Everyone involved with measurement technology knows the somewhat flippant ? but very catchy ? statement: ?If you measure a whole lot, you measure nothing!? What’ ไดอะแฟรม ซีล meant by that is: You can measure a lot. But the values are just useful if you can validate them. In everyday life, for example, one may be surprised when the scales at home show a big deviation from those at the doctor?s or the bicycle speedometer deviates many a huge selection of metres from the GPS instrument. The word also often alludes to our tendency to generate an increasing number of data inside our modern world, without considering its evaluation. So as 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 highest accuracy may not be important. In industrial applications, however, it really is precisely this that may 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 if the values are correct.
Traceability to the national standard
The keyword here is thus the traceability to the national standard. Understanding that the respective measuring instrument measures the right value could be of great importance for most applications. For example, ISO 9000 requires that the deviations of the test equipment used should be monitored. Having 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 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 necessary for quality assurance, optimising resource utilisation and reducing energy consumption. Finally, probably the most convincing reason to have 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 in accordance with the German accreditation body
The illustration shows the way the four calibration sequences in accordance with DKD-R 3-3 differ.
The highest standard because of this is 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.
Just what a DAkkS-certified calibration of force measuring instruments means is shown by the example of high-end force transducers, which are employed in calibration machines. In their case, the test sequence follows the EN ISO 376 standard. At ไดอะแฟรม ซีล measuring stages are approached, with a complete 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 price for such a calibration goes hand in hand with this.
Regarding เพรสเชอร์เกจ , 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 can be selected in line with the requirements. WIKA and tecsis also have DAkkS certification because of this.
An additional option for regular calibration may be the non-standardised 3.1 inspection certificate.
Practical examples
An illustrative example of the usefulness of regular calibration may be the checking of hydraulic compression force transducers. These instruments gauge 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, however they may 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 used for monitoring very precise production steps. When pressing in cellular phone displays, for example, both the measuring instruments and their calibration can easily pay back: If one in that process isn’t noticed immediately (for instance, if only the travel is controlled), thousands of euros in material value can be destroyed within minutes.
Adjustment before calibration can be handy
Depending on the instrument, application and regulation, it might 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, an individual has the option of choosing the sort and procedure, both for our own and for third-party products.
Note
On the WIKA website you will 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). In case you have any questions, your contact will gladly help you.
Also read our post
Calibration or adjustment ? Where?s the difference?