1、BS ISO7146-1:2008ICS 21.100.10NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDPlain bearings Appearance andcharacterization ofdamage to metallichydrodynamicbearingsPart 1: GeneralThis British Standardwas published under theauthority of the StandardsPolicy and St
2、rategyCommittee on 31 October2008 BSI 2008ISBN 978 0 580 56413 0Amendments/corrigenda issued since publicationDate CommentsBS ISO 7146-1:2008National forewordThis British Standard is the UK implementation of ISO 7146-1:2008.The UK participation in its preparation was entrusted to TechnicalCommittee
3、MCE/12, Plain bearings.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application.Compliance with a British Standard cannot
4、confer immunityfrom legal obligations.BS ISO 7146-1:2008Reference numberISO 7146-1:2008(E)ISO 2008INTERNATIONAL STANDARD ISO7146-1First edition2008-10-15Plain bearings Appearance and characterization of damage to metallic hydrodynamic bearings Part 1: General Paliers lisses Aspect et caractrisation
5、de lendommagement des paliers mtalliques couche lubrifiante fluide Partie 1: Gnralits BS ISO 7146-1:2008ISO 7146-1:2008(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the ty
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10、eb www.iso.org Published in Switzerland ii ISO 2008 All rights reservedBS ISO 7146-1:2008ISO 7146-1:2008(E) ISO 2008 All rights reserved iiiContents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 1 4 Descriptions, causes, and features of damage . 2 4.
11、1 Damage 2 4.2 Damage causes. 2 4.3 Damage appearances. 2 4.4 Damage characterization . 3 4.5 Relationship between damage appearance and damage characterizations 3 5 Guidelines for damage analysis 5 5.1 General. 6 5.2 Step 1 . 6 5.3 Step 2 . 6 5.4 Step 3 . 6 5.5 Step 4 . 6 5.6 Step 5 . 6 6 Damage to
12、 the bearing surface damage characteristics, typical damage appearances and possible damage causes 7 6.1 General. 7 6.2 Static overload 7 6.3 Dynamic overload. 8 6.4 Wear by friction. 15 6.5 Overheating . 18 6.6 Insufficient lubrication (starvation). 20 6.7 Contamination. 25 6.8 Cavitation erosion.
13、36 6.9 Electro-erosion 38 6.10 Hydrogen diffusion. 39 6.11 Bond failure . 41 7 Damage to the bearing back 42 7.1 General. 42 7.2 Dynamic overload on the bearing back42 7.3 Wear by friction on the bearing back 44 7.4 Contamination with particles on the bearing back . 46 8 Special position of damage a
14、ppearances 47 Annex A (informative) Example of use of Table 1. 50 BS ISO 7146-1:2008ISO 7146-1:2008(E) iv ISO 2008 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing In
15、ternational 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
16、with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of techn
17、ical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn
18、 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. ISO 7146-1 was prepared by Technical Committee ISO/TC 123, Plain bearings, Subcommittee SC 2, Materials and lubricants,
19、 their properties, characteristics, test methods and testing conditions. This first edition of ISO 7146-1, together with ISO 7146-2, cancels and replaces ISO 7146:1993 the technical content of which has been technically revised and augmented. ISO 7146 consists of the following parts, under the gener
20、al title Plain bearings Appearance and characterization of damage to metallic hydrodynamic bearings: Part 1: General Part 2: Cavitation erosion and its countermeasures BS ISO 7146-1:2008ISO 7146-1:2008(E) ISO 2008 All rights reserved vIntroduction In practice, damage to a bearing may often be the re
21、sult of several mechanisms operating simultaneously. It is the complex combination of design, manufacture, assembly, operation, maintenance, and possible reconditioning which often causes difficulty in establishing the primary cause of damage. In the event of extensive damage or destruction of the b
22、earing, the evidence is likely to be lost, and it will then be impossible to identify how the damage came about. 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 damage established in thi
23、s part of ISO 7146 is based primarily upon the features visible on the running surfaces and elsewhere, and consideration of each aspect is required for reliable determination of the cause of bearing damage. Since more than one process may cause similar effects on the running surface, a description o
24、f appearance alone is occasionally inadequate in determining the cause of damage. Thus Clause 4 is subdivided into several subclauses including damage appearance and damage characteristics. For the procedure of damage analysis, Clause 5 may give a helpful guide. In Clauses 6 and 7, examples of all d
25、amage characteristics with typically associated damage appearance are given. BS ISO 7146-1:2008BS ISO 7146-1:2008INTERNATIONAL STANDARD ISO 7146-1:2008(E) ISO 2008 All rights reserved 1Plain bearings Appearance and characterization of damage to metallic hydrodynamic bearings Part 1: General 1 Scope
26、This part of ISO 7146 defines, describes and classifies the characteristics of damage occurring in service to hydrodynamically lubricated metallic plain bearings and journals. It assists in the understanding of the various characteristic forms of damage which may occur. Consideration is restricted t
27、o damage characteristics which have a well-defined appearance and which can be attributed to particular damage causes with a high degree of certainty. Various appearances are illustrated with photographs and diagrams. 2 Normative references The following referenced documents are indispensable for th
28、e application 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 4378-1, Plain bearings Terms, definitions, classification and symbols Part 1: Design, bearing materials
29、and their properties ISO 4378-2, Plain bearings Terms, definitions, classification and symbols Part 2: Friction and wear ISO 4378-3, Plain bearings Terms, definitions, classification and symbols Part 3: Lubrication ISO 4378-4, Plain bearings Terms, definitions, classification and symbols Part 4: Bas
