Sheet Metal Enclosure

Sheet Metal Enclosure Design Basics and Its Tips

Sheet metal enclosure is an enclosure made of sheet metal materials. It is a popular choice for housing electronics and protecting internal components and can be used as panel enclosures, industrial electrical boxes, cable enclosures, and wiring enclosures. They can also be found in chemical storage, blood pressure machines, and even cabinets to protect medication. Sheet metal enclosure has the characteristics of lightweight, high strength, good electrical conductivity, low cost, emission reduction, and resistance to harsh industrial environments. 

Based on these characteristics, sheet metal enclosure design is a go-to choice for engineers and designers when creating robust and functional enclosures. Proper enclosure design ensure the overall design meets market and client demands while providing a positive user experience.

Why is Sheet Metal Enclosure So Important?

It isn’t easy to overstate the importance of sheet metal enclosures for industrial designers. Their various benefits make sheet metal the ideal choice for enclosures for many electronic and industrial applications. Here are a few reasons why sheet metal enclosures are important:

Durability: Sheet metal can withstand impacts, weather, and other environmental conditions. For example, sheet metal enclosures protect sensitive components from other machine components, human contact, external contaminants, temperature fluctuations, electricity, and vibrations. This makes it ideal for protecting sensitive electronics and components.

Customizability: Sheet metal is generally simple to fabricate. With a little forethought, sheet metal enclosures can be designed in nearly any shape and size. This allows enclosures to be tailored exactly to the needs of the application. Complex 3D forms are possible with sheet metal bending and welding. 

Electrical Conductivity: Sheet metal enclosures provide the advantage of electrical conductivity, rendering them essential regarding EMI (electromagnetic interference) applications, emission reduction, defense against external noise, and endurance in harsh environments.

Electromagnetic Shielding: Properly grounded sheet metal enclosures provide excellent electromagnetic shielding to prevent interference from affecting circuitry. This is important for many electronic devices.

Versatility: Sheet metal enclosures are used in a wide range of applications. They can protect electrical components, display collectibles, and even contain fluids on a vehicle. They protect switches, control panels, contactors, and circuit breakers, preventing them from blowing should the unit come into contact with rainwater.

Heat Dissipation: Sheet metal is an excellent conductor of heat. Enclosures made of metals like aluminum can efficiently dissipate heat generated by components through conduction, helping prevent overheating.

Aesthetics: Sheet metal enclosures allow for attractive industrial designs. Metal finishes, paints, logos, and other decorative elements can be added to customize the look.

Cost-effectiveness: Sheet metal is lightweight, readily available, and cost-effective, making it a popular choice for enclosure fabrication. Although material costs are higher, fabricating sheet metal enclosures is often cheaper than techniques like plastic molding for low to medium production volumes

sheet metal enclosure design

Understand the Product Design Requirements 

In any design process, it is critical to understand the product’s aesthetic and functional needs. Ingenious design results in an excellent product. Numerous factors must be taken into account:

Dimensional Requirements: Consider whether the enclosure should be light or heavy, as well as the size and weight standards, among other things.

Working Conditions: Working circumstances encompass waterproofing, operating temperature, corrosion resistance, vibration resistance requirements, antioxidant characteristics, industrial or food-grade standards, maximum load capacity, etc.

Component Specifications: Determine the components that can be housed within the enclosure, including their height, size, connector positions, and additional relevant details.

Mounting Requirements: Determine the appropriate mounting choices, such as wall mounting, pole mounting, tabletop installation, etc.

Aesthetic Needs: Consider any desirable aesthetic aspects or design elements.

Surface Treatment: Select the desired surface finish, whether glossy or matte.

Fixing Technique: Determine the suitable fixing technique, like utilizing screws or bolts, and the needed working force and maximum force. Consider pressed rivet nut posts or pivots as well.

Logo: Identify whether the enclosure needs the logo to be silk-printed or laser-engraved.

Color Confirmation: Confirm the needed color according to the Pantone or RAL color number.

Choose Material for Sheet Metal Enclosure Design 

After knowing the product design requirements, the next step is to choose the metal that fits your needs. Choosing metals that can withstand corrosion and wear is very important. A description of the distinguishing features of each metal is provided below to assist you in making an informed decision.

Aluminum 

Aluminum is an ideal material for enclosures and sheet metal components due to its lightweight and resistance to corrosion. Aluminum can be powder-coated. It can also be left unfinished as bare metal or a grained finish. If electrical contact is necessary, chem-filming (chromate coating) is required. Additionally, aluminum can be anodized to get a protective oxide coating that is hard and long-lasting.

Aluminum has a lower stiffness compared to steel under specific conditions. Nonetheless, two principal aluminum alloys are utilized in sheet metal enclosures. 5052 Aluminum and 6061 Aluminum make up the two. 5052 Aluminum is ideal for sheet metal enclosures and components due to its good weldability, machinability, and no cracking when bent to a tight radius. Although 6061 aluminum is simple to machine, it cracks more easily when bent to tight radii.

