EMI (electromagnetic interference), which is also sometimes known as RFI (radio frequency interference), is a type of disturbance caused by external forces that interfere with electrical circuits and signals. EMI enclosures, named after electromagnetic interference, are a type of housing designed specifically to insulate susceptible devices against exposure to electromagnetic fields and radiation and the damage such exposure can do. They can also block devices from falling victim to the coupling effect, which is when energy is transferred from one medium to another. This can happen inadvertently when products are exposed to electrostatic fields, electromagnetic radiation and radio waves. EMI enclosures block all these interferences by creating a conductive or magnetic barrier between the product and the electromagnetic interference surrounding it, which absorbs any energy of the kind that it encounters.
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Applications of EMI Enclosures
EMI enclosures are used to protect systems in a number of settings, including in telecommunications, healthcare, food and beverage production, and sound and stage production. EMI-susceptible everyday items include AM radios, FM radios, televisions, and cell phones. Common EMI enclosure examples include shielded cable, metallic boxes, and conductive plastic boxes.
EMI Enclosure Design and Function
EMI enclosures may be built from a number of different materials. The main criteria of an EMI enclosure material is the ability to absorb magnetic energy or high magnetic permeability. Metals such as these include aluminum, copper, nickel, steel, stainless steel, and their alloys. The industry standard EMI shielding material, though, is Mu-Metal®, which is an alloy that is composed of copper, iron, molybdenum, and nickel. Mu-Metal® is highly permeable and soft, with a low coercivity, which means that it saturates at low magnetic fields. Its greatest advantage over other enclosure materials is the fact that it is more ductile and workable than them. Because of this, it is more easily formed than them into the thin sheets that EMI shielding requires.
Metal EMI enclosures can be made from solid metal, but they may also be made from perforated metals, provided the perforations are closer together and smaller than the electromagnetic waves they intend to block. One of the most widely shared examples of the latter type of enclosure is the microwave door, which is covered in a perforated EMI shield. Microwave doors are also one of the few examples of EMI enclosures that are not products separate from the device they are meant to protect. Other materials from which enclosures may be made include ionized gases and metal foam. In addition, manufacturers may spray an EMI shielding copper or nickel spray over a regular plastic enclosure to turn it into an EMI enclosure.
Electromagnetic interference can come from sources as diverse as toaster ovens, automobile ignition systems, thunderstorms, the sun, the Northern Lights, electric blankets, bluetooth devices, CRT computer monitors, and baby monitors. In the most imprecise sense, EMI can come from nearly anything. Fortunately, the world of EMI enclosures is just as varied as the events and items that cause it. They are typically available as multi-piece enclosures, single piece enclosures, and shields with removable covers. In addition, EMI can be built to fit any number of regional and/or industry standard regulations, including NEMA (National Electrical Manufacturing Association) standards, EPA (Environmental Protection Agency) standards and ISO (International Standards Organization) standards.
Finding the Right EMI Enclosure Manufacturer
When shopping for one or more EMI enclosures, customers have many options to fit their many needs. For quotes, answers to questions, and/or consultations, interested parties should reach out to an experienced enclosure specialist today. Listed on this page are many excellent manufacturers that can address customer needs today. Learn more by contacting them.