Certified calibration standards: the foundation for reliable measurement results
What you should know about traceability, certificates, and the proper handling of standards
Correct calibration of measuring instruments using certified standards is the prerequisite for every reliable measurement and for precise, reproducible results. Dr. Tanja Haas, Head of our in-house DAkkS accredited calibration laboratory at the FISCHER site in Sindelfingen, explains in this interview what makes FISCHER calibration standards so special, why traceability is essential for your measurement results, when a DAkkS certificate may be beneficial, and what you should keep in mind when handling your standards.
What role does calibration play in surface testing and what are the biggest challenges?
For our customers, the question “Am I measuring correctly?” is crucial. As a result, our instruments provide a coating thickness that is generally already very close to the true value. Nevertheless, verification (calibration) and, if necessary, adjustment are always advisable. This makes the results even more precise and also ensures reproducibility. Our standards with precisely known values are used for this purpose.
How does our DAkkS accredited calibration laboratory specifically support our customers?
Our customers require proof that they can be certain the values of the standards they use to calibrate their instruments are correct. This proof is provided by our in-house accredited laboratory. All standards with a DAkkS certificate are traceable, meaning we can demonstrate exactly how the certified value was determined. Incidentally, the same also applies to our standards without a DAkkS certificate; they simply do not have official confirmation of traceability.
You mentioned so-called “traceability.” Why is it so important? What risks arise if it is not ensured?
Traceability means that we can relate our measurement values—officially confirmed in the case of a DAkkS certificate—to fundamental official definitions such as the metre and the kilogram, and demonstrate the complete chain back to the original values maintained by national institutions. In other words, we can prove that the values “did not simply come out of nowhere.”
How does our DAkkS accredited calibration laboratory ensure traceability and thus the reliability of our calibration standards?
We regularly verify our master standards and measurement results using independent methods. We are also accredited for this: we determine the mass and area of our standards directly in-house. The results are documented in a traceable manner. In addition, we undergo extensive regular audits to verify our competence. Ongoing training and continuous improvement are also fundamental pillars of an accredited laboratory.
All standards we manufacture at FISCHER are therefore traceable. If I can also use a standard with a factory certificate, when is a standard with a DAkkS certificate actually useful or necessary?
Our factory standards are measured according to the same specifications as our DAkkS-certified standards. However, many companies now require a DAkkS certificate or a corresponding ISO/IEC 17025 certificate for the standards or measuring instruments used in their own processes or in the processes of their suppliers. This officially guarantees and documents traceability. In addition, DAkkS-certified standards generally have lower uncertainties. Our product portfolio includes well over 500 different certified standards, allowing customers to choose exactly what meets their requirements. We are, of course, always happy to advise them.
How does choosing high-quality, certified FISCHER standards affect the quality of my results?
Our standards are characterized by highly accurate values and therefore very low uncertainty. If customers calibrate their measuring instruments using our standards, they can rely on their own measurement results also having very low uncertainty. They can therefore determine more precisely whether their materials, coatings or samples are within the desired range. In general, the smaller the measurement uncertainties, the greater the precision in the production process itself.
Which values in the certificates we issue are relevant for customers in day-to-day practice?
The certificates contain all the important information customers need for successful calibration and measurement. In addition to informative details such as address and order number, the measurement conditions under which the certificate was issued and the date of the measurement are documented precisely. Naturally, the result is the most important part: we certify the coating mass per unit area, from which the coating thickness used by the customer is calculated. For alloys, we certify the exact elemental concentrations.
Finally, is there anything users should pay attention to when working with standards?
Yes, absolutely. Our standards, especially those for X-ray fluorescence measurements, are often only a few micrometres thick and are therefore very sensitive. They must be handled with great care. If the measuring area is damaged—for example by a dent, scratch or crack—the standard should be replaced. The measuring area should never be touched, as this can affect the measurement and distort the results.
Some materials also undergo colour changes over time; silver, for example, tarnishes. However, this does not impair the quality of the standards, and they should never be cleaned to remove such changes. Colour changes do not affect the measurement result. Cleaning, however, removes material, changes the certified values and renders the standard unusable.
