Index terms ac motors, bearing, failure analysis, failure methodology, root cause, rotor, stator. Journal bearing design, lubrication and operation for enhanced performance gregory f simmons issn. Babbitt is used mainly because of its conformability and embedability properties. Review of different types of bearing failure abstract bearing is moving object, so friction force of comes into play, and must be surpassed to move the bearing. Since typically the journal position relative to the bearing is of interest, an eccentricity ratio is defined using the radial clearance. Uniquely, this publication contains current news and technical articles, as well as.
Journal bearings of the crank pin of a few tyre moulding presses were failing frequently. The simplest way to identify the failure mode of a bearing is to examine the sleeve surface and characterize how the material itself failed. Where, h is the variable film thickness is due to the journal eccentricity. Journal bearing fatigue damage is usually visible at an early stage and allows for better diagnostics of failure modes so that corrective action can be taken to. Conformability implies that the babbitt will conform to the rotor, therefore not damaging the journals when the rotor and bearing are in contact. Use of journal bearings is also an advantage in many applications when it comes to maintenance. Heavy duty truck and trailer bearing failure analysis an iso ts 16949 certi. Roughly, there is approximately 1020% reaming life on the bearing. Journal bearing is a hydrodynamic bearing where, due to rotation of the journal in the bearing the lubricant is forced into the system. Bearing temperature and measurement bearing problems and failures are in most cases reflected by elevated oil film temperatures. Lubricant has gradually been used up or has lost its lubricating properties. Bearing inspector meets the need for a fast, more consistent, highquality decisionmaking process for bearing damage and failure investigations.
The friction between bearing and shaft is reduced by means of lubricants with high viscosity. Failure mode and effect analysis of journal bearing article pdf available in international journal of applied engineering research 1016. The failure mechanism of discussed sample which was related to an interfering part of steam turbine journal bearing determined as fretting fatigue with considering the conditions of fretting wear and some visible features of fretting pits and cracks on the surface without any changes through microstructure and chemical composition. Root cause ac motor failure analysis with a focus on shaft. Engineering failure analysis publishes research papers describing the analysis of engineering failures and related studies papers relating to the structure, properties and behaviour of engineering materials are encouraged, particularly those which also involve the detailed application of materials parameters to problems in engineering structures, components and design. Bearing failure defects in the appearance of bearings are referred to as bearing failures. Failure modes for bearing pads include crushing, delamination, and slippage. Engine bearing failure analysis guide edge wear due to distorted connecting rod imperfect journal geometry cavitation erosion spinning of the bearing in the housing.
Pdf after the power plant blackout, lubrication pumps of turbogenerator journal bearings were not turned on. Remember, the failure of the oil film can be seen in a variety of ways on the bearings. Fatigue failure in diagonally opposed areas in top and bottom halves causes load concentration on one area of bearing. Severe brinell marks can cause premature fatigue failure. Fluid film journal bearing with fixed profile from kingsbury. Overload on the bearing premature failure of the bearings may result from the bearing being either radially or axially loaded beyond its normal capacity. The bearing has a rotating shaft guided by a bearing, which is fixed. They are reliable even under the toughest conditions and premature failure is very rare. Each failure mode can have several different root causes that lead to the eventual failure of the bearing surface. An introduction to bearing failure osborne engineering. The first sign of rolling bearing damage is primarily unusual operating behaviour of the bearings. A bearing is a machine element which supports another moving machine element known as journal.
Introduction amethodology is provided that will lead operations personnel to the most likely root causes of failure. Bearing melting heat is generated in bearings by friction in the lubricant as it forms an oil wedge. Due to geometry misalignment axial mismatch between journal and bearing centre lines misalignment of bearing housing or shaft journal deflection under. A manufacturing company urgently sought for causes for the failure and suitable remedy.
Bearing failures and their causes bearing, linear motion. The first thing to look for is an illustration that depicts similar damage to the failed bearing. This does not mean to say that the bearing cannot be used after then. Precision ball bearings are designed to have a long and useful iie. The bearing named from the fact that it bears a turning axle or shaft. In order to examine the causes of failure, the units were dissembled and cleaned.
Cannot run for any length of time if starved for lubricant such as a lube system failure radial positioning of rotor less precise. Careful inspection of the failed bearing will usually reveal vital visual clues that can lead to a potential cause for the failure. Types of failure bearing failures main cause reference failures failure details rolling fatigue flaking. Examination of th6 failure mode ohn reveals the true cause of failure. Tribology comes from the greek word, tribos, meaning rubbing or to rub and from the suffix, ology means the study of therefore, tribology is the study of rubbing, or the study of things that rub. Diagnosing plain bearing failures is all about recognising the telltale signs of different wear out and other failure modes. Bearing failure analysis ipt publishing and training ltd.
