How to Design Sheet Metal Enclosures: Tips and Best Practices

Sheet metal enclosures offer numerous manufacturing advantages, including faster turnaround times and reduced manufacturing costs. With proper design techniques, these enclosures can be optimized for both functionality and aesthetics. In this article, we will explore tips and best practices for designing sheet metal enclosures. By following these guidelines, you can make informed decisions and achieve high-quality results. SendCutSend’s expertise in cutting, bending and finishing makes them an ideal partner for realizing your sheet metal enclosure designs.

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8 Tips for Sheet Metal Enclosures Design

Designing an effective sheet metal enclosure requires a little bit of planning and few considerations. By following these tips you can both design and build quality enclosures from sheet metal. If sheet metal fabrication is outside your current skill set or you don’t have the time or desire, SendCutSend can assist with most of the fabrication. We’ve compiled a short list of tips here to consider when designing your enclosure. 

1. Understand your product’s functional and aesthetics requirements 

As with any design, it’s a good idea to start with a set of requirements. Basically the what, where and how for what you want your enclosure to do.

• Size – Presumably it will enclose some type of components. How will these components be laid out? Are you housing a simple PCB or will you be enclosing an array of rack mounted electronics? 
• Features – How will the components be secured to the enclosure? This might require mounting features such as holes, slots, tabs or maybe shelves. It’s also common for enclosures to have some sort of cutouts for things like switches, lights or other controls, maybe wire or fluid tubing. How will the enclosure itself be mounted? If it’s wall mounted, you might add holes, slots or tabs. Consider what, if anything, may need to flow in and out of the enclosure, such as power, data, heat, air, etc.
• Access – Will the components need to be accessed regularly, requiring an opening, a door or possibly a removable panel? Will you need to see into the enclosure without opening it? Possibly include a window.
• Strength – How rigid does your enclosure need to be? Will it need to support heavy loads? Will it be mounted to a vehicle or somewhere where shock and vibration may be a factor?
• Ventilation – Do your components require ventilation or cooling/heating of any kind? 
• Environment – Where will your enclosure be used? This could require external mounting features. It could also drive things like seals or weatherstripping to keep it weather-tight. Electrical enclosures are often rated using a NEMA rating.
• Aesthetics – Finally, consider how you want your enclosure to look. You may want a subtle looking enclosure to blend in or you may want your enclosure to showcase what’s inside. There’s no reason an enclosure can’t be functional and attractive.

2. Figure out the desired material for your sheet metal enclosures

Your requirements should help you decide what material (or multiple materials) to build your enclosure from. Each will have a set of advantages and disadvantages. We’ve listed materials here that can be bent, but you could extend your list of materials greatly by joining the walls of your enclosure by other methods such as welding, adhesives, fasteners, etc. You should also keep in mind that depending on the cut method, cut sheet metal can leave sharp jagged edges, so take care in cutting and handling. Laser cutting is an excellent method for cutting sheet metal as it leaves clean edges.

• Steel – Carbon steel is a strong, low-cost choice. It will need to be finished in some way for corrosion protection. Zinc plating and powder coating are excellent options. Galvanized steel is lso available from SendCutSend. For a slightly higher cost but significantly more strength, consider Chromoly.
• Aluminum – Aluminum provides a natural corrosion resistance or it can be anodized or powder coated for additional protection and the desired look. Aluminum is also lighter than steel for similar thicknesses. Aluminum is softer than steel, so it may be slightly less durable in high-wear applications. SendCutSend offers Type III anodizing, which provides a harder surface for more wear resistance. Aluminum can work well as a heat sink since it conducts heat very well. This may be useful if your enclosure houses anything needing cooling.
• Stainless Steel – With excellent corrosion protection, stainless offers all the benefits of steel without needing to be protected. It can be more expensive than steel.
• Titanium – Used in aerospace applications, titanium is a high performing choice offering high strength, low weight and excellent corrosion resistance. The benefits of titanium come at a higher cost.
• Copper/Brass – Both copper and brass offer a unique decorative aesthetic. They may not offer the same strength as the other materials listed here, but should be plenty strong in the right applications. Copper is also significantly more conductive electrically and thermally than the other materials listed here, which could be useful for certain applications.
• Bonus Polycarbonate – While polycarbonate isn’t a sheet metal, it could be an excellent material for an enclosure or even just as a window in an enclosure. It can be bent, offers relatively good strength, is optically clear and has great corrosion resistance. Polycarbonate would be an excellent material for a display case type of enclosure.

