While selecting parts for shaft angle sensing, I often have difficulty selecting magnets to act as the rotating magnetic field for a Hall angle sensor.
I've ended up selecting diametrically magnetized neodymium disc-magnets in the past, but these have some difficulties:
They're very cylindrical which makes it tough to fix them in place rotationally, there is nothing to key against
They don't have any visual indication of installation angle; how can an assembly procedure take this into account?
They seem to have very poor availability
I'm not looking for specific suppliers here, I'm wondering about the general engineering approach: is this a very niche application where I should expect to consult with suppliers, spend the effort getting low-volume quotes, or is there a simpler approach?
I've been wondering whether it would make more sense to use a rectangular magnet, which are obviously easier to tell the direction of polarization, and insert this magnet into a slot cut into the end of the shaft. This would solve the availability and alignment issues.
However, this approach never seems to be used in manufacturer white-sheets for configuring Hall sensors.
What's the typical approach for designing or sourcing an end-of-shaft angle-sensing magnet?
