In automotive fan motors, the slot commutator is a relatively common commutator type. It consists of a fixed conductive ring and a number of brushes, usually placed at regular intervals in slots on the motor's stator.
The electrical conductivity of graphite is very good, surpassing many metals and hundreds of times that of non-metals, so it is manufactured into conductive parts such as electrodes and carbon brushes;
Specific role of carbon brush
NdFeB magnets are currently the most powerful permanent magnets.