Metrology is an aspect that has transitioned over the years from a theoretical concept to practical applications. From accessing the science of measurement in theoretical and practical means during ancient times, to current development of national and industry standards for quality control purposes of manufactured parts, metrology has provided a means of accountability and certainty. Industrial measurement labs provide users with a resource for theoretical and practical use of metrology, to ensure consistency and quality.
What is Metrology?
According to the International bureau of weights and measures (BIPM), metrology is defined as the following: “The science of measurement, embracing both experimental and theoretical determinations at any level of uncertainty in any field of science and technology.” In essence, metrology is simply the theoretical and practical use of the science of measurement.
The joint committee for guides in metrology (JCGM) is responsible for the language and international vocabulary of metrology (VIM). This committee is a combination of eight international organizations, including the International bureau of weights and measures.
Basic Principle: Metrology
Although metrology covers a spectrum of different units of measures and is implemented differently for every organization, there are a few common aspects to consider when practicing metrology. The understanding, implementation and practice of the units of measures to be utilized is the most important principle of metrology. Commonly, the internationally accepted units of measures are used for any specific project or study, which could include temperature, linear distance, mass etc. All aspects of metrology are regularly documented and national and/or industry standards must be referenced, as a source for traceability. A significant factor metrologists must understand is the concept of metrological traceability. According to the Joint Committee for Guides in Metrology, metrological traceability is defined as “property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty.” Traceability can be attained by calibrating testing equipment, in order to ensure accuracy and manage the quality control process.
Functions of metrology
Metrology can be used for many different functions, depending on multiple variables including the purpose of the study or project. Commonly, the concept of metrology is utilized to qualify, verify and validate test data. Metrology is often miscommunicated as simply the science of measurement. Although this is the case, in recent years, the term “metrology” has molded to include the practice of retrieving, verifying and qualifying measurements according to national and/or industry standards. This assists users in retrieving measurements and qualifying a part with confidence and certainty, in regards to accuracy, reliability, repeatability, traceability, quality and consistency.
“The science of measurement” can be applied across multiple different industries to serve different purposes. Commonly used for scientific or fundamental metrology, industrial metrology and legal metrology, the concept of metrology has developed from merely theory to practicality. Industrial metrology is the use of “the science of measurement” in theory and practicality, to the manufacturing process, ensuring quality and accuracy of manufactured parts and components. The method of testing these parts to ensure accuracy and reliability must be calibrated according to national and/or industry standards.
Industry standards: Industrial Metrology
In order to ensure all theoretical and practical features of measurements are accounted for, national and industry specific standards are put into place. These standards allow users to proceed with manufacturing of parts, with confidence and certainty. In the United States, the National Institute of Standards and Technology (NIST) is responsible for working with the industry to develop a process for sustaining and improving the technology, measurements and standards.
Standards are developed on an international basis, national basis as well as industry specific. For example, a common standard for quality control of manufactured parts and components is known as ISO 9000 – Quality Systems Management. Some organizations develop customized standards for internal purposes, based on industry standards, for extensive quality and control.
Purpose of Metrology and Calibration
Metrology is a necessary concept which must be understood and implemented for manufacturing process in regards to industrial parts and components. Since metrology now encompasses both the theory and the practice of obtaining measurements, users are able to utilize metrology and calibration for the following purposes:
- Ensures consistency and repeatability
- Tool for reliability and measuring accuracy
- Metrological traceability
- Documentation subject to industry regulations and standards
- Comparison analysis
- Quality management tool
- Dimensional metrology, Dimensional analysis on industrial parts
- Failure investigation and detection
- Ensure no faulty parts are processed
- Qualification tool – part approval process
Testing technologies: Metrology
Industrial metrology labs have become a significant aspect of the industry, not only providing theoretical features of measurements and calibration, but accessing measurements according to relevant standards, for traceability and quality control. There are many technologies that exist which can help users attain measurement of industrial part and components. A radiographic testing technique which can help users conduct 3D metrology, by accessing internal and external measurements in 3D is Industrial Computed Tomography (CT). This testing method is completely nondestructive, helping users access geometry, dimensional metrology as well as qualify and validate parts with confidence, certainty and accuracy.