As people, we rely heavily on measurements for innovation, well-being and prosperity throughout our modern lives. We also depend on the accuracy of these measurements for confidence in the products and services we consume and the industries and organisations that provide them.
In industry, to use measurements with a high degree of confidence, they must be standardised with known uncertainties. This is an important aspect of traceability.
This article introduces measurement traceability and explains why it is so vital.
What is Measurement Traceability?
A measurement of something will produce a value. For example, a sheet of metal may be 500 millimetres long. However, another measurement of the same sheet may show 501 millimetres depending on factors such as who the measurer is and what equipment is used. Measurement traceability allows us to look at measurements and understand the value and uncertainty produced by that measurement with confidence.
The Vocabulary of Metrology defines measurement traceability as the 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.
Standardisation and known uncertainty are vital to this traceability. For it to be met in an international-wide context, consensus should exist for measurement practices, units of measurement, calibration, certification and reporting.
Within the UK, our National Measurements System facilitates measurement science and technology. UKAS is the National Accreditation Body appointed by the government to assess and accredit organisations that provide certification, testing, inspection and calibration services. UKAS can accredit organisations to demonstrate their competencies in measuring.
For example, Eleymet is a metrology company that has a UKAS-accredited laboratory. They perform several specialised measurement services that uphold metrology standards . One of those is the calibration and resurfacing of granite surface plates, which are used as flat surfaces from which accurate measurements can occur.
At their laboratory, Eleymet is accredited to calibrate and resurface plates to meet BS standard BS817 (2008). Once complete, the surface will be flat with a known uncertainty. The user of that plate can then make measurements, using the plate as a base, knowing how the surface will affect their measurements. There will be documented proof. Hence, traceability exists.
Why is Measurement Traceability Important?
Without the ability to trace measurements to standards and known uncertainties, there will be far less consistency in accuracy. Confidence in measurements will drop, and errors will be more prevalent. This would affect all aspects of industry and life.
Safety critical sectors such as Medicine, Energy, Transport and Waste depend on accurate and precise measurements to underpin the infrastructure that supports our well-being. For example, when a critical component is delivered to a UK nuclear power station from a French manufacturer, the component must be made to specification.
To ensure this, the producer must be able to demonstrate the uncertainty in the accuracy of their measurements. They should be able to provide the necessary traceability.
What happens if traceability does not exist? In a sector as safety critical as nuclear, additional steps will need to be taken to prove conformity.
This may include re-measuring or sourcing another supplier. In other words, without traceability, additional costs will be incurred. If traceability does not exist internationally, supplier choice would be reduced, or closer cooperation between supplier and customer would be needed.
How can Measurement Traceability Benefit Different Industries?
Medicine is one industry that relies upon measurement traceability. From the production and delivery of medicines to the production and maintenance of equipment, there must be a high degree of confidence in measurement. In the radiotherapy treatment of cancer, for example, accurate administration of the dose and site of delivery must take place.
Aerospace is another industry depending on traceability. Many components are connected to form systems and subsystems. These components may be manufactured, tested, assembled and maintained in many places. Minor inaccuracies can quickly become problematic as components are fitted together. Therefore, traceability is paramount.
All industries today are concerned with environmental sustainability. Data is the key to achieving the positive outcomes we desire. Using data, we can understand our environmental impact and make decisions to mitigate environmental damage. However, to do this, we need standards and traceability.
The Automotive industry is transforming from the combustion engine to electric. Relying upon batteries will require battery and fuel cell development, which requires complete lifecycle measurement to test reliability and environmental concerns. Through traceability, the industry can demonstrate its environmental and economic advantages.
Who Does Traceability Benefit?
Traceability gives confidence to the entire system of production and consumption in our world. In a safety-critical environment, it is mandated for our safety and well-being. In others, it can contribute to productivity and commercial advantage. Whilst not always necessary, it is clear why it exists.