SIST ISO 15243:2020

Rolling bearings - Damage and failures - Terms, characteristics and causes

ISO 15243:2017 classifies different modes of failure occurring in service for rolling bearings made of standard bearing steels. For each failure mode, it defines and describes the characteristics, appearance and possible root causes of failure. It will assist in the identification of failure modes based on appearance.
For the purposes of this document, the following terms are explained:
- failure of a rolling bearing: the result of a damage that prevents the bearing meeting the intended design performance or marks the end of service life;
- in service: as soon as the bearing has left the manufacturer's factory;
- visible features: those that are possible to observe directly or with magnifiers or optical microscopes, also those from pictures, but only with the use of non-destructive methods.
Consideration is restricted to characteristic forms of change in appearance and failure that have well-defined appearance and which can be attributed to particular causes with a high degree of certainty. The features of particular interest for explaining changes and failures are described. The various forms are illustrated with photographs and the most frequent causes are indicated.
If the root cause cannot be reliably assessed by the examination and characterization of visual features against the information in this document, then additional investigations are to be considered. These methods are summarized in A.3 and may involve, for example, the use of invasive methods possibly including taking of cross sections, metallurgical structural analysis by visual and electronic microscopes, chemical and spectrographic analysis. These specialized methods are outside the scope of this document.
The failure mode terms shown in the subclause titles are recommended for general use. Where appropriate, alternative expressions or synonyms used to describe the submodes are given and explained in A.4.
Examples of rolling bearing failures are given in A.2, together with a description of the causes of failure and proposed corrective actions.

Roulements - Détérioration et défaillance - Termes, caractéristiques et causes

ISO 15243:2017 classe les différents modes de défaillance survenant en cours de fonctionnement pour les roulements en aciers standards. Elle définit et décrit, pour chaque mode de défaillance, les caractéristiques, l'aspect et les possibles causes racines de la défaillance. Elle contribuera à l'identification des modes de défaillance en s'appuyant sur l'aspect.
Les termes suivants sont expliqués pour les besoins du présent document:
- défaillance d'un roulement: résultat d'une détérioration qui empêche le roulement de satisfaire à ses performances initialement prévues ou marque la fin de sa durée de vie;
- en service: état du roulement tel qu'il sort de l'usine du fabricant;
- caractéristiques visibles: caractéristiques qu'il est possible d'observer directement ou avec une loupe ou un microscope optique, ainsi que celles observées sur des images, mais en utilisant uniquement des méthodes non destructives.
L'analyse se limite aux formes caractéristiques du changement d'aspect et aux défaillances ayant un aspect bien défini et pouvant être imputables à des causes particulières avec un degré de certitude élevé. Les caractéristiques d'intérêt particulier relatives à l'explication des changements et des défaillances sont décrites. Les formes diverses sont illustrées par des photographies et les causes les plus fréquentes sont indiquées.
Si la cause racine ne peut pas être évaluée de manière fiable par l'examen et la description des caractéristiques visuelles confrontés aux informations fournies dans le présent document, des examens complémentaires sont à envisager. Ces méthodes sont résumées au A.3 et peuvent impliquer, par exemple, l'utilisation de méthodes invasives pouvant inclure le prélèvement de coupes transversales, des analyses métallurgiques structurelles au moyen de microscopes visuels ou électroniques et des analyses chimiques et spectrographiques. Ces méthodes spécialisées ne sont pas incluses dans le domaine d'application du présent document.
Les termes des modes de défaillance exprimés dans les titres des paragraphes sont recommandés pour un usage général. Le cas échéant, les expressions alternatives ou synonymes utilisés pour décrire les sous-modes sont indiqués et expliqués en A.4.
Des exemples de défaillances des roulements, accompagnés d'une description des causes de la défaillance et des mesures correctives proposées, sont donnés en A.2.

Kotalni ležaji - Poškodbe in napake - Izrazi, karakteristike in vzroki

General Information

• Status: Published
• Publication Date: 10-Mar-2020
• ICS: 21.100.20 - Rolling bearings
• Technical Committee: ISEL - Mechanical elements
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 10-Mar-2020
• Due Date: 15-May-2020
• Completion Date: 11-Mar-2020
• Ref Project: ISO 15243:2017 - Rolling bearings - Damage and failures - Terms, characteristics and causes

Relations

• Revised: SIST ISO 15243:2004 - Rolling bearings -- Damage and failures -- Terms, characteristics and causes
• Effective Date: 16-Apr-2011

Overview - SIST ISO 15243:2020 (Rolling bearings - Damage and failures)

SIST ISO 15243:2020 provides a structured, visual-based classification of failure modes for rolling bearings made of standard bearing steels. The standard defines terminology, describes characteristic appearances, and indicates the most likely root causes for each failure mode. It is intended to assist engineers and analysts in bearing failure identification using non‑destructive observations (direct view, magnifiers or optical microscopes, photographs). Where visual evidence is insufficient, the standard points to additional investigative methods in Annex A (A.3), while noting that specialized invasive techniques are outside the document’s scope.

Key technical topics and requirements

• Terms and definitions: Clarifies failure-related vocabulary (failure, damage, event sequences, failure mode) in line with ISO 5593.
• Classification of failure modes: Six principal groups based on visible characteristics:
  • Rolling contact fatigue
  • Wear
  • Corrosion
  • Electrical erosion
  • Plastic deformation
  • Cracking and fracture
• Detailed failure-mode descriptions: For each mode the standard describes:
  • Typical visual characteristics and appearance
  • Sub-modes (e.g., subsurface-initiated and surface-initiated rolling contact fatigue)
  • Probable root causes and common initiating conditions
• Guidance on evidence and limits: Emphasizes reliance on visible features and operational history; recommends further investigations (metallography, cross-sections, chemical/spectrographic analysis) when necessary.
• Illustrative material: Photographs and examples (Annex A.2) to support identification and corrective recommendations.

Practical applications - who uses SIST ISO 15243:2020

ISO 15243 is directly useful for:

• Failure analysis and forensic teams performing bearing damage investigations
• Maintenance and reliability engineers diagnosing machine symptoms and planning corrective actions
• OEMs and bearing manufacturers for quality assurance, warranty assessments and design improvements
• Tribologists and materials engineers investigating wear, fatigue and corrosion mechanisms
• Training and documentation for technicians and inspectors in condition monitoring and preventive maintenance

Typical uses include root-cause analysis, maintenance planning, interpreting visual inspection evidence, and deciding when to escalate to destructive testing.

Related standards

• ISO 5593 - Rolling bearings - Vocabulary (normative reference)
• ISO 281 - Bearing life calculation (referenced for life concepts)
• ISO 8785 and ISO 6601 - referenced for surface defect and wear terminology
• ISO Online Browsing Platform and IEC Electropedia - for terminological resources

Keywords: SIST ISO 15243:2020, rolling bearings, bearing failure analysis, rolling contact fatigue, wear, corrosion, electrical erosion, plastic deformation, cracking and fracture, failure modes, bearing damage identification, root cause analysis.

Standards Content (Sample)

SLOVENSKI STANDARD
01-maj-2020
Kotalni ležaji - Poškodbe in napake - Izrazi, karakteristike in vzroki
Rolling bearings - Damage and failures - Terms, characteristics and causes
Roulements - Détérioration et défaillance - Termes, caractéristiques et causes
Ta slovenski standard je istoveten z: ISO 15243:2017
ICS:
21.100.20 Kotalni ležaji Rolling bearings
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 15243
Second edition
2017-03
Rolling bearings — Damage and
failures — Terms, characteristics and
causes
Roulements — Détérioration et défaillance — Termes,
caractéristiques et causes
Reference number
©
ISO 2017
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2017 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Classification of failure modes occurring in rolling bearings . 2
5 Failure modes . 3
5.1 Rolling contact fatigue . 3
5.1.1 General description of rolling contact fatigue . 3
5.1.2 Subsurface initiated fatigue . 4
5.1.3 Surface initiated fatigue . 4
5.2 Wear . 6
5.2.1 General description of wear . 6
5.2.2 Abrasive wear . 6
5.2.3 Adhesive wear . 7
5.3 Corrosion . 9
5.3.1 General description of corrosion . 9
5.3.2 Moisture corrosion. 9
5.3.3 Frictional corrosion .10
5.4 Electrical erosion .12
5.4.1 General description of electrical erosion .12
5.4.2 Excessive current erosion .12
5.4.3 Current leakage erosion .13
5.5 Plastic deformation .14
5.5.1 General description of plastic deformation .14
5.5.2 Overload deformation .14
5.5.3 Indentations from particles .16
5.6 Cracking and fracture .17
5.6.1 General description of cracking and fracture .17
5.6.2 Forced fracture .17
5.6.3 Fatigue fracture .18
5.6.4 Thermal cracking .19
Annex A (informative) Failure analysis — Illustrations of damage — Other investigations
— Explanation of terms used.20
Bibliography .53
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,
as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the
Technical Barriers to Trade (TBT) see the following URL: www . i so .org/ iso/ foreword .html.
The committee responsible for this document is ISO/TC 4, Rolling bearings.
This second edition cancels and replaces the first edition (ISO 15243:2004), which has been technically
revised.
iv © ISO 2017 – All rights reserved

Introduction
In practice, damage and/or failure of a rolling bearing can often be the result of several mechanisms
operating simultaneously. The failure can result from improper transport, handling, mounting or
maintenance or from faulty manufacture of the bearing or its adjacent parts. In some instances, failure
is due to a design compromise made in the interests of economy or from unforeseen operating and
environmental conditions. It is the complex combination of design, manufacture, mounting, operation
and maintenance that often causes difficulty in establishing the root cause of failure.
NOTE Be aware that counterfeit bearings are circulated in the market. They might look as original bearings,
but their use often lead to very early damage or failure.
In the event of extensive damage to or catastrophic failure of the bearing, the evidence is likely to be
lost and it will then be impossible to identify the root cause of failure. It is therefore important to stop
equipment in time to enable appropriate bearing damage analysis (see Figure 1). In all cases, knowledge
of the actual operating conditions of the assembly and the maintenance history is of utmost importance.
NOTE The spall started just behind the dent in the raceway [a)]. Over a period of time, the spalling becomes
more severe [b) and c)]. If not stopped in time, the proof of the root cause disappears [d)].
Figure 1 — Progression of bearing damage
The classification of bearing failure established in this document is based primarily upon the features
visible on rolling contact surfaces and other functional surfaces. Consideration of each feature is
required for reliable determination of the root cause of bearing failure. Since more than one failure
mechanism may cause similar effects to these surfaces, a description of appearance alone is often
inadequate for determining the cause of the failure. In such cases, the operating conditions need to be
considered. In some cases, the analysed damage is too advanced, and can be originated from different
primary causes. In these cases, it is interesting to look for simultaneous presence of indications to
determine the primary cause of the failure.
This document covers rolling bearings having steel rings and rolling elements. Damage to the rings of
bearings with ceramic rolling elements shows similar failure modes.
[1]
In this document, bearing life is as described in ISO 281 , which provides formulae to calculate bearing
life taking a number of factors into consideration, such as bearing load carrying capacity, bearing load,
type of bearing, material, bearing fatigue load limit, lubrication conditions and degree of contamination.
INTERNATIONAL STANDARD ISO 15243:2017(E)
Rolling bearings — Damage and failures — Terms,
characteristics and causes
1 Scope
This document classifies different modes of failure occurring in service for rolling bearings made of
standard bearing steels. For each failure mode, it defines and describes the characteristics, appearance
and possible root causes of failure. It will assist in the identification of failure modes based on
appearance.
For the purposes of this document, the following terms are explained:
— failure of a rolling bearing: the result of a damage that prevents the bearing meeting the intended
design performance or marks the end of service life;
— in service: as soon as the bearing has left the manufacturer’s factory;
— visible features: those that are possible to observe directly or with magnifiers or optical microscopes,
also those from pictures, but only with the use of non-destructive methods.
Consideration is restricted to characteristic forms of change in appearance and failure that have well-
defined appearance and which can be attributed to particular causes with a high degree of certainty.
The features of particular interest for explaining changes and failures are described. The various forms
are illustrated with photographs and the most frequent causes are indicated.
If the root cause cannot be reliably assessed by the examination and characterization of visual
features against the information in this document, then additional investigations are to be considered.
These methods are summarized in A.3 and may involve, for example, the use of invasive methods
possibly including taking of cross sections, metallurgical structural analysis by visual and electronic
microscopes, chemical and spectrographic analysis. These specialized methods are outside the scope of
this document.
The failure mode terms shown in the subclause titles are recommended for general use. Where
appropriate, alternative expressions or synonyms used to describe the submodes are given and
explained in A.4.
Examples of rolling bearing failures are given in A.2, together with a description of the causes of failure
and proposed corrective actions.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 5593, Rolling bearings — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5593 and the following apply.
NOTE Explanations for terms for damage and failures are listed in A.4.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
3.1
characteristics
visual appearance that results from service performance
[3]
Note 1 to entry: Surface defects and types of geometrical change are defined in ISO 8785 and partly in
[2]
ISO 6601 (related to abrasive wear).
3.2
damage
any visible deterioration of the bearing operating surfaces or structures
3.3
event sequences
sequence of events leading to bearing failure (3.4) starting with initial damage (3.2) to the bearing
Note 1 to entry: At an early stage, this damage can result in loss of function or failure. In many cases, however,
the initial damage does not result in failure and the bearing continues to operate. This continued operation most
often leads to secondary damage which eventually results in failure. Secondary damage can introduce competing
modes of failure, which can make root cause analysis difficult.
3.4
failure
any condition where the bearing can no longer deliver its designed function
Note 1 to entry: This will include degradation of important rotational properties and warning of imminent
more extensive or complete failure, but may not be so advanced as to prevent rotation or support of the subject
machine elements.
Note 2 to entry: The extent of damage (3.2) required to cause a declaration of operational failure will depend on
the application. Applications requiring accurate smooth rotation will tolerate only very minor loss of properties.
Applications not sensitive to increased vibration, increased noise or reduced rotational accuracy may be able to
continue to deliver their performance for a restricted period.
3.5
failure mode
manner in which a bearing fails
4 Classification of failure modes occurring in rolling bearings
Preferably, one would classify rolling bearing damage and failures according to the root cause. However,
it is often not easy to distinguish between causes and characteristics (symptoms) or, in other words,
between failure mechanisms and failure modes. The large number of articles and books written on the
subject confirms this (see Bibliography). Therefore, in this document, failure modes are classified in
six main groups and various sub-groups (see Figure 2), based on their visible distinctive characteristic
appearance in service.
2 © ISO 2017 – All rights reserved

