The importance of calibration in test and manufacturing

Thomas North, Calibration & Applications Engineer explains about the importance of calibration to engineers and manufacturers involved in every aspect of measuring technology.

Calibration accurately determines the correlation between the input and the measured output of whatever quantity an instrument is measuring under specified conditions. This then determines the accuracy of the instrument and the results can then be documented. It is very important, particularly for companies meeting ISO 9001 standards – the ultimate global benchmark for quality management – since it ensures that the equipment is working within its correct specifications.

The fundamental benefit of calibration, when done correctly, is the traceability and standardisation of all measured quantities needed to test any structure or device. It is important for companies to prove traceability to national standards. Traceability means a calibration certificate covering the test equipment can be displayed proving that the equipment meets the appropriate standards.

According to the International Standards Organisation, “ISO 10012 specifies the generic requirements and provides guidance for the management of measurement processes and metrological confirmation of measuring equipment used to support and demonstrate compliance with metrological requirements”. All on-site working standard calibrations done by HBM meets the ISO 10012 standards.

Over the past several years there has been a significant movement in industry towards universal amplifiers, such as HBM’s QuantumX range. A universal amplifier is one that can be used for gathering data covering a wide range of measurements from numerous different technologies. The advantage of this approach is that engineers benefit from far greater flexibility while the capital cost outlay is reduced. However, each channel must be calibrated for each of the possible measurements and technologies that might be used.

HBM’s MX840 is an 8-channel universal amplifier from the Quantum X range. It is capable of accepting inputs from a wide range of different signal types including voltages, ½ Bridge, and full bridge giving users tremendous flexibility. Calibrating one of these machines requires 13 steps per channel so that each MX840 module requires a total of 104 calibrations to ensure that it provides the traceability required in modern industry. Calibrating one of these instruments can take a lot of time and expertise to ensure the calibration is carried out properly.

Previously this could have meant excessive downtime and loss of production as the measuring equipment was removed and sent to a calibration laboratory. However, it is now possible to have most data acquisition equipment calibrated on site.

HBM offers a comprehensive travelling calibration service based on the so-called “Blue Tower” that houses all of the complex calibration equipment needed to complete the service on-site and issue a properly authenticated calibration certificate. The “Blue Tower” enables HBM’s team of highly qualified engineers to calibrate a range of high-end data acquisition equipment including the MGCplus, QuantumX series of modules, Spider8, CANhead and the single channel SCOUT55.

Once any DAQ equipment has been properly calibrated an electronic copy of the calibration certificate is sent by email directly to the customer. A signed copy of the calibration certificate is sent out separately. The security of every customer’s data is very important to HBM and a back up of all calibration data is saved on central servers in both company’s UK headquarters in Harrow and its international headquarters in Darmstadt, Germany.

In addition to calibrating HBM equipment in the field, the HBM UK team can also calibrate SoMaT equipment, such as the eDAQ, although this service is performed using a different set of calibration equipment based at Harrow. Equipment calibrated by either calibration tower that fails to meet the calibration standards is sent for repair.

HBM’s on-site service is an extension of one of the best-known and most capable DAkkS standards calibration labs worldwide, which is based at HBM in Darmstadt. Its calibration service provides very high accuracy with measurement uncertainty ranging from 0.005% to 0.02% of the actual value. In addition the calibration service covers a range from 2.5 N to 5 MN for tensile and compressive force; this is the largest range available through DAkkS.

This laboratory is also used to ensure the continued accuracy of the “Blue Tower” as it is returned annually for its own calibration and upgrading to incorporate any recent changes to HBM’s product line up. The SoMaT calibration tower is also checked annually in a similar manner, although this is carried out locally.

HBM recommends that calibration be undertaken approximately once a year for electronic devices and at a maximum interval of two years for transducers although, ultimately, the end-user is responsible for determining calibration intervals. HBM offers maintenance contracts and additional support such as hardware, software and training to reduce the total cost of ownership while ensuring continued reliability and conformance with national standards.

HBM

Founded in Germany in 1950, HBM is today the technology and market leader in the field of test and measurement. HBM’s product range comprises solutions for the entire measurement chain, from virtual to physical testing. The company has production facilities in Germany, USA and China and is represented in over 80 countries worldwide. 

For more information, please visit www.hbm.com