Everyone involved with measurement technology knows the somewhat flippant ? but Faux ? statement: ?In the event that you measure a whole lot, you measure nothing!? What’s meant by this is: It is possible to measure a lot. But the values are only useful when you can validate them. In everyday activity, for example, one may be surprised once the scales at home show a large deviation from those at the physician?s or the bicycle speedometer deviates many a huge selection of metres from the GPS instrument. The saying also often alludes to your tendency to generate a growing number of data inside our modern world, without considering its evaluation. To be able to obtain valid data with which to keep working, it really is worthwhile for industrial measuring instruments to be calibrated regularly.
For the individual, the best accuracy might not be important. In industrial applications, however, it is precisely this that can make the key difference between rejects and the best quality ? hence the calibration of the measuring instruments. It serves to match the measuring device with the national standard ? in short: to check whether the values are correct.
Traceability to the national standard
The keyword here is thus the traceability to the national standard. Realizing that the respective measuring instrument measures the proper value can be of great importance for most applications. For Easy , ISO 9000 requires that the deviations of the test equipment used should be monitored. With an up-to-date calibration, passing the audit is no problem. This avoids the repetition of the audit, production downtime or even a recall ? and therefore reduces Agitated , time and costs. The expenditure on the calibration has thus quickly paid for itself. Many people are happy.
Besides meeting the audit requirements, traceability can also be required for quality assurance, optimising resource utilisation and reducing energy consumption. Finally, the most convincing reason to possess one?s own measuring devices checked in accordance with the current standard may be the feeling of security: The measuring instruments will continue steadily to supply the correct values!
Certification relative to the German accreditation body
The illustration shows the way the four calibration sequences in accordance with DKD-R 3-3 differ.
The highest standard for this may be the calibration certificate of the German accreditation body (Deutsche Akkreditierungsstelle ? DAkkS). WIKA has offered certification for pressure, temperature and electrical measurands (DC current, DC voltage and DC resistance) for some time. Since the beginning of 2022, tecsis has been accredited in accordance with DIN EN ISO / IEC 17025 for the measurand force.
What a DAkkS-certified calibration of force measuring instruments means is shown by the example of high-end force transducers, which are used in calibration machines. In their case, the test sequence follows the EN ISO 376 standard. At least eight measuring stages are approached, with a total of five preloads, two upward series and two up-down series. Furthermore, the force transducers are each rotated by 120�, which results in three installation positions. With 65 measured values (eight stages), your time and effort is correspondingly high. The purchase price for this type of calibration goes together with this.
In the case of industrial devices, the question arises as to whether this type of procedure is worthwhile. Alternatively, the DKD-R 3-3 directive could be applied. It describes four test sequences that may be selected based on the requirements. WIKA and tecsis likewise have DAkkS certification for this.
A further option for regular calibration may be the non-standardised 3.1 inspection certificate.
Practical examples
An illustrative exemplory case of the usefulness of regular calibration may be the checking of hydraulic compression force transducers. These instruments measure the clamping forces of industrial machines such as for example punches, pneumatic presses, sealing presses, spindle presses, tablet presses and toggle lever presses. Here, calibration provides a contribution to ensuring safe working conditions.
Another example may be the instrumentation for checking the contact forces of welding tongs. Ideally, these are monitored continuously by built-in tension/compression force transducers, but they can also be checked at set intervals using a test set for measuring electrode forces (model FSK01). This ensures the standard of the welding points and reduces wear on the electrodes.
For the tension/compression force transducers mentioned, calibration can be worthwhile, should they be utilized for monitoring very precise production steps. When pressing in cellular phone displays, for example, both the measuring instruments and their calibration can quickly pay off: If an error in such a process is not noticed immediately (for example, if only the travel is controlled), thousands of euros in material value could be destroyed within minutes.
Adjustment before calibration can be handy
With respect to the instrument, application and regulation, it could be worthwhile with an adjustment completed before calibration. In this way, the user means that their measuring instrument achieves the corresponding accuracy during calibration. For the calibration itself, the user gets the option of choosing the sort and procedure, both for our own and for third-party products.
Note
On the WIKA website you will discover further information on the individual calibration services as well as on WIKA force measuring instruments (offers are also available in the web shop). In case you have any questions, your contact will gladly help you.
Also read our post
Calibration or adjustment ? Where?s the difference?g