Have it your own way

ESUK Jul13 p30 Hammond1Manufacturer modified standard enclosures are the best option, says Hammond Electronics‘ European account manager, Russell Irvine

Standard enclosures for the electronics industry are produced in a huge variety of sizes, styles and types and they are available from a multitude of specialist manufacturers. Although these moulded, extruded or die-cast enclosures may appear to be just a simple box, they are, in fact, the result of extensive design expertise resulting in a feature-rich housing, suitable for a use in a variety of applications and environments.

The initial choice facing a project engineer is whether to commission a custom enclosure for the particular project, or whether to choose a standard product from a reputable manufacturer. There are two main advantages to selecting a standard enclosure. Firstly, there are no non-recurrent engineering and tooling charges and secondly, the majority of manufacturers hold finished goods stock. They are also widely available through the distribution channel.

Off-the-shelf options

When it comes to selecting the right off the shelf-product, it is vital to consider the end-use application. Extruded or die-cast aluminium enclosures are strong and robust. They offer good electro-magnetic attenuation and heat dissipation and can be easily upgraded to achieve IP67 environmental sealing. For applications where protection against shock is important, where EMC is likely to be an issue or where dust or water are expected to be present, the extruded or die-cast enclosure is an ideal choice.

Plastic enclosures are typically injection moulded in polycarbonate or ABS. Both are lightweight, non-conductive and can be moulded to extremely fine tolerances. Both materials are designed to provide good shock resistance and are shatterproof. Polycarbonate has an advantage, in that it can be moulded in clear or translucent material, enabling infra-red emitters to be located inside the enclosure. ABS offers superior hardness and better electrical insulation. Again, IP67 sealing is easily achievable.

Making modifications

Any standard enclosure will have to be modified to accept the external components required for the application in question. Typically, it will be machined or drilled with suitable apertures for the various external components and silk-screened with legends and logos.

To produce the modified unit required for the project, there are three options. Standard enclosures can be modified in-house by the purchaser, the modifications can be carried out by the purchaser’s sub-contractors, or the enclosure can be modified by the manufacturer and supplied as a finished unit.

If the enclosures are to be modified in house, buyers will have to purchase more standard units than required to allow for set-up and prototypes. If the modification processes are outsourced, there are also the additional costs and logistics associated with managing the sub-contracting process.

This is why Hammond Electronics believes that by far the best option is for the enclosure manufacturer to provide the enclosure as a finished unit, modified to meet the customer’s specification.

Working closely with the enclosure manufacturer ensures that any potential design conflicts are overcome at an early stage in the project cycle and the specialist manufacturer will be able to provide astute advice on any potential design or layout problems. As a final advantage, bear in mind that the number ordered will be the number supplied.