The cast iron frame forms the outer shell of an electric motor and sets its mechanical strength. Made from grey cast iron, this frame is heavier than aluminium but far more rugged; with its ability to damp vibration and spread heat evenly, it is the standard choice for heavy industrial motors.

Cast Iron Versus Aluminium

An aluminium frame is light, cools faster and is an advantage on small-kW motors. A cast iron frame, by contrast, resists mechanical impact, torsion and vibration far better. On demanding lines such as crushers, pumps and compressors, frame rigidity keeps the bearings aligned, which means long life. That is why cast iron stands out at medium and high kW.

Vibration Damping and Quiet Running

The high internal damping of cast iron absorbs the vibration energy produced during operation. This both reduces noise and lowers the fatigue load on the windings and bearings. On vibrating floors and outdoors, this property noticeably lengthens the interval between failures.

Heat Management and Protection

The mass of the cast iron frame acts as a thermal buffer; together with external fins and IC411 fan cooling, the winding temperature stays under control. Combined with Class F insulation and IP55 protection, the frame safely shields the windings in dusty and humid environments.

Sourcing a Cast Iron Frame Motor

DRG Motor offers cast iron three-phase motors from 0.55 to 355 kW in IE3 efficiency class, 2/4/6 poles and B3/B5 mounting options. Share the power, speed and operating environment of your application and we can settle on the most suitable frame and configuration together.