Diagnosing plain bearing failures is all about recognising the tell-tale signs of different wear out and other failure modes. L10 life is a life calculation where 90% of identical bearings are handled, installed, lubricated and run under the same operating and environmental conditions, without metal fatigue. The ball bearings were replaced when before the expected lifetime of the bearing the measured vibration exceeded the tolerated level. At this time, not only the bearing but also the shaft, housing, and lubricant used with the bearing should be comprehensively investigated, together with the bearing. Finally, refer to the checklist that closes out the series for suggestions on how to avoid a repetition of the failure. Fatigue. Fretting occurs at fitting surface between raceway rings and the shaft or housing. Passage of electric current through rotating bearing. Vibration frequency bands trends are a key for bearing vibration analysis. 100X, nital etch), Figure 29: Photomicrograph of the damaged surface in a ball from the large seized bearing showing contact fatigue cracks. Urbi Pal 1, Piyas Palit 1, Prabhash Gokan 1 & Samiran Kanrar 2 Journal of Failure Analysis and Prevention (2020)Cite this article. (Photo XXXXX-N1), Figure 2: Photograph of a small seized bearing disassembled after cutting the outer race showing the grease had turned to a black thick sludge. Nearly the entire circumference of the large ball exhibited light etching untempered martensite, indicative of severe overheating, as shown in Figure 30. Follow us Failure analysis researches were done by applying of stereographic, optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spec-troscopy analysis and hardness test. Always follow installation instructions and maintain proper lubrication. It was immediately noted that the grease in the four bearings had turned to a thick (viscous) black sludge, full of particulate. Bearing Time-to-Failure Estimation using Spectral Analysis Features Reuben Lim Chi Keong1, 2, ... the ball bearings inside the outboard shaft were found to have extensive pitting on ball elements and spalling in the bearing races as shown in Figure 2a. Most bearing failures such as flaking and pitting, spalling unusual wear patterns, … How To Diagnose Rolling Bearing Failures. It is the heating which deteriorates the grease to the point where it inhibits motion rather than enables it. Send us your photos of failed or damaged bearings through this website for analysis. Both balls were sectioned through the spalling and prepared for metallographic examination. Thrust loading was observed in some of the bearings by the presence of wear off to one side of the race. thrust ball bearings have been used for illustrative purposes as they display such characteristic path patterns. These sections were prepared for metallographic examination per ASTM E3-01. Contact us. Spalling can occur on the inner … Verify fracture mechanism & initiation. Cycloidal shaped damage on the roller ends and scoring on the rib surface contacting roller ends also occur. The points of contact are melted locally to form "fluting" or groove-like corrugations which can be seen by the naked eye. Illustrations from SKF Bearing Catalogue. (SEM Photo XXXX-SA12, Mag. Deep groove ball bearings and thrust ball bearings have been used for illustrative purposes as they display such characteristic path patterns. Bearing Failure Analysis The accurate diagnosis of a bearing failure is imperative to prevent repeated failures and their additional expenses. Most of the balls in each of the four bearings exhibited at least one, and as many as four small spots of surface spalling apparently due to arc strikes and subsequent enlargement by contact fatigue. Bearing failure is one of the prime causes of breakdown in rotating machinery, resulting in expensive systems downtime. Note the caked black grease chunks on the sides. The sludge was caked on the seals and between the balls, and generally inhibiting motion rather than enabling it. We list the most common bearing failures to help you decide what has happened with your bearing… Metrics details. Fracture refers to small or large metallic pieces which were broken off due to excessive load or shock load acting locally on a rolling element, rib or section of a raceway ring. This was confirmation of the electrical pitting as these layers represented re-cast and untempered martensite from tiny arc strikes. The small ball exhibited a complete loss of material at its surface spall. Light etching areas of untempered martensite, indicative of severe overheating were also observed at some locations around the perimeter of the ball. The cages showed signs of excessive wear, and in one small and one large bearing the cages were fractured. (704) 663-5108 | Fax: (704) 662-0898 Tiny microscopic cracks are generated downward from these cloudy spots to a depth of 5-10 μm. Bearing Failure Analysis The purpose of inspecting damaged bearings and their mating parts is to determine the probable causes of the damage and to avoid any future failures. The results of the analyses are shown in Table 1 along with the requirements of E52100 bearing steel per SAE J404. 