Measurement accuracy and precision form the foundation of reliable measurement technology. Correct demagnetisation plays a key role in ensuring accurate measurement results, especially for transducers. The following technical article highlights the various aspects of demagnetisation and its practical applications.
The basics of magnetisation and its effects on measuring transducers
Magnetic remanence is a fundamental challenge in measurement technology. Measuring transducers in particular react sensitively to residual magnetic fields that can build up in the material. This residual magnetisation is caused by external magnetic fields or the normal operation of the measuring devices themselves. Various physical effects play a role here: The Weiss districts in the material align themselves and partially retain this alignment.
Magnetic materials exhibit different behaviours with regard to remanence. Soft magnetic materials, which are often used in measuring transducers, have a lower remanence, but can still be magnetised by external influences. The resulting residual magnetisation influences the transmission behaviour of the transducer and leads to measurement deviations.
Why demagnetisation is important for measuring transducers
Effects on the measurement accuracy
Residual magnetism in measuring transducers causes systematic measurement errors. These deviations are caused by distortions in the transmission characteristic of the transducer. The residual magnetic field is superimposed on the actual measurement signal and leads to non-linear distortions. This effect is particularly critical with small measurement signals, where the relative influence of remanence is particularly strong.
The problem is exacerbated with consecutive measurements. Without intermediate demagnetisation, the remanence effects add up, which increases the measurement deviations. Precision measurements therefore require regular demagnetisation cycles to ensure the accuracy of the measurement results.
Economic aspects of incorrect measurements
Inaccurate measurements due to remanence effects have considerable economic consequences. Incorrect measurements lead to rejects in production if good parts are incorrectly classified as rejects. Conversely, faulty parts can pass through quality control, leading to complaints and warranty claims.
Regular demagnetisation significantly reduces these risks. The investment in professional demagnetisation systems pays for itself by avoiding error costs. In addition, the improved measuring accuracy increases process reliability and enables tighter tolerances in production.
Modern demagnetisation processes at a glance
Thermal demagnetisation
Thermal demagnetisation makes use of physical material properties. When heated above the Curie temperature, the material completely loses its magnetic properties. During controlled cooling, the magnetic domains arrange themselves randomly, causing the remanence to disappear. This process is particularly suitable for smaller components and sensors.
The process requires precise temperature control and a protective atmosphere to prevent oxidation. Modern systems work with infrared heating or induction heating for fast, even heating. The cooling rate has a significant influence on the quality of the demagnetisation.
Alternating field demagnetisation
Alternating field demagnetisation works with alternating magnetic fields of decreasing amplitude. The process is based on the gradual remagnetisation of the material. The magnetic domains follow the external field and take on increasingly random orientations as the field strength decreases.
The frequency and amplitude of the alternating field are decisive for the effectiveness. Digital controls enable optimised demagnetisation cycles for different materials. The field geometry is adapted to the component shape using special coil systems.
Automated demagnetisation systems
Modern demagnetisation systems integrate various methods into automated processes. Sensors continuously monitor the residual magnetisation and control the demagnetisation process. Robot systems enable integration into production lines with high throughput.
The systems document each demagnetisation process for quality assurance purposes. Various demagnetisation programs can be called up for specific materials. Network connection enables centralised monitoring and control of several systems.
Practical applications of demagnetisation
Demagnetisation in quality control
Quality control places special demands on the measuring accuracy of transducers. Precise measurement results are essential for reliable good/bad sorting. Regular demagnetisation of the measuring transducers ensures constant measuring conditions over long production cycles. The integration of demagnetisation into the test sequence plays an important role here.
Automated testing systems carry out demagnetisation between the measuring cycles. The cycle time of the test determines the requirements for the speed of the demagnetisation process. Modern systems optimise the parameters of the demagnetisation process according to production requirements.
Applications in research and development
Research institutions require maximum measurement accuracy for their experiments. The demagnetisation of instrument transformers is carried out according to strict protocols. Precise measuring conditions play a decisive role, particularly in materials research and the development of new sensor technologies.
Special demagnetisation processes enable the investigation of magnetic material properties. The analysis of demagnetisation behaviour provides important findings for the development of improved transducer technologies. Scientific measurement series require documented demagnetisation cycles to ensure reproducibility.
Preventive measures against unwanted magnetisation
Correct handling of instrument transformers
Proper handling of measuring transducers prevents unwanted magnetisation. External magnetic fields, for example from electric motors or transformers, must be avoided. Correct storage of the transducers takes into account magnetic shielding and sufficient distances from magnetic materials.
Training courses sensitise staff to the correct handling of the measuring devices. Standardised work instructions define handling regulations and protective measures. Regularly checking the working environment for sources of magnetic interference is one of the preventive measures.
Regular maintenance and calibration
Systematic maintenance intervals include checking the magnetic properties of measuring transducers. Calibration also includes checking the remanence. Any deviations detected lead to immediate demagnetisation and recalibration of the affected transducers.
Documented maintenance processes ensure the traceability of all measures. The maintenance history enables the analysis of long-term trends and the optimisation of maintenance intervals. Regular functional tests of the demagnetisation devices are part of the maintenance scope.
Future prospects and trends
Innovative technologies and processes
New developments are aimed at more efficient demagnetisation processes. Adaptive systems automatically adjust the demagnetisation parameters to the material properties. Quantum sensors enable the precise measurement of the smallest residual magnetic fields and optimise the demagnetisation process.
The miniaturisation of demagnetisation technology opens up new fields of application. Integrated demagnetisation functions in measuring transducers prevent remanence effects during measurement. Energy-efficient processes reduce the consumption of resources during demagnetisation.
Digitalisation and Industry 4.0
The networking of demagnetisation systems enables central monitoring and control. Digital twins simulate the magnetic behaviour of instrument transformers and optimise demagnetisation strategies. Artificial intelligence supports the detection of anomalies and predictive maintenance.
Cloud-based systems collect process data and enable cross-location analyses. Integration into manufacturing execution systems (MES) automates quality assurance. Real-time data on remanence flows into process control.
Conclusion and recommendations for action
The correct demagnetisation of instrument transformers forms the basis for precise measurements. The selection of suitable methods depends on the specific requirements of the application. Preventive measures and regular maintenance ensure long-term measurement accuracy.
The continuous further development of demagnetisation technology opens up new possibilities for quality assurance. Digitalisation and networking optimise processes and increase efficiency. Investments in modern demagnetisation systems pay off through improved measuring accuracy and reduced error costs.