Figure 2 — Classification of failure modes
5 Failure modes
5.1 Rolling contact fatigue
5.1.1 General description of rolling contact fatigue
Rolling contact fatigue is caused by the repeated stresses developed in the contacts between the rolling
elements and the raceways. Fatigue is manifested visibly as a change in the structure (microstructure)
and as spalling of material from the surface (macrostructure) that, in most of the cases, could be
consequential to a change in microstructure.
NOTE Spalling and flaking are synonyms (see A.4).
5.1.2 Subsurface initiated fatigue
Under the influence of cyclic loading in the rolling contacts described by the Hertzian theory,
stresses and material structural changes occur and microcracks are initiated at a location and depth
which depend on the applied load, the operating temperature, the material and its cleanliness and
microstructure. The initiation of the microcracks is often caused by inclusions in the bearing steel.
The changes might appear at metallurgical investigation (see A.3). These cracks propagate and when
they come to the surface, spalling occurs (see Figures 3 and 4).
Figure 3 — Initial subsurface spalling in a deep groove ball bearing — Rotating inner ring
Figure 4 — Advanced subsurface spalling in a tapered roller bearing — Stationary inner ring
5.1.3 Surface initiated fatigue
Fatigue initiated from the surface is typically caused by surface distress.
Surface distress is damage initiated at the rolling contact surfaces due to plastic deformation of the
surface asperities (smoothing, burnishing, glazing). Contact between the asperities of the rolling
element and bearing raceway is most often the result of inadequate lubrication conditions (insufficient
lubricant film thickness). This contact may be caused by insufficient lubrication flow/availability,
improper lubricant for the application, operating temperatures beyond the expected level or rough
surface finishes. Contact and plastic deformation of the surface asperities can lead to
— asperity microcracks (see Figure 5),
— asperity microspalls (see Figure 6), and
4 © ISO 2017 – All rights reserved

— microspalled areas (grey stained) (see Figure 7).
Sliding motion under low lubricant film conditions can significantly accelerate the surface damage.
For cases where film thickness is sufficient for normal operating conditions, surface-initiated fatigue
may still occur. This can happen when particles are introduced into the contact area (see 5.5.3),
extreme loads plastically deform the surface or handling nicks are present. All three conditions result
in indentations in the raceways. Protrusions around the indentation exceed the height of the oil film,
resulting in deformation of surface asperities. Surface initiated fatigue caused by indentation arising
from plastic deformation is shown in A.2.6.2.
[1]
NOTE ISO 281 includes surface related calculation parameters that are known to have an influence on the
bearing life such as material, lubrication, environment, contamination particles and bearing load.
Figure 5 — Asperity microcracks and microspalls on a raceway
Figure 6 — Surface initiated microspalls on a raceway
Figure 7 — Microspalled areas on a raceway
5.2 Wear
5.2.1 General description of wear
Wear is the progressive removal of material from the surface, resulting from the interaction of two
sliding or rolling/sliding contacting surfaces during service.
5.2.2 Abrasive wear
Abrasive wear (particle wear, three-body wear) is the removal of material due to sliding in presence
of hard particles. It is the result of a hard surface or particle removing material from another surface
through a cutting or ploughing action when sliding across it. The surfaces become dull to a degree, which
varies according to the coarseness and nature of the abrasive particles (see Figure 8). These particles
gradually increase in number as material is worn away from the running surfaces and, possibly, the
cage (see Figure 9). Finally, the wear becomes an accelerating process that results in a failed bearing.
Although the surfaces normally become dull to a certain extent, when the abrasive particles are very
fine, a polishing effect might occur, resulting in very shiny surfaces (see Figure 10).
NOTE The “running-in” of a rolling bearing is a natural short process after which the running behaviour,
e.g. noise or operating temperature, stabilizes or even improves. As a consequence, the running path or running
track becomes visible; however this is not indicating that the bearing is damaged.
6 © ISO 2017 – All rights reserved

Figure 8 — Abrasive wear on the inner ring of a spherical roller bearing
Figure 9 — Advanced abrasive wear on the cage pockets of a solid metal cage
Figure 10 — Abrasive wear on the raceway of the large rib surface of the inner ring and on the
large end face of rollers in a tapered roller bearing
5.2.3 Adhesive wear
Adhesive wear is characterized by a transfer of material from one surface to another with frictional heat
and, sometimes, tempering or rehardening of the surface. This produces localized stress concentrations
with the potential for cracking or spalling of the contact areas.
Smearing (skidding, galling, scoring, frosting) occurs because of inadequate lubrication conditions
when sliding occurs and localized temperature rises from friction cause adhesion of the contacting
surfaces, resulting in material transfer. This typically happens between rolling elements and raceways
if the rolling elements are too lightly loaded and subjected to severe acceleration on their re-entry
into the load zone (see Figures 11 and 12). In severe cases of smearing, seizing may result. Smearing is
usually a sudden occurrence as opposed to an accumulated wear process.
Smearing can also occur on the rib faces and on the ends of the rollers due to inadequate lubrication (see
Figure 13). In full complement (cageless) bearings, smearing can also occur in the contacts between
rolling elements, depending on lubrication and rotation conditions.
If a bearing ring moves (creeps) relative to its seat because of inadequate retention on the shaft or in
the housing, then smearing (also called scuffing) can occur in the bearing bore, the outside diameter
or on the shaft or in the housing seat. Because of the minute difference in the diameters of the two
components, they will have a minute difference in their circumferences and, consequently, when
brought into contact at successive points by the radial load rotating with respect to the ring, will rotate
at minutely different speeds. This rolling motion of the ring against its seating with a minute difference
in the rotational speeds is termed “creep”.
When creep occurs, the asperities in the ring/seat contact region are over-rolled, which can cause the
surface of the ring to take on a shiny appearance. The over-rolling during creeping is often, but not
always, accompanied by sliding in the ring/seat contact, and then other damage will also be visible, e.g.
score marks, fretting corrosion and wear. Under certain loading conditions and when the ring/seating
interference fit is insufficiently tight, fretting corrosion will predominate (see A.2.4.2.1 and A.2.4.2.2).
Furthermore, with a loose radial fit, creep can also occur between the face of a ring and its axial
abutment. In severe cases, this can lead to transverse thermal cracks and finally cause cracking of the
ring (see 5.6.4).
Figure 11 — Smearing on the outer ring raceway of a cylindrical roller bearing
Figure 12 — Smearing on the outer ring raceways of a spherical roller bearing
8 © ISO 2017 – All rights reserved

Figure 13 — Smearing on the side face of rollers of a cylindrical roller bearing
5.3 Corrosion
5.3.1 General description of corrosion
Corrosion is the result of a chemical reaction on metal surfaces.
5.3.2 Moisture corrosion
When bearing components are in contact with moisture or aggressive media (e.g. water or acids),
oxidation or corrosion (rust) of surfaces takes place (see Figure 14). Subsequently, the formation of
corrosion pits occurs and finally spalling of the surface occurs (see Figure 15).
A specific form of moisture corrosion can be observed in the contact areas between rolling elements
and bearing rings where the water content in the lubricant or the degraded lubricant reacts with the
surfaces of the adjacent bearing elements. During static periods, the advanced stage will result in dark
discolouration of the contact areas at intervals corresponding to the ball/roller pitch (see Figure 16);
eventually producing corrosion pits.
Figure 14 — Moisture corrosion on the cage and rollers of a needle roller thrust bearing
Figure 15 — Moisture corrosion on the outer ring raceway of a cylindrical roller bearing
Figure 16 — Contact corrosion at roller pitch on the inner ring raceway of a tapered roller bearing
5.3.3 Frictional corrosion
5.3.3.1 General description of frictional corrosion
Frictional corrosion (tribo-corrosion, tribo-oxidation) is a chemical reaction activated by relative
micromovements between mating surfaces under certain friction and load conditions. These
micromovements lead to oxidation of the surfaces and released material becoming visible as powdery
rust and/or loss of material from one or both mating surfaces.
5.3.3.2 Fretting corrosion
Fretting corrosion occurs in fit interfaces between components that are transmitting loads under
oscillating contact surface micromovements. Surface asperities oxidize and are rubbed off and vice
versa; powdery rust develops (fretting rust, iron oxide). The bearing surface becomes discoloured
blackish red (see Figure 17). Typically, the damage develops when loads and/or vibrations overcome
the radial clamping given by the mounting fits. Excessively rough and/or wavy surface finish of bearing,
shaft and housing surfaces can also reduce the effective mounting fit and induce fretting corrosion (see
Figure 18).
NOTE 1 Some abrasive wear might occur as a resultant effect of the presence of the corrosion products (iron
oxide) and micromovements.
NOTE 2 In this document, fretting corrosion is classified under corrosion. In other documents, it is sometimes
classified as fretting wear.
Figure 17 — Fretting corrosion in the inner ring bore of a deep groove ball bearing
10 © ISO 2017 – All rights reserved

