NEMA enclosures are boxes that are designed to protect electrical components from the surrounding environment. Depending on the specific NEMA rating, devices in a NEMA enclosure are protected in...
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This article will take an in-depth look at electronic enclosures.
The article will bring more detail on topics such as:
This chapter will discuss what electronic enclosures are and how they are made.
Electronic enclosures are box-like structures that are designed to protect, contain, and enclose electronic components such as switches, relays, printed circuit boards (PCB), integrated circuits, power supplies, processors, etc. They can be made from different material types at different sizes depending on the use, purpose, environment, design, cost, etc. The diagram below shows an electronic enclosure protecting the components inside.
Imagine an electronic device where water can easily penetrate, where children can easily touch the components inside, where the components are exposed to heat or moisture. This device will not last long as it can be easily damaged by the near environment and will be hazardous to the users. Electronic and electrical engineers came up with structures that protect the entire device from the harm it can cause to the environment and other negative effects associated with uncovered components. These structures are known as electronic enclosures.
A metal box is a designed fabrication to give shelter, store, and enclose something. Aluminum enclosures and stainless steel enclosures are all referred to as the types of metal boxes. Metal boxes are commonly used as fuse boxes and outdoor electrical meters. In business companies, these metal boxes are often used for enclosing electrical equipment for the supply of power around the premises.
In industries, these boxes protect and keep sensitive and fragile electronic components from accidental impacts, debris and dirt and keep them from contamination. Accidents from workers and machinery may happen at any time but with these boxes, further damage like an explosion and other electrical faults can be prevented from happening.
The International Electrotechnical Commission is a board that helps professionals choose boxes and ratings that are appropriate to the purpose of the box. Some metal boxes are used for very important purposes like in telecommunication and if inappropriate boxes are chosen, that may lead to the blocking or unintended traffic flow of information.
There are many methods for fabricating electronic enclosures with some of the most common below.
Computer numerically controlled (CNC) machining is a type of machine that uses subtractive machining processes by reading CAD files to direct a cutting tool on the workpiece to cut the material according to the CAD program.
The process on CNC machines is repeatable if the program files are still accessible to the machine. This is an advantage because the same program used to manufacture a plastic enclosure can be used to fabricate a metal enclosure. CNC machining enables the fabrication of complex geometric designs.
Sheet metal fabrication is the process of converting flat metal sheets of aluminum or steel into metallic structures by folding, assembling, or folding the sheets. It is an effective and economical way of producing electronic enclosures. When comparing sheet metal fabrication to CNC machining, it has been revealed that metal fabrication is fast and has less complication.
Many outdoor electronic enclosures and desktop enclosures are made from metal sheet fabrication. The initial costs associated with buying sheet metal fabrication machinery and tools are high but as the production volume increases a rapid decrease in cost per part is expected.
Injection molding is a manufacturing process that involves shaping materials such as plastic, metals, glasses, elastomers, polymers, and injecting heated material into the mold. This method is mainly used when manufacturing simple enclosures like car remote controls, tv remote controllers, gamepads, kiosk displays, calculators, etc.
3D printing is an additive manufacturing process that allows the formation of enclosures using the 3D printer reading CAD files and creating layers of materials that will build into the 3D model. 3D printing can produce complex designs that other methods like the injection mold may fail to create.
Both plastic and metal can be 3D printed however most 3D printers are not fast compared to the other production methods. 3D printers can be used for small production volumes and are suitable for custom enclosures where the designs are not commonly used or for prototyping models before passing them for mass production.
Various factors should be considered when designing electronic enclosures. These factors include:
Product requirements refer to the features, functions, and behavioral patterns that a product (in this case electronic product) should have. This information is usually contained in the special document known as the product requirement document (PRD) and is read by people so that they understand how the product will function.
This information will help create a model for electronic enclosures that compliments and fulfills the enclosure requirements. In the PRD of an electronic product common functions that may require the design of an enclosure may include the need to reflect heat, prevent moisture, absorb vibrations, LED visible, and accommodate the fan. If this information can be obtained from the PRD, the designer is expected to know what material to use for the enclosure, the associated costs, suitable manufacturing process, etc.
