1、BS ISO 7146-1:2008 ICS 21.100.10 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BRITISH STANDARD Plain bearings Appearance and characterization of damage to metallic hydrodynamic bearings Part 1: GeneralThis British Standard was published under the authority of the Standards
2、Policy and Strategy Committee on 31 October 2008 BSI 2008 ISBN 978 0 580 56413 0 Amendments/corrigenda issued since publication Date Comments BS ISO 7146-1:2008 National foreword This British Standard is the UK implementation of ISO 7146-1:2008. The UK participation in its preparation was entrusted
3、to Technical Committee MCE/12, Plain bearings. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance wit
4、h a British Standard cannot confer immunity from legal obligations.BS ISO 7146-1:2008Reference number ISO 7146-1:2008(E) ISO 2008INTERNATIONAL STANDARD ISO 7146-1 First edition 2008-10-15 Plain bearings Appearance and characterization of damage to metallic hydrodynamic bearings Part 1: General Palie
5、rs lisses Aspect et caractrisation de lendommagement des paliers mtalliques couche lubrifiante fluide Partie 1: Gnralits BS ISO 7146-1:2008 ISO 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 b
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8、se by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. COPYRIGHT PROTECTED DOCUMENT ISO 2008 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in
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10、 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2008 All rights reservedBS ISO 7146-1:2008 ISO 7146-1:2008(E) ISO 2008 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 1 4 Descriptions,
11、 causes, and features of damage . 2 4.1 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
12、 Step 4 . 6 5.6 Step 5 . 6 6 Damage to 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 Cont
13、amination. 25 6.8 Cavitation erosion. 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 ba
14、ck . 46 8 Special position of damage appearances 47 Annex A (informative) Example of use of Table 1. 50 BS ISO 7146-1:2008 ISO 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 m
15、ember 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, governm
16、ental 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. International Standards are drafted in accordance with the rules given in the ISO/IEC Dir
17、ectives, Part 2. 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 for voting. Publication as an International Standard requires approval by at least 75 % of the member bo
18、dies casting a vote. 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. ISO 7146-1 was prepared by Technical Committee ISO/TC 123, Plain bearings, Subco
19、mmittee SC 2, Materials and lubricants, 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
20、of the following parts, under the general title Plain bearings Appearance and characterization of damage to metallic hydrodynamic bearings: Part 1: General Part 2: Cavitation erosion and its countermeasures BS ISO 7146-1:2008 ISO 7146-1:2008(E) ISO 2008 All rights reserved v Introduction In practice
21、, damage to a bearing may often be the result 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
22、 extensive damage or destruction of the bearing, 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 classifica
23、tion of bearing damage established in this 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 effect
24、s on the running surface, a description of 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 gui
25、de. In Clauses 6 and 7, examples of all damage characteristics with typically associated damage appearance are given. BS ISO 7146-1:2008BS ISO 7146-1:2008 INTERNATIONAL STANDARD ISO 7146-1:2008(E) ISO 2008 All rights reserved 1 Plain bearings Appearance and characterization of damage to metallic hyd
26、rodynamic bearings Part 1: General 1 Scope 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 whi
27、ch may occur. Consideration is restricted to 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 re
28、ferenced documents are indispensable for the 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
29、 symbols Part 1: Design, bearing materials 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, definiti
30、ons, classification and symbols Part 4: Basic 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 i
31、n ISO 4378-1, ISO 4378-2, ISO 4378-3, ISO 4378-4 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 7146-1:2008 ISO 714
32、6-1:2008(E) 2 ISO 2008 All rights reserved4 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
33、and develops to the end of service life. As 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
34、 lubricant pressure, noise, vibration, and bad 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 a
35、nd/or of the bearing back. Damage appearances 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).
36、List of damage appearances: a) depositions; 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;
37、 k) blue, black colour; l) corrosion, fluid erosion; m) embedded particles, particle-migration tracks, formation of wire wool; n) electric arc craters; o) cavitation erosion appearance: worn-out material. BS ISO 7146-1:2008 ISO 7146-1:2008(E) ISO 2008 All rights reserved 3 4.4 Damage characterizatio
38、n 4.4.1 General. A damage characterization is 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
39、 in 4.4.2 to 4.4.11. 4.4.2 Static overload: material 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 b
40、y weakening the fit. 4.4.4 Wear by friction: wear 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 lub
41、ricant, the bearing, the environment, and the 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,
42、therefore, cannot operate stably if cooling cannot 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 embe
43、dded between bearing backing and housing also 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 su
44、rfaces. 4.4.9 Electroerosion: a potential difference 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 bear
45、ing. If hydrogen diffusion is blocked by a layer, 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 ch
46、aracterizations Damage characterization and damage 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 a
47、ppearances. Multiple damage characteristics can 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 fo
48、r diagnosis of the final damage cause from the damage appearances via the damage characteristics. BS ISO 7146-1:2008 ISO 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.
49、cDamage appearances. Figure 2 Damage characteristics provide the basis for analysing the cause BS ISO 7146-1:2008 ISO 7146-1:2008(E) ISO 2008 All rights reserved 5 5 Guidelines for damage analysis Table 1 Interaction of damage appearances and damage characterizations Damage appearance Damage characterizations Subclause Depositions Creep deformation Deformations due to temperature cycles Thermal cracks Fatigue cracks Material relief (loss of bond) Frictional corrosion Melting out, scoring Poli