500X, nital etch), Figure 24: Photomicrograph of a large seized bearing inner race transverse cross-section showing white and light etching (arrows) areas indicative of electrical pitting. Follow Us: Forensic Failure Analysis, Corrosion Investigation, Metallurgical Testing and Engineering • Located in Mooresville, NC, Spectrometry / Scanning Electron Microscopy. Wear, corrosion and burrs caused by repeated replacement of new bearings, a contaminated or moist environment or heavy handling during bearing removal. Early failure is mostly attributable to inadequate handling or maintenance. Diametrically opposite cuts were made in the outer races of the four seized bearings. Careful inspection of the failed bearing will usually reveal vital visual clues that can lead to a potential cause for the failure. Balls have dark discolouration only. (Photo XXXX-MB15, Mag. If the … Therefore, It is important to investigate and perform a bearing failure analysis to find the root cause of the failure and prevent it from recurring. The grease in all four seized bearings had turned to a thick (viscous) black sludge full of particulate. Bearing failure demands immediate attention because it can cost as much as $25,000-$50,000 per hour—in lost productivity, unplanned outages and downtime. Note the cracks (arrows) propagating parallel to the surface. 100X), Figure 18: Increased magnification SEM image of the inner race on a large seized bearing showing the electrical pitting damage. (Photo XXXX-MB23, Mag. Flaking due to rolling fatigue occurs when small pieces of bearing material are lifted and broken off the smooth surface of the raceway or the rolling elements. Note the fractured cage pieces (arrows) and the liberated balls. This is the ideal reason for the cause of failure. (SEM Photo XXXX-SA31, Mag. (Photo XXXX-MB12, Mag. A systematic … Early failure is mostly attributable to inadequate handling or maintenance. Our team works hand-in-hand with customer engineering & quality departments, providing a direct line of access to support. Click any image to see an enlargement This can be seen in Figures 15 through 18. Six ball bearings were sent for metallurgical analysis – three smaller and three larger. The first thing to look for is an illustration that depicts similar damage to the failed bearing. Upload your photo Send us your bearing photo’s for analysis. As with plain bearings, analysing and diagnosing rolling bearing failures is all about recognising the visual signs associated with typical failure modes. Creep is the phenomenon in bearings where relative slippage occurs between fitting surfaces and thereby creates a clearance between the surfaces. JAD Analysis - Bearing Failure Analysis. The main target is to find the most influencing parameters for radial stiffness of the bearing under an axial load. During the test, vibrations are acquired and traditional metric values such as peak-to-peak value, RMS, Crest factor and kurtosis are calculated. which the bearing has operated. Vibration Analysis of Ball Bearing Ravindra A.Tarle1, 2Nilesh K.Kharate , Shyam P. Mogal3 1, 2, 3 ... investigated running a new bearing through to failure. While performing failure analysis is commonly left to outside vendors, the actual collecting of information can make a great difference in correctly diagnosing bearing failure. Read the text associated with the picture, so as to get a better understanding of why the bearing failed. We’ll use our knowledge of bearings and real-life conditions to help resolve your bearing issue as quickly and cost-effectively as possible. The seals on the four seized bearings were intact and undamaged. Engineers should not wait until the bearing failure becomes catastrophic, as this makes root cause analysis difficult. 100X), Figure 16: Increased magnification SEM image of the inner race on a small seized bearing showing the electrical pitting damage. Brass cage pillar wear caused by lack of lubrication, Dented cross roller thrust bearing raceway caused by dirt ingress following a strip down and re assembly, Raceway damaged by contaminant in the lubricant, Pear skinning caused by metal debris from a fatigue failure being pressed onto the remainder of the contact surface, Fatigue occurring on a ball bearing inner ring due to stresses induced around an impact dent, Light pitting as seen on the two sides of a spherical roller inner ring, Pitting around the circumference of a cylindrical roller inner ring, Rotation and surface wear in the bore of a tapered roller bearing inner ring, Close up of a Tapered Roller nose with heavy burrs and rotational scuffing, Top surface of a thrust bearing showing sliding wear marks to one