30、ic symbols ISO 7146-2, Plain bearings Appearance and characterization of damage to metallic hydrodynamic bearings Part 2: Cavitation erosion and its countermeasures 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 4378-1, ISO 4378-2, ISO 4378-3, ISO 4
31、378-4 and the following apply. 3.1 damage to plain bearings bearing damage all changes in appearance occurring on the bearing surface and/or on the bearing back during operation that adversely affect the performance of the bearing BS ISO 7146-1:2008ISO 7146-1:2008(E) 2 ISO 2008 All rights reserved4
32、Descriptions, causes, and features of damage 4.1 Damage 4.1.1 General Damage to plain bearings is a phenomenon that adversely changes their tribological function, usually accompanied with a change in appearance. The damage is initiated by the damage cause and develops to the end of service life. As
33、long as no abnormal conditions occur, service life of the plain bearing relates to the service life of the machine. 4.1.2 Indicators of damage Typical indicators observed during machine operation are: continuously increasing service temperature, decline of lubricant pressure, noise, vibration, and b
34、ad smell. 4.2 Damage causes The cause is the practical event that initiates and leads to damage. The majority of damage causes will be found outside the bearing. 4.3 Damage appearances Damage appearance is a defined visible picture of the bearing surface and/or of the bearing back. Damage appearance
35、s are clearly different from each other. A plain bearing failure can show various damage appearances. Usually damage appearances are directly associated with damage characteristics, but not directly with the damage cause (for exceptions, see 6.8 and 6.9). List of damage appearances: a) depositions;
36、b) creep deformation; c) deformation due to temperature cycles; d) thermal cracks; e) fatigue cracks; f) material relief (loss of bond); g) frictional corrosion; h) melting out, seizure; i) polishing, scoring; j) traces of mixed lubrication, worn material; k) blue, black colour; l) corrosion, fluid
37、erosion; m) embedded particles, particle-migration tracks, formation of wire wool; n) electric arc craters; o) cavitation erosion appearance: worn-out material. BS ISO 7146-1:2008ISO 7146-1:2008(E) ISO 2008 All rights reserved 34.4 Damage characterization 4.4.1 General. A damage characterization is
38、a description of what has happened based on a detected typical combination of damage appearances. Defined characteristics provide the basis for establishing the cause of damage. Damage characterizations are clearly different from each other, as specified in 4.4.2 to 4.4.11. 4.4.2 Static overload: ma
39、terial is loaded above compressive yield strength corresponding to actual operation temperature. 4.4.3 Dynamic overload: material is loaded above fatigue strength corresponding to actual operation temperature. Intensive dynamic load also favours damage by weakening the fit. 4.4.4 Wear by friction: w
40、ear by friction is confined to changes in microgeometry and to the loss of material as a result of interaction between journal and bearing. Movement between backing and housing also favours wear by friction. 4.4.5 Overheating: the heat balance in the lubricant, the bearing, the environment, and the
41、cooling system as required at design stage is not realized resulting in a higher temperature than anticipated. The viscosity and, therefore, the load capacity decrease with increasing temperature. This results again in temperature increase. The bearing, therefore, cannot operate stably if cooling ca
42、nnot stop further temperature increase. 4.4.6 Insufficient lubrication (starvation): affecting the tribological system. 4.4.7 Contamination of lubricant with foreign particles or reaction products can result in damage to a bearing. Foreign particles embedded between bearing backing and housing also
43、favour damage. 4.4.8 Cavitation erosion: decreased pressure in liquids leads to evaporation of liquids and formation of vapour bubbles, which, when liquid pressure increases, implode, generating locally very high pressure, and cause erosion on sliding surfaces. 4.4.9 Electroerosion: a potential diff
44、erence between journal and bearing can lead to an electric arc with locally high current flow which damages journal and bearing surface. 4.4.10 Hydrogen diffusion: hydrogen may be incorporated in the steel backing or in an electroplated layer of the bearing. If hydrogen diffusion is blocked by a lay
45、er, blisters will occur. 4.4.11 Bond failure: delamination between lining and backing or between layers. A metallographic examination is required to distinguish from other damage characterizations. 4.5 Relationship between damage appearance and damage characterizations Damage characterization and da
46、mage appearance alter with the progress of damage from a primary to a secondary characteristic (see Figure 1). Different damage characterizations can correspond to the same damage appearance. One damage characterization can correspond to various damage appearances. Multiple damage characteristics ca
47、n be found in one failure event. The damage characteristics provide the basis for analysing the cause (see Figure 2). Typical relationships are shown in Table 1 for damage to sliding surface and to bearing back. In most cases, Table 1 is the guideline for diagnosis of the final damage cause from the
48、 damage appearances via the damage characteristics. BS ISO 7146-1:2008ISO 7146-1:2008(E) 4 ISO 2008 All rights reservedFigure 1 Damage appearances alter with the progress from primary to secondary characteristics aDamage cause. bDamage characteristics. cDamage appearances. Figure 2 Damage characteri
49、stics provide the basis for analysing the cause BS ISO 7146-1:2008ISO 7146-1:2008(E) ISO 2008 All rights reserved 55 Guidelines for damage analysis Table 1 Interaction of damage appearances and damage characterizations Damage appearance Damage characterizations SubclauseDepositionsCreep deformation Deformationsdue totemperature cyclesThermalcracksFatigue cracksMaterialrelief(lossofbond) Frictionalcorrosion Meltingout,scoring Polishing,scoring Trace ofmixedlubrication,worn materialBlue,blackcolo
