DOCSLIB.ORG

Effect of Surface Traction and Non-Metallic Inclusions on the Premature Failure of Wind Turbine Gearbox Bearings

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Effect of Surface Traction and Non-Metallic Inclusions on the Premature Failure of Wind Turbine Gearbox Bearings Department of Mechanical Engineering Effect of Surface Traction and Non-Metallic Inclusions on the Premature Failure of Wind Turbine Gearbox Bearings Author: Hamza Abdulrasool Al-Tameemi Registration No: 130249562 December 2017 Supervisors: Dr. Hui Long Prof. Rob Dwyer-Joyce Thesis submitted to the Department of Mechanical Engineering, University of Sheffield in partial fulfilment of the requirements for the degree of Doctor of Philosophy Abstract Abstract The reliability of offshore Wind Turbine (WT) operation has been affected by costly maintenance and replacement of critical mechanical components such as bearings in the gearbox which often fail prematurely much earlier than the designed life-time of 20~25 years. It has been observed that irregular microstructural changes known as the White Etching Area (WEA), which could appear as butterfly wings, and the cracks associated with it, termed as White Etching Cracks (WECs), are present in most of the prematurely failed WT bearings. Currently no agreed theories regarding their causes and failure mechanisms, nor an effective solution have been established. In this research, two failed planetary bearings from WT gearboxes were destructively investigated to develop an in-depth understanding on the characteristics of the irregular microstructural changes and damages initiated from defects such as non-metallic Inclusions. One of the investigated bearings had a Black Oxide (BO) coating. The characterisation of the BO coating layer was performed to assess its effectiveness in preventing and delaying the premature WT gearbox bearings failure. To investigate the effect of various tribological parameters on surface and subsurface initiated damage, Rolling Sliding Tests (RSTs) using bearing steel specimens were conducted on a benchtop twin-disc machine. To understand the subsurface initiated damage, the stress distribution around an inclusion was investigated using Finite Element (FE) analysis and the results were correlated to the experimental observations. The investigation of the failed bearings consisted of metallurgical examinations to categorise the key characteristics of surface and subsurface initiated cracks, with a focus on those cracks initiated from non-metallic inclusions. The examinations were conducted using optical microscopy, Scanning Electron Microscope (SEM), Atomic Force Microscopy (AFM) and Energy Dispersive X-ray spectroscopy (EDX). The micro- and Nano-indentation were also used to investigate the mechanical properties of the inclusions, WEA, BO layer and the steel matrix. The RSTs were conducted using the tribometer and rolling contact fatigue testing system (SUROS), the Sheffield University Rolling Sliding twin disc machine; and metallurgical examinations were conducted for the specimens. The FE analysis software ABAQUS was used to model a part of a WT bearing under various loading conditions. The models were 2D with an imbedded Manganese Sulphide inclusion (MnS) of a micro-scale with consideration of the debonding between the inclusion and the steel matrix. It was found that the MnS inclusion was the dominating defect in the uncoated bearing, and those inclusions which are not perfectly bonded to the steel matrix initiated most micro cracks and WEAs. It was also found that the depth of these inclusions from the contact surface was not within the zone of the maximum principal shear stress 휏1(max) which could imply they were affected by surface traction since surface traction and subsurface shear stress are linked. In the BO coated bearing, oxide inclusions initiated most I Abstract of the subsurface microstructural damage. The examination of both bearings in the axial direction showed a direct relationship between the length of initiating inclusions with the total length of WEA (butterfly wings) or micro-cracks. In addition, surface initiated cracks with similar appearance to the WECs were found to propagate to form surface pitting and spalling of the examined bearings, similar features were observed on some of the RSTs specimens with high surface traction. The RST results confirmed that micro-cracks were initiated by the inclusions and by the effects of non-perfect bonding between the inclusion and the steel matrix. These test results also showed the effect of high surface traction at rotation direction reversed. This work also demonstrated the effect of the sequence of applying different loading conditions on the surface and subsurface initiated damage in certain degrees. The FE modelling results showed that surface traction and the non-perfect bonding between inclusion and steel matrix had a significant effect on initiation of localised ratcheting and tensile stress around an inclusion due to high loads as well as loading- unloading cycles after each roller pass. The stress distribution around inclusion tips showed a similar pattern of butterfly wings at certain surface traction direction. This research identified a number of types of microstructural damage in WT gearbox bearings, some of which had not been reported before. The damage observations were correlated with the findings from the completed RSTs, and the FE modelling showed the effect of non-metallic inclusions and surface traction. Another contribution of this research was the characterisation of the BO coating layer based on hardness measurements, showing that premature WT bearing failure still occurred in spite of employing this coating technique currently recommended by manufacturers. II Contents Contents Abstract .................................................................................................................................. I