Possibilities and advantages
The advantages of the sintered neodymium magnets are:
- Highest magnet strength available
- High resistance to demagnetization
- Operating temperature up to 240°C
- Good at withstanding low temp. (down to – 100°C)
- Possibility of more coils
- Less waste – especially with complex geometries
Sintered NdFeB magnets are the most powerful magnets known. Maximum allowed temperature varies, but is up to 240°C for some grades. This max temperature is important, because the price of the magnet increase with temperature.
Magnets consists of powder compacted in a magnetic field therefore they have process-fixed and limited magnetizing directions. Usually the magnetic field-lines have to be parallel.
Corrosion protection is however always recommended for sintered neodymium magnets, because of the materials low corrosion resistance. The corrosion resistance can be compared to pure untreated iron. A range of different coatings are available but sometimes complete encapsulation in i.e. stainless steel is preferable.
Characterizing magnets
The most important properties to take into consideration for characterizing the magnets are:
- Magnetic properties such as remanence Br, coercivity Hcb, intrinsic coercivity Hci and max. energy product (BH) max.
- Dimensions and tolerances
- Force (for holding magnets), Torque (for motors), Field strength (for sensors)
- Minimum and maximum operation / working temp.
- Area of application usage – e.g. aquatic environment
- Requirements concerning surface coating
