Cases & enclosures PRECISION MEETS
PERFORMANCE SPECIFYING METAL ENCLOSURES FOR HIGH-END INSTRUMENTATION
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t is said that elegance is deeper and more enduring than beauty because it is characterised by precision, sophistication and simplicity. Such excellence is a key factor in the innovation of advanced instrumentation – especially when it is intended for niche applications.
And the more sensitive the electronics, the greater the demands placed on the enclosure in terms of protection and aesthetics. Cutting-edge instrumentation calls for a superior enclosure that does much more than simply safeguard fragile circuitry. It must showcase and differentiate the leading technology, underlining its quality from the outset.
Not all aluminium electronic enclosures are created equal. There are certain design nuances that separate premium standard and customisable housings from their more prosaic counterparts. But first come some fundamental questions... What form will your electronics take? Will you be slotting modules and Eurocards into a 42/84HP subrack? Or will you mount the components directly on PCB pillars and/or guide rails? Subracks slot neatly into a desktop mini-rack, offering a well-structured, modular housing with good torsional strength. The spacing of modules is fixed, allowing for controlled airflow and more predictable management of temperatures. Fans or convection paths can be designed around evenly spaced, vertically mounted cards.
Direct mounting is generally lighter, as it avoids the additional mass of the subrack. This can be better for portable or weight-sensitive applications. It is also more cost-effective. Look for enclosure ranges that include both mini-racks and ‘direct mount’ models in plenty of standard sizes: a shared design language helps you to maintain styling consistency between different devices. Ranges such as METCASE’s TECHNOMET desktop instrument enclosures and TECHNOMET 19” mini-racks exemplify this principle. Both are based on the same design ethos, creating an enclosure with front and rear bezels that fit flush with the main case body for a smooth appearance. The fixings are hidden beneath snap-on trims in the bezels that frame the front and rear panels. Bezels are a key feature of premium enclosures but there are pros and cons. They look very smart – but they can limit the options when it comes to custom sizes. Not so with the TECHNOMET family
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of enclosure models which can be specified in custom heights, widths and depths thanks to their clever design.
If subracks are not used, then the choice for direct mounting of components comes down to pillars or guide rails. The main advantages of pillars are their low cost and straightforward design. They require minimal machining of the enclosure and allow the board to sit flat, making cable routing and connector mounting easy. This method is robust for one-off designs or small production runs, especially when boards are not intended to be removed or swapped frequently.
The drawbacks are that pillars provide no inherent guidance during insertion or removal, so boards must be aligned by hand and fixed with screws each time. This makes assembly slower and less convenient if boards need to be changed often. Guide rails allow PCBs to slide in and out quickly and easily. The rails provide a consistent spacing between boards – improving cooling by maintaining clear airflow channels. However, this solution can cost slightly more (both for the rails and for the additional machining). Furthermore, mechanical support is concentrated along the board edges, so very large or heavy PCBs may require supplementary fixings to avoid flexing. In some cases, vibration resistance may not be as good as with fully fixed standoffs (unless retention clips or rear fixing points are used). Tower-style housings – such as the TX variant of TECHNOMET – support components on three or four shelves, depending on the height of the enclosure. The space-to-footprint benefits of towers are obvious, hence their increasing popularity. At 350 x 220 x 300 mm, the largest of the new TX sizes offers approximately 40 per cent more internal space than the existing TECHNOMET desktop models, while occupying only 60 per cent of the workstation footprint – all because the TX is at least twice the height.
If a tower enclosure is the desired option then think about side handles for added portability. They are a basic but useful safety feature for any large and bulky housing, not just towers – especially if the device is likely to be weighed down with a lot of heavier assemblies and components. After all, accidentally dropping a hefty but sensitive electronic instrument does not bear thinking about.
Smaller desktop instrumentation may need to be canted for ease of viewing and operation. There are various ways to achieve this. One method is to specify a sloping front. Angles vary between models and manufacturers. For TECHNOMET, the front panel inclines 108° away from the top panel (18° from the vertical). On UNIDESK, the angle is more pronounced – it is 30° from the base (60° from the vertical). Another option is to specify foldable tilt legs at the front. Kits such as the round TECHNOFEET and rectangular CASE FEET are a handy solution. And being universal, they can be added to existing models. The third way is to opt for an enclosure which offers a tilt/swivel carry handle bar as standard. Enclosures such as TECHNOMET, UNIMET and UNIMET-PLUS can be specified with an adjustable carry handle that doubles as a desk stand. Users can
September 2025 Instrumentation Monthly
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