Robust repeatability with the U15 force transducer at Ibertest

Material testing machines are used extensively  for testing metals, plastics and even foodstuffs as a suitable means of  achieving and guaranteeing production quality. Material testing machines are used extensively for testing metals, plastics and even foodstuffs as a suitable means of achieving and guaranteeing production quality. Ibertest in Spain manufactures a wide range of material testing machines with nominal loads from 5 N to 5 MN for the following applications:

1. Tensile testing - for static testing of metallic and non-metallic materials
2. Compression testing - for static testing of building materials
3. Dynamic compression and tension testing
4. Multi-axis fatigue testing.

For reasons of quality as well as traceability to national standards it is periodically necessary to calibrate material testing machines. Calibration is performed on site where the material testing machine is operating. A reference transducer - with a valid calibration according to the ISO 376 international standard for force transducer calibration - is mounted in the machine in place of the test sample. The calibration procedure (in accordance with ISO 7500-1) provides the instructions for the calibration of the material testing machine. Different forces must be applied incrementally, and the transducer has to be fitted in different mounting positions. The results are given in a calibration certificate, indicating the class of the machine, its uncertainty factors and characteristics. The traceability of an Ibertest calibration certificate is documented by ENAC (Spanish calibration service) accreditation. Multilateral agreements ensure that the certificates of secondary ISO 17025 accredited calibration laboratories are accepted worldwide. The first calibrations using HBM’s new U15 force transducer have now been accomplished at Ibertest. The transducer was specially selected due to its high capability of up to 1MN in tension and compression. It is also a highly robust transducer which is ideal for use on site and with a high accuracy class of 0.5 according to ISO 376. The mounting attachments (tension and base adapters) also help to guarantee excellent results, like high repeatability in different mounting positions as well as the minimizing of interpolation errors. Two additional, available options are helpful for on-site calibrations: A protective cover around the plug is useful for harsh operational conditions. And, TEDS - the transducer electronic data sheet - inside the transducer enables amplifiers to be set up quickly and economically. To ensure enhanced repeatability and accuracy, Ibertest’s calibration service is equipped with automated, computerized systems; semi-automated sytems are also available for machines with older measurement devices. The measuring chain comprises HBM’s MGCplus amplifier and a notebook PC. This enables calibration protocols to be issued in real time. Computer-driven calibration chains provide noise-free results and are protected from eventual human error. As a manufacturer Ibertest perform both force calibration (from 5 N up to 5 MN), and displacement calibration (0 to 50 mm). They additionally offer to routinely carry out maintenance work on material testing machines to ensure operational safety. After a service the customer is assured that his material testing machine is in compliance with the quality regulations according to ISO 9000 standards and that the results of his material tests are correct.