Choosing the Right Enclosure for Your Electronic Device: A Guide for Hardware Engineers

When designing electronic products, selecting the appropriate enclosure is a critical step. The enclosure not only protects the internal components but also affects the device’s usability, aesthetics, and compliance with certain industry standards.

In this blog post we explore the more common types of enclosures used in electronics manufacturing and product design, highlighting their pros and cons, and offering insights into when and why to choose each type based on product complexity, volume, and pricing considerations.

Additionally, we will look at environmental considerations that are crucial for ensuring the durability and safety of electronic devices.

Enclosure Types

1. CNC Machined Enclosures

Pros:

• Precision: CNC machining provides high precision and tight tolerances, ideal for complex geometries.
• Material Versatility: Can be made using various materials, including metals (aluminium, steel etc) and plastics.
• Strength and Durability: These enclosures are particularly strong and durable, making them ideal for rugged applications.
• Customization: It’s possible to modify the designs without significant additional costs.

Cons:

• Cost: Higher per-unit cost, especially for low volumes.
• Time: Longer production times compared to some other methods.
• Weight: Metal enclosures particularly can be heavier than plastic alternatives.

Applications:

• The appearance of the metal enclosures can be enhanced with bead blasting (for a brushed surface look) and anodization. Used to give a premium look to a product.
• Low to Medium Volume Production: CNC enclosures can be ideal for prototypes and low to medium volume runs. For instance, custom industrial controllers or specialised scientific and laboratory instruments.
• Industrial Products: They are also suitable for products requiring robust and durable enclosures, like ruggedised tablets used in construction or out in the field.
• Custom Projects: CNC enclosures are perfect for highly customised designs where precision and personalisation is crucial, such as bespoke medical devices and consumer electronics.

2. Plastic Injection Moulding

Pros:

• Cost-Effective for High Volumes: Low per-unit cost at high production volumes.
• Consistency: High repeatability and consistency in large batches.
• Variety of Finishes: Can produce smooth, textured, or coloured finishes directly.
• Lightweight: Plastic materials offer lightweight solutions compared to enclosures made from metal.

Cons:

• High Initial Tooling Cost: There can be significant upfront investment needed for moulds.
• Design Flexibility: Changes to the product design after the moulds have been created can be costly.
• Environmental Impact: E-waste from consumer goods continues to raise environmental concerns when non-recyclable plastics are used in the design.

Applications:

• High Volume Production: Plastic Injection Moulding is ideal for products with large production runs, such as smartphone cases, TV remote controls, smart meters, children’s toys etc.
• Consumer Electronics: Ideal for mass-market products like coffee machines, routers and set-top boxes.
• Medical Devices: These enclosures offer compliance to industry standards when specific plastics for medical use (e.g., biocompatible plastics) are used in products such as insulin pumps or wearable health monitors.

Silicone & Urethane Mould Casting

• Cost-viable alternative to machined moulds.
• Moulds have much shorter life cycle (around 10 castings).
• Suitable for prototype runs where part needs to have surface texture and material properties of injection moulded parts.

Low pressure moulding (overmoulding) of electronics

• Used to seal and environmentally protect electronic assemblies.
• Suitable for sealing of connectors and adding strain relief to overmoulded parts.

3. 3D Printed Enclosures

Pros:

• Rapid Prototyping: A huge benefit of 3D printed enclosures is the fast turnaround times possible for prototypes.
• Design Flexibility: Thanks to the ever-growing 3D printing community it’s easy to find inspiration for new enclosure designs and modify these to suit specific projects or end user requirements.
• Low Initial Cost: The initial investment costs are minimal compared to plastic injection moulds or CNC setups.
• Complex Geometries: 3D printing allows the creation of complex and intricate designs that are often difficult to replicate with other methods.

Cons:

• Limited Production Volume: Less cost-effective for high-volume production.
• Surface Finish: In some cases, 3D printed enclosures may require post-processing for a smoother finish.
• Material Limitations: Although options are growing, typically there are fewer material choices compared to CNC or injection moulding.

