DOCSLIB.ORG

Guide to Engineering Metrology

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

Guide to Engineering Metrology Carl Hitchens MSc. CEng FIMechE Technical contributions: S. Cavill, R. Smalley and P. Hulme Version 4 TABLE OF CONTENTS Introduction.............................................................................................................................................. 3 Dimensional Metrology ............................................................................................................................ 4 SI units, the international system ............................................................................................................ 5 The 10% Rule ......................................................................................................................................... 7 Hand Tools .............................................................................................................................................. 8 Abbe’s Principle .................................................................................................................................... 11 Accuracy and Precision ......................................................................................................................... 12 Measurement Process .......................................................................................................................... 13 Calibration ............................................................................................................................................. 16 Traceability ............................................................................................................................................ 17 Design for Inspection ............................................................................................................................ 18 Measurement Strategy .......................................................................................................................... 20 Measurement System Analysis ............................................................................................................. 21 Uncertainty ............................................................................................................................................ 29 Introduction to GD&T (Geometric Dimensioning and Tolerancing) ...................................................... 32 Variations of Form Rule #1: Envelope Principle Taylor Principle ............................................................. 33 Material Condition Modifiers ................................................................................................................................ 34 Bonus Tolerance ......................................................................................................................................................... 34 Regardless of feature size (RFS).......................................................................................................................... 37 Virtual Condition ........................................................................................................................................................ 37 Datum ............................................................................................................................................................................. 38 Airy and Bessel points ........................................................................................................................... 40 Inspection Methods for GD&T ............................................................................................................... 41 Straightness Feature ................................................................................................................................................. 41 Flatness Feature ......................................................................................................................................................... 44 Circularity (Roundness) Feature ......................................................................................................................... 46 Cylindricity Feature ................................................................................................................................................... 46 Profile of a Line Feature .......................................................................................................................................... 49 Profile of a Surface Feature .................................................................................................................................... 51 Angularity ...................................................................................................................................................................... 52 Perpendicularity ......................................................................................................................................................... 55 Parallelism..................................................................................................................................................................... 58 1 C. Hitchens The contents of this document should not be reprinted or redistributed. Position ..........................................................................................................................................................................60 Concentricity (Coaxiality) Feature ...................................................................................................................... 61 Symmetry ...................................................................................................................................................................... 62 Runout Feature ........................................................................................................................................................... 63 Total Runout Feature ................................................................................................................................................ 63 Inspection Gauges ................................................................................................................................ 66 Threads ................................................................................................................................................. 67 Coordinate Measuring Machine ............................................................................................................ 71 Coordinate Measuring Machines and GD&T .................................................................................................. 75 On-Machine Probing ............................................................................................................................. 77 Large Volume Metrology ....................................................................................................................... 83 Laser Tracker .............................................................................................................................................................. 83 Optical Tracking ......................................................................................................................................................... 85 Auto Collimator, Optical Alignment Telescope and Inclinometer .......................................................... 86 Autocollimator ............................................................................................................................................................ 86 Optical Alignment Telescope ................................................................................................................................. 86 Inclinometer ................................................................................................................................................................. 87 Non-Contact Measurement and Scanning Instruments ........................................................................ 88 Laser Line Scanners and laser strip scanners ................................................................................................88 Structured light .......................................................................................................................................................... 89 Photogrammetry ....................................................................................................................................................... 90 Inspection Process for Scanning Instruments ....................................................................................... 92 Reverse Engineering ............................................................................................................................. 94 Manufacturing Process Capabilities .................................................................................................... 100 Bibliography ........................................................................................................................................ 102 2 C. Hitchens The contents of this document should not be reprinted or redistributed. INTRODUCTION Metrology is the science of measurement and the understanding of a measurements quantity and quality. Quality is shown by providing evidence of traceability and accuracy. Measurements should be repeatable, reproducible and reliable and the engineer making these measurements should have an understanding
Recommended publications
  • Fundamental Good Practice in Dimensional Metrology