Figure 18 — Fretting corrosion on the outer diameter of a roller bearing
5.3.3.3 False brinelling
False brinelling (vibration corrosion) most commonly occurs in rolling element/raceway contact areas
of non-rotating bearings due to micromovements and/or resilience of the elastic contacts under cyclic
vibrations. Depending on the intensity of the vibrations, the load and lubrication conditions, depressions
are formed on the raceways, mostly also leading to corrosion (due to lack of protective lubricant) and
resultantly abrasive wear.
In the case of a stationary bearing, the depressions appear at rolling element pitch and may be
discoloured reddish or shiny (see Figures 19 and 20).
False brinelling occurring in stand-by equipment, when long stopped periods in the presence of
vibrations from nearby operating equipment are alternated with rather short running sessions, could
result in closely spaced flutes. These should not be mistaken for electrically caused flutes (see 5.4.3
and Figures 23, 24 and 25). The fluting resulting from vibration has bright or fretted bottoms to the
depressions compared to fluting produced by the passage of electric current, where the bottoms of the
depressions are dark greyish in colour. The damage caused by electric current is distinguishable by the
fact that the rolling elements show corresponding marks, but normally in a less advanced stage.
NOTE In this document, false brinelling is classified under corrosion. In other documents, it is sometimes
classified as wear.
a)  Outer ring of a tapered roller bearing b)  Washer raceways of a needle roller
thrust bearing
Figure 19 — False brinelling
Figure 20 — False brinelling on the outer ring raceway of a self-aligning ball bearing
5.4 Electrical erosion
5.4.1 General description of electrical erosion
Electrical erosion is the localized microstructural change and removal of material at the contact
surfaces caused by the passage of damaging electric current.
5.4.2 Excessive current erosion
When an electric voltage between bearing rings and rolling element(s) exceeds the insulation
breakdown threshold value, an electrical current passes from one bearing ring to the other through the
rolling elements and their lubricant films. In the contact areas between raceways and rolling elements,
a concentrated discharge takes place resulting in localized heating within very short time intervals, so
that the contact areas melt and weld together.
This damage (electrical pitting) may appear as a series of craters with diameters of up to 500 μm (see
Figures 21 and 22). The craters are duplicated on the rolling element and raceway contact surfaces,
typically in bead-like procession in the rolling direction (see Figure 21).
Figure 21 — Roller of a spherical roller bearing — Craters formed by the passage of excessive
electric current
12 © ISO 2017 – All rights reserved

Figure 22 — Enlargement of Figure 21 showing craters and molten material
5.4.3 Current leakage erosion
When a damaging (capacitive or inductive) electric current becomes continually established, the erosion
takes on a different appearance as to 5.4.2. Initially, the surface damage may take the shape of shallow
craters, which are closely positioned to one another and very small in size, in the order of micrometres.
This happens even if the intensity of the current is relatively low. Flutes may develop due to current
passing through the whole contact ellipse (ball bearing) or line (roller bearing), as shown in Figures 23,
24 and 25 (electrical fluting). Flutes can be found on roller and ring raceway contact surfaces, but not
on balls, which have dark colouration only. The visual appearance of balls is mostly dull varying from
light to dark grey (see Figure 24). Inspection on microscale usually shows craters.
Additionally, the lubricant can also deteriorate by the electric current passage. The damaged grease
exhibits black discolouring and hardened consistency.
Figure 23 — Fluting (washboarding) as a result of current leakage on the inner ring raceway of
a tapered roller bearing
Figure 24 — Fluting on the inner ring raceway and matt dark grey coloured balls of a deep
groove ball bearing
Figure 25 — Fluting on the outer ring raceway of a deep groove ball bearing
5.5 Plastic deformation
5.5.1 General description of plastic deformation
This is a permanent deformation that occurs whenever the yield strength of the material is exceeded.
Typically, this can occur in two different ways:
— on a macroscale, where the contact load between a rolling element and the raceway causes yielding
over a substantial portion of the contact footprint;
— on a microscale, where a foreign object is over-rolled between a rolling element and the raceway and
yielding occurs over only a small part of the contact footprint.
5.5.2 Overload deformation
Overload deformation can occur while the bearing is stationary (most common), or while rotating
(uncommon).
Overloading of a stationary bearing by static load or shock load leads to plastic deformation at the
rolling element/raceway contacts (true brinelling), i.e. the formation of shallow depressions or flutes
on the bearing raceways in positions corresponding to the pitch of the rolling elements (see Figures 26
and 27).
Overload can be distinguished from false brinelling or electrical fluting by the visibility of surface
finish or residual machining marks at the bottom of the depression or flute. Furthermore, overloading
can occur by excessive preloading or due to incorrect handling during mounting (see Figure 26).
14 © ISO 2017 – All rights reserved

Inappropriate handling can also cause overloading and deformation of other bearing components, e.g.
shields, washers and cages (see Figure 28). Raceways and rolling elements can incur indentations and
nicks caused by hard, possibly sharp objects or by incorrect assembly (see Figure 29).
Overload of a rotating bearing can take different aspects depending on the type of overload.
— Instantaneous overload can lead to fluting (washboarding) with individual, non-symmetrical marks
that are more or less extended.
— Instantaneous overload can lead to depressions at rolling element pitch.
— Permanent overload can result in lamination and macroscopic plastic deformation of the whole
circumference of the overloaded part of the raceway.
Figure 26 — Overload on a stationary inner ring of an angular contact ball bearing
Figure 27 — Spalling as a result of shock load deformation on the inner ring raceway of
an angular contact ball bearing, resulting from impacts in radial direction, which further
developed in spalling
Figure 28 — Cage deformation of an angular contact ball bearing caused by a shock load during
handling
Figure 29 — Indentations on the inner ring raceway of a cylindrical roller bearing caused by
incorrect assembly
5.5.3 Indentations from particles
When particles are over-rolled, indentations are formed on raceways of rings (see Figure 30) and
rolling elements (see Figure 31). The size and shape of the indentations will depend on the nature of the
particles. Figure 32 depicts the following types of indentation:
a) from soft particles, e.g. fibres, elastomers, plastics and wood [see Figure 32 a)];
b) from hardened steel particles, e.g. from gears and bearings [see Figure 32 b)];
c) from hard mineral particles, e.g. from sand particles (silica) in the oil [see Figure 32 c)].
Figure 30 — Indentations from particles on the inner ring raceway of a tapered roller bearing
16 © ISO 2017 – All rights reserved

Figure 31 — Indentations from particles on tapered rollers
a b c
Figure 32 — Enlargements of indentations on raceways resulting from over-rolled particles
5.6 Cracking and fracture
5.6.1 General description of cracking and fracture
Cracks are initiated and propagate when the ultimate tensile strength of the material is locally exceeded.
Fracture is the result of a crack propagating completely through a section of the component or
propagating such that a portion of the component is completely separated from the original component.
5.6.2 Forced fracture
Forced fracture is due to a stress concentration in excess of the material (tensile) strength and is
caused by local over-stressing, e.g. from impact (see Figure 33), or by over-stressing due to an excessive
interference fit, e.g. too high hoop stress (see Figure 34).
Figure 33 — Forced fracture of a tapered roller bearing inner ring shoulder, caused by an
impact load during assembly procedures
NOTE Fracture caused by an excessive interference fit during mounting, for example, by driving a tapered
bore inner ring too far up the shaft taper.
Figure 34 — Forced fracture of a spherical roller bearing inner ring
5.6.3 Fatigue fracture
Frequent exceeding of the fatigue strength limit under bending, tension or torsion conditions results
in fatigue cracking. A crack is initiated at a stress raiser and propagates in steps over a part of the
component cross-section, ultimately resulting in a forced fracture. Fatigue fracture occurs mainly on
rings (see Figure 35) and cages (see Figure 36).
NOTE The origination of fracture is near the right raceway, centred in the characteristic sea shell signature
left by a progressing fatigue crack (the damage above the outside surface is secondary and occurred when the
ring fractured).
Figure 35 — Section of fatigue fracture of a cam roller outer ring caused by bending
18 © ISO 2017 – All rights reserved

Figure 36 — Fatigue fracture of cage bars of a needle roller thrust bearing
5.6.4 Thermal cracking
Thermal cracking (heat cracking) is caused by high frictional heating due to sliding motion. Cracks
usually appear at right angles to the direction of sliding (see Figure 37). Hardened steel components are
generally sensitive to thermal cracking due to local rehardening of the surfaces in combination with the
development of high residual tensile stress.
Figure 37 — Thermal cracks on the small end of the inner ring of a tapered roller bearing
Annex A
(informative)
Failure analysis — Illustrations of damage — Other investigations
— Explanation of terms used
A.1 Failure analysis
A.1.1 General
— The purpose of this document is to promote and assist in a logical objective investigation of bearing
failure to identify possible causes.
— Careful identification of the most probable causes and modes of a failure can be an important input
to development of a long term preventive solution.
— Targeted countermeasures can be devised to guard against the identified causes.
— An open objective approach by all participants is essential to successful application of this document.
A.1.2 Securing evidence before and after removal
A.1.2.1 Important points
— When a bearing fails, it is vital to collect as much evidence as possible before attempting a diagnosis
of the causes.
— An impartial enquiring approach is required.
A.1.2.2 Conserving evidence
— Equipment operator/owner to disturb as little evidence as possible prior to investigation.
— The different interested parties need to devise a logical investigation procedure.
— Avoid destroying or compromising some evidence before it can be assessed and recorded.
— Gather as much recent operational data as possible from operator and other involved organizations
and persons.
— Instant diagnoses and conclusions should be treated as preliminary.
— Note these initial possible diagnoses, but put them to one side until evidence has been gathered and
assessed.
— When a plan has been devised and agreed, dismantling of the equipment to reach the bearing can
commence.
The matrix in Table A.1 provides a guide to making a plan.
A.1.2.3 Gathering evidence
— At each stage, be sure to make the following:
— photographs and/or sketches;
20 © ISO 2017 – All rights reserved

— notes of the condition and positions of components.
— Related parts should be kept together:
— label, mark and put in clean plastic containers where possible.
— Be sure to obtain all evidence that needs a complete assembly or component before:
— dismantling which is difficult or impossible to reverse;
— cleaning including disturbing lubricant or contaminant;
— especially cutting that destroys a circular surface.
— The bearing will contain the evidences of its own failure:
— when removed, it would be incapable of further acceptable running;
— it may have “failed” more than once already;
— it may, or may not, contain the original cause;
— other components may have important evidence:
— investigate them in parallel as far as possible;
— record any available design, system, service and operational history;
— bearing designation and manufacturer to be recorded:
— if still visible or deducible from physical features;
— check manufacturer’s specification if possible;
— the bearing may be unsuitable:
— inappropriate service replacement for an originally installed bearing;
— not a valid equivalent;
— does not meet the equipment manufacturer’s specification.
NOTE Lubricants and contaminants are to be considered as parts just as much as the solid metallic and any
polymeric or rubber components.
A.1.2.4 Interpreting the evidence
It is important to bear in mind that, depending on the time between damage initiation and its detection,
the damage can be more or less advanced when the mechanical system is dismounted and inspected.
If the detection of the damage occurred comparatively late after its initiation, the clues on the initial
cause may have been suppressed, hidden or worn off, so
...

INTERNATIONAL ISO
STANDARD 15243
Second edition
2017-03
Rolling bearings — Damage and
failures — Terms, characteristics and
causes
Roulements — Détérioration et défaillance — Termes,
caractéristiques et causes
Reference number
©
ISO 2017
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2017 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Classification of failure modes occurring in rolling bearings . 2
5 Failure modes . 3
5.1 Rolling contact fatigue . 3
5.1.1 General description of rolling contact fatigue . 3
5.1.2 Subsurface initiated fatigue . 4
5.1.3 Surface initiated fatigue . 4
5.2 Wear . 6
5.2.1 General description of wear . 6
5.2.2 Abrasive wear . 6
5.2.3 Adhesive wear . 7
5.3 Corrosion . 9
5.3.1 General description of corrosion . 9
5.3.2 Moisture corrosion. 9
5.3.3 Frictional corrosion .10
5.4 Electrical erosion .12
5.4.1 General description of electrical erosion .12
5.4.2 Excessive current erosion .12
5.4.3 Current leakage erosion .13
5.5 Plastic deformation .14
5.5.1 General description of plastic deformation .14
5.5.2 Overload deformation .14
5.5.3 Indentations from particles .16
5.6 Cracking and fracture .17
5.6.1 General description of cracking and fracture .17
5.6.2 Forced fracture .17
5.6.3 Fatigue fracture .18
5.6.4 Thermal cracking .19
Annex A (informative) Failure analysis — Illustrations of damage — Other investigations
— Explanation of terms used.20
Bibliography .53
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,
as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the
Technical Barriers to Trade (TBT) see the following URL: www . i so .org/ iso/ foreword .html.
The committee responsible for this document is ISO/TC 4, Rolling bearings.
This second edition cancels and replaces the first edition (ISO 15243:2004), which has been technically
revised.
iv © ISO 2017 – All rights reserved

