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Neodymium magnets (rare earth)

Short description

Neodymium-Ferro-Boron (rare earth) magnets are delivered by Goudsmit under the brand name Neoflux®. It is the most powerful magnet, with a very high energy product.

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Characteristics

  • Energy product above 52 MGOe possible
  • Very powerful magnets
  • Lower resistance to corrosion
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Neodymium magnets (NdFeB)

Detailed product description

Neodymium-iron-boron

Neodymium-iron-boron (NdFeB), commonly called neodymium and also often described as ‘rare-earth magnet’, is the strongest and most powerful magnetic material, with a maximum energy product of 52 MGOe. Since its discovery in 1980, the processes related to the performance of NdFeB have been systematically improved, resulting in an ever higher maximum energy product. Goudsmit sells neodymium-iron-boron (rare earth) magnets under the brand name Neoflux®.

Today Neodymium-iron-boron (NdFeB) is the most popular and commonly used magnetic alloy. Disadvantages of NdFeB are the low temperature-resistance, the mechanical brittleness and the fact that the material is subject to corrosion, so it can not be used in certain applications.
Despite these disadvantages, NdFeB offers the highest available magnetic energy density, with a BHmax value of 33 to 52 MGOe. As such, far less magnetic material is needed compared to other magnetic alloys, which explains the huge popularity.

Applications

With their high strength and performance, neodymium magnets are used in many applications, such as:

  • motors
  • wind turbines
  • spindle drives of hard disks
  • speakers
  • MRI scanners
  • magnetic separators
  • electronics
  • cars
Often in combination with sensors.

Advantages

  • exceptionally powerful performance;
  • supplies more energy per cubic metre than any other magnetic material;
  • relatively inexpensive, one-twentieth the weight of ferrite magnets and, based on ‘euro per BHmax’, approximately three-quarters the price of ferrite magnets;
  • relatively easy to process, especially compared to samarium-cobalt and alnico magnets.

Disadvantages

  • the standard maximum application temperature is 80 °C; this can be increased to a maximum of 200 °C through the addition of the (expensive) material dysprosium;
  • susceptible to corrosion: oxidation protection is usually necessary; this can be achieved by coating the magnets and/or enclosing them in a housing.

Technical details of NdFeB

  • density: 7612 kg/m³ (0.275 lbs./in³);
  • magnetic field required for saturation: ±35 kOe;
  • BHmax value of the available range of neodymium grades: 170-422 kJ/m³.

Production methods

  • Sintering is the most common and widely used process: a combination of heat and pressure produces a solid mass of magnetic material.

Plastic-bonded materials are becoming increasingly important as a magnetic material. They are formed by combining magnetic powder with a polymer. So the possible production processes are:

  • with injection moulding it is possible to form bonded magnetic material in complex contours and pour it directly onto other components to form magnetic assemblies;
  • compression bonding results in stronger magnetic force than injection moulding, but it is only suitable for simple geometries;
  • with calendering bonded magnetic material is formed into flexible magnetic tapes and rolls of sheet.

Processing neodymium magnets

Neodymium magnets are typically processed using diamond grinding techniques. Carbide tools are also occasionally used, but the resulting surface finish may then be less optimal.
Bonded neodymium is easier to process. Coolants must then be used to prevent spontaneous ignition of the powder. During processing the protective coating is removed, so the product must be recoated afterwards to restore its corrosion resistance.

Goudsmit Magnetics is fully equipped to process these materials to arrive at your design specifications.

Surface treatment for NdFeB

Due to the poor corrosion resistance of neodymium magnets, it is advisable to provide them with a coating. A number of things are important to consider in this regard:

  • even though ‘stabilized’ neodymium is more resistant to oxidation, the magnet is usually nevertheless coated;
  • coating NdFeB is a difficult process; only coating companies with specialized knowledge of coating NdFeB are able to achieve good adhesion to neodymium magnets;
  • NdFeB magnets are also commonly coated with ion vapour deposition (IVD) techniques: the IVD coating process allows precise control of the coating thickness and excellent adhesion of the coating to the material;
  • in extreme cases it may be desirable to opt for a fully over-moulded plastic version, which ensures that the magnet itself can never come into contact with the air.

