How to save costs when making a custom enclosure

You have developed an electronic gadget and decided that you can take that product to the next level with a few improvements and insights in the target market. So, pumped up, you modify your electronics and add features that might require a custom or customised housing instead of that diecast box you bought online.

You decide to contact an industrial designer to help you develop a professional-looking custom enclosure. They proceed to tell you it will cost upwards of tens of thousands of dollars ($50K–$120K) to design and tool for what you thought was a relatively simple custom enclosure. Deflated, you balk at the cost and wonder if this is really a viable project.

This is a common scenario in electronic design. Making a custom enclosure can be complicated and frustrating when you consider the amount of options that are now available. From years of experience in this space, here are some considerations that we believe can help minimise time/cost and maximise value in the process of making a custom enclosure:

• Think about your enclosure design first.
• Can I customise instead of custom design?
• To tool not to tool: that is the question.

Think about your enclosure design first

This sounds obvious, right? Tooling is expensive, so it is important to get your design right. Design is expensive and charged by the hour; therefore, it is also important to specify your requirements clearly to reduce the amount of information loops and adjustments (ie, hours) required. It’s an easy thing to say, but in practice it can be hard to know where to start when you have not even fleshed out your system design. Here are some tips on what to consider when embarking on enclosure design that might help you avoid pitfalls later in the process.

First, consider your realistic quantity for the lifetime of product. What will be the continuity plan for this design? Are you developing to grow to an ultimate quantity over time, or will you this be a staged process with redesign each production run?

Next, write down functional specification and relate it to desired enclosure features. Typical things to consider are:

• PCB dimension
• Material
• IP rating
• Connectors
• Sensors
• Buttons
• External indicators/displays
• Type of mounting
• What are the other unique functions special to your design?
   

For example, see the below functions for an IoT sensor enclosure:

Function	Feature	Comments
Handheld and wall mountable	Small, clip mount	Target space profile WxHxD = 50 x 20 x 45
Must be accessible for service, battery change	Removable lid or door
Ingress protection	IP65	Or higher
Sun-proof	UV stabilised
Non-flammable plastic	UL94
Enclosed wireless transmitting	Must be plastic
External button	IP65 button gland	Reset button
Drop-proof	Thick enough plastic or bumper shock proof

Now decide how important cosmetic appearance is. Appearance is usually high on the list of reasons why to develop a custom enclosure in the first place. However, there are only so many ways to implement some features.

Now you have laid bare what is critical you can start analysing what is viable.

Customise instead of design custom

• If you consider that your ongoing quantity point is not in the hundred thousands, it may be more sensible to look at standard options that can be modified to suit, eg, under 2000 pieces it might be best to go with a rapid prototyping technology:
  • Additive manufacture
  • Custom metal enclosure
  • Modify a standard enclosure
• Consult with enclosure manufacturers to get advice on what’s possible and what’s not.
• Avoid I/O and connections on too many edges.
• Metal or plastics?
• Where possible, use standard options and materials.

To tool or not to tool: that is the question

Injection moulds are expensive but result in low cost in volume. Personally, I would look at low-volume injection moulding using cheaper aluminium tooling. The tooling wears much more quickly but can get you started faster/cheaper. You would design the part (sketches → 3D CAD), 3D print to verify function, pass the design to the injection moulding company (design verification and pricing), pay for the tooling, run first article(s), verify function/aesthetics, make changes/verify again, and go into production. The process is expensive and time-consuming no matter what.

At 2000 cases, go with rapid prototype tooling.

The key to tooling with these vendors is to be a very good designer of injection moulded components. If you don’t follow the design guidelines dead on, your parts will suffer cosmetically.

ERNTEC has been designing and manufacturing enclosure solutions for many years. Talk to us for standard, modified or fully custom solutions.