Introduction
In practice, damage and/or failure of a rolling bearing can often be the result of several mechanisms
operating simultaneously. The failure can result from improper transport, handling, mounting or
maintenance or from faulty manufacture of the bearing or its adjacent parts. In some instances, failure
is due to a design compromise made in the interests of economy or from unforeseen operating and
environmental conditions. It is the complex combination of design, manufacture, mounting, operation
and maintenance that often causes difficulty in establishing the root cause of failure.
NOTE Be aware that counterfeit bearings are circulated in the market. They might look as original bearings,
but their use often lead to very early damage or failure.
In the event of extensive damage to or catastrophic failure of the bearing, the evidence is likely to be
lost and it will then be impossible to identify the root cause of failure. It is therefore important to stop
equipment in time to enable appropriate bearing damage analysis (see Figure 1). In all cases, knowledge
of the actual operating conditions of the assembly and the maintenance history is of utmost importance.
NOTE The spall started just behind the dent in the raceway [a)]. Over a period of time, the spalling becomes
more severe [b) and c)]. If not stopped in time, the proof of the root cause disappears [d)].
Figure 1 — Progression of bearing damage
The classification of bearing failure established in this document is based primarily upon the features
visible on rolling contact surfaces and other functional surfaces. Consideration of each feature is
required for reliable determination of the root cause of bearing failure. Since more than one failure
mechanism may cause similar effects to these surfaces, a description of appearance alone is often
inadequate for determining the cause of the failure. In such cases, the operating conditions need to be
considered. In some cases, the analysed damage is too advanced, and can be originated from different
primary causes. In these cases, it is interesting to look for simultaneous presence of indications to
determine the primary cause of the failure.
This document covers rolling bearings having steel rings and rolling elements. Damage to the rings of
bearings with ceramic rolling elements shows similar failure modes.
[1]
In this document, bearing life is as described in ISO 281 , which provides formulae to calculate bearing
life taking a number of factors into consideration, such as bearing load carrying capacity, bearing load,
type of bearing, material, bearing fatigue load limit, lubrication conditions and degree of contamination.
INTERNATIONAL STANDARD ISO 15243:2017(E)
Rolling bearings — Damage and failures — Terms,
characteristics and causes
1 Scope
This document classifies different modes of failure occurring in service for rolling bearings made of
standard bearing steels. For each failure mode, it defines and describes the characteristics, appearance
and possible root causes of failure. It will assist in the identification of failure modes based on
appearance.
For the purposes of this document, the following terms are explained:
— failure of a rolling bearing: the result of a damage that prevents the bearing meeting the intended
design performance or marks the end of service life;
— in service: as soon as the bearing has left the manufacturer’s factory;
— visible features: those that are possible to observe directly or with magnifiers or optical microscopes,
also those from pictures, but only with the use of non-destructive methods.
Consideration is restricted to characteristic forms of change in appearance and failure that have well-
defined appearance and which can be attributed to particular causes with a high degree of certainty.
The features of particular interest for explaining changes and failures are described. The various forms
are illustrated with photographs and the most frequent causes are indicated.
If the root cause cannot be reliably assessed by the examination and characterization of visual
features against the information in this document, then additional investigations are to be considered.
These methods are summarized in A.3 and may involve, for example, the use of invasive methods
possibly including taking of cross sections, metallurgical structural analysis by visual and electronic
microscopes, chemical and spectrographic analysis. These specialized methods are outside the scope of
this document.
The failure mode terms shown in the subclause titles are recommended for general use. Where
appropriate, alternative expressions or synonyms used to describe the submodes are given and
explained in A.4.
Examples of rolling bearing failures are given in A.2, together with a description of the causes of failure
and proposed corrective actions.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 5593, Rolling bearings — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5593 and the following apply.
NOTE Explanations for terms for damage and failures are listed in A.4.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
3.1
characteristics
visual appearance that results from service performance
[3]
Note 1 to entry: Surface defects and types of geometrical change are defined in ISO 8785 and partly in
[2]
ISO 6601 (related to abrasive wear).
3.2
damage
any visible deterioration of the bearing operating surfaces or structures
3.3
event sequences
sequence of events leading to bearing failure (3.4) starting with initial damage (3.2) to the bearing
Note 1 to entry: At an early stage, this damage can result in loss of function or failure. In many cases, however,
the initial damage does not result in failure and the bearing continues to operate. This continued operation most
often leads to secondary damage which eventually results in failure. Secondary damage can introduce competing
modes of failure, which can make root cause analysis difficult.
3.4
failure
any condition where the bearing can no longer deliver its designed function
Note 1 to entry: This will include degradation of important rotational properties and warning of imminent
more extensive or complete failure, but may not be so advanced as to prevent rotation or support of the subject
machine elements.
Note 2 to entry: The extent of damage (3.2) required to cause a declaration of operational failure will depend on
the application. Applications requiring accurate smooth rotation will tolerate only very minor loss of properties.
Applications not sensitive to increased vibration, increased noise or reduced rotational accuracy may be able to
continue to deliver their performance for a restricted period.
3.5
failure mode
manner in which a bearing fails
4 Classification of failure modes occurring in rolling bearings
Preferably, one would classify rolling bearing damage and failures according to the root cause. However,
it is often not easy to distinguish between causes and characteristics (symptoms) or, in other words,
between failure mechanisms and failure modes. The large number of articles and books written on the
subject confirms this (see Bibliography). Therefore, in this document, failure modes are classified in
six main groups and various sub-groups (see Figure 2), based on their visible distinctive characteristic
appearance in service.
2 © ISO 2017 – All rights reserved

Figure 2 — Classification of failure modes
5 Failure modes
5.1 Rolling contact fatigue
5.1.1 General description of rolling contact fatigue
Rolling contact fatigue is caused by the repeated stresses developed in the contacts between the rolling
elements and the raceways. Fatigue is manifested visibly as a change in the structure (microstructure)
and as spalling of material from the surface (macrostructure) that, in most of the cases, could be
consequential to a change in microstructure.
NOTE Spalling and flaking are synonyms (see A.4).
5.1.2 Subsurface initiated fatigue
Under the influence of cyclic loading in the rolling contacts described by the Hertzian theory,
stresses and material structural changes occur and microcracks are initiated at a location and depth
which depend on the applied load, the operating temperature, the material and its cleanliness and
microstructure. The initiation of the microcracks is often caused by inclusions in the bearing steel.
The changes might appear at metallurgical investigation (see A.3). These cracks propagate and when
they come to the surface, spalling occurs (see Figures 3 and 4).
Figure 3 — Initial subsurface spalling in a deep groove ball bearing — Rotating inner ring
Figure 4 — Advanced subsurface spalling in a tapered roller bearing — Stationary inner ring
5.1.3 Surface initiated fatigue
Fatigue initiated from the surface is typically caused by surface distress.
Surface distress is damage initiated at the rolling contact surfaces due to plastic deformation of the
surface asperities (smoothing, burnishing, glazing). Contact between the asperities of the rolling
element and bearing raceway is most often the result of inadequate lubrication conditions (insufficient
lubricant film thickness). This contact may be caused by insufficient lubrication flow/availability,
improper lubricant for the application, operating temperatures beyond the expected level or rough
surface finishes. Contact and plastic deformation of the surface asperities can lead to
— asperity microcracks (see Figure 5),
— asperity microspalls (see Figure 6), and
4 © ISO 2017 – All rights reserved

— microspalled areas (grey stained) (see Figure 7).
Sliding motion under low lubricant film conditions can significantly accelerate the surface damage.
For cases where film thickness is sufficient for normal operating conditions, surface-initiated fatigue
may still occur. This can happen when particles are introduced into the contact area (see 5.5.3),
extreme loads plastically deform the surface or handling nicks are present. All three conditions result
in indentations in the raceways. Protrusions around the indentation exceed the height of the oil film,
resulting in deformation of surface asperities. Surface initiated fatigue caused by indentation arising
from plastic deformation is shown in A.2.6.2.
[1]
NOTE ISO 281 includes surface related calculation parameters that are known to have an influence on the
bearing life such as material, lubrication, environment, contamination particles and bearing load.
Figure 5 — Asperity microcracks and microspalls on a raceway
Figure 6 — Surface initiated microspalls on a raceway
Figure 7 — Microspalled areas on a raceway
5.2 Wear
5.2.1 General description of wear
Wear is the progressive removal of material from the surface, resulting from the interaction of two
sliding or rolling/sliding contacting surfaces during service.
5.2.2 Abrasive wear
Abrasive wear (particle wear, three-body wear) is the removal of material due to sliding in presence
of hard particles. It is the result of a hard surface or particle removing material from another surface
through a cutting or ploughing action when sliding across it. The surfaces become dull to a degree, which
varies according to the coarseness and nature of the abrasive particles (see Figure 8). These particles
gradually increase in number as material is worn away from the running surfaces and, possibly, the
cage (see Figure 9). Finally, the wear becomes an accelerating process that results in a failed bearing.
Although the surfaces normally become dull to a certain extent, when the abrasive particles are very
fine, a polishing effect might occur, resulting in very shiny surfaces (see Figure 10).
NOTE The “running-in” of a rolling bearing is a natural short process after which the running behaviour,
e.g. noise or operating temperature, stabilizes or even improves. As a consequence, the running path or running
track becomes visible; however this is not indicating that the bearing is damaged.
6 © ISO 2017 – All rights reserved

Figure 8 — Abrasive wear on the inner ring of a spherical roller bearing
Figure 9 — Advanced abrasive wear on the cage pockets of a solid metal cage
Figure 10 — Abrasive wear on the raceway of the large rib surface of the inner ring and on the
large end face of rollers in a tapered roller bearing
5.2.3 Adhesive wear
Adhesive wear is characterized by a transfer of material from one surface to another with frictional heat
and, sometimes, tempering or rehardening of the surface. This produces localized stress concentrations
with the potential for cracking or spalling of the contact areas.
Smearing (skidding, galling, scoring, frosting) occurs because of inadequate lubrication conditions
when sliding occurs and localized temperature rises from friction cause adhesion of the contacting
surfaces, resulting in material transfer. This typically happens between rolling elements and raceways
if the rolling elements are too lightly loaded and subjected to severe acceleration on their re-entry
into the load zone (see Figures 11 and 12). In severe cases of smearing, seizing may result. Smearing is
usually a sudden occurrence as opposed to an accumulated wear process.
Smearing can also occur on the rib faces and on the ends of the rollers due to inadequate lubrication (see
Figure 13). In full complement (cageless) bearings, smearing can also occur in the contacts between
rolling elements, depending on lubrication and rotation conditions.
If a bearing ring moves (creeps) relative to its seat because of inadequate retention on the shaft or in
the housing, then smearing (also called scuffing) can occur in the bearing bore, the outside diameter
or on the shaft or in the housing seat. Because of the minute difference in the diameters of the two
components, they will have a minute difference in their circumferences and, consequently, when
brought into contact at successive points by the radial load rotating with respect to the ring, will rotate
at minutely different speeds. This rolling motion of the ring against its seating with a minute difference
in the rotational speeds is termed “creep”.
When creep occurs, the asperities in the ring/seat contact region are over-rolled, which can cause the
surface of the ring to take on a shiny appearance. The over-rolling during creeping is often, but not
always, accompanied by sliding in the ring/seat contact, and then other damage will also be visible, e.g.
score marks, fretting corrosion and wear. Under certain loading conditions and when the ring/seating
interference fit is insufficiently tight, fretting corrosion will predominate (see A.2.4.2.1 and A.2.4.2.2).
Furthermore, with a loose radial fit, creep can also occur between the face of a ring and its axial
abutment. In severe cases, this can lead to transverse thermal cracks and finally cause cracking of the
ring (see 5.6.4).
Figure 11 — Smearing on the outer ring raceway of a cylindrical roller bearing
Figure 12 — Smearing on the outer ring raceways of a spherical roller bearing
8 © ISO 2017 – All rights reserved

