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How to specify electronics enclosures

Your guide to specifying enclosures

Standard enclosures have become increasingly specialised while still remaining versatile enough to suit a wide range of applications. You can now specify high-quality off-the-shelf housings that need very little customisation – because their design is already so close to the requirements of the end product.

However, the range of standard enclosures available is now so large that the sheer amount of choice can sometimes feel a little overwhelming. Seemingly similar enclosures may offer very different technical benefits.

This useful guide will help you to specify the best enclosures for your electronic devices. There are eight main technical factors that will affect your choice of enclosures:

1. PCB
2. Physical application
3. Materials
4. Interfaces and controls
5. Power
6. Assembly
7. Customising
8. Specifying defined types of enclosures

Fitting PCBs in enclosures

1. PCB – Specify the enclosure BEFORE you finalise the PCB layout

Benefit: Smaller enclosures – choosing the enclosure before finalising the component layout enables you to choose the smallest possible case, reducing costs significantly. Getting it wrong – specifying an enclosure after the layout has been decided – could increase the size of your finished product by up to 30%.

Benefit: Greater choice – you will have a much wider range of standard enclosures for your project. This gives you cost effective access to more specialised models to suit your precise requirements.

Benefit: High quality – greater choice and cost savings gained from specifying smaller cases enable you to choose the best possible quality enclosures, enhancing the aesthetics and ergonomics of your product.

Benefit: Improved product features – specifying the enclosure first can offer you design advantages you may not have previously considered. It can help to influence the final layout of your electronics.

Benefit: Less machining – integrating the PCB layout into an enclosure you have already chosen can reduce any machining required.

Enclosures applications

2. Physical applications – How and where will the electronics be used?

Will your product be handheld, wearable, desk-based or wall mounted? Fitted to a DIN rail or suspension arm?

OKW offers a wide range of enclosures to suit all applications. We even have highly versatile modular cases to house electronic devices that need to be readily accessible in a variety of environments – handheld, desk-based for charging and data transfer or mounted to a vehicle dashboard for use on the move.

Plastic and aluminium enclosures

3. Materials – Selecting plastic or extruded aluminium enclosures

Plastic enclosures and extruded aluminium enclosures offer different benefits to suit a wide range of applications.

Advantages of Plastic Enclosures:

  • Enclosures are light, modern and tactile. They offer a high-quality scratch-resistant finish.
  • Special features – such as battery compartments or recesses for membrane keypads – can be pre-moulded.
  • Plastic enclosures are easy to assemble because they need fewer components.

ABS (Acrylonitrile butadiene styrene) was traditionally the thermoplastic of choice for many standard plastic enclosures because it is tough and has a low melting point. This makes it good for injection moulding.

However, in recent years ABS has been superseded by ASA (Acrylonitrile styrene acrylate, aka Acrylic styrene acrylonitrile) which offers much greater protection from damaging UV rays. Many of OKW’s newer enclosures ranges are moulded from an ASA+PC-FR blend which combines the UV stability of ASA with the strength of polycarbonate. Its UL 94 V-0 flammability resistance also outperforms ABS (UL 94 HB).

View OKW plastic enclosures >>

Advantages of Extruded Aluminium Enclosures:

  • Housings are strong, relatively lightweight and modern looking.
  • Good EMC characteristics.
  • Easy to modify the size – extrusions can be cut to bespoke lengths.
View OKW aluminium enclosures >>
Interfaces and controls fitted to enclosures

4. Interfaces and Controls

OKW’s plastic enclosures feature recesses for membrane keypads as standard. Buttons can also be mounted in these areas. Specifying non-recessed enclosures from other manufacturers could result in costly machining.

Where is the split-line in the enclosure? Many plastic enclosures feature the line mid-way between top and bottom – not always ideal when fitting connectors. Some more advanced cases have an off-centre split-line to create large flat areas for mounting connectors. Some housings have removable end panels for easier drilling and assembly.

Previously, some enclosures were offered with pre-moulded display windows – but today OKW can machine a window to suit the exact profile of the module you are using.

Many OKW enclosures are designed to house modern touchscreen displays – whether for desktop, wall-mount, mobile/handheld or portable electronics. Find out more in this blog post >> 

Some enclosures – such as desktop/wall-mountable SMART-TERMINAL and handheld CARRYTEC – have deep recesses or inset areas to accommodate and protect connectors. NET-BOX wall-mount enclosures conceal connectors beneath a removable front lid.

Enclosures with battery compartments or cable connections

5. Power – Do you need a battery compartment or cable connection?

Plastic enclosures offer the best solution for smaller battery-powered devices (AAA, AA, 9V, N, round cells).

