Sintered Neodymium Magnets
Sintered Neodymium Iron Boron (NdFeB) Magnets
Sintered Neodymium (NdFeB), the lanthanide series of elements in the periodic table, also known as a second generation rare earth magnet, are the most powerful magnets available today with outstanding magnetic properties. By some, they are considered exotic materials, even though significant amounts of ore deposits are found around the world. The two most commonly known rare earth magnets are: Sintered Neodymium Iron Boron (NdFeB) simply known as Neo’s and Samarium Cobalt (SmCo) magnets known as Cobalt magnets. Due to their high magnetic strength extreme caution should be taken during handling and assembly.
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 (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.
Sintered Neodymium (NdFeB) magnets come in many shapes, e.g. disks, cylinders, rings, rectangular shapes, squares, arc segments, wedges and other custom shapes, with many types of inside holes e.g. tapered or countersunk types. Sintered Neodymium (NdFeB) can be manufactured less than one millimeter in diameter.
Precautions for handling NdFeB magnets:
Never allow the magnets to snap together, because of their high attractive magnetic strength these magnets can shatter, chip or crack, which can cause a potential hazard if any chips become airborne. Eye protection must be worn at all times when handling.
Keep all small magnets away from children; they could be swallowed causing asphyxiation.
These magnets must not be used as mechanical or structural components in design integrity.
Grade |
Residual Induction Br - kGs |
Coercive Force Hc - k Oe |
Intrinsic Coercive Hci- kOe |
BHmax Energy MGOe |
Curie Temp. ⁰F / ⁰C |
Max. Operating Temp.⁰F/ ⁰C |
Density Lb/in.³/ g/cm³ |
N35 |
11.7-12.1 |
10.5-11.2 |
≥12 |
33-35 |
590/310 |
≥176/80 |
0.27/7.4-7.5 |
N38 |
12.2-12.6 |
10.5-11.2 |
≥ 12 |
35-38 |
590/310 |
≥176/80 |
0.27/7.4-7.5 |
N40 |
12.6-13.0 |
10.5-11.2 |
≥ 12 |
38-40 |
590/310 |
≥176/80 |
0.27/7.4-7.5 |
N42 |
13.0-13.3 |
10.5-11.2 |
≥12 |
40-43 |
590/310 |
≥176/80 |
0.27/7.4-7.5 |
N45 |
13.3-13.7 |
10.5-11.2 |
≥12 |
42-45 |
590/310 |
≥176/80 |
0.27-7.4-7.5 |
N48 |
13.7-14.3 |
≥10.5 |
≥11 |
45-49 |
590/310 |
≥176/80 |
0.27-7.4-7.5 |
N50 |
14.0-14.6 |
10.5-13.0 |
≥11 |
47-51 |
590/310 |
≥176/80 |
0.27-7.4-7.5 |
N52 |
14.4-15.0 |
10.5-13.5 |
≥11 |
50-54 |
590/310 |
≥176/80 |
0.27/7.4-7.5 |
N38M |
12.2-12.6 |
10.8-11.5 |
≥14 |
35-38 |
608/320 |
≥212/100 |
0.27/7.4-7.5 |
N40M |
12.6-13.0 |
10.8-11.5 |
≥14 |
38-40 |
608/320 |
≥212/100 |
0.27/7.4-7.5 |
N42M |
13.0-13.3 |
10.8-11.5 |
≥14 |
40-42 |
608/320 |
≥212/100 |
0.27/7.4-7.5 |
N45M |
13.3-13.8 |
10.8-11.5 |
≥14 |
42-46 |
608/320 |
≥212/100 |
0.27/7.4-7.5 |
N48M |
13.7-14.3 |
12.8-14.0 |
≥14 |
45-49 |
608/320 |
≥212/100 |
0.27/7.4-7.5 |
N50M |
14.1-14.7 |
13.1-14.3 |
≥14 |
48-52 |
608/320 |
≥212/100 |
0.27/7.4-7.5 |
N30H |
10.8-11.2 |
10.1-10.6 |
≥17 |
28-30 |
626/330 |
≥248/120 |
0.27/7.5-7.6 |
N33H |
11.4-11.7 |
10.1-10.6 |
≥17 |
31-33 |
626/330 |
≥248/120 |
0.27/7.5-7.6 |
N35H |
11.7-12.2 |
10.5-11.2 |
≥17 |
33-35 |
626/330 |
≥248/120 |
0.27/7.5-7.6 |
N38H |
12.1-12.5 |
≥11.3 |
≥17 |
36-39 |