To come up with an ideal enclosure the designer needs to have in-depth knowledge of how the components inside the enclosure will be arranged. This starts from understanding circuit designing and electronic design. Where there is a need for holes, they should be drilled, where there is a need for heat absorption spaces should be left for air circulation or heat-absorbing components.
Some components cannot be placed next to each other in an electronic circuit for many reasons, resulting in false readings, short circuits, melting, shortened life span, etc. All this information should be a consideration and for best results professionals should be hired.
Once the electronic components have been modeled, the enclosure shell can be drawn or drafted by considering the part’s arrangements. Before choosing an appropriate manufacturing process for the enclosure it is important to do a 3D CAD model of the enclosure to give room for modifications if there is misalignment.
The wall thickness of the shell is very important because if it is too thin, the enclosure may be prone to damage from harsh conditions, and if the wall is too thick, the enclosure may trap hot air, which may be hazardous to the entire device.
Before production of the actual enclosure, it is essential to compare the CAD and BOM to avoid communication issues. This process can be done effectively using a software program.
Electronic enclosures can be classified according to the material type and application.
The common material types used for fabricating electronic enclosures are metals and plastics, hence the names metal enclosures and plastic enclosures.
In many buildings, there are enclosures made with metals and are used in equipment such as fuse boxes, meter boxes, etc. They are called metal enclosures and are used to protect components from accident impacts, prevent them from contaminations like dust, dirt, and other hazardous conditions. Metal enclosures are often used where portability is not an important consideration.
For industrial purposes, metal enclosures are used to provide an effective and safe working environment for the equipment. There is a lot of dirt and debris produced in industries and these enclosures save well in such instances because metals are stronger and can withstand hard conditions that are in many industries.
Metal enclosures come in many sizes, depending on their use. The sizes vary for example in substations (Electrical and power distributions) most enclosures used are very big and there are also very small metallic enclosures such as those used in consumer light switch fixtures. They can take many shapes such as box, cylindrical, rectangular cylindrical depending on the use and the ability of the manufacturer to punch the metals.
These are structures made from aluminum to protect electronic components from damage such as interference. Aluminum enclosures are applicable for outdoor and indoor use to protect the instruments from unfavorable weather conditions like excessive heat, water, UV light, and to prevent dirt and dust from entering and contaminating components.
Electronic components can be easily damaged from such conditions, resulting in electromagnetic interference and other circuit interruptions. Computers are often enclosed in unibody enclosures made from aluminum for protection. Handheld devices such as remotes, power switches, electrical conduits, garage door openers, car starters are common examples where aluminum enclosures are used.
The design of Aluminum electronic enclosures requires an understanding of:
Aluminum enclosures are made from aluminum, although other materials can be used for enclosures. Aluminum has different alloys, which are applied differently to these enclosures depending on the use and type of environment the device is exposed to.
Most of the aluminum enclosures have a box-like shape with corresponding dimensions but in general, they have lengths ranging from 10 cm to 20 cm. Other different dimensions can be used depending on the specific design of the enclosure.
These types of enclosures usually have a hinged solid lid door. A hinged door can be used where security is needed the most to lock the enclosure. In other enclosures, there are internal gaskets used as well continuous flanges for complete closure of the box and this protects the device from dirt, dust, and moisture. Sometimes the doors are made from the bezel and corner screws, especially when a tight closure is required. These methods of closing aluminum enclosures can be combined for an effective enclosure if need be.
Stainless steel is an alloy of iron, chromium, and sometimes nickel and is resistant to corrosion. Researchers consider stainless steel as a “green material” and it is recyclable. They are used to protect and contain electronic components for outdoor and indoor applications. They have similar designs and production methods except for other differences like density, corrosion, cost, etc.
