Avoid exposure with the right enclosure

What is the (true) cost in specifying your enclosure?

When implementing any complex electronic or electrical project, the housing of the equipment can often be an afterthought. That’s understandable when you consider that generally the equipment to be installed accounts for a significant proportion of the project cost, and so that receives the greatest focus.

It is, however, often the enclosure design or selection that will play a central role in determining the total cost of ownership (TCO) for the project. Hidden costs and risks may only become apparent after a selection has been made. Refer to Figure 1.

Figure 1: Total cost of ownership for an electrical or electronic enclosure. For a larger image, click here.

If the expectation is that total cost of ownership for an enclosure should be low, then the enclosure itself should require little maintenance or attention once installed.

Generally, the expectation is that the equipment and systems housed will require more frequent attention. However, if the solution selected does not adequately conform to project specifications or mitigate you project risks, the project may incur hidden costs either upfront or further down the track.

Considerations for selecting the right enclosure

Let’s consider a project that requires a small batch of enclosures for an application. Example applications could be managing process control, automation, data, communications or power, or it could be a specialised defence or medical application. The scope is wide as there as so many types of enclosures, as shown in Figure 2.

Figure 2: Examples of enclosures with various levels of customisation.

When selecting a solution, the system builder or project manager must consider critical aspects of the project, such as:

• project risk (eg, target cost vs features required)
• project deadlines and milestones
• total cost of ownership (TCO — eg, overall costs in specification, logistics, rework, maintenance, etc)
   

This requires substantial amounts of information regarding subsystems, standards and installation issues, to name a few.

When specifying an enclosure, you might look broadly at the following options:

1. An off-the-shelf enclosure.
2. A customised modular enclosure.
3. Full custom manufactured solution.

Let’s look at each to consider the typical parameters for sourcing and selection, as well as factors that affect lead time and overall cost.

Off the shelf

Standard off-the-shelf products can provide the shortest lead time option. However, typically accessories and/or modifications are required. Management of these can represent a hidden cost both in time and dollar value.

In addition, once these modifications have been performed you also need to ensure that all project specifications and compliances are maintained.

For example, consider any or all of the following:

• IP rating integrity
• EMC integrity
• Has any electrical specification been compromised? (eg, AS3000, AS3008, AS3015, etc)
• Surface protection integrity (has the modification left exposed metal which could cause surface degradation?)
• If the modification required parts to be repainted, does the colour match?
• Have all details of modifications been properly documented on project drawings for version control?

Pros:

• Cost-effective and fast if standard offering is an exact match to project specifications
   

Cons:

• If relatively complex modifications are required, the time spent in meeting project specifications may cost more in terms of labour and delivery.
• For non-assembled solutions, BOM and delivery management. (As an example, parts may have to arrive in stages, typically over quite a number of deliveries.) Additionally, the assembly of this type of solution may often require additional customisations (both foreseen and unseen).
   

If your requirement can be easily and efficiently specified whilst minimising the amount of modifications, then off the shelf may be a suitable option. In all other scenarios, the true cost of this solution needs to account for the complexity in assembly, BOM control and labour for modifications.

Customised modular solution

Some companies offer a modular system that can be manufactured to incorporate your specifications at design time. The specification process includes modifications at manufacture and then assembly. The outcome is intended to be a unit with minimal or no need to modify. Often drawings for the modular system will already exist and can be modified by the system builder.

Figure 3 below outlines typical considerations in delivering for this type of solution for a project.

Figure 3: Considerations in the process of sourcing a customised modular enclosure, delivered fully assembled.

Pros:

• Flexibility for system builder to design upfront.
• Costs are known upfront when compared to the hidden costs that accrue when making modifications to standard options.
• The enclosure arrives fitted out and ready for equipment installation and testing.
• Enclosure specification control once approved requirements can be manufactured without traversing the same process, in effect becoming a standard product.
   

Cons:

• Longer specification period than using off the shelf
   

This option is most suitable for applications for system builders that need a single part delivery with a high level of modifications and additions included, ready to fit out and test the system. In addition, if the system builder has capability to engineer the modular system themselves and work with a manufacturer then they can create designs upfront and work with the manufacturer to finalise a specification.

Full custom manufactured solution

Typically, this solution is required when there are special project requirements including specific dimensions and shapes, higher IP ratings and accommodating environmental factors (solar, wind, vibration and corrosion), none of which can be achieved with standard offerings or modular component designs. Special attention and time need to be spent preparing the specification, so it is as accurate as possible.

Figure 4 below outlines what should be considered when delivering a project with a fully custom manufactured solution.

Figure 4: Considerations in the process of sourcing a fully custom manufactured enclosure solution.

Pros:

• Costs are known upfront when compared to the hidden costs that accrue when making modifications to standard options.
• The enclosure arrives fitted out and ready for equipment installation and testing.
• Enclosure specification control once approved requirements can be manufactured without traversing the same process, in effect becoming a standard product.
   

Cons:

• Cost for engineering and bespoke solution typically higher upfront.
• More time is required for engineering because you are starting from scratch. Interaction between system builder and manufacturer is paramount.
   

This option is most suitable for applications which cannot be fulfilled with any of the other solutions. This process delivers an enclosure with all modifications and additions included, ready to fit out and test the system. Design approval time increases the lead time for the initial production, but for serial orders the delivery time is reduced significantly.

Summary

For medium-run system building, the total cost of ownership for an enclosure is more complex than just the purchase price plus logistics.

Summarising the costs can be represented in Figure 5.

Figure 5: Total cost of ownership for an enclosure.

In selecting any solution, a clear definition of the specification for the project is critical. The value of any one solution needs to be considered within the full context of your project parameters.