Enclosures: Think Outside the Box

Non-Metallic Enclosures are Gaining Market Share, but Sheet Metal Still Has Distinct Manufacturing Advantages

Non-metallic enclosures are gaining market share, but the relatively flexible manufacturing advantages of sheet metals will limit the increase until weight-reduction is more important than cost.


Virtually all industrial machines, robots and skid-mount systems contain a number of enclosures. These enclosures range from the very small, housing a few terminal blocks, to the very large, housing power control and distribution equipment. Enclosures also range widely in cost with the price dependent on size, the materials it's constructed from and customization.

The customization trend is perhaps one of the most pronounced for industrial applications because OEMs tend to design equipment around major items of mechanical and process equipment. Enclosures need to fit into the available space.

Customization not only encompasses an enclosure's external dimensions and the materials it's constructed from, it also covers such design characteristics as access and available space for mounting internal and front-panel components. As with most machine components, enclosures must be cost-competitive, while OEMs specifying them need quick answers about cost and delivery.

Stahlin (http://www.stahlin.com) aims to satisfy OEM enclosure specification requirements with an on-line configuration and quote delivery system. Industrial OEMs can log onto the company's web site and download detailed drawings of the company's enclosures.

The drawings then can be modified using AutoCAD, SolidWorks or any other .dxf file format-compatible software. "Our customers can make any drawing modifications that they want except for changes in the overall dimensions of the enclosure itself," says Teresa Ramirez, Stahlin's national sales manager.

Once modifications are made, a designer can attach the updated drawings to an e-mail. Stahlin will respond with a firm price quote within 24 hours.

Customization options can include NEMA rating, silk screening, locking mechanisms, holes/cutouts, EMI/RFI shielding, color and the size and location of front-panel windows.

If a machine builder requires a customized enclosure with dimensions different than those listed on the web site, Stahlin can accommodate those requests, albeit with a longer turnaround time. Customization even can encompass unique non-metallic material formulations.

One of the constants of metallic enclosure design has been the parallel sides and perpendicular edges that provide that classic boxy appearance.

A new design concept from Bebco Industries (http://www.okbebco.com) eliminates perpendicular edges. "Our rolled and radius-edge design produces an enclosure with rounded corners, unique in appearance and aesthetically pleasing," claims Michael Baucom, sales and marketing coordinator for Bebco.

According to Baucom, rounded corners are important for reasons other than appearance. "An enclosure with sloped or rounded surfaces is much less likely to be used as a table top to catch clutter, or as a place to carelessly perch a soft drink that can spell disaster if spilled onto an electronic instrument," argues Baucom.

It's also a safety concern. An inadvertent collision between the sharp corner or edge of a rectangular enclosure and an employee's head can result in an OSHA-recordable injury.

Sharp corners and edges also tend to collect dirt and dust. "With continuing efforts to make pharmaceutical and food-processing areas more germ-free, soft edges are a more-effective solution," adds Baucom. "Nothing traps germs and contamination like a sharp inside corner, and crevices and cracks also factor highly in workplace contamination."

Bebco combines rolled and radius edges with germ-fighting coated stainless steel such as Algon. "Stringent health and cleanliness standards are being tightened and more closely scrutinized by regulatory agencies and a more health-conscious public, so the advantages of soft edges are becoming increasingly important," concludes Baucom.

Bebco and Stahlin provide products and services that extend and improve on current concepts in enclosure manufacturing. Other suppliers are speculating on future trends that may shape enclosure requirements.

"Non-metallic enclosures will win increased consideration as alternatives to painted sheet metals and stainless steel in corrosive environments or where aesthetic requirements dictate," says Ed Calhoun, engineering manager at ITS Enclosures (http://www.itsenclosures.com).

Calhoun says non-metallic enclosures are gaining market share, but the relatively flexible manufacturing advantages of sheet metals will limit the increase until weight-reduction is more important than cost.

"The early acceptance of computerization increased the need for enclosures to support and protect sensitive electronics," continues Calhoun. "But development of electronics hardened for direct application in industrial environments reduced the need for the additional protection afforded by an enclosure. Implementation of embedded control and monitoring devices with wireless communication capabilities will further reduce traditional enclosure requirements. The enclosure will become a custom housing designed to support environmental protection and the advanced thermal requirements of each device."                                          

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