Smaller, more flexible enclosures still need to be rugged

Cabinets allow for safe and accessible storage, but can generate dangerous heat.

11/27/2012


Courtesy: HoffmanTechnology advancements are resulting in electronics playing a greater role in the daily activities of business and manufacturing plants than ever before. A direct effect of the additional network and electronics is the growing demand for connectivity and network equipment to be relocated from centralized data centers—where conditions can be carefully monitored and controlled—to localized network and wireless applications,  placing them at the point of control or activity. This increases the potential for exposure to the often harsh manufacturing conditions or environmental elements. To accommodate these changing needs, enclosure solutions have had to adapt to provide more flexible and controlled access, enhanced protection, durability, and performance versatility.

As component size decreases, PCB density increases, allowing more electronics and networking equipment to fit into smaller spaces. Now, control, networking, and security monitoring equipment that once filled full-size electronic enclosures easily fit into a smaller enclosure that can be affixed to a wall or mounted directly onto a machine—freeing up valuable floor space.

Wall-mount cabinets allow manufacturers to safely store electronics where they are needed most, without exposing them to industrial conditions. However, these small, highly dense electronics generate a significant amount of heat. Therefore, the ideal wall-mount enclosure will offer thermal management capabilities, adapt to changing networking requirements, and accommodate a wide variety of applications.

Along with selecting enclosures to complement equipment size and location, cabinet specifiers must also consider the application challenges and environmental conditions that can compromise an enclosure’s integrity. Exposure to extreme temperatures, corrosive agents, or impact can damage enclosures, ultimately subjecting the electronics within to these destructive elements.

Wall-mount enclosures

Ideal wall-mount enclosures will offer thermal management capabilities and accommodate a wide variety of applications. Courtesy: HoffmanWithin industrial facilities, floor space is valuable, and many companies measure productivity and efficiency by dividing the amount of floor space by dollars generated. Consequently, installing a full-size electronics enclosure can take up valuable floor space that could otherwise be designated for equipment or machines and becomes detrimental to plant productivity. Wall-mount cabinets house and protect a variety of electronics and networking devices, while conveniently mounting on walls or machines.

To accommodate the demand for networking flexibility, wall-mount enclosures can be used to extend the data center via intermediate distribution frame (IDF), which further supports remote access points (AP) for wireless applications. An IDF is a free-standing or wall-mounted rack used to manage and interconnect cables between end-user devices and a main distribution frame (MDF).

AP applications utilize dedicated hardware devices that act as a central transmitter and receiver for wireless signals. By supporting both IDF and AP networking applications, wall-mount enclosures aid in extending networks to remote locations to handle a broad scope of activities, such as industrial controls, access control, HVAC, monitoring, security/cameras, communications, building automation systems, and more.

When selecting the ideal wall-mount solution, users should take multiple factors into consideration, such as space limitations, enclosure size, cable management, and any thermal issues. Wall-mount cabinets should provide easy access to equipment. For instance, single-door cabinets offer a cost-effective solution for protecting, securing, and cooling a host of equipment, while double-hinged door cabinets facilitate easy front and rear equipment access, enhancing access to cabling and reducing time to install and connect system components.

Wall-mount cabinets are available in standard sizes and with custom options to support all types of networking and industrial electronics—both 19-in. rack-mounted and traditional back panel mounted. In addition to the enclosure size, users must also consider how far the cabinet will extend from the wall or machine on which they intend to mount the unit. To avoid collisions in public aisle ways, cabinets should typically extend less than 12 in., but requirements can vary depending on application. 

Cable management

Cable management is a crucial aspect in cabinet selection. Proper, efficient cable management provides organization and support. For applications requiring a simple solution, cable knock-outs allow cables to easily enter and exit the cabinet. Alternatively, in demanding applications where the enclosure’s rating integrity must be maintained, gland plates, which are removable sections of the enclosure, offer an outlet for cable egress. Gland plates not only provide cable management without compromising the enclosure, but they also accommodate evolving network needs by allowing cables to be frequently changed or added.

