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Select Magnet Materials Among SmCo, Neodymium Magnets and Others
Posted on May 25, 2017
When choosing a magnet material to be incorporated into your specific application, their
properties need to be identified and compared to correctly evaluate their functional workability
and economic feasibility. Design engineers should consider the magnetic requirement, physical
requirement, working temperature range, product cost and manufacturing lead time. There is a list
of commercially available permanent magnet materials to choose from:
neodymium magnets, samarium cobalt,
alnico, ceramic and flexible. Let take a quick look at their difference.
Table: Key properties comparisons among the magnet materials
| Material | Max. Available Remanence, Br (KGs) | Max Energy Products, (BH)max (MGOe) | Max Intrinsic Coercivity, Hci (Oe) | Maximum Working Temp | Machinability Index | $ Index /Weight | $ Index /BHmax | Special Characters |
| Neodymium, NdFeB (sintered) | 14.8 | 53 | 35,000 | 220°C /428°F | 50% | 40% | 16% | Can be easily corroded and need plating, Brittle, Strongest |
| SmCo | 11 | 30 | 25,000 | 350°C /662°F | 70% | 100% | 64% | Very Brittle, Good magnetic property |
| Alnico | 13.5 | 9 | 2,050 | 550°C /1022°F | 100% | 32% | 100% | Withstand high temp, corrosion resistant |
| Ceramic | 3.85 | 3.5 | 3,050 | 450°C /842°F | 50% | 5% | 13% | Hard, Brittle |
| Flexible | 1.7 | 2 | 3,000 | 100°C /212°F | 10% | 3% | 20% | Like rubber, Can be easily cut using simple cutting tools |
- Remanence, or residual induction, is how strong a magnet can be.
- Max. Energy Product is the maximum amount of magnetic energy stored in a magnet.
- Intrinsic Coercivity Force is the irreversibility of magnetization by external magnetizing field.
- Neodymium magnets are the strongest with highest resistance to demagnetization. However, it can be easily corroded or oxidized with high content of iron and almost always require plating.
- If the operating temperature is close to the recommended working temperature for a specific material and grade, be extra cautious that the magnet would not be permanently demagnetized.
- Price index shown above is only a general guideline. Material cost is also dependent on magnet grade, order volume, magnetization orientation, size and shape complexity.
- Production lead time is dependent on the shape complexity and size of magnet, especially if the magnets are highly brittle. Molds are often required to be made first.