Contents ............................................................................................................................... III List of Tables .........................................................................................................................VI List of Figures .......................................................................................................................VII Publications and Presentations ....................................................................................... XVIII Acknowledgments .............................................................................................................. XIX Abbreviations ....................................................................................................................... XX Nomenclature .................................................................................................................... XXII 1 Introduction.................................................................................................................... 1 1.1 Background ............................................................................................................. 1 1.2 Aims and Objectives ................................................................................................ 2 1.3 Thesis Outlines ........................................................................................................ 3 1.4 Contributions to Knowledge ................................................................................... 5 2 Literature review ............................................................................................................ 7 2.1 Failure of Wind Turbine Gearbox Bearings ............................................................. 7 2.1.1 Bearings Failure Modes ................................................................................... 7 2.1.2 Normal and Tangential Loading on WTGBs ..................................................... 9 2.1.3 RCF Cracks and Shakedown ........................................................................... 12 2.1.4 WECs and WEAs Characterization and Initiation .......................................... 13 2.1.5 Steel Cleanliness and Butterflies ................................................................... 16 2.1.6 Bearing Life Assessment ................................................................................ 19 2.2 Experimental Investigation of Bearing Failure...................................................... 20 2.3 Black Oxide Coating and Other Surface Treatment .............................................. 22 2.4 Tribological and Stress Analysis in Rolling Contact Fatigue .................................. 24 2.4.1 Bearing Load Calculations.............................................................................. 24 2.4.2 Hertzian Contact Pressure ............................................................................. 25 2.4.3 Elasto-hydrodynamic Lubrication Theory (EHL) ............................................ 26 2.4.4 Subsurface Stress Analysis ............................................................................. 29 2.5 Modelling of Inclusions Initiated Damage ............................................................ 31 2.6 Identification of Current Research Gaps .............................................................. 33 2.7 Summary ............................................................................................................... 34 III Contents 3 Destructive Investigation on the Failed Bearings ........................................................ 36 3.1 Investigated Bearings ............................................................................................ 36 3.2 Sample Preparation for Subsurface Metallography ............................................. 39 3.2.1 Sectioning
Load more

Recommended publications
  • काय-योजना Programme of Work उ पादन एवं सामा य इंजीिनय रंग वभ P
    काय-योजना (01अगत 2013) PROGRAMME OF WORK (As on 01 August 2013) PG 14 PG 13 PG 28 PG 33 PG 15 PG 23 PG 34 PG 25 PG 18 उपादन एवं सामाय इंजीिनयरंग वभाग (पी.जी.ड) Production & General Engineering Department(PGD) BUREAU OF INDIAN STA NDARDS MANAK BHWAN, 9 BAHADUR SHAH ZAFAR MARG New Delhi – 110002 1 P R E F A C E A Programme of Work is prepared every year for each Division of Bureau of Indian Standards to indicate the latest position of published Indian Standards and draft standards at different stages of processing. The Programme of Work for Production and General Engineering Division Council (PGDC) has been prepared Sectional Committee-wise as on 01 April 2013 and arranged in the sequential order of the Committee numbers. The present scope of Production and General Engineering Division Council (PGDC) is as under: “Production engineering and general engineering such as engineering drawings, screw threads, fasteners, transmission devices, weights and measures, engineering metrology, ergonomics, bearings and tribology, gears, horology, machine tools, hand tools, cutting tools, pneumatic tools, fluid power systems, meteorological instruments, mountaineering equipment, arms & ammunition for civilian use, automation in manufacturing and robotics and consumer products & allied equipment.” In the Programme of Work, an asterisk mark (*) given before a printed standard indicates that the standard is under revision and its relevant document is available at different stages of processing; whereas, double asterisk mark (**) indicates standard identified for revision for which document is yet to be prepared. Below the designation of a published standard, wherever ‘/ISO/IEC…..’ standard number is given , it implies that the Indian Standard is the total adoption of ISO/IEC standard under dual numbering scheme (The designations such as IS/ISO 9001:2000 also indicate dual number standards).
