It houses the armature conductors or coils and causes them to rotate
and hence cut the magnetic flux of the field magnets. In addition to this, its most
important function is to provide a path of very low reluctance to the flux through the
armature from a N-pole to a S-pole. It is cylindrical or drum-shaped and is built up of
usually circular sheet steel discs or laminations approximately 0.5 mm thick. The slots
are either die-cut or punched on the outer periphery of the disc and the keyway is
located on the inner diameter as shown. In small machines, the armature stampings are
keyed directly to the shaft. Usually, these laminations are perforated for air ducts which
permit axial flow of air through the armature for cooling purposes.