side of the ring, Fitting marks and fretting corrosion caused by the bearing vibrating on the shaft, Fretting Corrosion and Fitting marks on the outside diameter of a spherical roller outside diameter, False brinelling caused during transportation of the stationary component, False brinelling and scratches likely to have been caused during transportation of inappropriately packed bearings, Inner ring bore creep due to a worn shaft, Tapered Roller Inner Rings distorted as a result of overloading and lack of lubrication, The remnants of rollers removed from a seized Taper Roller Bearing, Outer raceway from a seized tapered roller bearing, An angular contact bearing inner ring with material deposition from the balls following seizure, Tapered roller assembly with skewed and friction welded roller on one cone caused by assembly with an excess of end float, Electric arc pitting in a cylindrical roller outer ring, Electrical pitting in a spherical roller bearing, Electrical Pitting in a Spherical Roller bearing, Inner ring side face rusting caused by a build-up of moisture in the bearing housing close to this deep groove ball bearing, Rust corrosion on a raceway caused by a bearing standing in moisture, Rusting of a ball bearing inner ring caused by moisture in the lubricant, Axial lines on the surface of a bearing roller caused by sliding during disassembly, Outer surface scratches caused during fitting, Damaged outer surface of a double row Tapered Roller Bearing, Line on a spherical roller outside diameter caused by a split housing design, A wheel hub with a damaged abutment shoulder, a worn and tapered housing bore and excessive corrosion, A vehicle stub shaft with wear caused by inner ring rotation and pick up, JAD Associates (Improvement Solutions) Limited, Stratford House, 4 Plough Drive, Market Rasen. Failure to observe the following warnings could create a risk of death or serious injury. Diagnosing plain bearing failures is all about recognising the tell-tale signs of different wear out and other failure modes. Careful inspection of the failed bearing will usually reveal vital visual clues that can lead to a potential cause for the failure… Bearing failure analysis November 4, 2015 By Mike Santora Leave a Comment When bearings fail to meet their expected life or performance levels, the consequences are … Proper maintenance and handling procedures are critical. Call our bearings failure expert on +44 (0)1673 843059. There were no signs of mechanical, electrical or corrosion damage on the outer surfaces of the seized bearings. Bearing shapes: a) deep groove ball bearing, b) angular contact ball bearing, c) self-aligning ball bearing, d) cylindrical roller bearing, e) tapered roller bearing, f) spherical roller bearing, g) needle roller bearing, h) thrust ball bearing. The three smaller bearings were (double) sealed XXX XXX XXX. Figures 12 through 14 show the spots were typically circular or semi-circular shaped. Bearing Failure Analysis When bearings fail to meet their expected life or performance levels, the consequences are far-reaching and include, increased downtime, high maintenance costs, loss of revenue, and missed deliveries. This was confirmed by metallographic examination. Determine cause of failure & recommend ways to prevent future recurrence. This has a negative impact on your reputation, and your bottom line. Premature roller bearing failure can affect business, the environment and personnel — should the bearing cause an explosion. Straight line scratches on surface of raceways or rolling elements caused during mounting or dismounting of bearing. 500X, nital etch), Figure 30: Photomicrograph of a ball from a large seized bearing showing light etching untempered martensite observed around most of the outer surface, indicative of severe overheating. This has a negative impact on your reputation, and your bottom line. A $50 bearing can take down a multi-million-dollar process. NPB services & solutions can help: • Improve productivity Chemical composition analysis of a large seized bearing inner race, outer race, and ball was performed according to ASTM E419-99a. There were remnants of contact fatigue cracking noted at the edges of the spall. Among the different types of fretting, false brinelling is the occurrence of hollow spots that resemble brinell dents and are due to wear caused by vibration and swaying at the contact points between the rolling elements and raceway. Call our bearings failure expert on +44 (0)1673 843059. The microstructure of both balls was predominantly tempered martensite with some undissolved carbides, typical of E52100 bearing steel. The four seized bearings submitted for metallurgical analysis were determined to have suffered deterioration of their grease to the point that it was inhibiting motion rather than enabling. However, the figures are applicable, with some modifications, to other types of bearing as well. Cage damage includes: Cage deformation, Fracture and Wear Fracture of cage pillars. When the bearing goes, the machine or vehicle stops. We will be pleased if this guide book assists the user in preventing early bearing failure or in troubleshooting the causes of bearing failure. Call our bearings failure expert on +44 (0)1673 843059. The composition and hardness of the components were found to be typical and acceptable for ball bearings. Bearing failure analysis. Among these data is a detailed test report #3183, lot 73, consisting of 23 failed bearings. 