    [Show full text]
  • Though There Are Some Standards Listed Below Available for Free, Many of the Documents in This List Are Addenda, Erratum Or Corrigenda
    Though there are some standards listed below available for free, many of the documents in this list are addenda, erratum or corrigenda. Title Abstract AAMI Standards Program National and Internation NONE Guidance for ANSI/AAMI/ISO 11607, Packaging for terminally sterilized medic Amendment 1 to ANSI/AAMI EC53:1995, AmericanNONE N Enteral feeding set adapters and connectors Specifies safety requireme Erratum- Active implantable medical devices - Electromagnetic compatibility - Underground dielectric optical fiber cable [T Especifica os requisitos m Educational Information About Carbon Monoxide This technical information Certified Ratings Program - Product Rating Manual The program applies to aco Certified Ratings Program Operating Manual (Rev. The purpose of the AMCA In Laboratory Accreditation Program The purpose of the AMCA La Certified Ratings Program - Product Rating ManualThe purpose of this manual Certified Ratings Program - Product Rating Man The purpose of the program Certified Ratings Program - Product Rating Manua The purpose of this manual Certified Ratings Program - Product Rating ManualThis publication is an exte The Financial Impact of Cyber Security - Questio <p><i>The Financial Impac The Financial Management of Cyber Risk: An Imp <p><i> The Financial Mana IDSP Workshop Report: Identity Verification Identity Verification, a wo IDSP Workshop Report: Measuring Identity Theft Measuring Identity Theft, Forced-Circulation Air-Cooling and Air-Heating Coils - Addendum 1 Erratum - American National Standard Technical InfNONE Technical
    [Show full text]
  • Service Contract (Lecom029)
    SERVICE CONTRACT (LECOM029) APPENDIX A TO STATEMENT OF WORK (SOW) DES LE PfMO PEng Eng - Technical Publications Portfolio Review As At 11 June 2014 11 June 2014 DES LE PfMO PEng Eng - Technical Publications Portfolio Review Summary This review covers 96 publications from the DES LE PEng Eng Technical Publications Portfolio. All of the standards were reviewed by experts in the various fields covered across the 96 documents. The documents’ content, spelling & grammar as well as the currency of any other standards, organisations or materiel referred to, were all taken into account during the reviews. In a few cases, the need for the document at all was questioned, these were: • AESP 0200-A-201-013 – Welding Cutting and Brazing • AESP 0200-A-207-013 – Wet Abrasive Cleaning Process • AESP 0200-A-210-013 – Repair of Threaded Holes by Insert • AESP 0200-A-232-013 – Timber Selection, Preservation and Finishing • AESP 0200-A-237-013 – Fibre Optic Technology • AESP 2610-A-409-8 Pneumatic Tyres and Tubes Associated Road Wheels • Def Stan 34-1 – Flux, Soldering (Zinc Chloride Solution) • Def Stan 68-199 – Windscreen Wash Liquid Concentrate It is recommended that the usage and necessity for these documents is investigated Additionally, it is noted that all Def Stans feature the following preliminary paragraph: “3.3 In consideration of clause 3.2 above, users shall be fully aware of the issue and amendment status of all normative references, particularly when forming part of an Invitation to Tender or contract. Responsibility for the correct application of standards rests with users.” This could be overcome by not making specific reference to issue levels and years of release in the main body of the document.
    [Show full text]
  • Ciuacademiccatalog2014-2015.Pdf
    Published by the Office of the University Registrar April 1, 2014 Columbia International University admits students of any race, color, national, and ethnic origin │to all the rights, privileges, programs, and activities generally accorded or made available to students at the school. The university does not discriminate on the basis of race, color, national, and ethnic origin in administration of its educational policies, scholarship and loan programs, athletic, and other school-administered programs. The course offerings and requirements of the university are continually under examination and revision. This catalog is not a contract. Individual Columbia International University colleges reserve the right to change curricula and requirements at any time. This catalog reflects the academic programs and policies for students entering during the 2014-2015 academic year. While requirements may be changed, this document serves as the institution’s statement of intent and is monitored by accrediting and governmental agencies for compliance and integrity. 2 COLUMBIA INTERNATIONAL UNIVERSITY INTRODUCTION │ Dear Prospective Student, In 1987, I enrolled as a student at Columbia International University because I shared the university’s heart for reaching the nations with the message of Jesus Christ. During my student years, I came to know and appreciate CIU’s five core values: the Authority of Scripture, World Evangelization, Prayer and Faith, Victorious Christian Living, and Evangelical Unity. These core values shape and define CIU because they represent our purpose and passion. Today, as in 1987, CIU continues its mission of training professional ministers and ministering professionals to impact the world with the message of Christ. Our programs of study are designed to equip you in the academic area or profession of your choice and to provide you with a strong foundation in God’s Word and His truth.
