Why is a squirrel-cage rotor rugged and economical to make?

The squirrel-cage rotor is considered rugged and economical primarily because it does not require electrically insulated windings, which simplifies its construction compared to other rotor types.1

In these motors, solid conductors are placed in rotor slots and shorted together at each end by conducting end rings. Because the conductors do not need to be insulated from the iron core, the manufacturing process is streamlined. For smaller motors, the entire assembly—including the conductors, end rings, and a cooling fan—can be produced as a single aluminum casting. For larger machines, the rotor is typically constructed by welding or brazing bars of copper, aluminum, or brass to end rings of a similar material. This straightforward design results in a highly durable component that is significantly more cost-effective to produce than rotors that require complex, insulated windings.1