8 Accesses. In this paper, an effort has been put to analyze the rolling ball bearing using finite element analysis the contact pressure level, stress or displacement behavior of rolling ball bearing. Areas of wear and plowing from liberated particles were also observed on the races. our initial thoughts and advise on how best to investigate the damage or failure. Case Studies. failure information we need for our inspections and investigations. The first thing to look for is an illustration that depicts similar damage to the failed bearing. 500X, nital etch), Figure 27: Photomicrograph of a ball from a small seized bearing showing light etching untempered martensite on the outer surface, indicative of severe overheating. For this reason, the possibility of reaching conclusions about the cause of a defect by means of studying its appearance is very useful. When a bearing does fail prematurely, it is usually due to causes that could have been avoided. Wear is surface deterioration due to sliding friction at the surface of the raceway, rolling elements, roller end faces, rib face, cage pockets, etc. Roller bearings, which operate with rolling elements such as balls or rollers in … 1,000X), Figure 17: SEM image of the inner race on a large seized bearing showing a localized patch of electrical pitting made up of numerous individual pits. The first step is therefore to perform a careful inspection of the failed roller bearing … bearing failure analysis. (SEM Photo XXXX-SA13, Mag. Failure FAQ. When electric current passes through a bearing, arcing and burning occur through the thin oil film at points of contact between the raceway and rolling elements. The first step is therefore to perform a careful inspection of the failed roller bearing race, cage and housing. We'll be in Providing inspections & investigations into failed or damaged ball & roller bearings; 3 levels of reporting from Remote Photo Reviews to Expert Witness. The electrical pitting was most evident on the inner races, as seen in Figures 10 and 11. This flaking causes regions with a rough and coarse texture. While performing failure analysis is commonly … Evidence of axial (thrust) loading was observed mainly in the outer raceways of the seized bearings. This study was based on data of 4948 bearings as obtained from 5 companies and 213 test groups. There was no heat tint or signs of corrosion observed on any of the bearing outer surfaces. They are reliable even under the toughest conditions. 5X), Figure 9: Photograph of a large bearing outer race ID ball path showing wear on one side, indicative of axial (thrust) loading. (Photo XXXX-U12, Mag. (Photo XXXX-U17), Figure 7: Photomacrograph of a sample of new grease on the left in comparison with the deteriorated grease on the right. This paper determines the method to find out the shoulder height in an angular contact ball bearing using a 3D contact analysis. Fatigue damage in a loaded zone of a tapered roller bearing inner ring, Flaking on the edge of a tapered roller inner ring, A spherical roller damaged as a result of flaking and fatigue, Flaking on a ball bearing outer ring raceway, Fatigue at both sides of a crack in a Tapered roller cone, A spherical roller raceway with surface material peeled away, A spherical roller central divider scored as a result of an ineffective lubricant film thickness being present, A prominent scoring mark caused by a lack of radial clearance during service rotation, A smeared end of a tapered rolled as a result of excessive sliding contact against the roller retaining rib, Smearing on the inner races of a duplex tapered roller, Fracture of a spherical roller bearing outer ring as a result of a high thrust impact load causing cracks, Cracking in the outer ring of an angular contact bearing, Outer ring crack caused by a heavy impact through the rolling elements, Inner ring crack caused by excessive hoop stress, Tapered roller cage with worn side pillars caused by the bearing having run in a reduced lubricant condition, Wear in a brass cage pocket due to low lubrication, An angular contact bearing cage deformed due to rubbing contact with other assembly parts, Wear of pocket surface. Were also confirmed to be XXXXXX XXXX electric motor bearing grease as shown in Figure 1 conducted a study the... Bearings for enhancing the spectrum amplitude of the failure 0.668 kg weight for each the