Figure 13 — Smearing on the side face of rollers of a cylindrical roller bearing
5.3 Corrosion
5.3.1 General description of corrosion
Corrosion is the result of a chemical reaction on metal surfaces.
5.3.2 Moisture corrosion
When bearing components are in contact with moisture or aggressive media (e.g. water or acids),
oxidation or corrosion (rust) of surfaces takes place (see Figure 14). Subsequently, the formation of
corrosion pits occurs and finally spalling of the surface occurs (see Figure 15).
A specific form of moisture corrosion can be observed in the contact areas between rolling elements
and bearing rings where the water content in the lubricant or the degraded lubricant reacts with the
surfaces of the adjacent bearing elements. During static periods, the advanced stage will result in dark
discolouration of the contact areas at intervals corresponding to the ball/roller pitch (see Figure 16);
eventually producing corrosion pits.
Figure 14 — Moisture corrosion on the cage and rollers of a needle roller thrust bearing
Figure 15 — Moisture corrosion on the outer ring raceway of a cylindrical roller bearing
Figure 16 — Contact corrosion at roller pitch on the inner ring raceway of a tapered roller bearing
5.3.3 Frictional corrosion
5.3.3.1 General description of frictional corrosion
Frictional corrosion (tribo-corrosion, tribo-oxidation) is a chemical reaction activated by relative
micromovements between mating surfaces under certain friction and load conditions. These
micromovements lead to oxidation of the surfaces and released material becoming visible as powdery
rust and/or loss of material from one or both mating surfaces.
5.3.3.2 Fretting corrosion
Fretting corrosion occurs in fit interfaces between components that are transmitting loads under
oscillating contact surface micromovements. Surface asperities oxidize and are rubbed off and vice
versa; powdery rust develops (fretting rust, iron oxide). The bearing surface becomes discoloured
blackish red (see Figure 17). Typically, the damage develops when loads and/or vibrations overcome
the radial clamping given by the mounting fits. Excessively rough and/or wavy surface finish of bearing,
shaft and housing surfaces can also reduce the effective mounting fit and induce fretting corrosion (see
Figure 18).
NOTE 1 Some abrasive wear might occur as a resultant effect of the presence of the corrosion products (iron
oxide) and micromovements.
NOTE 2 In this document, fretting corrosion is classified under corrosion. In other documents, it is sometimes
classified as fretting wear.
Figure 17 — Fretting corrosion in the inner ring bore of a deep groove ball bearing
10 © ISO 2017 – All rights reserved

Figure 18 — Fretting corrosion on the outer diameter of a roller bearing
5.3.3.3 False brinelling
False brinelling (vibration corrosion) most commonly occurs in rolling element/raceway contact areas
of non-rotating bearings due to micromovements and/or resilience of the elastic contacts under cyclic
vibrations. Depending on the intensity of the vibrations, the load and lubrication conditions, depressions
are formed on the raceways, mostly also leading to corrosion (due to lack of protective lubricant) and
resultantly abrasive wear.
In the case of a stationary bearing, the depressions appear at rolling element pitch and may be
discoloured reddish or shiny (see Figures 19 and 20).
False brinelling occurring in stand-by equipment, when long stopped periods in the presence of
vibrations from nearby operating equipment are alternated with rather short running sessions, could
result in closely spaced flutes. These should not be mistaken for electrically caused flutes (see 5.4.3
and Figures 23, 24 and 25). The fluting resulting from vibration has bright or fretted bottoms to the
depressions compared to fluting produced by the passage of electric current, where the bottoms of the
depressions are dark greyish in colour. The damage caused by electric current is distinguishable by the
fact that the rolling elements show corresponding marks, but normally in a less advanced stage.
NOTE In this document, false brinelling is classified under corrosion. In other documents, it is sometimes
classified as wear.
a)  Outer ring of a tapered roller bearing b)  Washer raceways of a needle roller
thrust bearing
Figure 19 — False brinelling
Figure 20 — False brinelling on the outer ring raceway of a self-aligning ball bearing
5.4 Electrical erosion
5.4.1 General description of electrical erosion
Electrical erosion is the localized microstructural change and removal of material at the contact
surfaces caused by the passage of damaging electric current.
5.4.2 Excessive current erosion
When an electric voltage between bearing rings and rolling element(s) exceeds the insulation
breakdown threshold value, an electrical current passes from one bearing ring to the other through the
rolling elements and their lubricant films. In the contact areas between raceways and rolling elements,
a concentrated discharge takes place resulting in localized heating within very short time intervals, so
that the contact areas melt and weld together.
This damage (electrical pitting) may appear as a series of craters with diameters of up to 500 μm (see
Figures 21 and 22). The craters are duplicated on the rolling element and raceway contact surfaces,
typically in bead-like procession in the rolling direction (see Figure 21).
Figure 21 — Roller of a spherical roller bearing — Craters formed by the passage of excessive
electric current
12 © ISO 2017 – All rights reserved

Figure 22 — Enlargement of Figure 21 showing craters and molten material
5.4.3 Current leakage erosion
When a damaging (capacitive or inductive) electric current becomes continually established, the erosion
takes on a different appearance as to 5.4.2. Initially, the surface damage may take the shape of shallow
craters, which are closely positioned to one another and very small in size, in the order of micrometres.
This happens even if the intensity of the current is relatively low. Flutes may develop due to current
passing through the whole contact ellipse (ball bearing) or line (roller bearing), as shown in Figures 23,
24 and 25 (electrical fluting). Flutes can be found on roller and ring raceway contact surfaces, but not
on balls, which have dark colouration only. The visual appearance of balls is mostly dull varying from
light to dark grey (see Figure 24). Inspection on microscale usually shows craters.
Additionally, the lubricant can also deteriorate by the electric current passage. The damaged grease
exhibits black discolouring and hardened consistency.
Figure 23 — Fluting (washboarding) as a result of current leakage on the inner ring raceway of
a tapered roller bearing
Figure 24 — Fluting on the inner ring raceway and matt dark grey coloured balls of a deep
groove ball bearing
Figure 25 — Fluting on the outer ring raceway of a deep groove ball bearing
5.5 Plastic deformation
5.5.1 General description of plastic deformation
This is a permanent deformation that occurs whenever the yield strength of the material is exceeded.
Typically, this can occur in two different ways:
— on a macroscale, where the contact load between a rolling element and the raceway causes yielding
over a substantial portion of the contact footprint;
— on a microscale, where a foreign object is over-rolled between a rolling element and the raceway and
yielding occurs over only a small part of the contact footprint.
5.5.2 Overload deformation
Overload deformation can occur while the bearing is stationary (most common), or while rotating
(uncommon).
Overloading of a stationary bearing by static load or shock load leads to plastic deformation at the
rolling element/raceway contacts (true brinelling), i.e. the formation of shallow depressions or flutes
on the bearing raceways in positions corresponding to the pitch of the rolling elements (see Figures 26
and 27).
Overload can be distinguished from false brinelling or electrical fluting by the visibility of surface
finish or residual machining marks at the bottom of the depression or flute. Furthermore, overloading
can occur by excessive preloading or due to incorrect handling during mounting (see Figure 26).
14 © ISO 2017 – All rights reserved

Inappropriate handling can also cause overloading and deformation of other bearing components, e.g.
shields, washers and cages (see Figure 28). Raceways and rolling elements can incur indentations and
nicks caused by hard, possibly sharp objects or by incorrect assembly (see Figure 29).
Overload of a rotating bearing can take different aspects depending on the type of overload.
— Instantaneous overload can lead to fluting (washboarding) with individual, non-symmetrical marks
that are more or less extended.
— Instantaneous overload can lead to depressions at rolling element pitch.
— Permanent overload can result in lamination and macroscopic plastic deformation of the whole
circumference of the overloaded part of the raceway.
Figure 26 — Overload on a stationary inner ring of an angular contact ball bearing
Figure 27 — Spalling as a result of shock load deformation on the inner ring raceway of
an angular contact ball bearing, resulting from impacts in radial direction, which further
developed in spalling
Figure 28 — Cage deformation of an angular contact ball bearing caused by a shock load during
handling
Figure 29 — Indentations on the inner ring raceway of a cylindrical roller bearing caused by
incorrect assembly
5.5.3 Indentations from particles
When particles are over-rolled, indentations are formed on raceways of rings (see Figure 30) and
rolling elements (see Figure 31). The size and shape of the indentations will depend on the nature of the
particles. Figure 32 depicts the following types of indentation:
a) from soft particles, e.g. fibres, elastomers, plastics and wood [see Figure 32 a)];
b) from hardened steel particles, e.g. from gears and bearings [see Figure 32 b)];
c) from hard mineral particles, e.g. from sand particles (silica) in the oil [see Figure 32 c)].
Figure 30 — Indentations from particles on the inner ring raceway of a tapered roller bearing
16 © ISO 2017 – All rights reserved

Figure 31 — Indentations from particles on tapered rollers
a b c
Figure 32 — Enlargements of indentations on raceways resulting from over-rolled particles
5.6 Cracking and fracture
5.6.1 General description of cracking and fracture
Cracks are initiated and propagate when the ultimate tensile strength of the material is locally exceeded.
Fracture is the result of a crack propagating completely through a section of the component or
propagating such that a portion of the component is completely separated from the original component.
5.6.2 Forced fracture
Forced fracture is due to a stress concentration in excess of the material (tensile) strength and is
caused by local over-stressing, e.g. from impact (see Figure 33), or by over-stressing due to an excessive
interference fit, e.g. too high hoop stress (see Figure 34).
Figure 33 — Forced fracture of a tapered roller bearing inner ring shoulder, caused by an
impact load during assembly procedures
NOTE Fracture caused by an excessive interference fit during mounting, for example, by driving a tapered
bore inner ring too far up the shaft taper.
Figure 34 — Forced fracture of a spherical roller bearing inner ring
5.6.3 Fatigue fracture
Frequent exceeding of the fatigue strength limit under bending, tension or torsion conditions results
in fatigue cracking. A crack is initiated at a stress raiser and propagates in steps over a part of the
component cross-section, ultimately resulting in a forced fracture. Fatigue fracture occurs mainly on
rings (see Figure 35) and cages (see Figure 36).
NOTE The origination of fracture is near the right raceway, centred in the characteristic sea shell signature
left by a progressing fatigue crack (the damage above the outside surface is secondary and occurred when the
ring fractured).
Figure 35 — Section of fatigue fracture of a cam roller outer ring caused by bending
18 © ISO 2017 – All rights reserved

Figure 36 — Fatigue fracture of cage bars of a needle roller thrust bearing
5.6.4 Thermal cracking
Thermal cracking (heat cracking) is caused by high frictional heating due to sliding motion. Cracks
usually appear at right angles to the direction of sliding (see Figure 37). Hardened steel components are
generally sensitive to thermal cracking due to local rehardening of the surfaces in combination with the
development of high residual tensile stress.
Figure 37 — Thermal cracks on the small end of the inner ring of a tapered roller bearing
Annex A
(informative)
Failure analysis — Illustrations of damage — Other investigations
— Explanation of terms used
A.1 Failure analysis
A.1.1 General
— The purpose of this document is to promote and assist in a logical objective investigation of bearing
failure to identify possible causes.
— Careful identification of the most probable causes and modes of a failure can be an important input
to development of a long term preventive solution.
— Targeted countermeasures can be devised to guard against the identified causes.
— An open objective approach by all participants is essential to successful application of this document.
A.1.2 Securing evidence before and after removal
A.1.2.1 Important points
— When a bearing fails, it is vital to collect as much evidence as possible before attempting a diagnosis
of the causes.
— An impartial enquiring approach is required.
A.1.2.2 Conserving evidence
— Equipment operator/owner to disturb as little evidence as possible prior to investigation.
— The different interested parties need to devise a logical investigation procedure.
— Avoid destroying or compromising some evidence before it can be assessed and recorded.
— Gather as much recent operational data as possible from operator and other involved organizations
and persons.
— Instant diagnoses and conclusions should be treated as preliminary.
— Note these initial possible diagnoses, but put them to one side until evidence has been gathered and
assessed.
— When a plan has been devised and agreed, dismantling of the equipment to reach the bearing can
commence.
The matrix in Table A.1 provides a guide to making a plan.
A.1.2.3 Gathering evidence
— At each stage, be sure to make the following:
— photographs and/or sketches;
20 © ISO 2017 – All rights reserved

— notes of the condition and positions of components.
— Related parts should be kept together:
— label, mark and put in clean plastic containers where possible.
— Be sure to obtain all evidence that needs a complete assembly or component before:
— dismantling which is difficult or impossible to reverse;
— cleaning including disturbing lubricant or contaminant;
— especially cutting that destroys a circular surface.
— The bearing will contain the evidences of its own failure:
— when removed, it would be incapable of further acceptable running;
— it may have “failed” more than once already;
— it may, or may not, contain the original cause;
— other components may have important evidence:
— investigate them in parallel as far as possible;
— record any available design, system, service and operational history;
— bearing designation and manufacturer to be recorded:
— if still visible or deducible from physical features;
— check manufacturer’s specification if possible;
— the bearing may be unsuitable:
— inappropriate service replacement for an originally installed bearing;
— not a valid equivalent;
— does not meet the equipment manufacturer’s specification.
NOTE Lubricants and contaminants are to be considered as parts just as much as the solid metallic and any
polymeric or rubber components.
A.1.2.4 Interpreting the evidence
It is important to bear in mind that, depending on the time between damage initiation and its detection,
the damage can be more or less advanced when the mechanical system is dismounted and inspected.
If the detection of the damage occurred comparatively late after its initiation, the clues on the initial
cause may have been suppressed, hidden or worn off, so that it can be difficult to determine the real
cause for damage or failure.
It is very important that to observe and analyse all indications on the bearing(s) and surrounding parts,
to establish the probable sequence of damage.
For example, propagated spalling can be originated from a surface spall initiated on a dent that resulted
from lubricant contamination, but also by surface defects such as nicks produced by plastic deformation
during mounting, corrosion, craters formed by excessive electric current, etc.
If in this case spalling is observed in conjunction with another initial damage indication on other areas
of a bearing component, all these indications worked out together can lead to a plausible scenario of
damage and original cause.
— Complete the agreed structured examination plan.
— Now, apply value judgement to all evidence.
— Do not approach conclusions yet.
— Strong evidence will be readily categorized.
— Any evidence that cannot be confidently matched against the examples in this document should be
treated with caution and labelled “probable”.
— The assessed evidence may then be studied to try t
...