    [Show full text]
  • ISO Update Supplement to Isofocus
    ISO Update Supplement to ISOfocus February 2021 International Standards in process TC 34 Food products ISO/CD 24583 Quantitative nuclear magnetic resonance spec- An International Standard is the result of an agreement between troscopy — Purity determination of organic the member bodies of ISO. A first important step towards an Interna- compounds used for foods and food products tional Standard takes the form of a committee draft (CD) - this is cir- — General requirements culated for study within an ISO technical committee. When consensus ISO/CD 27971 Cereals and cereal products — Common has been reached within the technical committee, the document is wheat (Triticum aestivum L.) — Determination sent to the Central Secretariat for processing as a draft International of alveograph properties of dough at constant Standard (DIS). The DIS requires approval by at least 75 % of the hydration from commercial or test flours and member bodies casting a vote. A confirmation vote is subsequently test milling methodology carried out on a final draft International Standard (FDIS), the approval criteria remaining the same. ISO/CD Horizontal methods for molecular biomarker 16577.2 analysis — Terminology for molecular bio- marker analytical methods in agriculture and food production ISO/CD Molecular biomarker analysis — isothermal 22942-1.2 polymerase chain reaction (isoPCR) methods — Part 1: General requirements TC 35 Paints and varnishes ISO/CD 8504-4 Preparation of steel substrates before applica- CD registered tion of paints and related products — Surface preparation methods — Part 4: Acid pickling TC 37 Language and terminology Period from 01 January to 01 February 2021 ISO/CD Management of terminology resources — Data These documents are currently under consideration in the technical 12620-1 categories — Part 1: Specifications committee.
    [Show full text]
  • Universidade Candido Mendes Instituto a Vez Do Mestre Pós-Graduação “Lato Sensu”
    1 UNIVERSIDADE CANDIDO MENDES Wi INSTITUTO A VEZ DO MESTRE PÓS-GRADUAÇÃO “LATO SENSU” O DESENVOLVIMENTO E A EVOLUÇÃO DO CONTROLE ESTATÍSTICO DE QUALIDADE E SUA APLICAÇÃO NAS ÁREAS DE PRODUÇÃO DE BENS DE CAPITAL E SERVIÇOS O PANORAMA BRASILEIRO Carlos Alberto Gonçalves Alfredo ORIENTADORA: Profª. Ana Paula Ribeiro Rio de Janeiro 2010 2 UNIVERSIDADE CANDIDO MENDES INSTITUTO A VEZ DO MESTRE PÓS-GRADUAÇÃO “LATO SENSU” O DESENVOLVIMENTO E A EVOLUÇÃO DO CONTROLE ESTATÍSTICO DE QUALIDADE E A SUA APLICAÇÃO NAS DE PRODUÇÃO DE BENS DE CAPITAL E SERVIÇOS O PANORAMA BRASILEIRO Carlos Alberto Gonçalves Alfredo Apresentação de monografia ao Conjunto Universitário Candido Mendes como condição prévia para a conclusão do Curso de Pós-Graduação Lato Sensu em Administração da Qualidade. Rio de Janeiro 2010 3 AGRADECIMENTOS Agradeço aos meus pais que, com a sua dedicação, amor e carinho me conduziram na edificação da minha personalidade, permitindo-me chegar até aqui. A minha esposa Kylma e aos meus filhos, Daniel, Davi, Nathália e Mere, pelo amor e incentivos recebidos durante a minha caminhada. Aos meus amigos, Wagner, Dr. Luiz de Rose e Padre Marcos William pela sua presença sempre amiga e presente, incentivo e apoio. A todos muito obrigado. 4 DEDICATÓRIA Dedico este trabalho ao amor de Deus, sem o qual nada poderia ser realizado. “Tomou então Samuel uma pedra e a pôs entre Mispa e Sem, e lhe chamou Ebenézer, e disse: até aqui nos ajudou o Senhor” (I Samuel, 7:12). 5 RESUMO O Controle Estatístico de Qualidade – CEQ é formado por um conjunto de atividades semelhantes entre si, abrangendo: Estudos de capacitação de processos, Inspeção por amostragem e estudos experimentais.