3. Choose the right shape 

Rectangular boxes are a fairly common shape for sheet metal enclosures, but other shapes can be used to best suit your needs. Shape could be driven by functionality, ease of manufacturing, space available or even purely aesthetics.

Display cases especially offer a great opportunity for uniquely shaped enclosures. Fluid tanks will often have a unique shape to direct fluid to a specific point, either a drain or a pickup point.

Manufacturing or fabrication of the enclosure itself may be the biggest driver of shape. Using bent panels can reduce the number of parts and joints. Short flanges on the edges of panels can give a convenient place for adhesive, weld or fasteners. SendCutSend’s hardware installation can be a great way to hold parts of sheet metal enclosures together.

4. Determine sheet metal gauge and thickness

A critical factor in building anything from sheet metal is determining the thickness of material to use. Strength, stiffness and weight are all clearly influenced by material thickness. Thicker material may provide increased strength and stiffness, but with the trade-off of weight and cost. Another important trait driven by thickness is the bend radius, which we’ll cover shortly.

5. Take dimensional tolerances into consideration

Accurate feature size and placement will affect the final fit and finish of your enclosure. When designing your enclosure, consider the tolerances on the manufacturing processes you’ll use. Consult with our guidelines page for details on the tolerances achievable using SendCutSend services. 

6. Mind the bend radius

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It’s common for sheet metal enclosures to be fabricated using bends. Your design will need to factor in the radius of those bends. Pay particular attention to the proximity of features near bends as they can become distorted if they’re too close.

If you’re having SendCutSend bend the parts for you, all of the information you’ll need, such as bend radius, k-factor, etc. for each of our bendable materials is available on the materials pages. Each material, thickness and machine used to form it will result in a unique bend geometry, so it’s important that your design accurately reflects that to get your bends and surrounding features in the correct relative positions.

For even more information on bending, we’ve put together a whole playlist of videos about bending. You can check it out here.

7. Decide how the enclosure will be assembled

Sheet metal parts can be assembled in multiple ways. Welding is a good choice when the enclosure needs to be sealed well, either to keep weather out or fluids in. Welding seams also allows for them to be ground smooth for a seamless appearance. 

Rivets are a common option for securing sheet metal panels together. They only require a series of matching holes through each panel. This also makes alignment of panels easy. 

Threaded fasteners can be used, either sheet metal screws, nuts and bolts, or PEM fasteners. Sheet metal screws are quick and dirty, but aren’t a good choice if disassembly and reassembly is likely to happen. They can also leave sharp protrusions. Nuts and bolts require tool access from both sides to tighten. PEM fasteners can be a little more work to install, but once installed provide a convenient way to assemble sheet metal parts. If you’d like to use PEM hardware, but don’t want the hassle of installing it yourself, parts ordered from SendCutSend can be ordered with PEM fasteners installed.

8. Consider how you want to finish your product

Whether it’s for corrosion protection, wear resistance or just a beautiful finished appearance, the finish on your enclosure is another design consideration. One option is to select a material that can be finished mechanically. Aluminum, stainless steel, copper and brass can look good polished or brushed. 

For some enclosures you may want a protective finish. Powder coating is a durable finish for nearly any material. For steel, zinc plating provides excellent protection and is available in multiple colors. Aluminum can be anodized, which is both aesthetic and protective. Type III anodize provides an even more durable finish. All of these are available from SendCutSend to make fabricating your enclosure easier. 

Why Should You Use Sheet Metal Enclosures?

Sheet metal enclosures are used in a wide range of applications. They can be used to protect electrical components, display collectibles and even contain fluids on a vehicle. Commercial enclosures are available in sheet metal, castings, extrusions and even plastic. Few of those offer all the advantages of making an enclosure from sheet metal.

Sheet metal is cost-effective, lightweight and generally simple to fabricate. With a little forethought, sheet metal enclosures can be designed in nearly any shape and size. Making your own enclosure allows you to include any and all features you may need for your application, such as windows, switches, ports, drains, doors, locks, etc.

