Sintered NdFeB Neodyminum Magnets

Sintered neodymium-iron-boron (NdFeB) magnets, also widely referred to as “neo” magnets, have be commercially available since 1984. They offer the highest energy product of any material today and are available in a very wide range of shapes, sizes and grades. The applications include voice coil motors (VCM’s) in hard disk drives, auto motors, Hi-Fi system, high performance motors, brushless DC motors, magnetic separation, MRI, sensors and other magnetic tools.

Sintered Neodymium ( NdFeB), magnets got their start in late 1970 and became commercially available in the early 1980’s. In the beginning they ranged in energy product from 14 MGOe to 18 MGOe. Presently their energy product range is from 30 MGOe to 52 MGOe and who knows what tomorrow will offer. The operating temperatures are from -40⁰C to 220⁰C maximum, this varies according to the grade type.

Sintered neodymium-iron-boron (NdFeB) magnets, also widely referred to as “neo” magnets, have be commercially available since 1984. They offer the highest energy product of any material today and are available in a very wide range of shapes, sizes and grades. The applications include automotive steering column, EPS motors, sense magnets, as well as voice coil motors (VCM’s) in hard disk drives, Hi-Fi system, high performance motors, brushless DC motors, magnetic separation, MRI, sensors and other magnetic tools.

Sintered Neodymium (NdFeB), magnets revolutionized the entire cordless power tool industry, wireless cell phone, MRI’s and miniaturized many sensors , computer hard drives, micro motors, optical isolators to name a few. Neodymium magnets are susceptible to oxidation mainly because of the Iron (Fe) element content in the formulation of the magnet. To overcome this problem many coatings are available to hinder or stop the oxidation, they are: Nickel (Ni), Nickel –Copper-Nickel (Ni-Cu-Ni), Zinc (Zn), Parylene, Epoxy, and Gold (Au). Consideration should be given to the operating environment the magnets will be exposed to so the proper coating can be determined.

Although the Curie temperature for NdFeB material is about 310 ºC for 0% cobalt material to greater than 370 ºC for 5% cobalt, some irreversible loss of output may be expected at even moderate temperatures. Neo magnets also have a moderately high Reversible Temperature Coefficient of Induction which reduces total magnetic output as temperature rises. Selection of neo magnets instead of SmCo, is a function of the maximum temperature of the application, required magnetic output at typical working temperature and total cost of the system.

Neo magnets also have some limitations due to their corrosion behavior. In humid circumstance, a protective coating or plating is highly recommended. Coatings which have been applied successfully include; e-coating, powder coating, nickel plating, zinc plating, parylene and combinations of these coatings.