Aluminum enclosure

CRCA

Cold rolled close annealed steel is abbreviated as CRCA. It is a good choice for indoor enclosures and parts. Generally, the cold rolled close annealed steel is not naturally corrosion-resistant. However, coated with a powder coat, it provides an excellent combination of cost and stiffness and has long-term durability in indoor applications. 

Stainless Steel

Stainless steel possesses the high stiffness and strength of cold rolled close annealed steel, but its chromium and nickel content render it exceptionally corrosion-resistant. Stainless steel can be powder coated or left uncoated as its bare metal. Its grained finish state can impart the desirable brushed appearance. Furthermore, stainless steel offers higher tensile strength than aluminum and is appropriate for high-impact applications in sheet metal enclosures. 

Galvanneal

Galvanneal is a kind of low-carbon steel subjected to zinc coating and subsequent annealing. Annealing aims to guarantee that zinc bonds by diffusion into the substrate. As a result, there will be no flaking off when forming or bending. Galvanneal is the ideal material when the metal enclosure is used in wet conditions. Depending on the type of coating on top of it, it is also corrosion-resistant. Therefore, it is mostly used in products exposed to fluids.

Copper

Copper is an excellent metal, although it is seldom employed in constructing sheet metal enclosures. Copper is soft, flexible, and ductile. Additionally, it has very high thermal and electrical conductivity. This makes copper ideal for electrical and electronic applications. A few enclosures are made from copper because it is too fragile to withstand much weight. Copper is best utilized for bus bars and other similar applications. Because of the softness of this metal, torquing fasteners into tapped holes must be done with caution, and self-clinching fasteners should be used wherever feasible. 

The following properties can be considered if you still can’t decide which metal you need.

  • Thermal and electrical conductivity
  • Weldability and machinability
  • Tensile strength
  • Corrosion resistance
  • Wear resistance
  • Electronics enclosure weight constraints
  • Assembly process
  • Cost

copper enclosure

Select Shapes of Sheet Metal Enclosures

Another vital choice a mechanical designer must make when designing a sheet metal enclosure is the shape of the enclosure. In sheet metal design, four different shapes are frequently utilized. Using these shapes can create useful, cost-effective, and aesthetically stunning enclosures.

Folded Box Shape

This is the classic four-sided box shape with a lid. Because of its unusual design, this enclosure shape allows for easier service and additional mounting possibilities. 

F-Shape 

F-shape sheet metal enclosures are commonly used to house printed circuit boards with two connections on opposite sides. This enclosure shape is simple to design and manufacture fast.

U-shape

U-shape boxes, like F-shape boxes, are simple to create. They typically have robust bases and are easily accessible for maintenance. U-shaped sheet metal enclosures are most commonly used to house circuit boards with connectors on one side. They allow for easy access during service or maintenance.

L-shape

It is easy to figure out how to make an L-shaped enclosure. Aside from being simple to understand, it also offers easy use. L-shaped sheet metal enclosures often house printed circuit boards with only one connector.

Determine Sheet Metal Gauge and Thickness

The thickness of the material used is an important consideration when creating anything out of sheet metal. Material thickness influences the enclosure’s strength, stiffness, weight, flange length, and punch size. Thicker material may offer greater strength and stiffness but needs weight and cost considerations. 

One of the most challenging decisions for a designer unfamiliar with sheet metal is determining which gauge to employ, as they all appear the same on paper until you have experience. In this case, a better understanding of sheet metal gauges will help you choose.

sheet metal gauge chart 1

Custom Cutout Design

Some custom enclosures may require cutouts. These are often functional cutouts for connectors, displays, switches, etc. There are a lot of unique cutout designs, such as company logos, brands, or product names, as well as creativity around ventilation cutouts, which combine form and function.

Dimensional Tolerances

Cutouts and folds are required for sheet metal enclosures. Consider the following when determining dimensional tolerances:

1. Leave the tolerance as wide as possible for tooling flexibility.

  • Prevent tight clearance around I/O components and fold to fold unless necessary.
  • Give symmetric tolerances for all clearances if feasible.
  • In your CAD drawings, highlight vital dimensions and tolerances.
  • Remember that fold allowance factors will differ across manufacturers.

2. Consider the ease with which it will be to create the necessary cutouts.

  • Are there any formed shapes or holes?
  • Is it permissible to have little burrs or ‘nibble’ markings inside the shape?

3. Avoid distortion.

  • Examine the cutout sizes and spacing. When cutouts are too close together, distortion might result.
  • Ensure the folding allowance does not distort the holes close to the fold or edge.

Consider Self-clinching Fasteners

Self-clinching fasteners consist of threaded nuts, studs, standoffs, and other similar parts that establish secure fastening points when inserted into sheet metal. While nuts can accommodate screws, studs are utilized for mounting connectors, and standoffs can be inserted to facilitate the mounting of circuit boards. 

