Magnetic metrology 

> Ring Magnets

Bogen has custom-tailored ring magnets  for a variety of customer utilisations in the areas of automation and automotives:

• For simple magnetic systems, such as for the quick ascertaining of the rotation speed of an engine shaft, ring magnets made from hard ferrite in a variety of sizes are on stock. The ring magnets can be delivered complete with an aluminium hub for direct mounting at the OEM. To do this, the hard ferrite rings are first glued to the hub and then the magnetically separated. Through the high fitting accuracy of the hub on the inner diameter, measuring error through eccentricities can be precluded due to the identical mounting conditions.
• For utilisations with customer-specific diameters and small quantities, rings are used that are first affixed to the tape substrate and then magnetised.
• If a high rotational frequency is required or if there are difficult environmental conditions, for instance in automobile engine uses, multipolar wheels are used that have a layer of elastomers vulcanised on them.
• For the most demanding magnetic parameters like the exactness of graduation and single pole accuracy, as are found in motor spindles in machine tools, a newly developed procedure for error compensation is utilised. This allows for exactness of graduation down to 10 arc seconds.

Thanks to the highly flexible magnetisation technology with real angle graduation, the pole value for every ring magnet can be determined freely. This makes it simple to make an optimal fit of the magnetic graduation to the required impulse value of the customer's sensors.

Magnetisation is possible both radially on the circumference as well as axially on the face of the ring.
The existing coding equipment allows for the economic production of prototypes and small series as well as of mid-sized and large productions. High-precision coding equipment is being developed for new utilizations for mid-sized and large shafts, with which circumferences up to 1200 mm can be magnetised.