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Metrology

Robert P. Jackson, P.E.


Course Outline

This course will examine in detail the subject matter given below.  I have chosen to list only the main titles subtitles but contained within those classifications are areas of interest relative to metrology. We will discuss the course in a logical matter moving through the sections as follows:

This course includes a multiple choice quiz at the end, which is designed to enhance the understanding of the course materials.

Learning Objective

At the completion of this course the student will have accomplished the following:

Intended Audience

When considering who should take this course, it might be beneficial to state an accepted definition for the Science of Metrology.  From the “International Bureau of Weights and Measurements”, we see the following definition:

Metrology comes from the Greek word “metron” and “logos” which literally means the study of measurement. This study covers both the experimental and theoretical aspects of measurement and the determination of the levels of uncertainty of these aspects. The study of measurement is a basic requirement in any field of science and technology, most importantly in engineering and manufacturing. Since metrology is the study of measurement, it is expected to enforce, validate and verify predefined standards for traceability, accuracy, reliability, and precision. All of these are factors that would affect the validity of measurement. Although these standards vary widely, these are mandated by the government, the agencies, and some treaties. Consequently, these standards are verified and tested against a recognized quality system in calibration laboratories.

With this being the case, the following people would benefit greatly from taking this course:

Benefit to Attendees

This six (6) hour course is intended to provide necessary information so the participant will gain an understanding of this technology and its use.  We go considerably further than the basics, thereby making it possible to gain knowledge facilitating informed conversations with vendors, hardware specialists and IT personnel within the profession.  The choice of “measuring devices” is always critical to the end user and it is imperative the proper selection of equipment be made for the best results.  We discuss this in the course.

METROLOGY is a very old technology and has greatly improved over the years with accuracy and increased speed being the main goals for the improvement.  The actual need dates back hundreds of years and even though the devices used were very rudimentary, they did do the job for their time.  As more accuracy and precision was needed, the measuring equipment improved so that now we have CMM equipment that can measure distances to the 0.00005 of an inch.

In addition to the text, a complete glossary of terms will be provided to facilitate understanding of the vocabulary used on a day-to-day basis.  The references provided will serve as material for further reading and knowledge.

Course Introduction

Metrology is NOT meteorology.  There is a very real difference.  According to the “Bureau of Weights and Measures” (BIPM), Metrology is defined as follows:

“ The science of measurement embracing both experimental and theoretical determinations at any level of uncertainty in any field of science and technology”.
That may be a bit nebulous so the definition I like is as follows:

“The science of weights and measurement determining conformance to specifications or technical requirements and development of standards.”

From an application standpoint, the key word here is conformance.  We measure to insure specifications are met to within an Upper Specification Limit (USL) and a Lower Specification Limit (LSL).  These limits are called the range of acceptability.  Within any basic field of science, technology or manufacturing environment, specification limits must be recognized and met.

The importance of measurement was recognized very early in our countries history as can be seen from the following quote:

“Weights and measures may be ranked among the necessaries of life to every individual of human society.  They enter into the economical arrangements and daily concerns of every family.  They are necessary to every occupation of human industry: to the distribution and security of every species of property; to every transaction of trade and commerce; to the labors of the husbandman; to the ingenuity of the artificer; to the studies of the philosopher; to the researches of the antiquarian; to the navigation of the mariner; to the marches of the soldier; to all the exchanges of peace, and the operations of war.  The knowledge of them, as in established use, is among the first elements of education, and is often learned by those who learn nothing else, not even to read and write.  This knowledge is riveted in the memory by the habitual application of it to the employments of men through life.”  John Quincy Adams, Report to Congress, 1821.

Metrology comes from the Greek word “metron” and “logos” which literally means the study of measurement. This study covers both the experimental and theoretical aspects of measurement and the determination of the levels of uncertainty. The study of measurement is a basic requirement in any field of science and technology, most importantly in engineering and manufacturing. Since metrology is the study of measurement, it is expected to enforce, validate and verify predefined standards for traceability, accuracy, reliability, and precision. All of these are factors that would affect the validity of measurement. Although these standards vary widely, they are mandated by the governments, specific agencies, and many international treaties.  These standards are verified and tested against recognized quality systems and in calibration laboratories.

Metrology is the science of measurement, and measurement is the language of science.  It is the language we use to communicate size, quantity, position, condition and time.  A language consists of grammar and composition.  Grammar is a science; composition is an art.  There are three reasons why we need measurements, as follows:

The basic principles of dimensional metrology are fascinating as well as practical.  They epitomize the scientific method that characterizes this modern age of manufacturing more than anything else.  These principals rely on logic and reflect philosophy.  They spring into life whenever we produce goods or search for scientific knowledge.

The experimental aspect of metrology is that which deals with the investigation of the relationship among variables. These variables are established depending on set of observations being considered or classified. As such, it is in this aspect that hypotheses are established and tested.

On the other hand, the theoretical aspect of metrology deals with the various concepts and principles underlying the study. This aspect is based on established theories and concepts derived from empirical observations which satisfy the baseline requirements. In other words, the theoretical aspect is expected to be functional and working.
In this six (6) hour course, we will investigate the following three sub-fields of metrology: 1.) Science or fundamental concepts, 2.) Applied or industrial concepts and 3.) Legal metrology.

Course Content

The course content is in a PDF file:

Metrology

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Course Summary

I feel quite sure that Metrology is a new word to individuals not closely involved with the STEM (Science, Technology, Engineering and Mathematics) professions.  No problem.  This course will, hopefully, provide information that will allow the reader to continue the learning process relative to this important technology.  The generally accepted definition of Metrology is as follows:

“The science of weights and measurement determining conformance to specifications or technical requirements and development of standards.”
As technology and invention progressed since the Industrial Revolution, newer and more rigorous methods of measuring and weighing have been necessary to quantify adherence to given specifications and requirements.  A system of metric measurement was devised centuries ago and represents the basis for all systems of measurement found in the ancient world and China.  This system was conceived prior to the appearance of cuneiform writing in Mesopotamia in approximately 2,900 B.C.   A system of measures became necessary with the advent of agricultural development as far back as 6,000 B.C., and became crucial to calculate the distribution of crops and the volume of food consumed by families.

It would not be until 1875 at the Meter Convention that scientists would recognize the need to establish a system of internationally agreed upon measurement standards. Prior to this, various systems existed across the world and were merged and transformed through trade and acculturation.  The operative word here is “international”.  An internationally accepted set of standards was necessary so that science and technology could advance and a general understanding of measurements could be accomplished.   The real breakthrough came in 1960 with development of the SI system of measurement.

The Système International d'Unités (SI) was adopted to ensure a practical and universal system of measurement. It established the use of seven SI base units as follows:

Metrology is absolutely critical to modern-day science and technology and provides a universal language, regardless of country, for technical communication.  This course strives to lay the groundwork for future study.

Quiz

Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

Take a Quiz

DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.