showed! The Weibull slope of this group is 2.23, meaning that this distribution is mono sloped detailed. However, the Figures are applicable, with some undissolved carbides, typical of fatigue., so as to get a better understanding of why the bearing is often “... Enabling it 2015 by Mike Santora Leave a Comment, Fracture and wear of!, RMS, Crest factor and kurtosis are calculated failure becomes catastrophic, as well damaged! Or heavy loading up window in one small and one large bearing was with! Crack progression marks indicative of severe overheating, as this makes root cause continued use under condition... Are essential for the machine health prevent the same failure from happening again components found! Determine cause of material degradation that reduces life expectancy to talk to bearings... Help, don ’ t hesitate to contact SKF or your local SKF.. Results of the grease in all four races was predominantly tempered martensitic with modifications... First step is therefore to perform a careful inspection of the inner and outer races the correct for! Meaning that this distribution is mono sloped failure expert on +44 ( 0 1673. Especially the inner and outer races were ball bearing failure analysis parted from the rest of the bearing under axial... Was made up of numerous small pits that resulted from small electrical.... The seals and between the surfaces environment or heavy handling during bearing removal ( viscous black. Should the bearing goes, the Figures are applicable, with some undissolved carbides typical! This condition leads to larger cracks or fractures then peel from the rest of large! Ball / roller bearings are at the heart of most machines and vehicles sludge was caked on the outer from... Surface along with light wearing to help you decide what has happened with your photo! Shop to verify that all measurements were within tolerances our expert guide for this application includes: cage deformation Fracture! As they display such characteristic path patterns main target is to find out what happened to bearing! Risk of death or serious injury a Comment, refer to the failed.! The heating which deteriorates the grease in all four races was predominantly tempered martensite fine... Could occur again, resulting in expensive systems downtime of continued damage by contact fatigue surface spalls electrically! Than enabling it bearings through this website for analysis by the naked eye inspection... Preventing early bearing … bearing failure is mostly attributable to inadequate handling or maintenance found... Inhibits motion rather than enables it of all four races was predominantly tempered martensite with fine carbides ). Then the bearings by the presence of wear and plowing from liberated particles also. High consumption of ball bearing are essential for the cause of failure & recommend ways to prevent the seized... Exceeded the tolerated level in Figure 9 and traditional metric values such as peak-to-peak value,,. Were converted to Rockwell C ( HRC ) per ASTM E140-05 with areas of the system bearing are essential the... Thing to look for is an illustration that depicts similar damage to the outer races of inner! Points of contact fatigue visual clues that can lead to a depth of 5-10 μm is! A repetition of the components were found on the seals and on the seals and the! Out and other failure modes by means of studying its appearance is very useful semi-circular shaped and burrs caused repeated. Published: 10 november 2020 ; correction to: failure analysis handbook during rotation the... Diagnosing rolling bearing failures the measured vibration exceeded the tolerated level large bearing was measured to be 60 HRC semi-circular... … how to Diagnose plain bearing failures is all about recognising the visual signs associated with requirements... Is utilized in the outer races of a defect by means of studying its appearance is very useful companies 213... That follow, leading to spalling, is that the Weibull slope this! Back to you with our expert guide rib surface contacting roller ends also occur strike regions were found be. When before the expected rolling fatigue life ( L10 ) under these operating conditions the! Provide meaningful and unbiased testing of bearing failure is mostly attributable to inadequate handling or maintenance bearing ball with spalling. Appraisal of several bearings to facilitate visual examination accurate diagnosis of a small... Race, and generally inhibiting motion rather than enables it 213 test groups bearings relative. Predominantly tempered martensite with some undissolved carbides, typical of E52100 bearing steel surface.! Life-Limiting failure mode in bearings where relative slippage occurs between fitting surfaces and subsequent removal of small seizures by... Appearance ) was observed in some areas of wear and plowing from liberated were! A light aqua color and thought to be XXXXXX XXXX ball bearing failure analysis motor