Applications:

• Prototyping and Testing: Ideal for prototyping and functional testing of designs, such as early models of wearables or IoT devices.
• Custom and Low Volume: Suitable for custom enclosures or small batch production.
• Complex Designs: 3D printed enclosures are a viable option when complex geometries difficult to manufacture traditionally are needed, such as bespoke lighting fixtures or aircraft interior panels with complex lattice structures.

4. Off-the-Shelf Enclosures

Pros:

• Availability: Readily available, reducing overall lead times.
• Cost-Effective: No tooling or design costs, making them affordable.
• Variety: There are a wide range of sizes, shapes, and materials to choose from.
• Standards Compliance: Often designed to meet standard regulations and industry specific certifications.

Cons:

• Customisation: Despite the wide range of ‘standard’ options, customisation is limited.
• Fit and Finish: Off-the-shelf enclosures will typically need to be modified slightly to fit specific components perfectly.
• Design Limitations: The product could be constrained by existing sizes and shapes.

Applications:

• Quick Turnaround: Ideal for projects needing a fast time-to-market, such as hobbyist electronics or early-stage startups.
• Low Budget Projects: Suitable for low-budget or cost-sensitive projects, like educational kits or simple DIY projects.
• Standard Products: Good for standard devices where customization is not critical, such as generic power supplies or basic network equipment.

5. Fabricated Enclosures

Pros:

• Customisation: These are highly customisable to specific end user requirements.
• Strength: Fabricated enclosures can be designed for high durability and strength making them ideal for high reliability and industrial end markets .
• Material Options: They can be made from a wide range of materials including metals and plastics.
• Scalability: Suitable for both low and medium volume production.

Cons:

• Cost: Generally, the unit cost will be higher than other options due to the custom fabrication work involved.
• Production Time: Longer lead times to produce compared to off-the-shelf options.
• Complexity: Requires a supplier with skilled labour, stringent quality controls and precision tools.

Applications:

• Custom Solutions: Fabricated enclosures are best for unique or highly specialised products, such as custom servers or laboratory equipment.
• Industrial Equipment: They are frequently used for industrial applications requiring robust enclosures, like control panels or heavy machinery interfaces.
• Special Compliance: Ideal for products needing compliance with specific regulations or standards, such as military-grade electronics or certified aerospace components.

Environmental Considerations

In many cases, the enclosure used to house electronic components or electrical items will also need to meet specific environmental requirements depending on the application and operating conditions. Some key factors to consider when choosing your enclosure include:

• Temperature Resistance: Materials should withstand the operating temperature range of the device. For example, industrial products may need enclosures that can endure extreme temperatures.
• Chemical Resistance: Devices used in chemical processing or medical environments might require enclosures made from materials resistant to chemicals and disinfectants.
• UV Resistance: Outdoor products need UV-resistant materials to prevent degradation from sunlight exposure.
• Compliance with Regulations: Certain industries have strict regulatory requirements. For example, medical devices must comply with ISO 13485, while consumer electronics often need to meet CE or FCC standards.
• Ingress protection: If the device is used in a wet or humid environment, an enclosure with an appropriate IP rating must be selected. In addition to defining the level of waterproofing, IP rating defines the level of protection from external foreign objects (dust, dirt, tamper attempts).
• Flammability protection: If the device is being used in flammable and explosive atmospheres compliance with ATEX and UL94 standards shall be maintained, depending on the region.

Conclusion

Choosing the right enclosure for your electronic device involves balancing various factors such as production volume, cost, material requirements, and environmental considerations. As each project is unique, here’s a quick summary to help you decide:

• CNC Machined: Best for precision, durability, and low to medium volumes.
• Plastic Injection Moulding: Ideal for high volume production and cost efficiency.
• 3D Printed: Perfect for rapid prototyping, custom, and low volume production.
• Off-the-Shelf: Great for quick, low-cost solutions with limited customization needs.
• Fabricated: Optimal for highly customized, durable solutions in low to medium volumes.

By understanding the strengths and limitations of each enclosure type and considering environmental factors, hardware engineers can make informed decisions that align with their project requirements and constraints.