NORME ISO
INTERNATIONALE 15243
Deuxième édition
2017-03
Roulements — Détérioration
et défaillance — Termes,
caractéristiques et causes
Rolling bearings — Damage and failures — Terms, characteristics
and causes
Numéro de référence
©
ISO 2017
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2017, Publié en Suisse
Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite ni utilisée
sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie, l’affichage sur
l’internet ou sur un Intranet, sans autorisation écrite préalable. Les demandes d’autorisation peuvent être adressées à l’ISO à
l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
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Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2017 – Tous droits réservés

Sommaire Page
Avant-propos .iv
Introduction .v
1 Domaine d’application . 1
2 Références normatives . 1
3 Termes et définitions . 2
4 Classification des modes de défaillance survenant dans les roulements .2
5 Modes de défaillance . 3
5.1 Fatigue de contact de roulement . 3
5.1.1 Description générale de la fatigue de contact de roulement . 3
5.1.2 Fatigue initiée en sous-couche . 4
5.1.3 Fatigue initiée en surface . 4
5.2 Usure . 6
5.2.1 Description générale de l’usure . 6
5.2.2 Usure par abrasion . 6
5.2.3 Usure par adhésion . 7
5.3 Corrosion . 9
5.3.1 Description générale de la corrosion . 9
5.3.2 Corrosion due à l’humidité . 9
5.3.3 Corrosion par frottement .10
5.4 Électroérosion .12
5.4.1 Description générale de l’électroérosion .12
5.4.2 Érosion due à une surtension .12
5.4.3 Érosion due à une fuite de courant .13
5.5 Déformation plastique .14
5.5.1 Description générale de la déformation plastique .14
5.5.2 Déformation due à une surcharge .15
5.5.3 Indentations par des particules .16
5.6 Fissuration et rupture .18
5.6.1 Description générale de la fissuration et de la rupture .18
5.6.2 Rupture forcée .18
5.6.3 Rupture par fatigue . .18
5.6.4 Fissuration thermique .19
Annexe A (informative) Analyse des défaillances — Illustration des détériorations —
Autres examens — Explication des termes utilisés .21
Bibliographie .55
Avant-propos
L’ISO (Organisation internationale de normalisation) est une fédération mondiale d’organismes
nationaux de normalisation (comités membres de l’ISO). L’élaboration des Normes internationales est
en général confiée aux comités techniques de l’ISO. Chaque comité membre intéressé par une étude
a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,
gouvernementales et non gouvernementales, en liaison avec l’ISO participent également aux travaux.
L’ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui
concerne la normalisation électrotechnique.
Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont
décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier de prendre note des différents
critères d’approbation requis pour les différents types de documents ISO. Le présent document a été
rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir www
.iso .org/ directives).
L’attention est appelée sur le fait que certains des éléments du présent document peuvent faire l’objet de
droits de propriété intellectuelle ou de droits analogues. L’ISO ne saurait être tenue pour responsable
de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant
les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de
l’élaboration du document sont indiqués dans l’Introduction et/ou dans la liste des déclarations de
brevets reçues par l’ISO (voir www .iso .org/ brevets).
Les appellations commerciales éventuellement mentionnées dans le présent document sont données
pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un
engagement.
Pour une explication de la nature volontaire des normes, la signification des termes et expressions
spécifiques de l’ISO liés à l’évaluation de la conformité, ou pour toute information au sujet de l’adhésion
de l’ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles
techniques au commerce (OTC), voir le lien suivant: w w w . i s o .org/ iso/ fr/ avant -propos .html.
Le présent document a été élaboré par le comité technique ISO/TC 4, Roulements.
Cette deuxième édition annule et remplace la première édition (ISO 15243:2004), qui a fait l’objet d’une
révision technique.
iv © ISO 2017 – Tous droits réservés

Introduction
Dans la pratique, la détérioration et/ou la défaillance d’un roulement peuvent souvent être le résultat
de plusieurs mécanismes se produisant simultanément. La défaillance peut être la conséquence d’un
transport, d’une manipulation ou d’un montage incorrects, d’une maintenance inadéquate ou d’un
défaut de fabrication du roulement ou de ses éléments adjacents. Dans certains cas, la défaillance est
due à un compromis fait au niveau de la conception pour des raisons d’intérêts économiques, voire à des
conditions de fonctionnement et environnementales imprévues. La combinaison complexe de plusieurs
facteurs de conception, de fabrication, de montage, de fonctionnement et de maintenance est souvent à
l’origine de difficultés au niveau de la détermination de la cause racine de la défaillance.
NOTE Il faut être conscient que des roulements de contrefaçon sont mis sur le marché. Ils peuvent ressembler
à des roulements originaux mais leur utilisation entraine souvent des défaillance et fracture prématurées.
En cas de détérioration importante ou de défaillance soudaine et totale du roulement, l’absence
d’indication évidente est probable, ce qui rend impossible l’identification de la cause racine de la
défaillance. De ce fait, il est important de mettre à l’arrêt l’équipement à temps pour permettre une
analyse appropriée des détériorations du roulement (voir Figure 1). Dans tous les cas, la connaissance
des conditions réelles de fonctionnement de l’ensemble et l’historique des travaux de maintenance se
révèlent de la plus haute importance.
NOTE L’écaillage a commencé juste derrière l’indentation dans le chemin de roulement [a)]. Il s’est
ensuite aggravé au fil du temps [b) et c)]. S’il n’est pas arrêté à temps, la preuve de la cause racine
disparaît [d)].
Figure 1 — Évolution de la détérioration du roulement
La classification des défaillances des roulements établie dans le présent document est principalement
fondée sur les caractéristiques visibles sur les surfaces de contact de roulement et sur d’autres surfaces
fonctionnelles. Chaque caractéristique est à prendre en compte pour déterminer de manière fiable la
cause racine de la défaillance du roulement. Dans la mesure où plusieurs mécanismes de défaillance
peuvent avoir des effets similaires sur lesdites surfaces, la description de l’aspect ne suffit généralement
pas, à elle seule, pour déterminer la cause de la défaillance. Dans certains/ces cas, il est nécessaire de
prendre les conditions de fonctionnement en considération. Dans certains cas, la détérioration analysée
est trop avancée et peut provenir de différentes causes primaires. Il est alors intéressant de rechercher
la présence simultanée d’indications pour déterminer la cause primaire de la défaillance.
Le présent document porte sur les roulements dotés de bagues en acier et d’éléments roulants. La
détérioration des bagues des roulements avec éléments roulants en céramique suit des modes de
défaillance similaires.
[1]
Dans le présent document, la durée de vie des roulements est comme décrit dans l’ISO 281 , qui prévoit
des formules pour calculer la durée de vie des roulements en prenant en compte un certain nombre de
facteurs, tels que la capacité de charge du roulement, le type de roulement, le matériau de fabrication, la
limite de fatigue du roulement, les conditions de lubrification et le degré de contamination.
NORME INTERNATIONALE ISO 15243:2017(F)
Roulements — Détérioration et défaillance — Termes,
caractéristiques et causes
1 Domaine d’application
Le présent document classe les différents modes de défaillance survenant en cours de fonctionnement
pour les roulements en aciers standards. Elle définit et décrit, pour chaque mode de défaillance,
les caractéristiques, l’aspect et les possibles causes racines de la défaillance. Elle contribuera à
l’identification des modes de défaillance en s’appuyant sur l’aspect.
Les termes suivants sont expliqués pour les besoins du présent document:
— défaillance d’un roulement: résultat d’une détérioration qui empêche le roulement de satisfaire à
ses performances initialement prévues ou marque la fin de sa durée de vie;
— en service: état du roulement tel qu’il sort de l’usine du fabricant;
— caractéristiques visibles: caractéristiques qu’il est possible d’observer directement ou avec une loupe
ou un microscope optique, ainsi que celles observées sur des images, mais en utilisant uniquement
des méthodes non destructives.
L’analyse se limite aux formes caractéristiques du changement d’aspect et aux défaillances ayant un
aspect bien défini et pouvant être imputables à des causes particulières avec un degré de certitude
élevé. Les caractéristiques d’intérêt particulier relatives à l’explication des changements et des
défaillances sont décrites. Les formes diverses sont illustrées par des photographies et les causes les
plus fréquentes sont indiquées.
Si la cause racine ne peut pas être évaluée de manière fiable par l’examen et la description des
caractéristiques visuelles confrontés aux informations fournies dans le présent document, des examens
complémentaires sont à envisager. Ces méthodes sont résumées au A.3 et peuvent impliquer, par
exemple, l’utilisation de méthodes invasives pouvant inclure le prélèvement de coupes transversales,
des analyses métallurgiques structurelles au moyen de microscopes visuels ou électroniques et des
analyses chimiques et spectrographiques. Ces méthodes spécialisées ne sont pas incluses dans le
domaine d’application du présent document.
Les termes des modes de défaillance exprimés dans les titres des paragraphes sont recommandés pour
un usage général. Le cas échéant, les expressions alternatives ou synonymes utilisés pour décrire les
sous-modes sont indiqués et expliqués en A.4.
Des exemples de défaillances des roulements, accompagnés d’une description des causes de la
défaillance et des mesures correctives proposées, sont donnés en A.2.
2 Références normatives
Les documents suivants cités dans le texte constituent, pour tout ou partie de leur contenu, des
exigences du présent document. Pour les références datées, seule l’édition citée s’applique. Pour les
références non datées, la dernière édition du document de référence s’applique (y compris les éventuels
amendements).
ISO 5593, Roulements — Vocabulaire
3 Termes et définitions
Pour les besoins du présent document, les termes et définitions donnés dans l’ISO 5593 ainsi que les
suivants s’appliquent.
NOTE Des explications de termes de détérioration et défaillance sont données en A.4.
L’ISO et l’IEC tiennent à jour des bases de données terminologiques destinées à être utilisées en
normalisation, consultables aux adresses suivantes:
— IEC Electropedia: disponible à l’adresse http:// www .electropedia .org/
— ISO Online browsing platftorm: disponible à l’adresse http:// www .iso .org/ obp
3.1
caractéristiques
aspect visuel résultant de la performance d’usage
[3]
Note 1 à l’article: Les défauts de surface et les types de changements géométriques sont définis dans l’ISO 8785
[2]
et, en partie, dans l’ISO 6601 (portant sur l’usure par abrasion).
3.2
détérioration
toute détérioration visible des surfaces ou structures de fonctionnement du roulement
3.3
séquences d’événements
séquence d’événements aboutissant à la défaillance (3.4) du roulement, en commençant par la
détérioration (3.2) initiale du roulement
Note 1 à l’article: À un stade précoce, cette détérioration peut causer une perte fonctionnelle ou une défaillance.
Cependant, dans de nombreux cas, la détérioration initiale n’aboutit pas à une défaillance et le roulement continue
de fonctionner. La poursuite du fonctionnement provoque généralement une détérioration secondaire qui aboutit
finalement à une défaillance. La détérioration secondaire peut introduire des modes de défaillance concurrents,
ce qui peut compliquer l’analyse de la cause racine.
3.4
défaillance
toute situation dans laquelle le roulement n’est plus en mesure d’assurer son fonctionnement prévu
Note 1 à l’article: Cela comprendra la dégradation de propriétés rotationnelles essentielles et l’avertissement
d’une défaillance plus étendue ou totale imminente, sans pour autant que le stade soit suffisamment avancé pour
empêcher la rotation ou le support des éléments de machine concernés.
Note 2 à l’article: L’étendue de la détérioration (3.2) requise pour enregistrer une déclaration de défaillance
opérationnelle dépendra de l’application. Les applications nécessitant une rotation précise et sans à-coups
ne toléreront qu’une perte très minime de propriétés. Les applications non sensibles à des amplifications de
vibrations ou de bruits ou à une précision rotationnelle réduite peuvent être capables de continuer à assurer
leurs performances pendant une période restreinte.
3.5
mode de défaillance
manière selon laquelle la défaillance d’un roulement se déclare
4 Classification des modes de défaillance survenant dans les roulements
Il conviendrait de préférence que les détériorations et défaillances des roulements soient classées
selon la cause racine. Cependant, il n’est pas souvent facile de distinguer les causes des caractéristiques
(symptômes); en d’autres termes, de faire la distinction entre mécanismes et modes de défaillance. Cela
est confirmé par le grand nombre d’articles et d’ouvrages traitant de ce sujet (voir Bibliographie). Par
conséquent, dans le présent document, les modes de défaillance sont classés en six groupes principaux
2 © ISO 2017 – Tous droits réservés

