Everyone involved in measurement technology knows the somewhat flippant ? but very catchy ? statement: ?In the event that you measure a whole lot, you measure nothing!? What’s meant by that is: You can measure a lot. However the values are just useful if you can validate them. In Download , 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 hundreds of metres from the GPS instrument. The word also often alludes to your tendency to generate a growing number of data inside our modern world, without considering its evaluation. So that you can obtain valid data with which to keep working, it really is worthwhile for industrial measuring instruments to be calibrated regularly.
For the individual, the highest accuracy is probably not important. In industrial applications, however, it really is precisely this that may make the key difference between rejects and the highest quality ? hence the calibration of the measuring instruments. It serves to match the measuring device with the national standard ? in a nutshell: to check if 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 many applications. For instance, ISO 9000 requires that the deviations of the test equipment used should be monitored. Having an up-to-date calibration, passing the audit is not any problem. This avoids the repetition of the audit, production downtime or even a recall ? and thus reduces stress, 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 to provide the correct values!
Certification in accordance with the German accreditation body
The illustration shows the way the four calibration sequences relative to DKD-R 3-3 differ.
The highest standard because of 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. Because the beginning of 2022, tecsis has been accredited relative to DIN EN ISO / IEC 17025 for the measurand force.
What a DAkkS-certified calibration of force measuring instruments means is shown by the exemplory case of high-end force transducers, which are used in calibration machines. Within their case, the test sequence follows the EN ISO 376 standard. At the very least eight measuring stages are approached, with a total of five preloads, two upward series and two up-down series. In addition, the force transducers are each rotated by 120�, which results in three installation positions. With 65 measured values (eight stages), the effort is correspondingly high. The price for such a calibration goes together with this.
Regarding 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 which might be selected in line with the requirements. WIKA and tecsis also have DAkkS certification for this.
An additional option for regular calibration is the non-standardised 3.1 inspection certificate.
Practical examples
An illustrative example of the usefulness of regular calibration is 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 offers a contribution to ensuring safe working conditions.
Another example is the instrumentation for checking the contact forces of welding tongs. Ideally, they are monitored continuously by built-in tension/compression force transducers, however 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 is also worthwhile, should they be utilized for monitoring very precise production steps. When pressing in mobile phone displays, for example, both the measuring instruments and their calibration can easily pay back: If one in such a process isn’t noticed immediately (for instance, only if the travel is controlled), thousands of euros in material value could be destroyed within minutes.
Fierce before calibration can be useful
Depending on the instrument, application and regulation, it may be worthwhile with an adjustment carried out before calibration. In this manner, the user ensures 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 the own and for third-party products.
Note
On the WIKA website you can find further information on the average person calibration services as well as on WIKA force measuring instruments (offers are also available in the online shop). Assuming you have any questions, your contact will gladly help you.
Also read our post
Calibration or adjustment ? Where?s the difference?