ISO/TR TECHNICAL REPORT 1281-2 First edition 2008-12-01 Rolling bearings Explanatory notes on ISO 281 Part 2: Modified rating life calculation, based on a systems approach to fatigue stresses Roulements — Notes explicatives sur Iiso 281 - Partie2:Calculmodifiedeladureenominaledebasefondesurune approche systeme du travail de fatigue Reference number ISO/TR 1281-2:2008(E) @ ISO 2008 HS under ed without license from IHS Not for Resale ISO/TR 1281-2:2008(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use 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 COPYRIGHTPROTECTEDDOCUMENT @ISO2008 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, IsO's'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 copyright@iso.org Web www.iso.org Published in Switzerland @ ISo 2008 - All rights reserved ed without license from IHS Not for Resale ISO/TR 1281-2:2008(E) Contents Page Foreword. iv Introduction. 1 Scope. 2 Normative references. 3 Symbols ...... 4 4.1 4.2 Derivation of the life modification factor for reliability............................ 5 Background to the life modification factor, aiso ... 5.1 General..... 5.2 The lubrication factor, np ..... 5.3 The contamination factor, ne. ... 5.4 Experimental results.... 14 5.5 Conclusions ... 18 5.6 Practical application of the contamination factor according to Reference [5], Equation. (... ........... 19 5.7 DifferencebetweenthelifemodificationfactorsinReference[5]andiSO281. .26 6 Background to the ranges of Iso 4406[3] cleanliness codes used in ISo 281, Clauses A.4 and A.5...... ..26 6.1 General...... 6.2 On-line filtered oil 28 6.3 Oil bath... 28 6.4 Contamination factor for oil mist lubrication..... 28 7 Influence of wear.. 29 7.1 General definition .. 29 7.2 29 7.3 Mild wear.. 29 7.4 Influence of wear on fatigue life ... 29 7.5 Wear with little influence on fatigue life .... 30 7.6 Adhesive wear....... 8 Influence of a corrosive environment on rolling bearing life 32 8.1 32 8.2 Life reduction by hydrogen .. 8.3 Corrosion..... 34 9 Fatigue load limit of a complete rolling bearing .... 37 9.1 Influence of bearing size.... 9.2 the fatigue load limit for roller bearings.... 39 10 Influence of hoop stress, temperature and particle hardness on bearing life ... 10.1 Hoop stress . .41 10.2 Temperature .... 41 10.3 Hardness of contaminant particles... 41 11 Relationship between xand A.... .42 11.1 The viscosity ratio, K..... 42 11.2 The ratio of oil film thickness to composite surface roughness, A. 42 11.3 Theoretical calculation of A.... 42 Bibliography .46 CopyrightInternatinal Oorganizain forstandardizalirnghts reserved ii ted withoutlicensefromIHS Not for Resale