Test and calibrate with one testing machine

Thanks to their technical versatility, Zwick materials testing machine can be used for calibration in addition to their accustomed role in destructive testing. Combining the two functions in a single machine reduces both overall investment and maintenance costs. A typical application is as a calibrating machine for external force sensors. The testing machine’s function in this case is to compare the force sensor installed in it with another load cell and determine the deviation present. In a second step the external sensor is corrected (adjusted) to achieve the specified tolerance.

An example of this can be found at HKM-Messtechnik, a medium-sized internationally active company based in the German town of Freiburg, near the border with France and Switzerland. HKM-Messtechnik develops and produces force-measurement components and systems and employs a Zwick electro-mechanical testing machine to test and calibrate these products, using forces up to 2,000kN. Force-measurement components and systems have many fields of application, including such diverse sectors as medical engineering, the construction industry, mechanical engineering, agriculture, automotive testing technology, aerospace and logistics.

The advantages of using a Zwick materials testing machine are clear. In addition to achieving savings on capital and maintenance costs by using the same machine for both calibration and testing, the versatility and flexibility of Zwick testing machines (available up to 2,000kN capacity as standard) are exploited to the full.

The Frauenfeld (Switzerland)-based sensor manufacturer Baumer also uses a Zwick materials testing machine. At Baumer, testing with a load cell up to a maximum force of 400kN is divided into load cycles, adjustment cycles and measurement cycles. It is possible to test sensor sensitivity, output signal and supply voltage at the same time. During evaluation of the test, various linearity errors are calculated, the linearity graph (errors over load) is displayed and calibration reports are printed out.

The open interface in testXpert allows data exchange of results with all established formats (e.g. NI Diadem, ASCII, Excel). Key technical aspects of the testing machine include crosshead positioning accuracy up to 0.5 μm, extremely low test speeds and high stiffness. Load cells range from Class 1 to 0.5 to 00.

Additional companies using Zwick testing machines for calibration include Liebherr-Aerospace GmbH in Lindenberg, Germany, and Hirschmann Automation and Control.