Plastic enclosures refer to a container that is used to protect or house electronic components. These are usually molded in various shapes according to the product requirements. They are easily customizable into any shape and size because of the flexibility of plastics materials. Besides their flexibility, plastic materials have light weights and can be used to design portable devices.
In cases where insulation is required, plastic enclosures are usually the best to use. Common examples of plastic enclosures are found in calculators, remote controls, desktop computers, laptop computers, wireless internet controllers, coolers, game controllers, and televisions.
The design of plastic enclosures should take into consideration:
Many plastic materials can be used as electronic enclosures and, in some cases, they are combined and in other cases, they are utilized in their natural states. Plastic enclosures can be made from various material types depending on the need. For more intensive and heavy-duty applications high-density polyethylene (HDPE) is usually used because it is a strong thermoplastic material.
HDPE is known for its cold resistance, liquid and corrosion resistance, longevity, extreme heat resistance, and low production costs. Other materials that can be used include acrylic, polyvinyl chloride (PVC), polypropylene, acrylonitrile butadiene styrene (ABS), styrene ethylene butadiene styrene (SEBS), and polyamide (PA).
Below are some of the common materials that are used in fabricating plastic electronic enclosures.
Acrylonitrile Butadiene Styrene is used to manufacture plastic enclosures and is very effective, especially when used in environments where resistivity to chemicals is required and shielding from impacts. ABS has poor resistivity to ultraviolet (UV) light and is effective for indoor enclosures.
Acrylonitrile Styrene Acryl Ester is used in applications such as food manufacturing, healthcare, pharmaceutical or laboratory facility, wellness because of its antimicrobial properties. In environments where there are fungi and viruses, ASA is well protected and can be mounted in bacteria-prone areas.
Sometimes the best electronic enclosures are brought about by combining the different properties in materials to bring the best enclosure. When Polycarbonate is combined with Acrylonitrile Styrene Acryl Ester, this enables the enclosure to have flame resistance, withstand high temperatures, ensure resistance to weather and chemicals, survive in impact-ridden environments, and make the product usable for outdoor environments. Many properties can be attained but combining materials and such enclosures is usually expensive and durable.
Carbon Neutral Bioplastic is a new type of plastic that is biodegradable. These types of materials are used where there is a need for soft case enclosures. They are naturally occurring, and they are certified biodegradable.
Enclosures can also be classified according to their application. Some of them include:
Computer enclosures are protective structures designed to secure and protect computer hardware components from possible contamination and accidents caused by dirt, moisture, and dust particles. Nowadays computer products are found in almost all works of life such as homes, offices, spacecraft industries, cars, factories, people’s bags, people’s pockets, etc.
Computer enclosures are designed based on the environment in which the computer is going to operate, for example a home computer is exposed to dust, exposure to liquids, and impacts from the accident. A computer used for industrial purposes is exposed to the same impacts but to a greater extent. In heavy manufacturing industries computer enclosures are supposed to be designed to protect the computer from flying debris, unwanted temperature ranges, and protection from moving machinery and workers.
The design of the computer enclosure should consider:
Computer enclosures that are found in cars must be designed in such a way that they prevent damage from vibrations and shocks experienced during car movement and engine rotations associated.
Enclosures used in computer systems and devices like laptops are supposed to be designed using light materials so that they can be easily carried around, at the same time, they should be strong enough to prevent damage from accidents.
Computer enclosures are made with different materials depending on the use, cost, strength, etc. The most used metal enclosures are made from aluminum and stainless steel, especially in cases where portability and weight are not important considerations. Most laptops are made from thin and lightweight metals. Some are made from plastics such as ABS (acrylonitrile butadiene styrene).
The National Electronics Manufacturers Association (NEMA) assists electronic manufacturers and professionals by providing ratings in the configurations that will determine if a certain material in an enclosure is suitable for an application. They can determine if an enclosure type is suitable for indoor or outdoor applications. For example the 1,2, 12, 12K, and 13 are suitable for indoor applications where contamination is less likely to occur. They have information and issue ratings of enclosures for low and high hazardous indoor and outdoor use.
