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1、 Reference number ISO 7146-1:2008(E) ISO 2008 INTERNATIONAL STANDARD ISO 7146-1 First edition 2008-10-15 Plain bearings Appearance and characterization of damage to metallic hydrodynamic bearings Part 1: General Paliers lisses Aspect et caractrisation de lendommagement des paliers mtalliques couche
2、lubrifiante fluide Partie 1: Gnralits Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Boeing Co/5910770001 Not for Resale, 01/29/2009 19:15:43 MSTNo reproduction or networking permitted without license from IHS -,-,- ISO 7146-1:2008(E) PDF dis
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6、TECTED DOCUMENT ISO 2008 All rights reserved. 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 ISOs
7、member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2008 All rights reserved Copyright International Organization for Standardization P
8、rovided by IHS under license with ISO Licensee=Boeing Co/5910770001 Not for Resale, 01/29/2009 19:15:43 MSTNo reproduction or networking permitted without license from IHS -,-,- ISO 7146-1:2008(E) ISO 2008 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative refer
9、ences. 1 3 Terms and definitions. 1 4 Descriptions, 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.
10、 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 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
11、Insufficient lubrication (starvation). 20 6.7 Contamination. 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 back 42 7.3 Wear by friction on the bearing back 44
12、7.4 Contamination with particles on the bearing back . 46 8 Special position of damage appearances 47 Annex A (informative) Example of use of Table 1. 50 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Boeing Co/5910770001 Not for Resale, 01/2
13、9/2009 19:15:43 MSTNo reproduction or networking permitted without license from IHS -,-,- ISO 7146-1:2008(E) iv ISO 2008 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of prepa
14、ring 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 l
15、iaison 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 o
16、f 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 bodies casting a vote. Attention i
17、s 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, Subcommittee SC 2, Materials and lubr
18、icants, 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 th
19、e general title Plain bearings Appearance and characterization of damage to metallic hydrodynamic bearings: Part 1: General Part 2: Cavitation erosion and its countermeasures Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Boeing Co/5910770001
20、 Not for Resale, 01/29/2009 19:15:43 MSTNo reproduction or networking permitted without license from IHS -,-,- ISO 7146-1:2008(E) ISO 2008 All rights reserved v Introduction In practice, damage to a bearing may often be the result of several mechanisms operating simultaneously. It is the complex com
21、bination 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 bearing, the evidence is likely to be lost, and it will then be impossible
22、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 this part of ISO 7146 is based primarily upon the features visible on the run
23、ning 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 of appearance alone is occasionally inadequate in determining the cause of
24、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 damage characteristics with typically associated damage appearance are give
25、n. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Boeing Co/5910770001 Not for Resale, 01/29/2009 19:15:43 MSTNo reproduction or networking permitted without license from IHS -,-,- Copyright International Organization for Standardization Prov
26、ided by IHS under license with ISO Licensee=Boeing Co/5910770001 Not for Resale, 01/29/2009 19:15:43 MSTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD ISO 7146-1:2008(E) ISO 2008 All rights reserved 1 Plain bearings Appearance and characterization of da
27、mage to metallic hydrodynamic 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
28、 forms of damage which 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 referen
29、ces The following referenced 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
30、, classification and 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 bear
31、ings Terms, definitions, 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
32、 definitions given in 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 Copyri
33、ght International Organization for Standardization Provided by IHS under license with ISO Licensee=Boeing Co/5910770001 Not for Resale, 01/29/2009 19:15:43 MSTNo reproduction or networking permitted without license from IHS -,-,- ISO 7146-1:2008(E) 2 ISO 2008 All rights reserved 4 Descriptions, caus
34、es, 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 long as no abnorma
35、l 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 bad smell. 4.2 Dama
36、ge 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 appearances are clearly diff
37、erent 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; b) creep deformati
38、on; 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 erosion; m) embedd
39、ed particles, particle-migration tracks, formation of wire wool; n) electric arc craters; o) cavitation erosion appearance: worn-out material. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Boeing Co/5910770001 Not for Resale, 01/29/2009 19:1
40、5:43 MSTNo reproduction or networking permitted without license from IHS -,-,- ISO 7146-1:2008(E) ISO 2008 All rights reserved 3 4.4 Damage characterization 4.4.1 General. A damage characterization is a description of what has happened based on a detected typical combination of damage appearances. D
41、efined 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: material is loaded above compressive yield strength corresponding to actual operation temperature. 4.
42、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: wear by friction is confined to changes in microgeometry and to the loss of material as a result of
43、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 cooling system as required at design stage is not realized resulting in a higher temperature than a
44、nticipated. 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 cannot stop further temperature increase. 4.4.6 Insufficient lubrication (starvation): affecting the
45、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 favour damage. 4.4.8 Cavitation erosion: decreased pressure in liquids leads to evaporation of liqu
46、ids 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 difference between journal and bearing can lead to an electric arc with locally high current flow which
47、 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 layer, blisters will occur. 4.4.11 Bond failure: delamination between lining and backing or between la
48、yers. A metallographic examination is required to distinguish from other damage characterizations. 4.5 Relationship between damage appearance and damage characterizations 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 appeara