The quality of a gearmotor depends on a number of different factors. Aside from elements such as the quality and type of gears in the gearmotor and the type of motor used, housing material also plays a role in determining gearmotor quality and performance.
There are a few common types of materials used in gearmotor housings. These include a variety of aluminum housings, cast iron, and stainless steel. Aluminum housings differ in their fabrication techniques. Some common options for aluminum housings are sand-casting, die-casting, permanent mold casting, and even working from billet aluminum.
Other material choices can include cast iron and stainless steel, but also more pricey options like cast zinc and even injection molded magnesium. So for instance, cast iron makes a good general purpose housing whereas stainless steel housings are more appropriate for corrosive environments or where high levels of hygiene are required. However, special stainless steel housings for washdown in food and beverage applications can cost twice as much or more than traditional and common aluminum or cast-iron housings.
Other factors beside the material itself can also determine quality and performance. For example, material thickness and reinforcement will change the strength of the gearmotor housing and thus its useful life span.