What is an Electromagnet? How It work and application ?

Part 1  What is an electromagnet ?

The electromagnet is a simple actuator device where the magnetic field is created by an electric current. Electromagnets are made up of copper wire wound into a coil. A current goes through the coil of wire building a magnetic field that is concentrated in the hole, indicating the center of the copper coil. When the power on, it can attach itself to a flat steel surface with strong force. When power off, the attracting force is disappeared. The magnetic field strength, in turn, is expressed as the vector H and is measured in units of amperes per meter.

Well, an electromagnet can be designed as a magnet that works with the help of electricity. But the electromagnets are not like permanent magnets, the strength of the electromagnets can be altered by repeated variation in the amount of electric current that flows through them. If the flow of electric current is disconnected, the property of magnetism will be lost, thus the effect of the electromagnets depends on the amount of electricity.

Part 2，what is the electromagnet Construction ?
The construction of electromagnets is illustrated as below, the device comprises of a steel disk core with a copper coil fitted in an  inside groove in the face of the electromagnet, the copper coil is commonly fixed it in place for environmental protection and improved thermal contact with the pot. the construction of electromagnet is very simple, it requires a copper coil and conducting bar, as usual, we take the iron as the support. If the copper coil or any wire carrying an electric current is formed into a series of loops (concentric loops), the concentration of the magnetic field can be varied within the loops, by altering it. The strength of the magnetic field generated can be strengthened by wrapping the wire up and around the core of the magnet. The magnetic materials behave like magnets, for example, iron, nickel, and cobalt, which appear to be behaving like tiny magnets

When the power is off, some residual magnetism may remain, in cases where this is problem, a spring-loaded ejector pin can be fitted to the device to separate this from the electromagnet.

Part 3,  How does an electromagnet work?

When the electric current goes through a straight wire, it creates a magnetic current all around it. A magnetic field intensity can be built up by winding the copper wire in a particular direction. Multiple winding of the copper wire will further increase the intensity. Indeed, the strength of the electromagnet is directly proportional to the number of turns in the coil. So the strength of an electromagnet can actually be doubled by doubling the number of turns. That said, winding the wire in the opposite direction will cancel the effect of previous winding. A straight line of one winding direction to another is needed, one that starts from the end of the winding to multiple winding.

The strength of the magnetic field is also influenced by the magnitude of the current flowing through it to a saturation point (where all atoms/ions in the core are aligned with the magnetic field). As soon as the flow of current through an electromagnet is stopped, the magnetism effect on the core and in the wires is lost.

 Part 4  the Advantages of electromagnets

The advantage of applying an electromagnet instead of a permanent magnet is that you can control the magnetic field of the former. Not one can easily turn on and off the device’s magnetic field, with many electromagnets, one can also control the strength of the magnetic field.

Electromagnets are also useful in situations where the changing of poles and discontinuation of the magnetic field is mandated. Magnetic separators capitalize on this very property of electromagnets. When magnetized by passing current, large electromagnets attract the iron scraps from the heap of scraps and once the operator has moved the scrap to another place, the current supply is stopped and at this point the scrap is dropped by them. 

Other advantages of electromagnets include the fact that they do not cost much and are rather easy to build. Also, they are lightweight and do not damage the test-piece which is a part of the electromagnet.

Part 5 Disadvantage of electromagnets

the disadvantages of electromagnets is that they take up a lot of energy and heat up very quickly. This heat generation in turn makes them lose a lot of electrical energy.

To use an electromagnet, you need a power supply that can provide an electrical current. Some electromagnets are plugged into an electrical outlet, and others contain a battery bank. Permanent magnets, meanwhile, don’t need a power source since they are naturally ferromagnetic.

In short, to maintain a constant magnetic field needs a continuous power supply. It is assured that an electromagnet can store huge amounts of energy in its magnetic field but the energy will start discharging as soon as the electric current is interrupted. 

By the way, to get a strong magnetic field, a lot of coiled of copper wire is needed and this in turn requires a large space. So electromagnets are not ideal for small spaces. There’s also the danger of a short-circuit that can damage the electromagnets and the surroundings, so attention must be taken to avoid the accident happened..

Part 6, Electromagnet’s Applications
Electromagnet application as holding/latching solenoid in machinery, as latching devices in security systems, and as door holdback devices in large buildings such as hospitals where doors are held open to permit easy access, but must be released to close if fire alarms are triggered, or in the case of power failure. Our small round electromagnet devices are used in applications such as cash drawers, smart door lock, drug dispensing trolleys, or key boxes / safes in secure environments where a limited level of security is needed to trace use of materials or prevent misappropriation.

In handling and installation, and in many of the applications where they are employed, the device can be subject to harsh treatment which can deform the surface and impair holding force. Dr. Solenoid electromagnets can be supplied with a hardened surface finish which makes them highly resistant to such damage, this will become standard for most such devices for future production.

Part 7 How to do the testing of Electromagnet ?
Electromagnets are tested with a shim of non-magnetic material inserted between the holding face of the electromagnet and the armature (or a flat steel surface) to simulate a gap between the two. The electromagnet is engineered, and increasing force applied until the two parts separate, the maximum force recorded is taken as the holding force.

The influence of the gap represented by the shim is similar to that of dirt, paint, or contamination on either surface, or to separation caused by damage to the surface. The influence of any likely contamination and separation this could cause should be considered when evaluating data on parts, in environments where contamination causing separation is likely, it may be desirable to choose a larger device which can achieve the required force at a separation corresponding to that caused by expected contamination.

Part 8  The strong and small electromagnet made by Dr. Solenoid

An electromagnet from drsolenoid.com provides you with a solution for handling ferrous materials that is safe, secure, economical, and best efficient. Round or rectangular flat-faced electromagnets give you the ability to control the strength of the electrical current running through the magnet at any given time. The ability to control the electrical current’s strength means that the magnetic field can be rapidly manipulated between a broad range of values. Round flat-faced electromagnets are suitable for use in a wide variety of manual and automated equipment /device applications. These electromagnets require minimal maintenance.

Pls find below link for more strong and small electromagnet made by Dr. Solenoid

https://www.drsolenoid.com/as-6845-dc-electromagnetic-spectrum/