Due to the remote location of the plant, the customer did not want to incur the costs of shipping the shaft overseas to be reconditioned in the workshop and requested that goltens. Checkoff sheets are provided to assist in the orderly collection of data to assist in the analysis. How to diagnose plain bearing failures neale consulting. Table 21 describes bearing failures, first assigning a general term to each type of failure, then adding more detailed classifications.
It permits a relative motion between the contact surfaces of the members, while carrying the load. Flaking is a relatively long, drawnout process and makes its presence known by increasing noise and vibration levels in the bearing. Overload may also occur due to abusive operating conditions. Bearing failure analysis type of damgefailure we ar wear caused by abrasive particles. Heavy duty truck and trailer bearing failure analysis. The concept of a bearing to lessen friction between an object and the surface over. It was noticed that journal near the root portion was built up by welding to fill the blowholes and then hand finished. Rolling bearing damage recognition of damage and bearing inspection a member of the schaeffler group. However, the conventional cyclostationarity is restricted to analyzing the realvalued signal, which is incapable of processing the constructed complexvalued signal obtained from the journal bearing supported rotor system. Finally, refer to the checklist that closes out the series for suggestions on how to avoid a repetition of the. A large number of operating conditions influence the bearing specification. Various types of bearings are used to reduce this friction force for moving mechanism.
Select a bearing material with higher load capacity check. Vibration signal analysis of journal bearing supported. Rolling bearing damage recognition of damage and bearing. Any static overload or severe impact can cause brinelling.
Major causes of bearing failure normal appearance uniform wear pattern over approximately 23 of the bearing s surface. This webenabled system is available for skf engineers to support customers in bearing damage and failure investigations. An investigation into failure analysis of interfering part. Pdf failure mode and effect analysis of journal bearing. Polymer linings are available to extend performance limits, to operate with nonoil lubricants such as water, or to be used in harsh environments. Diyaljee abstract an investigation of pavement distress occurring along a major twolane roadway 5 years after its construction is presented. So, if the oil pump capacity cannot meet this demand the pressure will fall. Check on such things as blocked oil passages, a malfunctioning oil pump, improper bearing selection or installation, oil seal failures, fuel dilution often caused by blowby of fuel and air past the piston rings or foaming or aeration, caused, ironically. Stage 2 signal appears at the first harmonic frequency of the bearing at 500 to 2,000 hz. Read the text associated with the picture, so as to get a better understanding of why the bearing failed. The presence of the beach mark shows fatigue fracture was.
Engine bearing clearance can cause early failures if not. Dark patches can be seen at some portions of the bearing in fig. Therefore, as a rule, there is plenty of time to prepare for a change of bearing. Grease discoloured green wear caused by inadequate lubrication. Plain or sliding bearings are lubricated by the formation of a hydrodynamic film of lubricant, where the wedge formed lifts the shaft or journal off the bearing. Journal bearing design, lubrication and diva portal. Review of different types of bearing failure journal. Hydrodynamic journal bearing is a bearing operating withhydrodynamic lubrication, in which the bearing surface is separated from the journal surface by the lubricant film generated by the journal rotation.
When a bearing does fail, it is important to determine the exact cause so apprcipriate adiusfments can be made. Journal bearing operation reynolds equation engineering calculations of journal. Please refer to the bearing distress guide located at. Tribology 101 introduction to the basics of tribology. Cyclostationarity has been widely used as a useful signal processing technique to extract the hidden periodicity of the energy flow of the mechanical vibration signature. The primary objective of the study was to determine the. A machine is capable of accepting a small shift of datum of the mating surface, and the life of. The chemical composition of the failed mainshaft material was determined by spectroscopy chemical analysis method. Journal bearing fatigue damage is usually visible at an early stage and allows for better diagnostics of failure modes so that corrective action can be taken to prevent recurrence. The journal of failure analysis and prevention jfap presents information gathering techniques, technical analysis, and emerging tools that assist failure analysis professionals in determining the cause of failures and eliminating failures in the future. The stress concentration at fillet area initializes the fatigue. Additionally, the main journal pocket was damaged by the main journal bearing failure and had to be line bored and so the crankshaft was removed from the engine. Excessive operating load is not, however, the only reason for bearing overload.
389 1460 489 828 103 1584 584 656 629 572 1071 652 740 440 1006 531 1585 739 574 1580 978 115 98 1238 1083 600 640 291 810 1418 610 290 855 549 656 81 1342 164 1355 1273