How enclosure accessories can make or break a design
06 March 2013
Enclosures and cabinets are ubiquitous, but they all have one thing in common: they are responsible for protecting their contents from external hazards. For the OEM and designer, choosing the accessories that will be used in the enclosure construction is important and will have a big impact on the life of the product. Chris Putman reports.
Specifying accessories and components for enclosures may seem like a simple task; however, it is important to consider that accessories such as hinges, latches, gas struts and anti-vibration mounts play a vital role in maintaining the integrity of an enclosure. Failure of any one of these components could result in the enclosure losing its integrity and failing in the field.
During the specification of an enclosure a number of criteria must be considered, such as the required IP, size and weight, access requirements, security requirements and the environment in which it will be located. These design criteria will also have a bearing on what accessories may be needed and their appropriate materials of construction. Specifying the correct products at the design stage will ensure that an enclosure performs its role with minimal maintenance over its expected life span.
Ingress protection is, arguably, the most important design criterion. For enclosures that will be located outside or even underwater, ingress protection levels will be correspondingly high, and this means the hinges must close any access door firmly against its seal and that the locks are suitably protected.
The operating environment of an application will play a role in deciding what accessories are required, and what materials are needed. An enclosure housing sensitive electronics in a heavy production plant may well benefit from effective anti-vibration mounts for protection. Equally, where an application will be subjected to wash-down, corrosion-resistant materials must be selected - 316 grade stainless steel, for example, would be suitable for these conditions.
Accessibility and security requirements can also vary greatly. The control cabinet of a CNC machine, for example, will rarely be opened and will need to be secured against unauthorised access. In this case, a strong and reliable locking system that can be integrated into the enclosure with no undue reduction of installation space, is desirable. Key locks, or quarter turn locks would meet these needs.
Other enclosures, such as storage cabinets or switchgear panels, may have to provide frequent access, and so the hinges must be able to withstand frequent use in order to avoid premature failure. The latch system will also need to prevent the enclosure from opening of its own accord while at the same time allowing users easy access. Some enclosures may hold emergency gear, in which case they will hopefully remain closed for all or most of their life span. However, should they ever need to be opened, the latching system must be wholly reliable and fast acting - a quick release pin would be ideal.
If an enclosure is particularly large it may be awkward or heavy to hold open its access door. Gas struts can be used to support the weight of the door allowing hands free access to the contents of the enclosure. Gas struts are available with a wide range of holding forces (the author's company offers struts between 20 and 2,500Nm, for example). These gas struts should also feature adjusting valves and long lasting seals to ensure that their performance is maintained over the life of the enclosure.
The small stuff
There are many small components and accessories that may need to be specified for an enclosure. It is tempting to consider these of trivial importance to the overall design; however, they will have an impact on the design life and must therefore be chosen carefully, with regards to their materials of construction and the quality of manufacture.
Chris Putman is with WDS
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