Materials and Configurations (Electric Motors)

3.3.1
The housings come in cast iron; in rolled, wrapped, and tube steel; and in both cast and extruded tube aluminum.
Cast Iron. Castings are usually found on motors of 3 hp and larger. The service application is in the industrial market where severe conditions may exist. Materials are usually of about 30,000 lb/in2 tensile strength and are free machining. In most cases, the mounting feet are cast as part of the housing.
Steel. As mentioned, steel housings come in several configurations—rolled, wrapped, and tube. The material is usually SAE 1010 to 1020. This type of housing may be found on all types and sizes of motors.
Aluminum. This material is also found on most motor types and sizes. The cast housings may be produced for a size as large as NEMA 360 but are usually not found on motors rated below 3 hp.
The tubing may be found on the smallest motors up to about 25 hp. The material
is usually SAE 6061.