ISO 15243 PDF

INTERNATIONAL ISO STANDARD First edition Rolling bearings — Damage and failures — Terms, characteristics and causes Roulements. Failure mode ISO Subsurface initiated fatigue. Is this normal Fatigue Failure, how many of you get to see a bearing actually fail. ribo lo gy, the Science fo r Maintenance. Fatigue on Inner Race. Ref.: ISO Rolling Bearings – Damages and Failures – Terms, Characteristics and Causes.

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Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO’s member body in the country of the requester. The work of preparing International Standards is normally carried out through ISO technical committees.

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The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies 152243 voting. Attention is drawn to the possibility that some of the elements of this document may isl the subject of patent oso. ISO shall not be held responsible for identifying any or all such patent rights.

The failure can result from ido assembly 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 conditions.

ISO FALLA EN RODAMIENTOS | Edicson Leonardo Briceño –

It is the complex combination of design, manufacture, assembly, operation and maintenance that often causes difficulty in establishing the primary cause of 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 primary cause of failure. In all cases, knowledge of the actual operating conditions of the assembly and the maintenance history is of the utmost importance. The classification of bearing failure established in this International Standard is based primarily upon the features visible on rolling element contact surfaces and other functional surfaces.

Consideration of each feature is required for reliable determination of the cause of bearing failure. Since more than one process may cause similar effects kso these surfaces, a description of appearance alone is occasionally inadequate for determining the reason for the failure.

In such cases, the operating conditions must be considered. It will assist in the understanding of the various forms of change in appearance and the failure that has occurred. Consideration is restricted to characteristic forms of change in appearance and failure, which have a well-defined appearance and which can be attributed to particular causes with a high 1543 of certainty.

The features of particular interest for explaining changes and failures are described. The ido forms are illustrated with photographs and diagrams, and the most 155243 causes are indicated. The failure mode designations shown in the subclause titles are recommended for general use, but similar expressions or synonyms are given within parentheses below the titles.

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Examples of rolling bearing failures are given in Annex A, together with a description of the causes of failure and proposed corrective actions.

For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document including any amendments applies. However, it is not always 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. In this International Standard, failure modes are classified in six main groups and various sub-groups see Figure 1. Fatigue is manifested visibly as a flaking of particles from the surface.

The initiation of the microcracks is often caused by inclusions in the bearing steel see Figure 2. The microcracks, which are observed at the edge of the white etched areas butterflieswill normally propagate to the rolling contact surface producing flaking, spalling pitting and then peeling see Figure 3.

BS ISO – Rolling bearings. Damage and failures. Terms, characteristics and causes

Indentations in the raceways caused either by contaminant particles or by handling can also lead to surface initiated fatigue see 5. Surface initiated fatigue caused by indentation arising from plastic deformation is shown in A. The surfaces become dull to a degree, which varies according to the coarseness and nature of the abrasive particles see Figure 7. These particles gradually increase in number as material is worn away from the running surfaces and cage.

Finally, the wear becomes an accelerating process that results in a failed bearing. This produces localized stress concentrations with the potential for cracking or flaking of the contact areas. Smearing can also occur between rolling elements and raceways when the load is too light in relation to the speed of rotation.

Smearing can occur on the guiding flange faces and on the ends of the rollers due to insufficient lubrication see Figure 9. In full complement bearings cagelesssmearing can also occur in the contacts between rolling elements depending on lubrication and rotation conditions.

This type of damage generally occurs when the radial load on the bearing rotates relative to the bearing ring and the bearing ring is mounted with a very small clearance loose fit to its seating. 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 one point by the radial load, will rotate at minutely different speeds.

Figure 8 — Smearing on Figure 9 — Smearing of Figure 10 — Smearing on ring raceway surfaces roller end end face ring is also fractured 5. Subsequently the formation of corrosion pits occurs and finally flaking of the surface see Figure 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.

Surface asperities oxidize and are rubbed off and vice versa; powdery rust develops iron oxide. The bearing surface becomes shiny or a discoloured blackish red see Figure Depending on the intensity of the vibrations, the lubrication conditions and load, a combination of corrosion and wear occurs, forming shallow depressions in the raceways. In the case of a stationary bearing, the depressions appear at rolling element pitch and can often be discoloured reddish or shiny see Figure False brinelling caused by vibrations occurring during rotation shows itself in closely spaced flutes see Figure These should not be mistakenr for electrically caused flutes see 5.

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 in colour. The damage caused by electric current is also distinguishable by the fact that the rolling elements are also marked.

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In other documents it is sometimes classified as wear.

BS ISO 15243:2017

In the contact areas between rings and rolling elements, the flow lines of the current are condensed, resulting in localized heating within very short time intervals, so that the contact areas melt and weld together.

The craters are duplicated on the rolling element and raceway contact surfaces in bead-like procession in the rolling direction see Figure This happens even if the intensity of the current is comparatively low. Flutes will develop from the craters in time, as shown in Figure They ios be found on roller and ring raceway contact surfaces, but not on balls, which have dark colouration only see Figure The flutes are equally spaced.

The raceways are isi in the bottoms of the depressions see Figures 20 and Eroded patches, next to the flutes on Figure 21, indicated by the pencil point, were caused by contact of the cage ribs with the inner ring.

Typically this can occur in two different ways: Furthermore, overloading can occur by excessive preloading or due to incorrect handling during oso see Figure Inappropriate handling can also cause overloading and deformation of other bearing components, e.

The size and shape of the indentations depend on the nature of 115243 particles. See Figures 25 ab and cwhich depict the following types of indentation: Fracture is the result of a crack propagating to kso point of complete separation of a part of the component.

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 and cages see Figures 29 and The fatigue crack striations are clearly visible in the fractured surface of the cage bar in the enlarged lower image in Figure Fatigue fracture is sometimes caused by insufficient support of the bearing ring in the housing or on the shaft see Figure Figure 31 — Fatigue fracture of an outer ring caused by insufficient support in the housing 5.

Cracks usually appear at right angles to the direction of sliding see Figure Hardened steel components are sensitive to thermal cracking due to rehardening of the surfaces in combination with the development of high residual tensile stress. To obtain the most reliable result, it is helpful to follow a systematic procedure when securing evidence and inspecting the bearing. The matrix given in Table A. The following items should be considered when investigating bearings: Important factors necessary to find the causes of failure may be lost if 152243 procedure selected is incorrect.

The types of load, operating clearance and possible misalignment may be clearly revealed. Isoo the following illustrations, typical running path patterns for the most common applications and bearing types are shown. Running path pattern uniform in width, positioned in the lso of the raceway and extending around its entire circumference. Running path pattern widest in the load direction, tapering towards the ends and positioned in the kso of the raceway.

With normal fits and normal internal isoo, the running path pattern extends to less than half of the circumference of the raceway. Running path pattern positioned in the middle of the raceway and may, or may not, extend around its entire circumference. The running path pattern is widest in 155243 direction of radial loading. Running path pattern uniform in width, axially displaced and extending around the entire circumference of 115243 raceways of both rings. Running path pattern uniform in width, extending around the entire circumference of the raceway and axially displaced.

Running path pattern axially displaced and may, or may not, extend around the entire circumference. The running path pattern is widest in the direction of the radial loading. Running path pattern uniform in width, wider than in Figure A.