Asking the manufacturer to customise the enclosure for your project makes sense
06 July 2018
The main advantages of standard enclosures: there are no upfront non-recurrent design, engineering and tooling charges; products are on the shelf ready for immediate delivery; and unit costs are low and the design well field-tested. Compared with application-specific custom enclosures, standard products are immediately available and often extremely cost effective.
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Standard products, however, are exactly that: standard. To meet the needs of a specific project, they will typically need to be machined with suitable apertures to accept switches, displays, I/O connectors, keyboards and other components. They will likely need to be printed with legends and logos, and may have to be finished in non-standard colours to meet corporate and/or product branding requirements.
To modify standard enclosures to meet the specific requirements of a project, the purchaser has three choices:
1) Purchase standard products, either directly from the manufacturer or through distribution, and then modify them as required in-house. However, many electronic OEMs simply may not have the plant, equipment, expertise or interest in undertaking machining and painting procedures in their own premises. If there is in-house capability, modifying the housing as a part of the overall assembly process could be the best way to proceed. However, users will have to purchase more than the required number of standard units, to allow for set-up procedures and wastage.
2) Buy standard products and outsource the modification processes to external contractors. In this scenario, there are the additional costs, time penalties and logistics complications associated with managing the process of sub-contracting, often to multiple suppliers – potentially further increasing costs, as each process will require extra units to allow for first-offs and set-up wastage.
3) But we believe that by far the best option is to have the original manufacturer provide a modified enclosure configured to the specific requirements of the project. With this option, there is no need to over-order to allow for set-up and wastage quantities. Arguably, given that the original manufacturer is best positioned to understand its own products, potentially expensive problems can be avoided with discussions during the initial design phase.
It is certainly of great benefit to involve the standard enclosure manufacturer as early as possible in the development cycle. While many international standards, such as Eurocard, define basic PCB dimensions, smaller PCBs would not normally conform to any external size standard, so modifying a PCB layout and size at an early stage might enable it to fit a standard off the shelf enclosure. Otherwise, manufacturers may end up with a size that definitely requires a custom box.
Hammond Electronics supplies moulded plastic, metal, extruded and die-cast aluminium enclosures to the electronics industry, offering more than 5,000 different sizes as standard products. Its ranges are widely available through major catalogue distributors, specialist enclosure distributors and direct, giving multiple sourcing options with ex-stock availability at competitive prices.
Hammond has also made substantial investments in equipment, people and systems at its Basingstoke facility – particularly to support increasing customer demand for the OEM to undertake in-house modifications. The latest £100k+ investment in CNC machines has increased modification capacity by some 35%, improving service levels and reducing lead times.
What sort of modifications can be undertaken?
Hammond has the capability to undertake many different types of modification; the choice of method will of course depend on the tasks required to achieve the required result.
- Milling – CNC XYZ milling allows both cut-outs and rebates. A comprehensive library of standard apertures exists and custom shapes can easily be achieved. A corner radius of 0.75mm can be created, enabling complex shapes to be readily achieved with high precision.
- Drilling – Large and small holes can be positioned to tolerances of 0.005mm, relative to each other, allowing holes to be positioned close together when required.
For example, a plain panel can be drilled with a repeating array of holes giving an open area in excess of 85% to allow maximum airflow into the enclosure.
- Punching – In sheet metal enclosures, punching is a very economical way of creating apertures of various shapes in flat panels. Metal enclosures would normally be punched in the flat before assembly.
- Engraving – Legends can be engraved in both plastic and metal using traditional techniques.
- Screen printing – Traditional screen printing enables single or multiple solid colour legends to be applied to enclosures and panels in a durable finish: one that resists erosion through normal wear-and-tear. Screen printing allows logos and gradients to be achieved on panels and enclosure bodies, opening up many design possibilities for the appearance of the finished product.
- EMC coatings – Moulded enclosures have one specific weakness for electronics: by virtue of the intrinsic properties of the material itself, plastic, unlike metal, offers no inherent attenuation to the passage of electric or magnetic fields. In many applications, this deficiency is of no consequence; however, if the radiation emitted by the housed electronics or their susceptibility to external fields is a potential problem, then the lack of screening could prove an issue.
Internal coatings in a variety of materials can be applied to the inner surfaces of a plastic enclosure to give different degrees of attenuation, dependent on the project requirements. By offering different materials in a range of thicknesses, the most cost-effective and technically competent solution can be provided.
- Custom moulding colours – Hammond plastic enclosures are available in ABS, flame retardant ABS and polycarbonate. All plastic enclosures are available ex-stock in a variety of colours and all materials can be moulded in any custom colour (subject to a minimum order quantity).
- Painted finishes – Aluminium die-cast enclosures are available as standard in natural and black finish. A wide range of different finishes and colours can be applied to both enclosures and panels – ranging from a deeply textured finish to an ultra-high gloss piano black paint.
The appearance of the unit can of course reflect both corporate and product identity.
- Overlays – Overlays are specified as the front panel finish, in standards such as IEEE1101.10/11 (used in cPCI applications). If required, overlays can be added to any size of front panel, to give a durable and attractive appearance.
In addition to the fabrication capability, service is another key focus. To specify the modifications required, customers can download PDF drawings or 2D and 3D CAD files for all products from www.hammondmfg.com. The required modifications are marked up on the drawings and returned; then, a quote is prepared, and upon receipt of order, the approval samples enter production. Once the samples are accepted, volume production starts.
Such a streamlined process reduces dwell time and removes possible errors, such as when information from a customer drawing needs to be re-entered into Hammond’s CAD system.
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