How To Choose Between Aluminum And Stainless Steel Enclosures For Industrial Electronics

Choosing between aluminium and stainless steel enclosures

FAILURE IS NOT AN OPTION

Strength is a key criterion when selecting industrial electronic enclosures – but are you specifying the right kind of robustness? There are significant differences in the performance of aluminum and stainless steel enclosures – and challenging environments have a nasty habit of punishing under-specification.

Heavy industry and the great outdoors will show no mercy to your fragile electronics if there’s a gap in your armour. Getting it right means ensuring your enclosures can withstand hard knocks, dust/water ingress and corrosion. There are also other important practicalities to consider such as weight and price – though savings on the latter are no comfort if your device’s survivability is compromized because you specified the wrong housing.

 

Enclosures for marine applications

ENCLOSURES FOR MARINE AND OFFSHORE ENVIRONMENTS

If you’re tempted to specify aluminum enclosures for marine and offshore applications – because of the alloy’s strong resistance to corrosion – then you’re in for a nasty shock. Stainless steel is the way to go, notably A4 stainless steel because of its high rigidity and anti-corrosion performance. Look for enclosures such as inoCASE A4 or inoBOX A4.

A4 has superior corrosion resistance to A2 stainless steel thanks to its higher nickel content and the addition of molybdenum. ROLEC’s A4 stainless steel enclosures also have Open Deck approval from Det Norske Veritas (DNV), the international registrar and classification society headquartered at Høvik near Oslo.

It’s safe to say that DNV (which merged with Germanischer Lloyd in 2013) knows a thing or two about the survivability of boxes in very heavy seas. DNV is responsible for helping to ensure that large offshore containers can survive being bashed against the side of oil rigs when they’re craned up from supply vessels.

 

Which enclosures are more robust?

WHICH ENCLOSURES ARE MORE ROBUST?

Stainless steel – no question. As a metal, steel is harder than aluminum because it contains more carbon. (However, this also makes it heavier.) Steel is less likely to warp, bend or deform than its aluminium equivalent.

Furthermore, enclosures fabricated from stainless steel sheet will be stronger than diecast aluminum housings due to the nature of the manufacturing process. This is because diecasting involves overheating the aluminum to beyond its melting temperature.

At this point, it’s also worth noting that steel is also easier to weld than aluminum. This is another reason why it’s so good for fabricating enclosures that require a lot of welding to ensure they remain watertight to the certified ingress protection rating.

 

Which enclosures are more watertight?

WHICH ROLEC ENCLOSURES ARE MORE WATERTIGHT? STAINLESS STEEL OR ALUMINUM?

That’s a loaded question…but we deliberately wrote it that way to alert you to a critical consideration: watertightness is not a binary concept. It’s not a simple yes or no. There are other factors at play – such as force/pressure and whether the enclosure must survive immersion.

This is why the IP ratings scale is not as simple as it appears at first glance. Whilst higher numbers may suggest superior levels of protection, there’s much more to it than that. Here are some examples…

Stainless steel inoBOX is rated to IP 66. That means it offers:

  • complete protection against dust ingress
  • protection against temporary flooding (such as in heavy seas) – the test involves the enclosures withstanding 100 litres of water per minute at a pressure of 100 kPa at a distance of three metres.

But diecast aluminium enclosures such as premium aluCASE and new aluDOOR offer different levels of protection. For instance, aluDOOR is rated to:

  • IP 66 – as described above
  • IP 67 – complete protection against dust ingress; protection against immersion in water (150-1,000 mm deep) for at least 30 minutes
  • IP 69K – complete protection against dust ingress; protection from high-pressure water jets and steam cleaning.

Find out more here about IP ratings. Click the second tab ‘IP Ratings Explained’.

 

Which aluminum enclosures?

WHICH ALUMINUM ENCLOSURES SHOULD I SPECIFY?

ROLEC offers plenty of choice – 10 models, with combinations of different technical features to suit specific applications. Ask us about:

  • ‘lid closed’ installation (to prevent dust/water ingress during fitting, maintenance and removal) versus space-saving single channel fixings
  • new extra-secure lid fixings with stainless steel screws and stainless steel threaded bushes (aluDOOR IP 66, IP 67, IP 69K)
  • fixings concealed under trims (some models offer a choice of trims as standard for color-coding or branding)
  • enclosures in industry-standard sizes (aluPLUS IP 66, IP 67)
  • multivariable construction to give a wide choice of sizes (aluNORM IP 66, IP 67)
  • enclosures with two internal chambers (aluTWIN IP 66)
  • built-in RFI/EMI shielding, no gaskets required (conFORM IP 66, IP 67; conTROL IP 66, IP 67)
  • recessed lids for membrane keypads, front panels or product labels
  • enclosures with an extra-deep lid recess to protect large buttons (conTROL IP 66, IP 67).

 

Which stainless steel enclosures?

WHICH STAINLESS STEEL ENCLOSURES SHOULD I SPECIFY?

Industrial applications requiring stainless steel enclosures tend to be more specialized so the range is concentrated on inoCASE and inoBOX, both of which are available in A4 stainless steel. (inoBOX is also offered in A2 stainless steel). Both models can be specified with either a ground or polished finish (which offers a higher degree of corrosion resistance).

inoCASE A4 (IP 66, IP 67, IP69K) provides very high levels of protection for industrial and marine equipment. Features include captive lid screws, injected full-silicone gaskets, and fastening brackets in the base for attaching circuit boards, terminal rails and mounting plates. Separate fastening channels mean these enclosures can be mounted without the need for external brackets or for drilling holes in the sealed interior.

inoBOX A2 (IP 66)  and A4 (IP 66) have no mounting channels, maximixing each enclosure’s internal space. There are spacers in the base section for installing circuits boards, supporting rails or mounting plates.

A2 stainless steel is also known as 304. It’s the most popular grade of stainless steel because it’s used for cutlery and household appliances. You’ll sometimes see it described as 18/8 (because it contains 18% chromium and 8% nickel).

A4 stainless steel provides greater corrosion resistance than A2. It is 18/10 (18% chromium, 10% nickel). It is also referred to as 316. Grade 316L has a lower carbon content, providing even greater protection from corrosion; 316L is surgical steel used for medical applications where the metal is in direct contact with the human body.

 

Customized ROLEC industrial enclosures

SPECIFY CUSTOMIZED ALUMINUM OR STAINLESS STEEL ENCLOSURES

All ROLEC enclosures can be supplied fully customized, ready for the installation of your components. They can go straight to your production line. Customization services include CNC machining, laser processing, engraving, powder coating, painting, printing (digital and silk screen), RFI/EMI shielding, display windows, membrane keypads and assembly of accessories.

FURTHER READING

GET EXPERT TECHNICAL ADVICE

Contact ROLEC for expert technical advice on specifying the right enclosures for your electronics and the best ways to customise them.

 

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