What material is the commutator of a DC machine usually made of?

The commutator of a DC machine is typically made of copper bars because copper has excellent electrical conductivity, which is essential for efficient electrical performance. The commutator serves the crucial function of reversing the direction of current in the armature winding as the machine operates. This reversal is necessary to maintain a unidirectional (DC) output in the machine.

Copper not only provides good conductivity but also possesses favorable mechanical properties, allowing it to withstand the wear and tear associated with the constant contact and friction involved in the commutation process. The choice of copper helps minimize energy losses and increases the overall efficiency of the DC machine.

Other materials, such as aluminum, while conductive, do not match the conductivity and durability required for the high-wear environment within a commutator. Steel is typically used in other parts of the machine, like the frame or core, but lacks conductivity suitable for a commutator. Gold, although an excellent conductor, is prohibitively expensive and unnecessary for the function required in this application. Thus, copper emerges as the ideal choice for manufacturing the commutator in DC machines.