OKW’s modern advanced enclosures provide fully functioning battery compartments which will accept push-in contacts (unlike some manufacturers which supply cases with a compartment but no battery holder or contacts). There are various options:

Battery contacts must conform to DIN EN 60601 to avoid short circuits should the cells be inserted wrongly. By law, the polarity of the cells must be moulded into the compartment floor.

A clip-on lid for the battery compartment is not always suitable. For medical applications, the lid must have tooled (screwdriver) access to avoid tampering or battery theft. All new OKW enclosures have this feature as standard.

For low-voltage cable-powered devices, OKW also offers pocket-sized handheld enclosures with integrated cable glands. See our SMART-CASE range for example. CONNECT wired enclosures offer cable gland kits as accessories. These housings also have long, flat sides – making them an excellent choice for applications that require multiple USB connections.

Furthermore, it is now possible to specify enclosures with integrated contacts for battery charging and data transfer between the enclosures and desk/wall stations. OKW’s DATEC-COMPACT range offers this as an option on request. Contact pins and spring contacts are available as accessories. We can install them for you as a custom service.

Inductive charging is an option for BODY-CASE wearable enclosures, as an alternative to mounting small round cells on the PCB. BODY-CASE can accommodate a rechargeable battery with receiving charging coils. Docking stations are available as accessories for recharging single or multiple devices.

Find out more about OKW enclosures with optional docking stations >> 

Enclosures assembly

6. Assembly – Fast assembly reduces your production costs

Plastic enclosures are generally easier to assemble than metal ones because – being moulded – they comprise fewer parts.

Also, many plastic cases feature clip-together sections that do not need fixing screws.

Where fixing screws are used, they should be special self-cutting screws designed specifically for plastics. The screws have a coarse thread to reduce the risk of cross-threading. All OKW enclosures use these types of screws.

Many new OKW enclosures are supplied with Torx assembly screws to prevent tampering. This is particularly important for enclosures used in medical electronics.

Also, specifying enclosures with a tooled access feature – in which a flat screwdriver or key is needed to open the enclosure – will allow it to conform to anti-tampering regulations.

SMART-PANEL enclosures for intelligent building control and monitoring systems have no fixing screws. They snap closed and can be reopened using a pair of plastic opening tools (accessory).

 

Customised enclosures

7. Customised Enclosures – Ready for mounting your electronics

OKW’s advanced standard enclosures are designed from the outset to be quicker, easier and more cost-effective to customise with all the necessary modifications to suit your electronic components.

Less work is needed to tailor enclosures precisely to your requirements because we offer so many specialised standard designs.

Find out more about OKW’s customising services – such as custom colours, materials, machining, lacquering, printing (digital, silk-screen, tampo), laser marking, decor foils, special materials, EMC shielding, installation and assembly:

  • CNC machining is now faster than ever  (thanks to OKW’s regular investment in new technology) – creating apertures for keypad wiring, buttons, potentiometers, displays, LEDs and interfaces.
  • Lacquering can be used to create a huge range of different finishes. Options include matt, glossy, colours (RAL and Pantone shades), metallics, soft-touch ‘velvet’, anti-bacterial and ESD conductive lacquers. We use UV-resistant, two-component lacquers for optimum quality.
  • Photo-quality digital printing is faster and more cost-effective to set up than traditional methods such as screen printing. This makes digital printing of legends, logos and graphics viable even for small batches.
  • Laser marking is perfect for creating very small machine-readable legends – such as individual numbering, QR codes, Data Matrix codes and barcodes. The process turns light or dark plastic grey at the point of marking. Colours include off-white, pebble grey, light grey, lava and black (depending on the material being marked).
  • Decor foils – photo-quality, digitally printed. Options include cut-outs (ie, for LEDs or display windows), consecutive numbering and codes.
  • Bespoke materials – have your enclosures moulded in non-standard colours (based on your chosen RAL or Pantone shade). Options also include V-0 flame-resistant plastics.
  • EMC shielding in accordance with UL 746C – our in-house vapour plating team applies a 99.98% pure aluminium coating to the inside of your enclosure to create a Faraday cage, blocking electromagnetic interference.
  • Installing and assembling accessories – such as mountings, carry handles, cable glands, belt/pocket clips and tilt foot bars. We can also fit keyboard foils and display windows, mount assemblies, install components and package products.
Overview OKW customising services >>

8. SPECIFYING ENCLOSURES – MORE INFORMATION

Further reading – find out more about…

Need more help? Get expert advice from the OKW sales team – phone 01489 583858 or email us.