Mastering Your Sheet Metal Enclosures Design 

5 Factors For Choosing Sheet Metal Fabrication

­ Written By: Tony Varela

Introduction:

One of the most adaptable building materials in the manufacturing industry, sheet metal has rightfully found its place as one of the most important materials in the industrial age.  Steel, aluminum, brass, copper, tin, nickel, titanium, or other precious metals are traditionally used to make sheet metal.  Thicknesses vary but are mostly broken into two distinctions; thin gauge and heavy plate.  Many different industries rely on the versatility and durability of sheet metal including aerospace, appliance manufacturing, consumer electronics, industrial furniture, machinery, transportation and many more.

Why Choose Sheet Metal?

Sheet metal offers plenty of advantages as compared to both non-metal alternatives and other metal fabrication processes, as well.  When compared to machining, sheet metal is much less expensive in both processing and material costs.  It does not have the extremely high tooling costs of injection molding, which makes sense at high volumes.

As found in machining, rather than starting with an expensive block of material, much of which is wasted in the milling process of removing unneeded material, sheet metal lets you buy what you need and use what you need with relatively low material waste.  The unused sheet can then be used for another project, while the shavings produced in machining, need to be discarded and recycled.

With the advancement of technology used in modern fabrication, automation and new CAD (computer aid design) programs make designing in sheet metal easier and easier.  CAD programs now have the ability to design in the same material you intend to fabricate with and will allow programming of the parts to come straight from the CAD model itself.  No longer is there a need to create a separate set of shop drawings to interpret the design.  Perhaps most significant, in a world of mass production, sheet metal has the ability to scale rapidly.  The greatest cost for sheet metal fabrication is in the first piece.  This is because the cost is all in the setup.  Once the setup is complete, and the costs are spread out across the larger volume of pieces being fabricated, the price drops significantly, greater so than most subtractive processes like machining.

The company is the world’s best applications of custom sheet metal enclosures supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

1. How is Sheet Metal Being Used?

Sheet metal can be cut, stamped, formed, punched, sheared, bent, welded, rolled, riveted, drilled, tapped, machined.  Hardware can then be inserted to fix electronic components, metal brackets or other pieces of sheet metal.  To finish sheet metal, it can be brushed, plated, anodized, powder-coated, liquid painted, silkscreen, laser-etched, and pad printed.  And of course, parts can be welded riveted into complex assemblies.

Just like any other technology, the processing of precision sheet metal is constantly evolving.  Materials, processes, tooling, and equipment are becoming highly specialized which is improving the time involved to make common sheet metal parts and speeding up the design process as well.  To fully leverage all the technological advantages, it is important that you select the right supplier and know the differentiation between metal fabricators; architectural sheet metal (HVAC and ductwork), heavy plate fabricators (staircases, fences, heavy structures) precision fabricators (thin gauge sheet metal, enclosures, brackets etc…).

Along these lines, this white paper will explore key components of the precision sheet metal fabricator, precision sheet metal fabrication.  This paper will focus on:

• Fabrication techniques
• Common Materials
• Design considerations
• Finishing options

2. Sheet Metal Fabrication Techniques

By definition, sheet metal starts out flat, but before this, it comes from large cast ingot and the rolled into a long ribbon in the desired thicknesses.   These rolled coils are then flattened and sent as large sheets cut to different lengths to accommodate the manufacturing shop’s needs. While this paper focuses on bending sheet metal along a single axis, there are processes out there, hot and cold forming techniques that include bending and forming sheet metal along multi-axis points in one process such as deep drawing, hydroforming, spinning and stamping.  These processes are most commonly found in the manufacturing of products like automobile panels, aluminum cans, and complex formed consumer appliances.  Another similar process is progressive stamping which moves a ribbon along a series of stamping which forms and punches different stages.  At the end of these progressive stages, you are left with a finished part.

Cold forming will be the focus of this paper.  Examples of cold-forming processes are as follows

Cutting

• Shearing was one of the longest standing means to cut sheet metal but has since been replaced by faster, more precise methods.
• Punch Press use tools called punch and dies, which punches holes and shapes to make any number of patterns.  Particularly effective for cutting simple patterns that are more economical than cutting on a laser cutter or a water jet. Punch presses can operate at hundreds of strokes per minute making this a suitable center for processing parts quickly.
• Laser Cutting works with a combination of oxygen, nitrogen, helium, or carbon dioxide to burn away material and produce a clean edge.  This form of cutting can hold very tight tolerances.
• Photochemical Machining is a process of controlling the etching using CAD-generated stencils to leave a pattern that is chemically activated to remove unwanted material.