et en différents sous-groupes (voir Figure 2), en fonction de leur aspect caractéristique distinctif en
service.
Figure 2 — Classification des modes de défaillance
5 Modes de défaillance
5.1 Fatigue de contact de roulement
5.1.1 Description générale de la fatigue de contact de roulement
La fatigue de contact de roulement est provoquée par les contraintes répétées développées au niveau
du contact entre les éléments roulants et les chemins de roulement. La fatigue se manifeste visiblement
sous la forme d’une modification de la structure (microstructure) et d’un écaillage à la surface du
matériau (macrostructure) qui, dans la plupart des cas, pourraient entraîner une modification de la
microstructure.
NOTE Ecaillage et écaillage avancé sont synonymes (voir A.4).
5.1.2 Fatigue initiée en sous-couche
Sous l’influence d’une charge cyclique exercée sur les contacts de roulement, décrite par la théorie de
Hertz, des contraintes et des changements structurels du matériau se produisent et des microfissures se
forment à des emplacements et à des profondeurs dépendant de la charge appliquée, de la température
de fonctionnement, du matériau et de sa propreté, ainsi que de la microstructure. La formation de
microfissures est souvent provoquée par des inclusions dans l’acier du roulement.
Les changements peuvent apparaître à l’examen métallurgique (voir A.3). Ces fissures se propagent et
provoquent un écaillage une fois arrivées en surface (voir Figures 3 et 4).
Figure 3 — Écaillage initial en sous-couche dans un roulement à billes à gorges
profondes — Bague intérieure tournante
Figure 4 — Écaillage avancé en sous-couche dans un roulement à rouleaux coniques — Bague
intérieure fixe
5.1.3 Fatigue initiée en surface
La fatigue initiée en surface est généralement provoquée par une dégradation de surface appelé aussi
surface distress (aplatissement des micro-rugosités).
La surface distress est la détérioration initiée aux surfaces de contact du roulement due aux
déformations plastiques des aspérités de surface (lissage, polissage, glaçage). Le contact entre les
aspérités des éléments roulants et du chemin de roulement est le plus souvent le résultat de conditions de
lubrification inappropriées (épaisseur du film de lubrifiant insuffisante). Ce contact peut être provoqué
par une circulation/un apport de lubrification insuffisant(e), un lubrifiant impropre à l’application, des
4 © ISO 2017 – Tous droits réservés

températures de fonctionnement au-dessus des niveaux attendus ou un état de surface rugueux. Le
contact et la déformation plastique des aspérités de surface peuvent entrainer:
— des microfissures (voir Figure 5),
— des micro-écaillages (voir Figure 6), et
— des zones micro-écaillées (taches grises) (voir Figure 7).
En cas de film lubrifiant de faible épaisseur, le glissement peut accélérer considérablement la
détérioration de la surface.
Dans les cas pour lesquels l’épaisseur du film est suffisante pour des conditions de fonctionnement
normal, une fatigue initiée en surface peut toujours apparaitre. Cela peut se produire quand des
particules sont introduites dans la zone de contact (voir 5.5.3), des charges extrêmes déforment
plastiquement la surface ou des empreintes de manipulation (coup d’angle) sont présentes. Ces
trois conditions entrainent des indentations dans les chemins de roulements. Des bourrelets autour
des indentations dépassent la hauteur du film d’huile, entrainant des déformations des aspérités de
surfaces. La fatigue initiée en surface, causée par l’indentation due à la déformation plastique, est
illustrée en A.2.6.2.
[1]
NOTE L’ISO 281 comprend des paramètres de calcul relatifs à la surface et connus pour avoir une influence
sur la durée de vie du roulement, tels que le matériau, la lubrification, l’environnement, les particules de pollution
et la charge au niveau du roulement.
Figure 5 — Microfissures et micro-écaillages sur un chemin de roulement
Figure 6 — Micro-écaillages initiés en surface sur un chemin de roulement
Figure 7 — Zones micro-écaillées sur un chemin de roulement
5.2 Usure
5.2.1 Description générale de l’usure
L’usure est l’enlèvement progressif de matière en surface résultant de l’interaction entre deux surfaces
en contact de glissement ou de roulement/glissement en cours de fonctionnement.
5.2.2 Usure par abrasion
L’usure par abrasion (usure sous l’action de particules, usure entre trois corps) est l’enlèvement de
matière dû au glissement en présence de particules solides. Elle est le résultat d’une surface ou particule
solide qui enlève de la matière d’une autre surface par une action de coupe ou de labourage en glissant
sur celle-ci. Les surfaces deviennent mates à un degré qui varie en fonction de la taille et de la nature
des particules abrasives (voir Figure 8). Le nombre de particules augmente progressivement avec
l’usure du matériau des surfaces en contact et potentiellement de la cage (voir Figure 9). Finalement, le
processus d’usure s’accélère jusqu’à détérioration du roulement.
Bien que les surfaces deviennent normalement mates dans une certaine mesure, un effet de polissage
peut se produire lorsque les particules abrasives sont très fines, résultant en des surfaces très brillantes
(voir Figure 10).
NOTE Le «rodage» d’un roulement est un processus naturel court à l’issue duquel le comportement en
rotation, par exemple le bruit ou la température de fonctionnement, se stabilise, voire s’améliore. La trace de
fonctionnement devient ainsi visible; cependant, cela n’indique pas que le roulement est détérioré.
6 © ISO 2017 – Tous droits réservés

Figure 8 — Usure par abrasion sur la bague intérieure d’un roulement à rotule sur rouleaux
Figure 9 — Usure par abrasion avancée des alvéoles d’une cage métallique solide
Figure 10 — Usure par abrasion sur le chemin de roulement du collet de la bague intérieure et
sur la grande face des rouleaux d’un roulement à rouleaux coniques
5.2.3 Usure par adhésion
L’usure par adhésion est caractérisée par un transfert de matière d’une surface à une autre avec
échauffement par frottement et, parfois, recuit ou retrempe de la surface. Cela génère des concentrations
de contraintes localisées avec possibilité de fissuration ou d’écaillage des zones de contact.
Le smearing (éraillure) (patinage, usure par frottement, strie, dépolissage) apparaît en cas de conditions
inappropriées de lubrification, lorsqu’un glissement se produit et que les augmentations locales de
température dues aux frottements provoquent une adhésion des surfaces en contact, résultant en
un transfert de matière. Cela se produit généralement entre les éléments roulants et les chemins de
roulement si les éléments roulants sont trop légèrement chargés et subissent une forte accélération
lorsqu’ils entrent de nouveau dans la zone de charge (voir Figures 11 et 12). Dans des cas sévères de
smearing (éraillure), un grippage avancé peut en résulter. L’apparition de smearing (éraillure) est
généralement soudaine, contrairement à un processus d’usure accumulée.
Le smearing (éraillures) peut également survenir sur les collets et sur les extrémités des rouleaux suite
à une lubrification inappropriée (voir Figure 13). Sur les roulements à éléments roulants jointifs (sans
cage), le smearing (éraillures) peut aussi survenir au niveau des points de contact entre les éléments
roulants en fonction des conditions de lubrification et de rotation.
Si une bague de roulement bouge (roule) sur sa portée, en raison d’un maintien inapproprié de l’arbre
dans le logement, le smearing (éraillure) (également appelé éraflure) peut alors se produire dans
l’alésage du roulement, sur le diamètre extérieur, sur l’arbre ou dans la portée du logement. Une
différence minime de diamètre entre deux composants entraîne un écart infime des circonférences
respectives, et donc un léger décalage des vitesses de rotation lorsqu’ils entrent en contact à des points
successifs sous l’effet de la charge radiale en rotation par rapport à la bague. Ce mouvement de rotation
de la bague par rapport à sa portée, avec une infime différence des vitesses de rotation, est désigné par
«reptation».
En cas de reptation, les aspérités situées au niveau de la zone de contact bague/portée sont laminées
par les passages répétés des éléments roulants, ce qui peut donner à la bague un aspect brillant en
surface. Ce «laminage» au cours du roulage s’accompagne souvent, mais pas systématiquement, d’un
glissement au point de contact bague/portée et fait ensuite apparaître d’autres détériorations, par
exemple stries, corrosion par frottement et usure. Sous certaines conditions de charge et lorsque
l’ajustement bague/portée n’est pas suffisamment serré, cela donne libre cours à la corrosion de contact
(voir A.2.4.2.1 et A.2.4.2.2).
Avec un ajustement radial libre, la reptation peut également survenir entre la face d’une bague et son
appui axial. Dans les cas sévères, cela peut créer des fissures thermiques transversales et provoquer
finalement la fissuration de la bague (voir 5.6.4).
Figure 11 — Smearing (éraillures) sur le chemin de roulement de la bague extérieure d’un
roulement à rouleaux cylindriques
Figure 12 — Smearing (éraillures) sur les chemins de roulement de la bague extérieure d’un
roulement à rotule sur rouleaux
8 © ISO 2017 – Tous droits réservés

