The purpose of this paper is to relate some of the experiences of using a coordinate measuring machine (CMM) to calibrate long end standards and step gages at measurement uncertainties of less than 0. 5[mu]m. It is not the intent of this paper to suggest that everyone should return to his or her laboratory and change the way CMMs are operated nor to suggest that the methods discussed here are even the best methods. The intent is to provide some food for thought, based on real experiences, about the use of a CMM to measure at low levels of uncertainty. As will become apparent, a lot of the issues discussed really apply to any dimensional measuring technique operating at low levels of uncertainty, not just a CMM. The discussion in this paper is based on measuring one-dimensional end standards and step gages placed along the x-axis of the Moore M-60 CMM located at the Oak Ridge Metrology Center, which is part of the Oak Ridge Centers for Manufacturing Technology at the Y-12 Plant (formerly used in manufacturing nuclear weapons parts) in Oak Ridge, Tennessee. When the Cold War ended, the U.S. Department of Energy (DOE) pushed to make nuclear weapons technology available to U.S. industry. As part of this technology transfer effort, it was determined that the M-60 could be used by the National Institute of Standards and Technology (NIST) to provide a calibration service for step gages. Previously, U.S. industrialists had to go to Germany for step gage calibrations at the lowest levels of measurement uncertainty. Much of the discussion that follows is based on the process developed to use the M-60 for the NIST calibration.

Since John Bosch edited and published the first version of this book in 1995, the world of manufacturing and coordinate measuring machines (CMMs) and coordinate measuring systems (CMSs) has changed considerably. However, the basic physics of the machines has not changed in essence but have become more deeply understood. Completely revised and updat

This handbook is a both a description of the current practice at the National Institute of Standards and Technology, and a compilation of the theory and lore of gauge block calibration. Most of the chapters are nearly self-contained so that the interested reader can, for example, get information on the cleaning and handling of gauge blocks without having to read the chapters on measurement schemes or process control, etc. This partitioning of the material has led to some unavoidable repetition of material between chapters. The basic structure of the handbook is from the theoretical to the practical. Chapter 1: basic concepts and definitions of length and units; Chapter 2: history of gauge blocks, appropriate definitions and a discussion of pertinent national and international standards; Chapter 3: physical characteristics of gauge blocks, including thermal, mechanical and optical properties; Chapter 4: a description of statistical process control (SPC) and measurement assurance (MA) concepts; and Chapters 5 and 6: details of the mechanical comparisons and interferometric techniques used for gauge block calibrations. Full discussions of the related uncertainties and corrections are included. Finally, the appendices cover in more detail some important topics in metrology and gauge block calibration.

This book focuses on effective methods for assessing the accuracy of both coordinate measuring systems and coordinate measurements. It mainly reports on original research work conducted by Sladek’s team at Cracow University of Technology’s Laboratory of Coordinate Metrology. The book describes the implementation of different methods, including artificial neural networks, the Matrix Method, the Monte Carlo method and the virtual CMM (Coordinate Measuring Machine), and demonstrates how these methods can be effectively used in practice to gauge the accuracy of coordinate measurements. Moreover, the book includes an introduction to the theory of measurement uncertainty and to key techniques for assessing measurement accuracy. All methods and tools are presented in detail, using suitable mathematical formulations and illustrated with numerous examples. The book fills an important gap in the literature, providing readers with an advanced text on a topic that has been rapidly developing in recent years. The book is intended for master and PhD students, as well as for metrology engineers working at industrial and research laboratories. It not only provides them with a solid background for using existing coordinate metrology methods; it is also meant to inspire them to develop the state-of-the-art technologies that will play an important role in supporting quality growth and innovation in advanced manufacturing.

The requirement for primary-level calibration of complex forms, e.g., gear profiles, has led to development of a method for quantifying the measurement uncertainty on the artifact being calibrated that does not rely on a transfer comparison. This method, developed jointly by National Institute of Standards and Technology (NIST) and Oak Ridge Metrology Center (ORMC) personnel, consists of breaking down the measurement method into simpler components and quantifying these components using generally accepted artifacts with low uncertainties (gage blocks, ring gages, spheres, etc.). Once quantified, these components are added vectorially according to NIST Technical Note 1297, 1994 Edition. Verification of this method can be accomplished by intercomparisons with other methods and laboratories.

“Evaluating Measurement Accuracy, 2nd Edition” is intended for those who are concerned with measurements in any field of science or technology. It reflects the latest developments in metrology and offers new results, but is designed to be accessible to readers at different levels: scientists who advance the field of metrology, engineers and experimental scientists who use measurements as tool in their professions, students and graduate students in natural sciences and engineering, and, in parts describing practical recommendations, technicians performing mass measurements in industry, quality control, and trade. This book presents material from the practical perspective and offers solutions and recommendations for problems that arise in conducting real-life measurements. This new edition adds a method for estimating accuracy of indirect measurements with independent arguments, whose development Dr. Rabinovich was able to complete very recently. This method, which is called the Method of Enumeration, produces estimates that are no longer approximate, similar to the way the method of reduction described in the first edition removed approximation in estimating uncertainty of indirect measurements with dependent arguments. The method of enumeration completes addressing the range of problems whose solutions signify the emergence of the new theory of accuracy of measurements. A new method is added for building a composition of histograms, and this method forms a theoretical basis for the method of enumeration.Additionally, as a companion to this book, a concise practical guide that assembles simple step-by-step procedures for typical tasks the practitioners are likely to encounter in measurement accuracy estimation is available at SpringerLink.

Results of measurements and conclusions derived from them constitute much of the technical information produced by the National Institute of Standards and Technology (NIST). In July 1992 the Director of NIST appointed an Ad Hoc Committee on Uncertainty Statements and charged it with recommending a policy on this important topic. The Committee concluded that the CIPM approach could be used to provide quantitative expression of measurement that would satisfy NIST¿s customers¿ requirements. NIST initially published a Technical Note on this issue in Jan. 1993. This 1994 edition addresses the most important questions raised by recipients concerning some of the points it addressed and some it did not. Illustrations.