Controller interface and strain gauge developments from HBM
15 October 2010

Measuring only 43 x 47mm in size, new rosette form strain guages from HBM (pictured) are believed to be the smallest optical strain gauges in the world. The K-OR rosette comprises three measuring grids – at angles of 0°, 60° and 120° – which enables the absolute value and direction of any mechanical stresses to be defined.
Optical strain gauges are based on so-called fibre Bragg gratings, and use light – rather than electrical signals – to measure strain. This makes them highly suitable for applications where it is inadvisable to use conventional, electrical strain gauges, such as those located in hazardous areas or where there is high voltage or powerful electromagnetic interference.
Optical strain gauges are also suitable for testing fibre composites because tests of up to 10 million load cycles with a strain of ±5.000 µm/m are now possible. Conventional, electrical strain gauges are not able to achieve this.
Detecting measurement data with optical strain gauges is very easy and HBM provides a comprehensive range of equipment and accessories to simplify data capture and subsequent analysis from a single source.
These include interrogators through to the data acquisition software catmanAP, which includes a special EasyOptics module for optical strain gauges.
Meanwhile, HBM has developed an IPM software interface for its MP85A FASTpress and MP85AS EASYswitch process controllers enabling easy connection to process data management software. The IPM interface ensures seamless integration of the controllers so that production data can be transmitted directly to a quality assurance server for visualisation and archiving.
The MP85A FASTpress and MP85AS EASYswitch process controllers are used for monitoring press-fitting processes (FASTpress) or implementing switch checks (EASYswitch). They acquire and evaluate measured values from the transducer to monitor production quality. IPM software has been developed by CSP GmbH & Co KG and is used by many leading manufacturers in production monitoring, quality control and documentation.
In addition to the overall status – whether the component is OK or Not OK – up to nine evaluation windows or complete curves of, for example, a press-fit process can be transmitted. Data can also be observed in real time via a web browser allowing the press-fit process to be monitored without manually operating the production machinery.
In the event of production problems an SMS or email is automatically sent enabling swift remedial action to be taken. This rapid error evaluation allows product quality to be improved. The data can also be analysed to determine trends in measured values, permitting corrective action before faulty parts are produced. All data are permanently stored in the IPM software database so that seamless traceability of produced parts is guaranteed.
Measuring only 43 x 47mm in size, new rosette form strain guages from HBM are believed to be the smallest optical strain gauges in the world. The K-OR rosette comprises three measuring grids – at angles of 0°, 60° and 120° – which enables the absolute value and direction of any mechanical stresses to be defined.
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