    Fundamental Good Practice in Dimensional Metrology

    Good Practice Guide No. 80 Fundamental Good Practice in Dimensional Metrology David Flack and John Hannaford Measurement Good Practice Guide No. 80 Fundamental Good Practice in Dimensional Metrology David Flack Engineering Measurement Services Team Engineering Measurement Division John Hannaford ABSTRACT This good practice guide is written for those who need to make dimensional measurements but are not necessarily trained metrologists. On reading this guide you should have gained a basic knowledge of fundamental good practice when making dimensional measurements. An introduction to length units and key issues such as traceability and uncertainty is followed by some examples of typical sources of error in length measurement. Checking to specification, accreditation and measurement techniques are also covered along with an introduction to optical measurement techniques. © Queen's Printer and Controller of HMSO First printed July 2005 Reprinted with minor corrections/amendments October 2012 ISSN 1368-6550 National Physical Laboratory Hampton Road, Teddington, Middlesex, TW11 0LW Acknowledgements This document has been produced for the Department for Business, Innovation and Skills; National Measurement System under contract number GBBK/C/08/17. Thanks also to Hexagon Metrology, Romer, Renishaw and Faro UK for providing some of the images and to Dr Richard Leach (NPL), Simon Oldfield (NPL), Dr Anthony Gee (University College London) and Prof Derek Chetwynd (University of Warwick) for suggesting improvements to this guide. i Contents Introduction
  • Measuring Long Gage Blocks with the NIST Line Scale Interferometer

    Measuring Long Gage Blocks with the NIST Line Scale Interferometer

    NATL INST. OF STAND & TECH R.I.C. Wm'M. NISI I P!PUBLICATIONS ^ '»,?r'/'; « '!';«> ^, AlllDM t.S7TbM . ed States Department of Commerce Technology Administration National Institute of Standards and Technology NIST Technical Note 1410 Measuring Long Gage Blocl<s With the NIST Line Scale Interferometer John S. Beers 2995 I 7 he National Institute of Standards and Technology was established in 1988 by Congress to "assist industry in the development of technology . needed to improve product quality, to modernize manufacturing processes, to ensure product reliability ... and to facilitate rapid commercialization ... of products based on new scientific discoveries." NIST, originally founded as the National Bureau of Standards in 1901, works to strengthen U.S. industry's competitiveness; advance science and engineering; and improve public health, safety, and the environment. One of the agency's basic functions is to develop, maintain, and retain custody of the national standards of measurement, and provide the means and methods for comparing standards used in science, engineering, manufacturing, commerce, industry, and education with the standards adopted or recognized by the Federal Government. As an agency of the U.S. Commerce Department's Technology Administration, NIST conducts basic and applied research in the physical sciences and engineering, and develops measurement techniques, test methods, standards, and related services. The Institute does generic and precompetitive work on new and advanced technologies. NIST's research facilities are located at Gaithersburg, MD 20899, and at Boulder, CO 80303. Major technical operating units and their principal activities are listed below. For more information contact the Public Inquiries Desk, 301-975-3058.
  • Fundamentals of Dimensional Metrology

    Fundamentals of Dimensional Metrology

    Fundamentals of Dimensional Metrology Carl Hitchens MSc. CEng FIMechE Agenda ■ Metrology Fundamentals ■ History, metre & micron, precision & accuracy, source of error and basic principles. ■ Geometric Design and Tolerancing ■ Rules, material modifiers, datum and features. ■ Inspection Methods ■ Methods for GD&T inspection, gauge design & gauges, transfer Instruments, virtual bodies, thread nomenclature. ■ Co-ordinate Measuring Machine (CMM) ■ Good practice, limitations and applications. ■ Introduction to the Measurement of Surface Texture ■ Manufacturing Process Capabilities What is Metrology? ■ The Science of Measurement. ■ Understanding of measurement of the quality and quantity. ■ Evidence of traceability and accuracy. ■ Repeatability, reproducibility, reliability. ■ Understanding the uncertainty. Origins of Metrology ■ The cubit believed to be the first unit of measurement 1550- 1069 BC. ■ Length based on the distance from the elbow to the tip of the middle finger (52cm). ■ Division: 7 palms or 28 fingers. wikimedia.org The Metre ■ Developed after the French Revolution (1789), replace the old units of measure that were associated with royalty . ■ Originally intended to be one ten-millionth of the distance from the Earth's equator to the North Pole (at sea level) distance along the meridian running from the North Pole to the equator through Dunkirk, France and Barcelona, Spain. wikimedia.org The Metre ■ French scientists worked nearly six years to complete the task in November 1798. ■ Platinum-iridium bar as the physical replica of the metre. ■ The surveyors made an error of about two miles. The error has not been corrected. wikimedia.org Dimensional Measurement ■ The National Measurement Institutes are responsible for ensuring consistency and traceability. ■ The metre is now determined by the distance that the light from an iodine-stabilised helium neon laser travels through a vacuum in 1/299,792,458 of a second.
  • Engineering Metrology and Measurements