Hemming – The edges of the sheet metal are folded over itself or folded over another piece of sheet metal in this forming operation to achieve a tight fit or a stronger, rounded edge.  Hemming is a technique to join parts together, improve the appearance, or increase the strength and reinforce the edge of the part.  Two standard hemming processes include roll hemming and conventional die hemming.   Roll hemming is carried out incrementally with a hemming roller.  An industrial robot guides the hemming roller and forms the flange.  Conventional die hemming is suitable for mass production.  With die hemming, the flange is folded over the entire length with a hemming tool.

Bending – Most sheet metal bending operations involve a punch and die type setup when forming along one axis.  Punch and dies come in all sorts of geometries to achieve varied different shapes.  From long gently curves to tight angles at, below, or above 90-degree angles bending metal can achieve many different shapes.   Press brakes are generally needed when a sharp angle is desired.   Rolling and forming methods are used when a long continuous radius is desired in one direction, or along one axis.

3. Common Types of Sheet Metals

There are many different metals and alloys that come in sheet form and are ultimately used in the fabrication of manufactured parts.   The choice of which material depends largely on the final application of the fabricated parts, things to consider include formability, weldability, corrosion resistance, strength, weight, and cost.   Most common materials found in precision sheet metal fabrication include:

Stainless Steel – There are a number of grades to choose from, for the purpose of this white paper we will focus on the top three found in precision sheet metal fabrication:

• Austenitic stainless is a non-magnetic – any of the 300 series steel – that contains high levels of chromium and nickel and low levels of carbon. Known for their formability and resistance to corrosion, these are the most widely used grade of stainless steel.
• Ferritic – Stainless steels that are magnetic, non-heat-treatable steels that contain 11-30% chromium but with little or no nickel. Typically employed for non-structural uses where either good corrosion resistance is needed such as with seawater applications or decorative applications where aesthetics are the main concern.  These metals are most commonly found in the 400 series stainless steel.
• Martensitic – A group of chromium steels ordinarily containing no nickel developed to provide steel grades that are both corrosion resistant and hardenable via heat-treating to a wide range of hardness and strength levels.

Cold Rolled Steel – A process in which hot rolled steel is further processed to smooth the finish and hold tighter tolerances when forming.  CRS comes in and alloys.

Pre-Plated Steel – Sheet metal material that is either hot-dipped galvanized steel or galvanealed steel, which is galvanized then annealed.  Galvanization is the process of applying a protective zinc coating to steel in order to prevent rust and corrosion.  Annealing is a heat treatment process that alters the microstructure of a material to change its mechanical or electrical properties, typically reducing the hardness and increasing the ductility for easier fabrication.

Aluminum – An outstanding strength to weight ratio and natural corrosion resistance, aluminum sheet metal is a popular choice in manufacturing sectors meeting many application requirements.  Grade offers excellent corrosion resistance, excellent workability, as well as high thermal and electrical conductivity.  Often found in transmission or power grid lines.  Grade is a popular alloy for general purposes because of its moderate strength and good

workability.  Used in heat exchanges and cooking utensils.  Grade and are commonly found in metal fabrication.  Grade is the most widely used alloy best known for being among the stronger alloys while still formable, weldable, and corrosion-resistant.  Grade is a solid structural alloy most commonly used in extrusions or high strength parts such as truck and marine frames.

Copper/Brass – With a lower zinc content brasses can be easily cold worked, welded and brazed.  A high copper content allows the metal to form a protective oxide later (patina) on its surface that protects it from further corrosion.  This patina creates an often highly desirable aesthetic look found in architectural or other consumer-facing products.

4. Design Considerations for Sheet Metal Fabrication

Engineers designing sheet metal enclosures and assemblies often end up redesigning them so they can be manufactured.  Research suggests that manufacturers spend 30-50% of their time and 24% of the errors are due to manufacturability.  The reason behind these preventable engineering errors is usually the wide gap between how sheet metal parts are designed in CAD programs and how they are actually fabricated on a shop floor.  In an ideal scenario, the designing engineer would be familiar with the typical tools that will be used to fabricate the sheet metal parts while also taking advantage of designing within the CAD programs available sheet metal settings.

