UKAS guidelines for metrological and dimensional calibration

Metrology, calibration and the international standardisation of measurements play vital roles in optimising the modern engineering and industrial process. Not only do they ensure the reliability and accuracy of equipment, but ensure the safety of those that use it after production.

Dimensional calibration is a key component of aerospace, automotive and medical applications. To ensure the precision of equipment used in these industries, UKAS accredited laboratories that follow metrological and calibration standards are trusted to provide the gold-standard of calibration services.

In this article, we dive into dimensional calibration, metrological calibration, and the importance of UKAS accreditation in precision engineering.

What is dimensional calibration?

Dimensional calibration, like all other forms of calibration, is used to test the accuracy and reliability of measuring equipment. Dimensional equipment in particular refers to devices that measure length, width and mass, such as micrometres, callipers and height gauges. These devices need to be regularly calibrated to ensure they maintain precise measurements, which would otherwise result in complications in varying degrees depending on the industry.

To perform mechanical calibration on dimensional measuring devices, specific masters and standard equipment is used to act as a comparison. These can range from gauge blocks and metre standards to profilometers and surveillance masters for precise applications. By regularly calibrating your dimensional measuring equipment, you will save time correcting errors and have confidence in the accuracy of your measurements.

What is metrological calibration?

Where calibration can be considered the process of comparing the measurements of equipment to an accurate master, metrology refers to the science behind measurements and, in turn, calibration. This science is separated into three areas; 

• The development, understanding and establishment of measurement units and methods to ensure a high and repeatable level of accuracy. 
• The engineering and industrial application of the measurements to ensure their stability through calibration.   
• The creation of international standards in relation to the specific area and industry of measurement. 

Metrological calibration demonstrates compliance with international standards that have been developed to establish a uniform environment of measurements in engineering and other industries. For dimensional equipment, this refers to ISO standards under ISO/TC 213 that covers specific testing requirements for different dimensional measuring devices to ensure uniform accuracy. Simply put, ensuring metrological calibration means your mechanical equipment is both precise and follows international standards applicable to your specific industry.

Why is UKAS accredited calibration important?

Following on from the importance of metrological calibration, UKAS accreditation acts as an additional form of insurance for the accuracy and reliability of dimensional measuring equipment. UKAS accreditation is provided to laboratories that directly comply with ISO 17025 and have objective proof that they comply with best practise and competence for calibration. It represents a market differentiator of quality where each and every variable of calibration is taken into account to produce accurate, reliable and repeatable dimensional measurements.

UKAS accredited laboratories take all variable factors of metrological and dimensional calibration into account, with a key factor being measurement uncertainty. Measurement uncertainty is the level of uncertainty that is guaranteed with each calibration. Perfection is unattainable, and as such the metrological factors that influence error must be measured and proven. For UKAS accreditation, laboratories must provide a 95% certainty of measurements, with full documentation and analysis of the 5% of uncertainty produced. LAB 45 comments directly on measurement uncertainty in relation to dimensional calibration in section 6.17;

“In dimensional calibration, the schedules of accreditation for the calibration of basic dimensional measuring tools and equipment have historically reported a CMC (calibration and measurement capability) for parameters most relevant to end users. This method however does not provide transparency with regards to auxiliary measurements such as flatness and parallelism of micrometer measuring faces etc. These additional measurement techniques shall be listed on the schedule of accreditation along with the corresponding measurement uncertainty.”

Have objective proof in the quality of your calibration with a UKAS accredited laboratory

Metrological and dimensional calibration, along with adherence to international standards, are crucial for optimising engineering and industrial processes. They ensure the accuracy of measuring equipment used in precision industries like aerospace, automotive, and medical applications, enhancing quality and assuring safety.

UKAS accreditation serves as a mark of quality to reinforce the above qualities, guaranteeing that laboratories comply with ISO 17025 and follow best practices for calibration. UKAS-accredited laboratories consider each and every factor involved in calibration, such as measurement uncertainty and complete traceability. By following UKAS guidelines and using an accredited laboratory, you can ensure the precision and compliance of your equipment, fostering trust and confidence in their measurements within your specific industries.

At DM, we have full UKAS accreditation that showcases our close attention to detail, process and accuracy. We have dedicated facilities that have been proven to be suitable for the calibration of a wide range of equipment including dimensional. We also provide UKAS accredited on-site calibration alongside the short turnaround time of our traditional testing, minimising the downtime of your operations.

Get in contact with our highly-trained professionals to ensure your dimensional testing equipment is calibrated to the best quality ahead of its scheduled testing date.