Maintain a Consistent Bend Radius

It is necessary to maintain a consistent bend radius. Bend radii should always sum up the content’s thickness in sheet metal enclosure design. The bend radius matches the product width. As a result, fractures and substance circulation troubles are avoided.

It is advisable to maintain a flange at a minimum length of about three to four times the thickness of the material. Note that some metals are resistant to bending. Consequently, an in-depth understanding of your metal’s chemical composition and surface state will enable you to assess its flexibility.

Before selecting bend radii, it is essential to consider the functional and aesthetic requirements of the enclosure. CAD software will assist you in digitally calculating the bend allowance of your metal.

keep Bend Radius of metal

Select Finishing Operations

There are several sheet metal finishing methods available. Each of them has distinct characteristics. Some of these methods will be discussed more below.

Powder Coating 

Powder coating is a form of dry thermoplastic powder. It fused and bonded to parts in an oven after being applied electrostatically. Powdercoat is accessible in many colors, gloss levels, and textures. It offers an economical, exceptionally durable quality finish. An additional benefit of powder coat is the availability of numerous textures. For instance, sandtex (rough) surfaces are excellent at masking fingerprints, making them ideal for electronic enclosures.

Anodizing

Anodizing is an electrochemical technique employed to prepare the surface of nonferrous metals, especially aluminum, to make it harder and less prone to corrosion. Because the anodized surface becomes integral to the metal, it will never peel, crack, flake off, or wear through under regular usage.

anodizing

Digital Printing and Silkscreening

Finishing techniques such as digital printing and silkscreening will give your design a professional appearance and feel. Both printing processes enable you to properly label your enclosure, part, or component to identify connectors, switches, ports, and other components. Digital printing is also great for graphics like corporate logos and artwork. Flat panels, parts, and assembled enclosures can all be printed digitally or silkscreened.

Chromate Conversion Coating

Chemical conversion coating is also known as chem-film or chromate coating. This type of finishing facilitates the passivation of metals using an immersion bath method. When chromate is applied to a metal substrate, it produces a corrosion-resistant and durable surface with stable electrical conductivity.

Tin Plating

Tin plating is a straightforward immersion process for depositing pure tin onto copper. Tin plating is commonly used to enhance corrosion resistance, electrical conductivity, and solderability. 

Nickel plating

This plating process includes coating your metal surface with a thin nickel layer. It provides an ideal mix of corrosion and wear resistance. It also increases the functionality, brightness, and attractiveness of your part. You can use nickel plating for your undercoats if you want high adhesion characteristics for other coats.

Painting

Spraying thin layers of paint over your metal surface is what the painting finish entails. It enhances the overall look of your sheet metal enclosure. In addition, it can aid in increasing client brand recognition.

Bare Metal Finishes 

There are three fundamental types of bare metal finishes available for aluminum and stainless steel:

No Finish – The deburred part lacks further finishing and could feature minute scratches or swirl marks. Although economical, its utility is limited to functional parts not intended for public display.

Tumbled Finish – This process creates a smooth and non-directional finish by tumbling in an abrasive medium. This is similar to frosted glass.

Grained Finish – The part is given a particular linear grain direction by brushing following deburring.

Carry on Prototypes and Validation Testing

With the sheet metal enclosure design ideas presented above, you will have a workable notion. The next step is to modify the original design by making prototypes and validation testing to satisfy the client’s demands and increase production efficiency.

Prototyping is the fastest and most effective way to do this. Your design will be tested in a real production environment. However, customers may be dissatisfied with the prototype you created for them.

This is why we need validation testing. It decides whether to produce products on a large scale or back to the design process. Validation testing may be done by utilizing the product or doing basic tests in the real world. You may discover areas that need to be updated or enhanced.

Summary

Sheet metal enclosures are a common type of protective housing used across many industries to enclose electronic components and control systems. When designing sheet metal enclosures, engineers must consider various factors to ensure proper functionality, safety, and manufacturability. Key considerations include material selection, fastening methods, accessibility, ventilation and cooling requirements, corrosion resistance, standards compliance, and aesthetics.

Are you still looking for a reliable sheet metal fabricator for your enclosure designs? LEADRP is your ideal partner with cutting, bending, and finishing expertise to realize your sheet metal enclosure demands. Our qualified teams can ensure every part is made with the utmost precision and expertise. Don’t hesitate to contact us today.

FAQs

The thickness of sheet metal is chosen depending on its intended purpose and the product you intend to create. Most common sheet metal products tend to be made from 1.2mm sheet thickness for general purposes. 

Round or rectangular holes can be punched or routed. Louvers allow airflow while preventing direct water ingress. Perforated metal also provides ventilation.

When selecting sheet metal for enclosure design, factors such as material strength, corrosion resistance, and formability should be carefully evaluated to ensure compatibility with the application's requirements.

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