Testing the Mettle of Metalic and Non-Metallic PLC Enclosures

At the heart of today’s automated manufacturing operations are 
programmable logic controllers (PLCs), which are miniaturized computers 
installed throughout a factory floor. These devices receive input from 
sensors throughout the line and use that data to issue commands to 
control machinery operations. Though PLCs are individually protected in 
rugged casing, they often are ganged together in enclosures specified 
according to application-specific needs. Hoffman

Chuck Ross

At the heart of today’s automated manufacturing operations are programmable logic controllers (PLCs), which are miniaturized computers installed throughout a factory floor. These devices receive input from sensors throughout the line and use that data to issue commands to control machinery operations. Though PLCs are individually protected in rugged casing, they often are ganged together in enclosures specified according to application-specific needs.

As with other types of enclosures, those designed for PLCs generally fall into metallic (including stainless steel and aluminum) and nonmetallic (such as polycarbonate, ABS, PVC and polyester) categories. Environmental conditions are a primary consideration for specifiers evaluating their options.

“For many corrosive industrial applications, a specifier’s preferred enclosure material will be stainless steel,” says Matt Steve Graf, Hoffman’s non-metallic product manager. “Stainless steel provides the best corrosion resistance, is available in more size options and is easier to develop into new or custom products.”

Where corrosion isn’t an important consideration, non-metallic products can provide strong protection at a lower cost, Graf says, especially where there’s a possibility of dollies or other equipment banging up against the boxes.

“Injection molded enclosures made from polycarbonate, ABS, PVC or polyester provide the best impact strength of any enclosure material,” he says, adding that on-site modifications are easier with these materials than with metallic options. He notes that polyester and PVC also can hold up in mildly corrosive environments, though all such products can face challenges where bigger enclosures are required. “Injection-molded enclosures do have size limitations in how large they can be made.”


Photo courtesy of Hoffman