These days, neodymium magnets have become quite popular in the industry and you can find many different applications by using this kind of magnet. This magnet is a rare earth magnet and generally termed as NIB, Neo or NdFeB because of its constituents are Iron (Fe) and Boron (B). It is one of the strongest magnets available in the market. This type of magnet was first developed in 1982.
NIB magnets are made in two following ways:
- Sintered
- Bonded
Sintered NIB magnets
These magnets have very high magnetic strength, but are available in very simple geometric shapes. They are also quite brittle. Various raw materials are compressed and go through various kinds of complex heating processes in order to create them. After that the blocks are cut in different shapes and are given coating, so that it does not get corroded.
Sintered magnets have anisotropic property and due to this reason they have magnetic field based on certain specific direction. Its magnetic property can be reduced by 50 per cent, if they are magnetized against the grain. Commercially available sintered NIB magnets are magnetized in certain preferred direction.
Bonded NIB magnets
As compared to sintered NIB magnets bonded magnets are about 50 per cent less in magnetic strength. That is why they are cheaper in price and can be made available in any size and shape. Epoxy is used as a binder where raw materials are mixed and then pressed into the cavity of the die and given heat treatment. This type of magnet has isotropic property and therefore it does not have grains and does not have natural preference for any direction of magnetic field.
Demagnetization
NIB magnets are considered to be permanent magnet as they lose their magnetic property very slowly. Typically their strength reduces approximately 1 per cent in a period of 100 years. You can use them within the temperature range of -138 degree centigrade to 80 degree centigrade. If you want to use magnets for much broader range of temperature then you must use Samarium Cobalt magnets.
Coating is necessary
In order to protect these magnets against atmospheric exposure, it is necessary to provide coating on them. Commercially available magnets are generally coated with nickel or copper. With the help of such coating, you can protect these magnets from high humidity and temperature, solvents and gasses, salt sprays etc.
Various grades of NIB magnets
You can get NIB magnets in many different grades in the market. The grade determines their magnetic strength. The weakest magnets are having grade N35 while N52 is the strongest and also more brittle magnet. If you are interested to know what is n52 magnet in more detail then you can you can refer to its product catalog. The cost of magnet will increase as you go to higher grade.
Generally for typical applications people prefer to use N40 to N42 grade. N52 magnets are 50 per cent stronger than N35 magnets. N35 magnets are preferred in such applications where weight and size is not very important consideration as it is very less expensive.