Along with providing environment protection and management for cables entering or exiting a cabinet, internal cable organization minimizes stress points while still supporting frequent cable moves, additions, and changes (MACs). To accommodate these needs, wall-mount enclosures contain vertical and horizontal cable managers. This allows the cabinet to support all categories of networking cables, providing flexible cable management capabilities.

Thermal management is another critical factor when selecting enclosure solutions. Electronics and networking equipment generate heat, requiring thermal management to protect components from overheating. Ranging from simple, passive cooling to complex solutions, thermal management capacities should correspond to the amount of heat generated by equipment being housed. The most advanced wall-mount cabinets combine protection, support, and access with integrated thermal management for a comprehensive enclosure solution. 

Enclosure materials

Protecting electronics and equipment from harsh industrial conditions requires enclosure and cabinet solutions that isolate and secure devices and connections from the surrounding environment. Non-metallic enclosure solutions provide rugged durability and enhanced longevity for applications repeatedly exposed to caustic chemicals or temperature changes, offering an alternative to traditional steel enclosures.

Two prevalent non-metallic options include fiberglass and polyester. Also, non-metallic cabinets allow Wi-Fi signals to freely exit, protecting the equipment without impeding signals.

Fiberglass

Fiberglass is a common non-metallic material used in networking applications, due to its capacity to resist chemical exposure and extreme temperature changes—providing a cost-effective alternative to stainless steel for corrosive environments. Composed of a high-performing, engineered composite resin, fiberglass enclosures are typically formed in one of two ways: compression molding or spray-up process.

Compression molding incorporates precision-designed molds to deliver superior part uniformity and material consistency, and utilizes a material known as SMC, which is a long-glass-fiber pigmented polyester resin. These long fibers provide superior strength and, when formulated with UV inhibitors and aluminum trihydrate, they resist material degradation.

Further, this combination enables the enclosure to achieve the UL 94 5V flammability rating, which classifies the rate of burning, time to extinguish, ability to resist dripping, and whether or not the drips are burning. This rating is the highest performance requirement for a UL 508 enclosure, the Standard of Safety for Industrial Control Equipment.

The second method of fiberglass enclosure forming, the hand lay-up or spray-up process, also delivers similar advantages. The molding used in this process also ensures part uniformity and material consistency, as well as achieves the UL 94 5V flame-resistance rating. Plus, its heavy, unfilled pigmented outer gel coat layer provides rugged protection against environmental contaminates or exposure. 

Polyester

Cabinet design must address the application challenges and environmnetal conditions of the space. Courtesy: HoffmanThe use of hybrid polycarbonate/polyester blends for non-metallic enclosures is a relatively new development. Providing an alternative to traditional non-metallic enclosures, its thermoplastic material delivers high impact resistance, enhanced electrical properties, and superior chemical and moisture resistance.

Unlike fiberglass enclosures, which eventually break under extreme pressure, polyester is engineered to absorb tremendous amounts of pressure without shattering. With its inherent durability, polyester is also less susceptible to scratches and abrasions. Featuring flame-retardant properties, polyester performs well in extreme temperatures and will not ignite when in contact with fire. Further, polyester’s corrosion and chemical resistance enables these units to withstand the highest range of solvents, alkalis, and acids without failure.

Additionally, since polyester produces virtually no dust, it can be easily drilled and punched for holes and cutouts—even in the field—without contamination. By lacking glass particles, polyester is not susceptible to fiber bloom, minimizing the risk of product contamination and skin irritation, as well as reducing wear on tools. Plus, constructed of recyclable, thermal molded components, polyester is an eco-friendly enclosure material. 

Conclusion 

By understanding the available enclosure options, their advantages and performance capabilities, cabinet specifiers can select the ideal solution to perform in virtually any application, from limited spacing to damaging environments. Implementing the proper enclosure is instrumental in maintaining continual network function, which, in turn, improves overall efficiency and productivity. 

Brian Mordick is senior product manager for the Hoffman brand of Pentair Technical Products. 



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