    Engineering Metrology and Measurements

    ENGINEERING METROLOGY AND MEASUREMENTS N.V. RAGHAVENDRA Professor & Head Department of Mechanical Engineering The National Institute of Engineering Mysore L. KRISHNAMURTHY Professor Department of Mechanical Engineering The National Institute of Engineering Mysore 3 Oxford University Press is a department of the University of Oxford. It furthers the University’s objective of excellence in research, scholarship, and education by publishing worldwide. Oxford is a registered trade mark of Oxford University Press in the UK and in certain other countries. Published in India by Oxford University Press YMCA Library Building, 1 Jai Singh Road, New Delhi 110001, India © Oxford University Press 2013 The moral rights of the author/s have been asserted. First published in 2013 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without the prior permission in writing of Oxford University Press, or as expressly permitted by law, by licence, or under terms agreed with the appropriate reprographics rights organization. Enquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, Oxford University Press, at the address above. You must not circulate this work in any other form and you must impose this same condition on any acquirer. ISBN-13: 978-0-19-808549-2 ISBN-10: 0-19-808549-4 Typeset in Times by Trinity Designers & Typesetters, Chennai Printed in India by Tara Art Printers (P) Ltd, Noida Third-party website addresses mentioned in this book are provided by Oxford University Press in good faith and for information only.
  • OIML R 98 (E), Edition 1991

    OIML R 98 (E), Edition 1991

    ORGANISATION INTERNATIONALE DE MÉTROLOGIE LÉGALE OIML INTERNATIONAL RECOMMENDATION High-precision line measures of length Mesures matérialisées de longueur à traits de haute précision OIML R 98 Edition 1991 (E) FOREWORD The International Organization of Legal Metrology (OIML) is a worldwide, intergovernmental organization whose primary aim is to harmonize the regulations and metrological controls applied by the national metrological services, or related organizations, of its Member States. The two main categories of OIML publications are: - International Recommendations (OIML R), which are model regulations that establish the metrological characteristics required of certain measuring instruments and which specify methods and equipment for checking their conformity; the OIML Member States shall implement these Recommendations to the greatest possible extent. - International Documents (OIML D), which are informative in nature and intended to improve the work of the metrological services. OIML Draft Recommendations and Documents are developed by technical committees or subcommittees which are formed by the Member States. Certain international and regional institutions also participate on a consultation basis. Cooperative agreements are established between OIML and certain institutions, such as ISO and IEC, with the objective of avoiding contradictory requirements; consequently, manufacturers and users of measuring instruments, test laboratories, etc. may apply simultaneously OIML publications and those of other institutions. International

  • Measuring Long Gage Blocks with the NIST Line Scale Interferometer

    NATL INST. OF STAND & TECH R.I.C. Wm'M. NISI I P!PUBLICATIONS ^ '»,?r'/'; « '!';«> ^, AlllDM t.S7TbM . ed States Department of Commerce Technology Administration National Institute of Standards and Technology NIST Technical Note 1410 Measuring Long Gage Blocl<s With the NIST Line Scale Interferometer John S. Beers 2995 I 7 he National Institute of Standards and Technology was established in 1988 by Congress to "assist industry in the development of technology . needed to improve product quality, to modernize manufacturing processes, to ensure product reliability ... and to facilitate rapid commercialization ... of products based on new scientific discoveries." NIST, originally founded as the National Bureau of Standards in 1901, works to strengthen U.S. industry's competitiveness; advance science and engineering; and improve public health, safety, and the environment. One of the agency's basic functions is to develop, maintain, and retain custody of the national standards of measurement, and provide the means and methods for comparing standards used in science, engineering, manufacturing, commerce, industry, and education with the standards adopted or recognized by the Federal Government. As an agency of the U.S. Commerce Department's Technology Administration, NIST conducts basic and applied research in the physical sciences and engineering, and develops measurement techniques, test methods, standards, and related services. The Institute does generic and precompetitive work on new and advanced technologies. NIST's research facilities are located at Gaithersburg, MD 20899, and at Boulder, CO 80303. Major technical operating units and their principal activities are listed below. For more information contact the Public Inquiries Desk, 301-975-3058.