One of the first steps in designing is choosing the right metal for your custom enclosure or part.
In this blog post, I will first examine some factors to consider when deciding which metal is the best choice for your project. Following that, I will review each of our metal options in detail so that you can make an informed choice, as you start your next design.
The metal you choose for your design will ultimately come down to a variety of factors:
- Price
Most of our metal options are similarly priced. The exception is stainless steel, which costs significantly more due to the nickel and chromium content. However, more cost-effective metals can be used for many indoor applications and be extremely durable and finishing options can add corrosion resistance. If price-consciousness is your ultimate priority, you have plenty of options.
- Environmental Conditions
If your enclosure is going to be residing outside, you will want to choose an ultra-durable, corrosion-resistant metal, along with the proper finishes. Consider if your enclosure will be partially-submerged or fully submerged in water (especially salt water), as additional protection will be required.
One of the biggest factors to think about when choosing the right metal for your custom enclosure or part is corrosion resistance. Metals will corrode at different rates when exposed to heat, UV light, harsh chemicals or moisture.
- Aesthetics
Of course, for any enclosure you design, particularly in the prototyping stage, function should trump form. However, having an aesthetically appealing and professional-looking prototype could be the difference-maker in getting approval and buzz from your colleagues, stakeholders and potential customers. Our metal material options each offer their own unique strengths when it comes to aesthetics, and we offer a wide variety of custom finishing options to help bring your design to the next level. Most metals will be visually indiscriminable if the same finish is applied.
- Weight
Sometimes, weight is a crucial factor in determining the most suitable material for your custom enclosure. Some of our clients, for instance, create custom enclosures for taking measurements out in the field, which means they are routinely moved from spot to spot. In this scenario, the lighter the enclosure, the better. The weight of your enclosure could be a very important consideration, especially when you consider the additional weight of your electronics and components once you’ve completed the final build.
The Metals We Offer
Now that we’ve reviewed all of the different factors that will go into your decision-making as you complete the preliminary work of designing your custom enclosure, we can now examine each of our stocked sheet metals, and their best use cases.
- Cold Rolled Steel
- Price: More cost-effective than stainless steel. Cold Rolled is an economical option.
- Environmental considerations: Not ideal in wet environments. It is the least corrosion resistant metal option we carry (this can be subverted with powdercoat, however).
- Aesthetics: Like all metals, it is basically indistinguishable looking to any other option with powdercoat. Cold rolled steel will rust if left uncoated.
- Weight: Heavy and stiff compared to aluminum. It is not as strong as Stainless, but has the same stiffness.
- Finishing options: Bare metal (though not recommended) or powdercoat.
Cold rolled steel is ideal for general purpose indoor enclosures. However, it will rust if not coated, so bare metal and grained finishes are not recommended. It can be extremely durable indoors when finished with powdercoat. However, it is not inherently corrosion resistant. Cold rolled steel will degrade quickly in harsh or wet environments, and is therefore not ideal for outdoor use. It is a very stiff metal compared to aluminum. For its structural integrity, it is an excellent cost-effective option.
- Stainless Steel
- Price: The most expensive of the options we carry for general purpose enclosures.
- Environmental Conditions: The most inherently corrosion resistant of our metal options.
- Aesthetics: Especially striking with grained finish, many people prefer the look of stainless steel.
- Weight: Stainless is the close to the same weight as cold rolled steel, with the same stiffness but a higher strength. It is heavier than aluminum.
- Finishing Options: Bare metal, grained finish, or powdercoat.
Stainless steel is the premium solution to corrosion resistance, because of its chromium and nickel content. However, that chromium and nickel comes at a cost and makes stainless more expensive than cold-rolled steel, aluminum or galvaneal. It is good for use with general purpose enclosures if corrosion or aesthetics are a concern.
Consider using Stainless steel if any of the following properties are important:
- Resistance to corrosion
- Prevention of product contamination
- Resistance to oxidation
- Ease of fabrication
- Excellent form-ability
- Beauty of appearance
- Ease of cleaning
- High strength with low weight
- Good strength and toughness at cryogenic temperatures
- Aluminum
- Price: The price is comparable to cold rolled steel. It is also a very economical general purpose metal.
- Environmental Conditions: Offers some corrosion resistance, but not to the extent of stainless steel.
- Aesthetics: Offers good finishing options.
- Weight: The most lightweight metal we offer, however, aluminum doesn’t offer the same strength as other metals.
- Finishing Options: Bare metal, grained finish, and powdercoat. It can also be chem-filmed and anodized.
Aluminum is one of the most lightweight metals for enclosures, however to get to the same stiffness as cold-rolled steel, it requires a thicker gauge. It does not have to be chem filmed form electrical contact, but chem film will increase the durability of aluminum.
Aluminum is corrosion resistant and lightweight. Its lower stiffness requires a thicker gauge to match that of steel. Finishing options include bare metal, grained finish or powdercoat. If electrical contact is required in your design, the aluminum must be chem-filmed (chromate coated). It can also be anodized to put on a durable oxide coating. Consider aluminum where minimum weight and/or corrosion resistance are your key priorities.
The two kinds of aluminum we carry are aluminum 5052 Aluminum – H32 and 6061 Aluminum – T6. For sheet-metal parts, 5052 is preferred, as the metal can bend to a tighter radius than 6061 without cracking. For CNC machined parts, panels and enclosures, 6061 Aluminum is ideal, because the material is softer and is easily milled.
- Galvanneal
- Price: Galvanneal is slightly more expensive than cold rolled steel or aluminum because of the coating.
- Environmental Conditions: It is corrosion resistant as long as the coating is intact.
- Aesthetics: Dull grey finish.
- Weight: Similar to cold rolled.
- Finishing Options: Bare or Powdercoat
Galvanneal is a low-carbon steel coated with zinc and annealed for the zinc to bond via diffusion into the substrate. This prevents it from flaking off when formed or bent. The finish acts like a primer and easily adheres to paint, and creates a rust-proof surface as well. Galvanneal is much more durable than cold-rolled steel in wet environments, but less so than aluminum or stainless steel. Galvanneal offers good paintability, corrosion resistance, and formability.
5. Copper
While we do offer copper within our sheet-metal offerings, it is very rarely used as the material option for an enclosure. Copper offers excellent electrical conductivity, however it is extremely soft, and thus not ideal to form an enclosure. Copper is very expensive, especially compared to other sheet-metal materials.
Customers typically use copper for bus bars or miscellaneous parts. Contact us to discuss your options.
Conclusion
When you are designing a custom enclosure for your specific project or prototype, it’s important to start on the right foot by choosing the metal that will best suit your needs.
To recap, there a few good questions to guide you in your choice:
- Where will my enclosure be stored?
- Will my case need to withstand harsh environmental elements?
- How much is weight an issue for my enclosure?
- How budget-conscious do I need to be?
Once you have answered these questions and considered your needs thoroughly, you will have some guidance on selecting the right metal for your custom enclosure or part.
And if you’re still unsure, or just want to talk through your design, contact us by emailing info@protocase.com or calling 1-866-849-3911! We are happy to help.
For more details on the basics of enclosure design, check out our Electronic Enclosure Design 101 blog post.