Figure 13 — Smearing (éraillures) sur la face latérale des rouleaux d’un roulement à rouleaux
cylindriques
5.3 Corrosion
5.3.1 Description générale de la corrosion
La corrosion est le résultat d’une réaction chimique se produisant au niveau des surfaces métalliques.
5.3.2 Corrosion due à l’humidité
Lorsque les composants de roulement entrent en contact avec des milieux humides ou agressifs (de
l’eau ou de l’acide par exemple), cela entraîne l’oxydation ou la corrosion (rouille) des surfaces (voir
Figure 14). Par la suite, cela donne lieu à la formation de piqûres de corrosion et finalement à l’écaillage
superficiel (voir Figure 15).
Une forme spécifique de corrosion due à l’humidité peut être observée sur les surfaces de contact entre
les éléments roulants et les bagues de roulements, où la teneur en eau dans le lubrifiant ou le lubrifiant
dégradé provoque une réaction au niveau des surfaces des éléments adjacents du roulement. Pendant
les périodes statiques, le stade avancé se traduira par une coloration foncée des zones de contact à des
intervalles correspondant au pas bille/rouleau (voir Figure 16), produisant pour finir des piqûres de
corrosion.
Figure 14 — Corrosion due à l’humidité sur la cage et les rouleaux d’une butée à aiguilles
Figure 15 — Corrosion due à l’humidité sur le chemin de roulement de la bague extérieure d’un
roulement à rouleaux cylindriques
Figure 16 — Corrosion de contact au niveau du pas des rouleaux sur le chemin de roulement de
la bague intérieure d’un roulement à rouleaux coniques
5.3.3 Corrosion par frottement
5.3.3.1 Description générale de la corrosion par frottement
La corrosion par frottement (tribocorrosion; tribo-oxydation) est une réaction chimique activée par
des micromouvements relatifs entre surfaces d’ajustement dans certaines conditions de charge et de
frottement. Ces micromouvements conduisent à une oxydation des surfaces et à un rejet de matière
constatés visuellement par la formation d’une rouille pulvérulente et/ou la perte de matière au niveau
de l’une ou des deux surfaces d’ajustement.
5.3.3.2 Corrosion de contact
La corrosion de contact affecte les surfaces en vis à vis entre les composants, transmettant des charges
sous l’effet des micromouvements oscillatoires des surfaces de contact. Les aspérités superficielles
s’oxydent, se détachent et se déposent sous forme de rouille pulvérulente (rouille de contact, oxyde de
fer). La surface du roulement se colore en rouge noirâtre (voir Figure 17). En général, la détérioration
se développe lorsque le serrage radial spécifié par les ajustements de montage n’est plus suffisant
pour supporter les charges et/ou vibrations auxquelles il est soumis. Un état de surface excessivement
rugueux et/ou ondulé des surfaces de roulement, d’arbre et de logement peut également réduire
l’efficacité de l’ajustement de montage et induire une corrosion de contact (voir Figure 18).
NOTE 1 La présence de produits corrosifs (oxyde de fer) et de micromouvements peut causer une usure par
abrasion.
NOTE 2 Dans le présent document, la corrosion de contact est classée dans la catégorie «corrosion». Dans
d’autres documents, elle est parfois classée dans la catégorie «usure de contact».
10 © ISO 2017 – Tous droits réservés

Figure 17 — Corrosion de contact dans l’alésage de la bague intérieure d’un roulement à billes à
gorges profondes
Figure 18 — Corrosion de contact sur le diamètre extérieur d’un roulement à rouleaux
5.3.3.3 Faux effet Brinell
Le faux effet Brinell (corrosion due aux vibrations) affecte les surfaces de contact entre les éléments
roulants et les chemins de roulement de roulements non tournants suite à des micromouvements et/ou
en raison de la résistance élastique des contacts sous l’effet de vibrations cycliques. Selon l’amplitude
des vibrations, les conditions de lubrification et de charge, des dépressions se forment sur les chemins
de roulement, induisant aussi une corrosion dans la plupart des cas (due au manque de lubrifiant
protecteur) et, par voie de conséquence, une usure par abrasion.
Dans le cas de roulement à l’arrêt, les dépressions apparaissent au niveau du pas des éléments roulants
et peuvent prendre une couleur rougeâtre ou un aspect brillant (voir Figures 19 et 20).
Le faux effet Brinell se produisant sur les équipements à l’arrêt, lorsque de longues périodes statiques
en présence de vibrations à proximité de l’autre équipement en fonctionnement, peut entraîner le
creusement de cannelures rapprochées. Il convient de distinguer ces cannelures de celles creusées par
le passage d’un courant électrique (voir 5.4.3 et Figures 23, 24 et 25). Les cannelures creusées du fait
des vibrations constituent des dépressions à fond brillant, comparées à celles produites par le passage
d’un courant électrique donnant des dépressions à fond noir grisâtre. Les détériorations causées par
le courant électrique peuvent également se distinguer par le fait que les éléments roulants en portent
aussi les traces, mais généralement à un stade bien moins avancé.
NOTE Dans le présent document, le faux effet Brinell est classé dans la catégorie «corrosion». Dans d’autres
documents, il est parfois classé dans la rubrique «usure».
a) Bague extérieure d’un roulement à rouleaux b) Chemins de roulement de la rondelle d’une butée
coniques à aiguilles
Figure 19 — Faux effet Brinell
Figure 20 — Faux effet Brinell sur le chemin de roulement de la bague extérieure d’un
roulement à rotule sur billes
5.4 Électroérosion
5.4.1 Description générale de l’électroérosion
L’électroérosion se traduit par un changement microstructural localisé et un enlèvement de matière au
niveau des surfaces de contact, provoqués par le passage d’un courant électrique perturbateur.
5.4.2 Érosion due à une surtension
Lorsqu’une tension électrique circulant entre les bagues de roulement et l’(es) élément(s) roulant(s)
dépasse le seuil de claquage de l’isolant, un courant électrique passe d’une bague de roulement à l’autre
au travers des éléments roulants et leurs films lubrifiants. Une décharge concentrée se produit au
niveau des surfaces de contact entre les chemins de roulement et les éléments roulants, provoquant
un échauffement localisé à des intervalles de temps très courts qui entraîne la fusion et le soudage des
surfaces de contact.
12 © ISO 2017 – Tous droits réservés

Cette détérioration (formation de piqûres par passage de courant) peut se traduire par la formation
d’une série de cratères d’un diamètre pouvant atteindre 500 µm (voir Figures 21 et 22). Les cratères se
multiplient en chapelets sur les surfaces de contact des éléments roulants et des chemins de roulement,
généralement dans le sens de la rotation (voir Figure 21).
Figure 21 — Rouleau d’un roulement à rotule sur rouleaux – Cratères formés par le passage
d’un courant électrique excessif
Figure 22 — Agrandissement de la Figure 21 montrant les cratères et le matériau fondu
5.4.3 Érosion due à une fuite de courant
Lorsqu’un courant électrique (capacitif ou inductif) perturbateur s’établit en continu, l’érosion prend
un aspect différent, comme indiqué en 5.4.2. Les détériorations superficielles peuvent tout d’abord
prendre la forme de cratères peu profonds, rapprochés et de très faibles dimensions, de l’ordre du
micromètre. Cela se produit même en cas d’intensité relativement faible du courant. Des cannelures
peuvent se développer en raison du courant qui passe dans l’ensemble de l’ellipse de contact (roulement
à billes) ou de la ligne (roulement à rouleaux), comme indiqué dans les Figures 23, 24 et 25 (formation
de cannelures par passage de courant). Les cannelures peuvent se creuser sur les surfaces de contact
des chemins de roulement des rouleaux et des bagues, mais non sur les billes, qui prennent uniquement
une teinte foncée. L’aspect visuel des billes est généralement mat, variant du gris clair au gris foncé
(voir Figure 24). Un examen à l’échelle micrométrique révèle généralement les cratères.
En complément, le lubrifiant peut être détérioré par le passage de courant électrique. La graisse
détériorée présente une décoloration noire et une consistance durcie.
Figure 23 — Creusement de cannelures (usure ondulatoire) résultant d’une fuite de courant sur
le chemin de roulement de la bague intérieure d’un roulement à rouleaux coniques
Figure 24 — Formation de cannelures sur le chemin de roulement de la bague intérieure et
billes mates gris foncé d’un roulement à billes à gorges profondes
Figure 25 — Formation de cannelures sur le chemin de roulement de la bague extérieure d’un
roulement à billes à gorges profondes
5.5 Déformation plastique
5.5.1 Description générale de la déformation plastique
Il s’agit d’une déformation permanente générée lors du dépassement de la limite élastique du matériau.
Typiquement, cela peut se produire de deux façons différentes:
— à une échelle macroscopique, quand la charge de contact entre un élément roulant et le chemin
de roulement provoque un dépassement de la limite élastique sur une partie substantielle de
l’empreinte de contact;
14 © ISO 2017 – Tous droits réservés

— à une échelle microscopique, quand un corps étranger est laminé entre un élément roulant et le
chemin de roulement et provoque un dépassement de la limite élastique uniquement sur une petite
partie de l’empreinte de contact.
5.5.2 Déformation due à une surcharge
Une déformation due à une surcharge peut se produire lorsque le roulement est à l’arrêt (dans la plupart
des cas) ou lorsqu’il est en rotation (rarement).
Une surcharge statique ou d’impact sur un roulement à l’arrêt conduit à la déformation plastique au
niveau des surfaces de contact entre éléments roulants et chemins de roulement (effet Brinell), c’est-à-
dire à la formation de dépressions de faible profondeur ou de cannelures sur les chemins de roulement à
des endroits coïncidant avec le pas des éléments roulants (voir Figures 26 et 27).
La surcharge peut être distinguée d’un faux effet Brinell ou du creusement de cannelures par passage
de courant par l’apparition visible d‘un état de surface ou de marques d’usinage résiduelles sur le fond
de la dépression ou de la cannelure. En outre, la surcharge peut se produire du fait d’une précharge
excessive ou suite à une manutention inappropriée lors du montage (voir Figure 26).
Une manutention inappropriée peut également conduire à une surcharge et à une déformation d’autres
composants de roulement, tels que les flasques, rondelles et cages, entre autres (voir Figure 28). Les
chemins de roulement et les éléments roulants peuvent comporter des indentations et des empreintes
causées par des objets durs, voire tranchants, ou par un assemblage incorrect (voir Figure 29).
La surcharge d’un roulement en rotation peut prendre différents aspects selon le type de surcharge:
— Une surcharge instantanée peut entraîner la formation de cannelures (usure ondulatoire) avec des
marques individuelles et non symétriques plus ou moins étendues.
— Une surcharge instantanée peut générer des dépressions au niveau du pas des éléments roulants.
— Une surcharge permanente peut provoquer un laminage et une déformation plastique macroscopique
sur toute la circonférence de la partie du chemin de roulement soumise à la surcharge.
Figure 26 — Surcharge sur une bague intérieure à l’arrêt d’un roulement à billes à contact
oblique. La force (axiale) a été appliquée sur les éléments roulants
Figure 27 — Propagation d’un écaillage causé initialement par une déformation due à un
choc du chemin de roulement de la bague intérieure d’un roulement à billes à contact oblique,
résultant d’impacts dans le sens radial
Figure 28 — Déformation de la cage d’un roulement à billes à contact oblique causée par un
choc au cours de la manutention
Figure 29 — Indentations sur le chemin de roulement de la bague intérieure d’un roulement à
rouleaux cylindriques, causées par un assemblage incorrect
5.5.3 Indentations par des particules
Lorsque des particules sont laminées, des indentations se forment sur les chemins de roulement des
bagues (voir Figure 30) et les éléments roulants (voir Figure 31). La taille et la forme des indentations
dépendront de la nature des particules. La Figure 32 représente les types d’indentations suivants:
a) par des particules molles, par exemples de fibres, d’élastomères, de plastiques et de bois [voir
Figure 32 a)];
b) par des particules d’acier trempé, provenant par exemple d’engrenages et de roulements (voir
Figure 32 b)];
16 © ISO 2017 – Tous droits réservés

c) par des particules minérales dures, par exemple par des particules de sable (silice) présentes dans
l’huile [voir Figure 32c)].
Figure 30 — Indentations par des corps étrangers sur le chemin de roulement de la bague
intérieure d’un roulement à rouleaux coniques
Figure 31 — Indentations par des corps étrangers sur des rouleaux coniques
a b c
Figure 32 — Agrandissement d’indentations sur les chemins de roulement causées par des
particules laminées
5.6 Fissuration et rupture
5.6.1 Description générale de la fissuration et de la rupture
Des fissures sont initiées et propagées quand la résistance à la traction du matériau est localement
dépassée.
La rupture est le résultat de la propagation complète d’une fissure au travers d’une section du
composant ou de la propagation d’une fissure entraînant la rupture d’une partie du composant.
5.6.2 Rupture forcée
La rupture forcée est due à une concentration des contraintes qui dépasse la résistance (à la traction)
du matériau et est provoquée par une surcharge locale, par exemple, suite à un impact (voir Figure 33)
ou à une surcharge due à un ajustement excessivement serré, par exemple des contraintes circulaires
trop élevées (voir Figure 34).
Figure 33 — Rupture forcée de l’épaulement d’une bague intérieure de roulement à rouleaux
coniques, causée par une charge d’impact au cours des procédures d’assemblage
NOTE Rupture causée par un ajustement excessivement serré au cours du montage, par exemple en
enfonçant trop profondément une bague intérieure d’alésage conque dans le cône de l’arbre.
Figure 34 — Rupture forcée d’une bague intérieure de roulement à rotule sur rouleaux
5.6.3 Rupture par fatigue
Un dépassement fréquen
...