls. Inclusion Origin SpallingInclusion Origin Spalling is theresult of bearing material fatigueat localized areas of sub-surface,non-metallic inclusions, followingmillions of load cycles.The damageis observed in the form of localized,elliptically shaped spalls. Bearingsteel cleanness has improved overthe past two decades to the extentthat this type of spalling is seldomencountered.Fig. 27: PSO spalling resulted from debrisor raised metal exceeding the lubricantfilm thickness on this tapered rollerbearing inner ring.9
Excessive Preload or OverloadExcessive Preload orOverloadExcessive preload can generate alarge amount of heat and causedamage similar in appearance toinadequate lubrication damage.Often the two causes may beconfused, so a very thoroughcheck is required to determinethe root problem.A lubricant thatis suitable for normal operationmay be unsuitable for a heavilypreloaded bearing, as it may nothave the film strength to carrythe very high loads.The breakdown of lubricant caused in highpreloads can cause the same typeof damage as shown in theprevious description of inadequatelubrication damage discussed onpage 8.Another type of damage canresult from heavy preloads, evenif a lubricant, such as an extremepressure type of oil that cancarry heavy loads, is used.Although the lubricant can takecare of the loads so that norolling element or race scoringtakes place, the heavy loads maycause premature sub-surfacefatigue spalling.The initiation ofthis spalling and subsequentlythe life of the bearing woulddepend upon the amount ofpreload and the capacity of thebearing.Fig. 28: Overloading on this cylindricalroller bearing caused roller surfaces tofracture.Fig. 29: A heavily overloaded taperedroller bearing resulted in premature,severe fatigue spalling on the rollers. Theload was so heavy that large pieces ofmetal broke off the rollers.Fig. 30: High loads and low speedscaused insufficient lubricant film on thistapered roller bearing cone.Fig. 31: Severe peeling and spalling isshown on this spherical bearing race.Fig. 32: High load and low speedconditions caused severe peeling andwear on this needle thrust race.10
Misalignment and Inaccurate Machining of Seats and ShouldersMisalignment and Inaccurate Machining of Seats andShouldersMisaligned bearings will shorten bearing life.The reduction in servicewill depend on the degree of misalignment.To get full life from thebearing, the seats and shoulders supporting the bearing must be withinspecified limits set by the bearing manufacturer. If the misalignmentexceeds the limits, the load on the bearing will not be distributed alongthe rolling elements and races as intended, but will be concentrated ononly a portion of the rollers or balls and races. In cases of extrememisalignment or off angle, the load will be carried only on the extremeends of the rolling elements and races. A heavy concentration of theload and high stresses at these points will result in early fatigue of themetal.Causes of misalignment: Inaccurate machining or wear of housings or shafts Deflection from high loads Out-of-square backing shoulders on shafts or housingsFig. 34A: Shaft MisalignmentFig. 33: High edge loads causedGeometric Stress Concentration (GSC)spalling on the inner race of this drawncup needle bearing.Fig. 35: Deflection, inaccurate machiningor wear of bearing seats caused anirregular roller path on this tapered rollerbearing outer ring.Fig. 36: This irreg
of bearing damage,explain possible causes and discuss cor-rective actions.In many cases,the bearing damage may be due to a combination of causes.This guide also contains useful bearing refer-ences and lubrication guidelines. For more information on bearing damage analysis, contact your Timken sales or service engineer, or visit www.timken.com. 2
4 TIMKEN METRIC TAPERED ROLLER BEARINGS BEARING DATA TIMKEN METRIC TAPERED ROLLER BEARINGS Bore Part Number Dimension Series (ISO 355) Bearing Dimensions Bore d O.D. D Width T B Width C mm mm mm mm mm mm 15 30302 2FB 15.000 42.000 14.250 13.000 11.000 17 30203 2DB 17.000 40.000 13.250 12.000 11.000 30303 2FB 17.000 47.000 15.250 14.000 12.000 20 File Size: 279KBPage Count: 20Explore furtherTapered Roller Bearing Catalog Timkenwww.timken.comTimken Tapered Roller Bearing Catalog - TIMKEN - PDF .pdf.directindustry.comTimken Metric Tapered Roller Bearing Catalogwww.timken.comTIMKEN METRIC TAPERED ROLLER BEARINGSwww.timken.comTimken-Tapered Roller Bearing Catalogue - THE TIMKEN .pdf.aeroexpo.onlineRecommended to you b
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TIMKEN SPHERICAL ROLLER BEARING CATALOG Bearings Steel Power Transmission Systems Precision Components Gears Seals Lubrication Industrial Services Remanufacture and Repair www.timken.com 30M 10-11: Order No. 10446 Timken and Where You Turn are registered trademarks of The Timken Company. 2011 The Timken Company Printed in U.S.A.
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TIMKEN CYLINDRICAL ROLLER BEARING CATALOG 5 OvERvIEW TIMKEN A ABOUT THIS CATALOG Timken offers an extensive range of bearings and accessories in both imperial and metric sizes. for your convenience, size ranges are indicated in millimeters and inches. contact your Timken sales representative to learn more about our complete
TIMKEN 2 TIMKEN CYLINDRICAL ROLLER BEARING CATALOG Download 3D Models and 2D Drawings at cad.timken.com. A PREMIUM BRASS CAGE, STEEL CAGE AND FULL-COMPLEMENT DESIGNS FOR PROVEN, RELIABLE PERFORMANCE For more than a century, original equipment manufacturers have trusted Timken to design roller bearings for long-lasting
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