626/330 |
≥248/120 |
0.27/7.5-7.6 |
N40H |
12.4-12.8 |
≥11.6 |
≥17 |
38-41 |
626/330 |
≥248/120 |
0.27/7.5-7.6 |
N42H |
12.8-13.2 |
10.8-11.5 |
≥17 |
40-43 |
626/330 |
≥248/120 |
0.27/7.5-7.6 |
N45H |
13.2-13.6 |
12.5 |
≥17 |
43-47 |
626/330 |
≥248/120 |
0.27/7.5-7.6 |
N48H |
13.6-14.2 |
12.8-13.8 |
≥16 |
45-49 |
626/330 |
≥248/120 |
0.27/7.5-7.6 |
N30SH |
10.8-11.2 |
10.1-10.6 |
≥20 |
28-30 |
644/340 |
≥302/150 |
0.27/7.5-7.6 |
N33SH |
11.3-11.7 |
≥10.6 |
≥20 |
31-34 |
644/340 |
≥302/150 |
0.27/7.5-7.6 |
N35SH |
11.7-12.1 |
≥11.0 |
≥20 |
33-36 |
644/340 |
≥302/150 |
0.27/7.5-7.6 |
N38SH |
12.2-12.6 |
10.8-11.5 |
≥20 |
35-38 |
644/340 |
≥302/150 |
0.27/7.5-7.6 |
N40SH |
12.4-12.8 |
≥11.8 |
≥20 |
38-41 |
644/340 |
≥302/150 |
0.27/7.5-7.6 |
N42SH |
12.9-13.2 |
≥11.8 |
≥20 |
38-42 |
644/340 |
≥302/150 |
0.27/7.5-7.6 |
N44SH |
13.0-13.6 |
12.2-13.4 |
≥20 |
41-45 |
644/340 |
≥302/150 |
0.27/7.57.6 |
N28UH |
10.2-10.8 |
≥9.6 |
≥25 |
26-29 |
662/350 |
≥356/180 |
0.27/7.5-7.6 |
N30UH |
10.8-11.3 |
≥ 10.2 |
≥25 |
28-31 |
662/350 |
≥356/180 |
0.27/7.5-7.6 |
N33UH |
11.3-11.7 |
≥ 10.7 |
≥25 |
31-34 |
662/350 |
≥356/180 |
0.27/7.5-7.6 |
N35UH |
11.7-12.2 |
10.5-11.2 |
≥25 |
33-35 |
662/350 |
≥356/180 |
0.27/7.5-7.6 |
N38UH |
12.2-12.9 |
11.0-12.5 |
≥25 |
36-39 |
662/350 |
≥356/180 |
0.27/7.5-7.6 |
N40UH |
12.5-13.3 |
11.3-12.8 |
≥25 |
38-41 |
662/350 |
≥356/180 |
0.27/7.5-7.6 |
N28EH |
10.4-10.9 |
≥ 9.8 |
≥30 |
26-29 |
680/360 |
≥392/200 |
02.7/7.5-7.6 |
N30EH |
10.8-11.3 |
≥10.2 |
≥30 |
28-31 |
680/360 |
≥392/200 |
0.27/7.5-7.6 |
N33EH |
11.4-11.8 |
≥10.5 |
≥30 |
31-34 |
680/360 |
≥392/200 |
0.27/7.5-7.6 |
N35EH |
11.7-12.4 |
10.9-12.1 |
≥30 |
33-37 |
680/360 |
≥392/200 |
0.27/7.5-7.6 |
N38EH |
12.2-12.9 |
11.5-12.7 |
≥30 |
36-40 |
680/360 |
≥392/200 |
0.27/7.5-7.6 |
N30AH |
10.8-11.5 |
10.1-11.3 |
≥35 |
28-32 |
698/370 |
≥428/220 |
0.27/7.5-7.6 |
N35AH |
11.6-12.4 |
10.7-11.9 |
≥35 |
32-36 |
698/370 |
≥428/220 |
0.27/7.5-7.6 |
Typical Mechanical & Thermal Properties for Sintered Neodymium Iron Boron (NdFeB) magnets
| Young's Modulus | 1.7 x 10⁴ kg/mm² | Recoil Permeability Nom. | 1.05 μrec. |
| Vickers Hardness | 500-600 Hv | Electrical Resistivity | 160 μ-Ω(ohms)-cm/cm² |
| Compressive Strength | 80 kg/mm² | Thermal Conductivity | 7.7 kcal/m-h-⁰C |
| Bending Strength | 24 kg/mm² | Coefficient of Thermal Exp. Parallel to orientation // to M | 5.2 x 10⁻⁶/⁰C |
| Temp. Coeff of Br (%/⁰C) | -0.11 Nom | Coefficient of Thermal Exp. ⊥ to M Perpendicular to orientation |
-.8 x 10⁻⁶/⁰C |
All of the data shown above is compiled from information available from industries and research sources.
Note: Sintered Neodymium Iron Boron (NdFeB) magnets should not be used for any structural components in any device because of its brittle nature. Due to their high magnetic strength they should be handled with extreme care. Never allow magnets to snap together, they can shatter and chip, become airborne, and can cause a potential hazard. Eye protection must be worn at all times when handling them. Keep Neodymium Iron Boron (NdFeB) magnets away from children especially young children, they can be swallowed and lodge in the child's throat causing asphyxiation.