Drives and Controls Magazine
‘Revolutionary’ encoder adapts to any shaft size
Published:  09 December, 2013

The German sensor manufacturer Baumer has developed a “revolutionary” magnetic encoder technology that provides precise angular and speed measurements from large shafts of almost any diameter.

The patent-pending HDmag flex encoder consists of a magnetic belt with high-precision encoding, which is customised in Baumer’s factory to suit the shaft diameter, and a matching sensing head. It is available in incremental and quasi-absolute variants.

For transport, the belt can be wound tightly. On site, it is buckled onto the shaft and secured in place easily and quickly using a snap lock. The shaft does not need to be detached for initial installation or later servicing, thus saving costs.

Sensors in the read head are aligned in the factory to match the shaft diameter. Intelligent real-time signal processing provides the specified signal resolution at all times, independent of the shaft diameter and tolerance.

A 3mm-wide air gap between the sensing head and magnetic belt, and a tolerance for up to ±5mm of axial backlash, simplify alignment. The bearingless, non-contact design of the sensing system is said to ensure a wear-free service life of many years.

Baumer's magnetic belt encoder can accommodate shafts of almost any size

The encapsulated electronics in the sensing head are unaffected by dust, dirt, shocks or vibration. In its standard incremental configuration, the encoder can produce up to 131,072 pulses per revolution. The quasi-absolute variant provides a maximum position resolution of 20 bits, and additional digital speed signals with a maximum resolution of 18 bits.

A multi-colour LED indicator shows the encoder status and, during set-up, warns if the distance between the belt and sensor is too large.

Baumer says that the encoder can be produced in any size almost immediately, and single versions can be produced without entailing extra initial costs.