NdFeB rings are sometimes also known as discs with central holes.
The NdFeB Rings exits in two styles – 'pure' rings and 'countersunk' rings. The holes are centrally located.
The countersunk ring allows for the magnet to be screwed onto another item such that the screw is flush with the magnet end face. The countersink is only on one side of the ring magnet so the A version has the countersunk end as a North Pole and the B version has the countersunk end as a South Pole. If the countersunk ring is to clamp onto ferromagnetic material then either the A or B version can be used. If two rings are to attract to each other such that the countersunk faces are attracted, one ring has to be an A version and the other a B version (unlike Poles attract).
Due to their shape, the ring magnets have a higher permeance coefficient than a same-sized disc magnet. This means they can resist demagnetisation better, making them ideal for repulsive applications.
The magnets are supplied in stock sizes varying from 6mm to 25mm in diameter and 2mm to 20mm in height with holes varying from 2mm up to 15mm diameter. The stock sizes supplied with +/-0.1mm tolerances and exist in axial magnetisation patterns.
We can produce the NdFeB circular rod magnets in different sizes, different grades (strengths and temperature ratings), different coatings/finishes and in axial and diametric magnetisation as part of our custom magnet (made-to-order) service.