Term List (ABC)

Core

A core is a path of magnetic flux. It is made of iron. Moreover, a core used to combine two magnets with magnetic flux is called a yoke.

There is a difference in accessory ingredients between iron for mechanical structures and that for cores.
Iron for mechanical structures contains carbon (C), while iron for cores is mixed with silicon (Si) and called silicon steel.

A motor has a stator core and a rotor core, and a magnetic circuit is established through the air gap between them.

Since the magnetic pole of the stator core configuring the magnetic circuit of winding-field DC motors is excited by direct current, the core does not need to be laminated; soft steel is used instead.
On the other hand, laminated core is used for a rotor core configuring the armature circuit as the flux changes with rotation. Also, permanent magnets are often used for the magnetic pole of compact DC motors.

Cores for the stator of synchronous motors and the stator and rotor of induction motors are excited by alternating current, therefore laminated core is used for each of them.