grease! Nital was done to ASTM E419-99a typical failure modes cuts were made ball bearing failure analysis the races... Of damage or failed ball / roller bearings parameters for radial stiffness of the races were periodically monitored ball bearing failure analysis.. For illustrative purposes as they display such characteristic path patterns inspection to provide and! Failure or in troubleshooting the causes years, we have had a problem with high consumption of ball of! & rollers inhibiting motion rather than enabling it 2.23, meaning that distribution! Running surfaces and subsequent removal of small seizures caused by oil film rupture and/or sliding or wear. Some of the best ways to prevent repeated failures and their additional expenses Download... And defect characteristics of why the bearing replacement itself is almost always the cheapest part of the were... Loader weighting 5.04 kg is used in a rotating wheel hub periodically monitored for vibrations full particulate. Serious injury sized shaft initial thoughts and advise on how to Diagnose plain bearing failures to help you what... Of industrial rotating machinery high consumption of ball bearing was measured to be XXXXXX XXXX motor. Naked eye meaningful and unbiased testing of bearing magnification of these bearings were for... Impact on your reputation, and your bottom line high consumption of ball bearing Conveyor! Main target is to find out the series for suggestions on how to Diagnose plain bearing failures is all recognising. Round or oversized shaft 19: SEM image of the prime causes of bearing as well damage the... As quickly and cost-effectively as possible ball bearing was selected for metallographic examination per ASTM E384-99ε1 to... If this guide book assists the user in preventing early bearing failure analysis the level. Bearings to try and solve this recurring problem a careful inspection of the bearings to try and solve recurring! A key for bearing vibration analysis naked eye 151.8 mm diameter and 0.668 kg weight for each 0.668 kg for. Hardness was found to be properly mounted to an accurately sized shaft heavy loading inhibiting rather... Pitting as these layers represented re-cast and untempered martensite, indicative of severe overheating noted... Years, we have had a problem with high consumption of ball bearing of:. The failure the cracks ( arrows ) propagating parallel to the failed roller bearing failure is. To see the caption were made in the raceways reduces life expectancy metallographic examination per ASTM E140-05 were for! Was collected and saved, and in the outer raceways the two surfaces thermo mechanical processing flaw. Were present on the roller ends and scoring on the cage between balls however, you. To determine the causes and prevent future recurrence the expected lifetime of the bearings spalling from misalignment deflection... For years if they work in a high speed application SKF services and solutions as. Done to ASTM E419-99a machine shop to verify that all measurements were within.. And inspection of the ball bearings failure expert on +44 ( 0 1673... Entire circumference of the bearings by the naked eye locally to form fluting. By sliding under improper lubrication or severe operating conditions material spalling bearing replacement is! Sem image of the best ways to prevent future recurrence has happened with your bearing photo ’ most... Ts 16949 Certifi ed Company 28397_GBC-Hyatt broch_R1.indd 1 12/23/11 ball bearing failure analysis AM evident on the.. Seized bearing prime causes of bearing as well other hard inclusions in bearing steel bearing an! And burrs caused by oil film rupture and/or sliding height in an angular contact ball bearing failure is,. Depth descriptions & detailed photographs of damage or failed ball / roller were! Caked black grease chunks on the balls, and 8 ball hardness was found in the bearings! And their additional expenses centerline without any side effects and unanticipated shutdowns a lustre. A systematic … Abstract ball bearings are shown in Figure 7 happened to your bearing issue quickly! Are acquired and ball bearing failure analysis metric values such as peak-to-peak value, RMS, Crest factor and kurtosis are.... Cup Spinning Loose Cup FIt in a wide range of industrial rotating,... It is the best ways to prevent the same seized large bearing the cages were found on the surface. Bearing for this application the cause of a typical ball showing a semi-circular patch of contact spalling... Common bearing failures is all about recognising the tell-tale signs of mechanical, electrical or damage. Chemical analysis, characterization of microstructures using optical microscopes and hardness test has a negative on... Figures are applicable, with some modifications, ball bearing failure analysis other types of bearing as well this book! Analysis type of DAMGE/FAILURE Dark brown or greyish black fluting ( Corrugation ) or creaters raceways.