Electromagnets – Power Magnets
Electromagnets are super powerful magnets used in a variety of uses some of which include cranes for wrecking yards, speakers, and magnetic separation to name a few. An electromagnet is a type of magnet in which the magnetic field is created by electricity. The electro field will disappear when the current is turned off. The main advantage of an electromagnet over a permanent magnet is that the magnetic field can be changed by controlling the amount of electricity.
Mechanically, an electromagnet is quite simple, usually consisting of conductive wire looped around a piece of metal. All you need to do is introduce electricity and this creates a magnetic field around the wire, magnetizing the metal and voila, you have an electromagnet.
Electromagnets are useful because you can turn the magnet on and off when you need to and you can increase the amount of electrical current changing the magnetic field. Electromagnets or permanent magnets are used for magnetic separation, by extracting metal contamination that can cause damage to machinery, compromise product purity and efficiency.
So the next thing you need to decide is do you require an electromagnet or a permanent magnet? They both extract metal from products, but one requires electricity and the other doesn’t. Finding the right fit for your facility, product and machinery is very important. You should contact a trained magnetic separation specialist that has experience with both types of uses for magnetic separation and they will consult with you on the right product purchase.
Electromagnet vs. Permanent Magnets: there will be pro’s and con’s to both depending on the product that you are processing and the equipment that you have in place.
Electromagnets are generally recommended for extremely high bed depths. These units utilize high current to “energize” the magnet. The magnet is cleaned by turning it off.
- The Suspended electromagnet can be turned on and off. Useful for cleaning the magnet without an additional device (belt, bar, etc.)
- Can Provide Deeper Magnetic Fields compared to a Permanent Magnet
- The Suspended Electromagnet is usually heavier
- Maintenance is required oil level, oil degradation, coil wear
- Higher operating cost (electricity)
- Not a uniform magnetic field across width of conveyor as the coil is round. Unit must be oversize to work properly.
- Produces substantial heat
Permanent Magnet suspended overhead requires no electricity. Although permanent magnets can be configured for manual cleaning, in most applications, a self-cleaning mechanism is recommended. Cleaning belts automatically move the tramp metal out and drop it into a chute or bin, outside the product stream.
- Lighter weight
- Less initial cost
- Almost zero operating cost
- Magnets lose only 0.5% of strength over 100 yrs
- Uniform magnetic field across entire width of Conveyor
- More flux lines agitate the material allowing for successful tramp removal
- Auto Cleaning requires a belt or bar around the magnet
- Limited on reach out
Purchasing the right magnet is vital and there are many variables to be considered before investing. The quality and design is equally as important. Having a magnet that is one size fits all is not recommended. What may work for one application may not work for another. Consulting with an experienced magnetic separation consultant is of the upmost importance. So whether it is determined you require an electromagnet or a permanent magnet you can be sure that you made a good investment that will save you time and money in the future.