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Plastic Electrical Enclosures: Solutions for Extreme Customization

Tue, 10/04/2011 - 11:33am
David Crooks, General Manager, Fibox Enclosures

David CrooksRather than create a custom package, OEMs often choose to modify or customize a standard enclosure to lower development cost, reduce final product cost, and achieve a faster time to market. Seeking a customized solution, OEMs request enclosure manufacturers to do precision machining of standard enclosures. The trend toward packaging multiple functions into a single enclosure has increased the complexity of these modifications. While this trend appears to limit using standard enclosures, in reality, advances in customization methods have increased using modified standard enclosures, and in particular, plastic enclosures. Let’s examine 3 designs that resulted in extreme customization. We’ll take them in order of increasing complexity.

Customized Fibox CAB enclosure for Liquid Process Control
This OEM develops liquid automation machinery based upon innovative chemical metering. The unit contains an operator interface, a power supply, pump and metering control modules, and optional externally mounted peristaltic pumps.

Figure 1 -  Customized Fibox CAB enclosure for Liquid Process ControlFigure 1 shows the modified front cover of a Fibox CAB enclosure. The rectangular cutout for the readout and round holes for tactile-feedback pushbuttons require critical positioning as they mate to a PCB assembly mounted using the 4 countersunk holes. Other groupings of precision hole patterns mount optional peristaltic pumps. The enclosure base also has extensive customization on all 4 sides. An overlay is applied to the cover, sealing all openings and restoring the ingress rating of the enclosure.

The modifications for this OEM consisted of precision hole patterns requiring tight tolerances on multiple sides of the enclosure. The next application goes beyond.

Customized Fibox MNX enclosure for Water Level Detection
This OEM develops indirect fluid level measuring instruments, based upon innovative radar technology. A compact package for moderately hostile environments was needed for a new design.

Figure 2 - Customized Fibox MNX enclosure for Water Level DetectionFigure 2 shows a Fibox MNX enclosure with extensive modifications. The large rectangular cutout holds an LCD display and the round holes below mount tactile-feedback pushbuttons. Threaded metal standoffs mount the operator interface.

Additional modifications for this OEM required precision holes and cutout patterns on 4 sides of the cover and 2 sides of the base. Using a secondary operation, threaded standoffs were press fit into the cover interior for mounting electronic PCBs.

Our third application moves the bar even farther.

Color Customized Fibox ARCA enclosures
Use of color is the ultimate extension of extreme customization. Color is often associated with application function, e.g. safety related equipment. There are specific colors associated with industry segments, e.g. the solar industry prefers light colored (often white) enclosures. An OEM’s brand identity is often defined by specific colors. Color provides uniqueness and differentiation, and OEMs are demanding more cost-effective implementation of custom color.

Figure 3 shows three applications of custom color. The blue enclosure is used for equipment monitoring water chemistry for the commercial swimming pool industry. The red enclosure is used for fire alarm pump control equipment. The white enclosure is for the solar industry. All of these enclosures also have extensive customized precision hole patterns.

The entry point for custom color is dependent on unit volume. The good news is that manufacturers of non-metallic enclosures are continually reducing that entry number with new cost-effective color molding techniques. 

Figure 3 -  Color Customized Fibox ARCA enclosures

Steps for Customization Success

1. Initiate early contact with the enclosure manufacturer.

The engineer should look for a manufacturer with a wide selection of standard enclosures. The manufacturer’s technical staff can guide the engineer to the correct enclosure for the application.

2. Verify the manufacturer’s level of customization expertise.

Most enclosure manufacturers offer customization, but achieving extreme customization in high ingress rated enclosures requires greater expertise and equipment designed for the task. This is especially true for custom color molding.

3. Understand the factors impacted by cost.

Engaging the manufacturer early is crucial. Understanding what is possible, and what it costs, ensures that selecting extreme customization over a custom enclosure is the correct choice.

4. Design using the manufacturer’s documentation and CAD files.

Enclosure manufacturers supply CAD files for their enclosures. Using the manufacturer’s files ensures dimensional accuracy, simplifies drawing interpretation, and eliminates errors.

Conclusion
Despite adding density by packaging multiple functions into a single enclosure, despite adding complexity and precision to modifications, despite more demanding environments, OEMs find that customized standard enclosures continue to increase their cost-effectiveness.

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