CamdenBoss explains how a DIN Rail enclosure system can be adapted to meet almost any conceivable requirement.
Some design changes to DIN Rail enclosure systems have been piecemeal, but to produce a much better product a long hard look is needed at how enclosures are being used and any problems user are encountering.
For example, some users machine ventilation slots into the enclosures to cope with the heat generated by circuitry contained within. This means that the overall strength of the enclosure is compromised. In addition, some also encounter difficulties in mounting pcbs correctly, especially with heavier components such as relays or transformers.
To combat these problems, enclosures should include pcb guides for holding boards firmly in place and moulded screw holes in the base to facilitate mounting pcb with heavy components. With this method, multiple pcbs can be mounted horizontally and vertically.
For those requiring ventilated enclosures, ventilation slots can be incorporated in the tooling to avoid the need for machining by the user. As well as delivering stronger mouldings compared with enclosures with machined slots, this also results in a significant cost reduction for the user. With mass produced products, generally such refinements are not available, except where users are willing to pay a premium for new tooling. This is only really economical for very high volume products, which is not realistic where DIN Rail enclosures are used.
This tooling design also lets enclosures be offered with an extended insulated side wall that can either be ventilated or plain, depending on requirements.
In choosing moulding materials, carefully consider the issue of flame retardancy. Most enclosures on the market are moulded from Noryl and similar materials. Although these materials themselves are UL94V0 flame retardant, mouldings made from them are not flame retarded as the thickness of the side-walls is insufficient. Flame retardancy characteristics are determined by the end thickness of the materials. In most cases, DIN Rail enclosures have walls that are too thin to qualify for full UL94V0 specification.
An alternative is polycarbonate (lexan), which produces mouldings that are fully UL94V0 flame retardant. This is an important consideration for many who mistakenly believe that products moulded from UL94V0 materials are flame retardant.
Polycarbonate also improves the robustness of the moulding, important where heavier components such as relays and transformers are being housed. Also, appearance can be improved with an aesthetically pleasing matt finish.
A fully sealed base, unlike products that use holes, avoids the requirement for insulating pads and reduces assembly costs for users. All tabs on the body can be eliminated to ensure that there are no small lugs that might break off during assembly. Consequently, such an enclosure system combines the convenience of simple snap fit assembly with strength and robustness.
Enclosures can be made with or without a top panel moulded in, which allows versatility. For example, with a top panel moulded in, the enclosure can be screen-printed and then protected with a transport snap-in panel. Alternatively, a label can be mounted between the moulded-in top panel and a snap-in panel. A third option would be to use a snap-in cover without a moulded panel allowing LED indicators to show through or for access to the circuitry within, if required.
If the lowest horizontal PCB slot is used plug-in terminal blocks can be mounted, thereby saving assembly time.
Options should be available for terminations and terminal blocks. Snap-on terminal covers can provide IP20 finger protection while perforated screwdriver and wire entry holes and tabs can let users select only those connections that are required for their application. Terminal covers and snap-in panels should also be provided to the customer specifications in volume quantities.
Spring loaded DIN Rail clips can be snapped open to allow direct chassis-surface mounting adding another level of versatility. In addition, an optional adaptor should be available for mounting the enclosures in legacy 32mm G-style rails or 15mm mini-Din systems.
Other optional features should include alternative materials such as black higher rated RFI and EMI shielding achieved with metallic coatings.
The concept behind such a DIN Rail enclosure should be one of convenience for the user. Nothing should be spared in evaluating the performance of previous generation and competing products to create a versatile and robust product line that genuinely improves the lot of users.
With thoughtful design of tooling and careful selection of moulding materials, a DIN Rail mounting enclosure system can offer flexibility and versatility to users and installers with additional benefits in reduced costs.
