An electric coil, also known as an electromagnetic coil, is an electrical conductor composed of wires wrapped around a cylindrical, disk-shaped, or toroidal ferromagnetic core. It is one of the most basic electronic components, providing inductance in an electric circuit. Inductance refers to an electrical property that opposes current flow through the circuit.

Electric coils are widely used in applications where electric currents interact with magnetic fields. These include the manufacturing, engineering, and medical industries. They are also found in devices and equipment such as electric motors, generators, transformers, inductors, and sensor coils.

Definition of a Self-Supported Coil

Self-supported or air core coils are created by coating magnet wire with an adhesive and then wrapping it in an insulating film. Solvents, hot-air heating, and post-baking can all be used to activate the adhesive and secure the adjacent strands of magnet wire. They are also wound on collapsible mandrels, allowing disassembly without damaging the wire insulation. The mandrels can be machined into nearly any shape to accommodate any desired coil configuration.

These coils are ideal for electronic applications where a bobbin or other coil form is impossible due to dimensional constraints. They reduce bobbin costs while increasing copper content in a given area.

Presently, bondable magnet wire with fundamental solutions up to 180° is available. However, the strand-to-strand bond typically begins to soften at temperatures 10° to 15° below the insulation rating. A bondable wire is also useful when magnet wire bonding is preferred to prevent movement or wire abrasion in applications where other processes, such as impregnation or varnishing, are not recommended.

Advantages of Self-Supported Coils

One of the most significant benefits of a self-supported coil is the low signal loss that occurs at higher magnetic field strengths. Ferromagnetic cores such as iron can become magnetically saturated when the magnetic field is too strong, causing an inductance loss. This is not a problem for self-supported coils as they can carry electromagnetic frequencies up to 1 GHz. Conversely, ferromagnetic core inductors lose efficiency once the frequency exceeds 100 MHz.

Self-supported coils are also simple to build since they are unaffected by the value of the electric current they transport. If there is no ferromagnetic core, they are more suitable for low-power devices, such as commodity electronic products, computer devices, communication equipment, and other consumer goods.

CNC Winding of a Self-Supported Copper Coil by Endicott Coil

Endicott Coil Company, Inc. manufactures a wide range of self-supported coil shapes and sizes for use in various space-constrained electronic applications. Based on customer specifications, the company uses CNC equipment to wind strands of coated 24-48 AWG copper magnet wire to the desired shape. The bondable coating is then activated via a solvent or heat cure to secure the magnet wire strand-to-strand.

Endicott also solders and trims the finished pieces using in-process gauging to maintain tolerances of less than 0.005 in.

Partner With Endicott Coil Company for High-Quality Custom Coils and Components

Endicott Coil Company, Inc. has been the leading supplier of magnetic components to a wide range of OEMs for over 65 years! We have earned a solid reputation for value and performance, enabling us to meet and exceed our customer’s needs and expectations.

Our company can significantly help with material selection, parameter testing, and cost-cutting redesigns of existing coil designs. Endicott Coil’s engineering team is also exceptionally skilled and specializes in custom electric coil winding assemblies! We can create and construct any coil type, including self-supported, injection molded, bobbin wound, impregnated, and sensing coils.

For more information on our coil services, contact us right away. You can also request a quote to start your next project with Endicott Coil Company!

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