    [Show full text]
  • Spring 2009 Semester at College of San Mateo, One of the Most Highly-Respected Community Colleges in the State
    Message from the President I want to personally welcome you to the Spring 2009 semester at College of San Mateo, one of the most highly-respected community colleges in the State. You’ll find an exciting semester ahead. As a student at CSM, you will be joining a long tradi- tion of excellence. Since 1922, CSM has served many generations from San Mateo County and the wider San Francisco Bay Area, helping students build their futures. Whether a first-time college student, a continuing student, or one who is returning to college after several years, you have a place at CSM. I am proud of our distinguished and dedicated faculty, some of whom are featured in the first section of our spring Schedule of Classes. These brief bios will give you a sense of the education, accom- plishments and interests of our faculty. To put faces with our other outstanding faculty members, please visit collegeofsanmateo.edu/faculty. Thanks to the voters of San Mateo County we have been able to make a number of sig- nificant capital improvements to the college. CSM’s award-winning Science Building and Planetarium and the Regional Public Safety Center are examples of recently completed construction projects. You will also notice that construction is underway on a new Allied Health and Wellness Center, including an aquatic facility, and we will soon break ground for the construction of the new Student Center. These projects will be completed in 2010 and College of San Mateo 2011, respectively. 1700 West Hillsdale Boulevard During the construction phase, we are committed to making the student experience as San Mateo, CA 94402-3784 positive as possible.
    [Show full text]
  • List of ISO Standards - Wikipedia, the Free Encyclopedia
    List of ISO standards - Wikipedia, the free encyclopedia Log in / create account Wikipedia: Making Life Easier. [Collapse] Article Discussion Edit this page History $3,376,364 Our Goal: $6 million Donate Now » List of ISO standards Navigation From Wikipedia, the free encyclopedia ● Main page ● Contents This is a list of ISO standards that are discussed in Wikipedia articles. For a list of all the more than 16,000 ISO standards (as of ● Featured content 2007), see the ISO Catalogue. ● Current events About 300 of the standards produced by ISO and IEC's Joint Technical Committee 1 (JTC1) have been made freely/publicly ● Random article [ ] available. 1 Search Contents [hide] ● 1 ISO 1–ISO 999 Interaction ● 2 ISO 1000–ISO 9999 ● About Wikipedia ● 3 ISO 10000–ISO ● Community portal 19999 ● Recent changes ● 4 ISO 20000–ISO ● Contact Wikipedia 29999 ● Donate to Wikipedia ● 5 ISO 30000–ISO ● Help 39999 Toolbox ● 6 Other standards ● What links here ● 7 See also ● Related changes ● 8 References ● Upload file ● 9 External links http://en.wikipedia.org/wiki/List_of_ISO_standards (1 of 20)05/12/2008 10:36:09 • List of ISO standards - Wikipedia, the free encyclopedia ● Special pages ● Printable version ISO 1–ISO 999 [edit] ● Permanent link ● ISO 1 Standard reference temperature for geometrical product specification and verification ● Cite this page ● ISO 3 Preferred numbers Languages ● ISO 4 Rules for the abbreviation of title words and titles of publications ● Deutsch ● ISO 7 Pipe threads where pressure-tight joints are made on the threads ● Español ● ISO 9 Information and documentation — Transliteration of Cyrillic characters into Roman characters — Slavic and non-Slavic ● ••••• languages ● Français ● ● •••••• ISO 16:1975 Acoustics — Standard tuning frequency (Standard musical pitch) ● Íslenska ● ISO 31 Quantities and units ● Italiano ● ISO 68-1 Basic profile of metric screw threads ● Nederlands ● ISO 216 paper sizes, e.g.
