Permanent rare earth magnets are not standard products and they could come in all shapes and sizes according to a great variety of applications from customers.
Some magnets are sintered into block or cylinder material and then through different machining methods as below, they can be made into the correct shape and size.
1. Wire-electrode cutting – to cut raw material from big into small, it is for curved face machining and big size plane
2. Slice – to cut raw material from big into small, it is on the direction of a plane
3. Surface grinding – to ground plane for high dimensional precision
4. Forming grinding – to process a curved face which has a high requirement for precision
5. Ultrasonic drilling – to process small hole
6. Chamfering – to process the sharp corner of product into the round or bevel angle.
7. CNC – to process very complex magnet shape.
8. Trepan boring – to process large hole
Some rare earth magnets are cast into a mold to get the specific magnet shape, but ultimately, they need grinding to achieve final dimensions.
They can be made into a bar, rectangle, block, horseshoes, round, rings, donuts, disc, segment, bread, multi-fingered rings or other custom shapes.
Every shape of magnets is customized based on their application. If conditions allow, use magnet as simple as possible, for using complex shape magnet will increase a lot of your cost.
The shapes of magnets determine how the magnetic field lines are arranged outside of the magnet, which also affects where the magnet can be used.
When it comes to the neodymium magnet, we will think of the horseshoe magnet immediately. Although in practical application, we hardly see it. It’s still considered the symbol for a magnet and used as teaching tool nowadays.
Neodymium arc magnets, segment or bread shape magnets are usually used on different motors because they can be fixed to round rotor or stator.