The more that is known about the fabrication process during the design phase the more successful the manufacturability of the part will be.  However, if there are issues with the way certain features were designed, then a good manufacturing supplier should be able to point those out and suggest good alternatives to address them.  In some cases, the suggestions may

same time and unneeded costs.  Here are some considerations while designing sheet metal for fabrication:

• Sheet metal fabrication is most cost-effective when standard tool sizes are used as opposed to costly custom tools that need to be made specifically for the job. If a single part becomes too complex, consider welding or riveting parts together that can be made using standard, or universal tools.
• Because bends will stretch material, features such as holes, cut-outs, inserted hardware should be located well enough away from bends to prevent distortion of the hole. To help with this rule, remember “4T” which means located features four times the material thickness away from any bends.
• Press brakes create bends by pressing sheet metal into a die with a linear punch, so the design does not allow the creation of closed geometry.
• Sheet metal tolerances are far more generous than machining or 3D tolerances. Factors affecting tolerances include material thickness, machines used, and the number of steps in the fabrication process.  Suppliers generally will provide detailed tolerance specifications as it related to their shop and machines.
• A uniform bend radius such as 0.030 in. (industry standard) should be used on every bend of a part to reduce multiple setups and accelerate production.
• Welding thin materials can lead to cracking or warping. Consider other joining methods when working with thin materials.
• Consider material thickness and manufacturers’ minimum requirements when installing PEM hardware.

5. Finishing Sheet Metal

There are several different methods and reasons to finish sheet metal parts.  Depending on the material chosen, some finishing techniques protect the material from corrosion or rust while other finishing materials are done for aesthetic reasons.  In some cases, finishing can achieve both purposes.  There are finishing processes that include simple alterations to the surfaces of the materials.  Other finishing processes consist of applying a separate material or process to the metal.  Standard finishing techniques include:

• Brushing is used to deburr and remove surface defects from sheet metal parts.  The surface pattern created is a uniform parallel grain resulting from the brush moving against the metal surface in one direction.
• Plating is a process of coating a layer of metal to an object of different types of metal.  This process is done, commonly, for aesthetic purposes or more practical reasons such as corrosion resistance and protection from wear and tear.
• Polishing sheet metal as a means of finishing is where a layer of oxidation and also a thin layer of the material itself is ground off.   In doing so it smooths out the metal, removing imperfections, and making it gleam once more.  Generally, start with a coarse grit of sandpaper, like a 40 to 80 grit and then work towards a finer grit to finish off the polish effect.
• Powder Coating creates a hard finish that is tougher than conventional paint.  Powder coating comes in any color and therefore makes a great custom finish method when both durability and aesthetics are desirable finishes.
• Abrasive Sand Blasting, more commonly known as sandblasting or media blasting, is the operation of forcibly propelling a stream of abrasive material against a surface under high pressure to smooth a rough surface, roughen a smooth surface, shape a surface or remove surface contaminants.

Concluding Thoughts

Selecting a material, in this case, sheet metal is the first step in any design process.  The process begins with the function of the part you are intending to design.  The function of the part will help determine the needed design.  Choosing a material and gauge are critical steps that involve balancing factors like strength, weight, and cost.  This is not a simple process but can be streamlined by using CAD models with the above design considerations found in this white paper.  The next real test, however, is prototyping.

While today’s engineering tools are powerful, it is only when you can see and handle a part that it becomes known whether the design will meet expectations.  Is it strong enough?  Light enough? Does it look, feel, and balance the way it should?  Does it sacrifice other components?  Even relatively simple components benefit from real-world try out before committing to hundreds or thousands of parts.   In some cases, it may take several prototype iterations to get the sheet metal part right.  With a good manufacturing supplier, this process

can be kept at a minimal impact on the overall project but getting it right earlier in the prototype process.

It is tempting for larger enterprises to outsource design to engineering service providers so they can focus on core activities.  However, selecting the right partner helps avoid further widening the gap between the ideal design and fabrication process and the all too common real-world scenario of poor designs making to the fabrication floor without resolution of design flaws.  Working with partners willing to collaborate, interested in knowing more about the manufacturing process, and involved in developing sheet metal products.  When selecting fabrication suppliers, look for companies with a proven track record in producing parts and who bring a vast wealth of fabrication knowledge to ensure fewer hiccups in the design to the fabrication process and product is brought to market faster.

Source:

The Aluminum Association. “Aluminum Alloys 101,” (n.d.) Retrieved from https://www.aluminum.org/resources/industry-standards/aluminum-alloys-101

Australian Stainless Steel Development Association. “Types of Stainless Steel” () Retrieved from https://www.assda.asn.au/stainless-steel/types-of-stainless-steel/austenitic

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