Most electronic enclosures are box-shaped but there are cases where irregular shapes are used and modifications should be done for an effective design. In some cases, customization must be done to allow for contours, curves, and complex shapes to be part of the design. Aluminum, galvanized steel, and stainless steel are often used because of their durable and strong properties. For small and complicated enclosure designs, plastics are usually used.
Portable enclosures have small sizes such that they can be put in a pocket or held in a hand. These enclosures are usually associated with LED’s and battery compartments. Examples of portable enclosures include car remote controllers, laptop covers, electronic mice, tv remote controllers, etc.
Desktop enclosures are designed to protect computers in office or industrial environments from dust, and other contaminants. Parts like the Central Processing Unit (CPU) are sensitive and in some cases, the enclosures are made with engravings, footpads, and removable stands so that the computers can be shifted if need be.
Boxes with touch screens and clear windows are examples of display enclosures that are commonly used nowadays. They protect the screens from unwanted sunlight, impacts, liquid splashes, etc. They are commonly made from glass and plastic materials since these are commonly used for colorless products.
As the name intel, wall-mounted enclosures are mounted on the wall while protecting electronic equipment from damage, contaminations, heat, and other hazardous environments. Most of them are made of plastic and metallic materials.
Cabinet enclosures are mainly used to protect equipment associated with video and audio productions such as cameras and television.
NEMA enclosures are common in many industries such as telecommunication, rain services, bus services, electronics, domestic and commercial appliances, security, aviation, sound and music, defense and rail services. They are seen in nuclear power plants housing the wiring in nuclear reactors and control rooms. NEMA is a group that intends to bring manufacturers together so that they come under the umbrella of expanding markets and increase their profits by reducing manufacturing costs of products.
The common materials used for NEMA enclosures are polycarbonate and steel and aluminum alloys such as the 316 Stainless steel, 304 stainless steel, 5022 Aluminum powder coating with carbon steel. Polycarbonate is a thermoplastic material with very high-temperature resistance and its impact resistance is much higher (About 5 times stronger) than that of fiberglass. It is also heat resistant, water-resistant, impact-resistant, flame resistant, and highly insulative. Enclosures made from polycarbonate can function properly in low-temperature working conditions. NEMA enclosures can be made from common enclosure designs such as the junction box, free-standing, trough, floor mount, wall mount, and free-standing with leg kit design.
The word EMI stands for electromagnetic interference. In electronics, EMI is also known as Radio Frequency Interference (RFI). It is a type of disturbance originating from external forces which tend to interfere with the electrical and electronic circuits and their components. EMI enclosures are designed to protect the electronic device from unwanted interferences that may be created by electromagnetic fields, radiation effects, coupling effects, and other possible disturbances. Other common sources of electromagnetic forces include toaster ovens, automobile ignition systems, thunderstorms, electric blankets, the sun, computer monitors, etc. The enclosures will work by preventing the interferences through blocking with their materials, and in some cases, they work by blocking conduction, absorbing energy, reflecting energy, etc.
EMI enclosures can be built from several metals, such as solid metals and perforated metals. A microwave door is an example of an EMI enclosure where the door blocks the microwaves from leaving the device. Metals such as aluminum, copper, nickel, steel, stainless steel, and their alloys are used for building EMI enclosures. In some cases, manufacturers spray these metals on top of another material such as plastic. This will still be classified as an EMI enclosure. They can be used in the food and beverage services, telecommunications, stage productions, health care, etc. In our everyday lives, common devices which are susceptible to interference include cell phones, FM radios, televisions, computers, etc.
The benefits of electronic enclosure differ depending on the type of material used. To fabricate enclosures most manufacturers use are plastic and metal, which are discussed below.
The benefits of plastic enclosures include:
Some electronic devices are affected by magnetic fields if they are close by and this is referred to as magnetic interference. If enclosures are built with plastic the chances of magnetic interference caused by the enclosure are almost zero.