    [Show full text]
  • Merlin Partner User Guide
    Merlin Partner User Guide Merlin - Version 1.18 Enterprise Europe Network 2 Merlin User Guide - updated 28 April 2015 Table of contents 1. Introduction 9 About Merlin 9 About this guide 9 Accessing Merlin 10 Merlin Logout 10 Browser Optimisation 11 What if I need help? 11 Icon Legend 11 Navigating Merlin 12 Exporting your Content 13 The Dashboards 13 Using the Filters 15 Clear Filters 16 Working with Technology, Market and NACE Keywords 17 When should I use different levels of keywords? 17 How do I select keywords in Merlin? 18 Where can I find a current list of Technology, Market and NACE keywords? 18 Who to Contact 18 Feedback 19 2. Change History 21 New features 21 Changes that impact your work 21 Features under development 21 3. Managing Profiles 23 Profile Workflow Overview 23 Profile creation 24 Internal Review Process 24 External Review Process 24 Blocking Scores 25 Enterprise Europe Network Profile expiry date 25 My Profiles Dashboard 25 Create a new profile 27 Review a profile 29 Edit a Draft profile 32 My Expired Profiles Dashboard 32 Modifying profile deadlines 33 Delete a profile 34 Archive a profile 35 Change your external reviewer status 35 Update your external reviewer information 36 Resign as an external reviewer 37 Reassign Profiles 38 4. Disseminating Profiles 39 Profile Search - Intranet 39 Intranet Simple Search 39 Intranet Advanced Search 40 Profile Search - Internet 43 Export Profiles 43 Export a Single Profile 43 Export All Profiles From Search Results 45 Merlin POD Web Service 45 5. Managing Clients and Queries
    [Show full text]
  • Handbook on Traceability in Legal Metrology
    Asia-Pacific Legal Metrology Forum Committee on Trade and Investment Sub-Committee on Standards and Conformance Handbook on Traceability in Legal Metrology March 2004 APEC Project CTI 25/2003T APLMF Symposium on Traceability in Legal Metrology Prepared by: Secretariat Asia-Pacific Legal Metrology Forum NMIJ/AIST Tsukuba Central 3-9 1-1-1 Umezono, Tsukuba, Ibaraki 305-8563, Japan Tel: (81) 29 861 4362 Fax: (81) 29 861 4393 Email: [email protected] Website: www.aplmf.org For: APEC Secretariat 35 Heng Mui Keng Terrace Singapore 119616 Tel: (65) 6775 6012 Fax: (65) 6775 6013 Email: [email protected] Website: www.apec.org © 2004 APEC Secretariat APEC#204-CT-01.4 ISBN 4-9901968-0-5 Contents Page I. Foreword Akira Ooiwa (APLMF President, Japan) 1 II. Opening Address John Birch AM (Former APLMF President, Australia) 3 1. Accreditation and Traceability in Legal Metrology Seta Katuo (NITE, Japan) 5 2. Uncertainty Analysis and Quality Control of Measuring Instruments Akira Ooiwa (NMIJ, Japan) 19 3. Uncertainty in Legal Metrology Jong Oh Choi (KRISS, Republic of Korea) 29 4. Legal Metrology in Toy Testing for Safety Foo-wing Lee, Yiu-chung Yip, and Wai-hong Fung (Government Laboratory, Hong Kong China) 47 5. Traceability of Analytical Measurement in Chemistry and CRMs-related Activities in China Yu Yadong (NRCCRM, People’s Republic of China) 61 6. Mutual Recognition Arrangement by the CIPM for Establishing Global Traceability of Measurement - its Role and Mechanism - Kozo Iizuka (JAMP, Japan) 81 7. Practical Ways in Establishing Traceability in Chemical and Other Measurements Yoshito Mitani (CENAM, Mexico) 93 8.
    [Show full text]
  • Standards News Late May 2013 Volume 17, Number 10 Table of Contents Ofcom Calls for Input on 2400 Mhz Spectrum Use
    PLASA Standards News Late May 2013 Volume 17, Number 10 Table of Contents Ofcom Calls for Input on 2400 MHz Spectrum Use..........................................................................................1 Two PLASA Standards in Public Review..........................................................................................................2 New TSP Project............................................................................................................................................... 2 Proposed ISO Technical Activity on Remanufacturing Mechanical Products....................................................2 FCC Proposed Rulemaking and Requests for Comments................................................................................3 WTO Notifications............................................................................................................................................. 3 ANSI Public Review Announcements...............................................................................................................4 Due 09 June 2013......................................................................................................................................... 4 Due 16 June 2013......................................................................................................................................... 4 Due 23 June 2013......................................................................................................................................... 4 Due 24 June 2013........................................................................................................................................
    [Show full text]