Metrology and Instrumentation

Practical Applications for Engineering and Manufacturing

Samir Mekid

• Éditeur: Wiley-ASME Press Series
• Année: 2021
• ISBN:
  9781119721710
• Édition: 1
• Sujet: Tecnologia e ingegneria
• Sous-sujet: Ingegneria meccanica

Metrology and Instrumentation: Practical Applications for Engineering and Manufacturing provides students and professionals with an accessible foundation in the metrology techniques, instruments, and governing standards used in mechanical engineering and manufacturing. The book opens with an overview of metrology units and scale, then moves on to explain topics such as sources of error, calibration systems, uncertainty, and dimensional, mechanical, and thermodynamic measurement systems. A chapter on tolerance stack-ups covers GD&T, ASME Y14.5-2018, and the ISO standard for general tolerances, while a chapter on digital measurements connects metrology to newer, Industry 4.0 applications.

1
Fundamental Units and Constants in Metrology

“When you can measure what you are speaking about and express it in numbers, you know something about it.”

—Lord Kelvin (1883). Source: Public Domain.

1.1 Introduction

Metrology is the science of measurement with various applications. It is derived from the Greek words metro – measurement and Logy – science. The BIMP (Bureau of Weights and Measures in France) defines metrology as “the science of measurement embracing both experimental and theoretical determinations at any level of uncertainty in any field of science and technology.”

Five pivots define the functions of metrology:

1. To establish the units of measurements;
2. To replicate these units as standards;
3. To guarantee the measurement uniformity;
4. To develop measurement methods;
5. To investigate the accuracy of methods‐related errors.

Based on this, the objectives of metrology are:

1. Selection of proper measuring instrument;
2. Proper measuring standards;
3. Minimizing inspection cost;
4. Defining process capabilities;
5. Standardization;
6. Maintaining accuracy and precision during inspection or as component of an instrument over time of use [1].

Therefore, two types of metrology exist:

1. Deterministic, or industrial, metrology.
2. Legal, or scientific, metrology.

Measurement is the process of revealing a single or multiple values to the characteristics of an object or property by conducting experiments to determine the value of this particular property. These properties may be physical, mechanical, or chemical, such as length, weight, force, strain, volume, angle, and molls.

Figure 1.1 Simplified methodology producing measurement results.

Metrology also includes precision, repeatability, and accuracy, which refers to how accurate the measured value is. It establishes a well‐known understanding of the measuring process and the related units that are critical in connecting various human activities and ensures that these measurements are linked to reference standards, which is commonly referred to as traceability. For as long as civilization has existed, measurements have been taken. It is necessary for a country's economic and social development. It provides precise measurements that have an impact on the economy, health, safety, and general well‐being. It could also be a legal problem. As a result, the topic is always in demand.

This chapter will introduce the fundamental units and constants in metrology through conversions between units and systems. To put measurements into context, a complete methodology of the act of measurement beginning with the object to measure and ending with the result that constitutes the information needed for the object is required. The complete process is summarized in Figure 1.1. The figure depicts a simplified methodology for producing measurement results with minimal conditions such as the units to be known, the calibration of the measurement instruments, and the uncertainty of su...