An insulator is a material that does not conduct electrical currents like plastic and rubber. A plastic enclosure can be used in applications where the enclosure is not supposed to be a conductor. An example is enclosures used in laptops to cover the motherboards and processors. These are made of plastic to eliminate the chances of short-circuiting between components.
Plastic enclosures are waterproof and can be used in humid environments where they can be exposed to water, snow, or rain without causing damage to them. Unlike metal enclosures, plastic enclosures do not rust when exposed to moisture.
Plastic is a cost-effective material and is highly economical. Compared to metal, plastic enclosures can be cheaply made.
Plastic enclosures are lightweight and due to this reason, they are commonly used especially for portable electronic devices so that they can be easily carried around. Such devices include car remotes, game controllers, cell phones, chargers, etc.
These types of enclosures are flexible because of their chemical structures. They can be used to make complex shapes for precise fittings because they can easily be machined.
Aluminum and Stainless steel are the metals that are commonly used for electronic enclosures. This section lists the benefits of using them as enclosures, but the benefits are not limited to these two only.
Some of the considerations when choosing an electronic enclosure are:
Electronic devices have become popular in our daily lives and are found in almost all industries. However, these devices are used in many conditions, some are harsh, some are favorable. Part of designing an electronic enclosure should consider the environment to which the enclosure will be exposed. Some environments are sunny, some are dusty, some are rainy, some are shaky, some have chemicals. This research should be done and will help in selecting an appropriate material type.
There are many governing bodies in electronics such as the International electro-technical Commission (IEC) and other policies from the governments that need to be followed and observed. These bodies develop and design regulations and standards in electrical and electronics-related technologies. They give product specifications that the product must conform with and must be taken into consideration when designing a proper enclosure.
The electronic circuit to be protected must be studied and understood such that one knows the amount of heat dissipated by the electronic parts inside. The specifications and power ratings should be taken into consideration as well as noting the components that release heat such as regulators, resistors, LED, power circuits, etc. Plastics are excellent when working as insulators, but if they are exposed to high heat-producing circuits they may melt, so they should be used in low heat applications. Metals are effective to use as enclosures in high heat-producing circuits
Nowadays many material types can be used as enclosures and many factors may affect the choice such as price, weight, size, and aesthetics. One of the most cost-efficient window materials that can be used in enclosures is acrylic because of its properties which include lightweight, impact resistance, and flexibility. Polycarbonate is gaining popularity as much as acrylic because of its thermal stability and impact resistance properties. Other materials can be used such as aluminum, glass, copper, steel, etc, especially in the case where cost-effectiveness is highly considered.
Electromagnetic compatibility of a system requires that a piece of equipment should possess the following characteristics.
The diagram below shows the ways in which emissions are spread in electrical and electronic devices.
The electronic industry is fast-growing, and this is evident especially when we look at the portable electronic devices that almost the whole world has been exposed to. We use devices like cell phones, radios, microwaves, remote control, laptops, etc on a daily basis and the information provided in this article will give either the consumer or the manufacturer of these devices some insight on how best to interact with these electronic enclosures.
NEMA enclosures are boxes that are designed to protect electrical components from the surrounding environment. Depending on the specific NEMA rating, devices in a NEMA enclosure are protected in...
EMI shielding is a technique of creating a barrier that prevents leakage of strong electromagnetic fields that can interfere with sensitive devices and signals. They can be installed to isolate the electromagnetic field source or as an enclosure of the device that needs protection...
Precision sheet metal fabrication is a common manufacturing process where the structure of a metal workpiece is cut, bent, and assembled by machining. There are any number of operations that are performed in the creation of a finished sheet metal product...
Radiofrequency (RF) shielding is the practice of blocking radiofrequency electromagnetic signals that cause radio frequency interference (RFI). RFI can disrupt the electrical circuits of a device from working normally...
Secondary manufacturing processes, or fabrication, work on products from primary processes to create a metal part or structure that is suitable for end-use. In these processes, semi-finished metal products are reshaped and joined...