Precautions when working with neodymium

  • NdFeB powder is extremely fine; in the dry state can ignite spontaneously. Therefore, for your safety, it is important to be extra careful and take precautions when handling NdFeB powder.
  • Neodymium magnets can be extremely powerful. You must stay alert when using these magnets to prevent injury.

Product design

Neodymium magnets have an unlimited number of applications. The exceptional performance of the material has made it invaluable. The strength/weight ratio allows it to be used in ways that were previously inconceivable, allowing present-day engineers to create revolutionary new designs.

Goudsmit Magnetics delivers a full range of neodymium magnets with various strengths and makes magnet assemblies that fully meet your requirements. Please contact us for more information on custom-made NdFeB magnets or if you would like to speak with someone for advice on the design of your magnetic component.

Neodymium (NdFeB) permanent magnets - table

Grade

Corrosion

stable

Remanence Normal
coercivity
Intrinsic
coercivity
Maximum
energy product
Max.
operating
Temp.
   

Br
mT

Hcb
kA/m
Hcj
kA/m
BH(max)
kJ/m3
 
  specify as min typ min typ min min typ °C
GSN-35   1170 1220 871 925 955 263 279 80
GSN-38   1220 1260 900 925 955 279 303 80
GSN-40   1260 1300 908 925 955 303 318 80
GSN-42   1300 1330 908 925 955 318 334 80
GSN-45   1330 1370 908 925 955 334 358 80
GSN-48   1370 1410 908 925 955 358 382 80
GSN-50   1410 1440 830 860 875 382 398 70
GSN-52   1430 1460 830 860 875 398 414 70
GSN-33M   1140 1170 848 887 1114 239 263 100
GSN-35M   1170 1220 871 925 1114 263 279 100
GSN-38M   1220 1260 908 955 1114 279 303 100
GSN-40M   1260 1300 938 986 1114 303 318 100
GSN-42M   1300 1330 967 1008 1114 318 334 100
GSN-45M   1330 1370 990 1039 1114 334 358 100
GSN-48M   1370 1410 1019 1069 1114 358 382 100
GSN-50M   1410 1440 1019 1069 1080 382 398 90
GSN-52M   1430 1460 1019 1069 1080 398 414 90
GSN-30H   1080 1120

807

853 1353 223 239 120
 GSN-33H    1140  1170  852  891  1353  239  263  120
 GSN-35H    1170  1220  875  930  1353  263  279  120
GSN-38H 38H/S 1220 1260 912 960 1353 279 303 120
GSN-40H 40H/S 1260 1300 942 990 1353 303 318 120
GSN-42H 42H/S 1300 1330 972 1013 1353 318 334 120
GSN-44H 44H/S 1330 1360 970 970 1353 334 350 120
GSN-46H 46H/S 1360 1380 994 1036 1353 350 366 120
GSN-48H 48H/S 1370 1410 1024 1074 1353 366 382 120
GSN-50H     1410 1440 1054 1097 1353 392 298 120
 GSN-30SH   1080 `1120 811 857 1592 223 239 150
 GSN-33SH    1140 1170 856 896 1592 239 263 150
 GSN-35SH

 35SH/S

 1170 1220 879 934 1592 263 279 150
GSN-38SH 38SH/S 1220 1260 916 965 1592 279 303 150
GSN-40SH 40SH/S 1260 1300 946 995 1592 303 318 150
GSN-42SH 42SH/S 1300 1330 976 1018 1592 318 334 150
GSN-44SH 44SH/S 1330 1360 999 1041 1592 334 350 150
GSN-28UH 1040 1080 770 810 1989 199 223 180
GSN-30UH 30UH/S 1080 1140 810 860 1989 223 239 180
GSN-33UH 33UH/S 1140 1170 830 880 1989 239 263 180
GSN-35UH 35UH/S 1170 1220  870 920 1989 263 279 180
GSN-38UH 38UH/S 1220 1260 900 950 1989 279 303 180
GSN-40UH 40UH/S 1250 1280 900 950 1989 303 318 180
GSN-42UH   1300 1330 981 1023 1989 318 334 180
 GSN-28EH    1040 1080 785 831 2387 199 223 200
 GSN-30EH

 30EH/S

 1080 1120 815 862 2387 223 239 200
 GSN-33EH

 33EH/S

 1140 1170 860 900 2387 239 263 200
GSN-35EH 35EH/S 1170 1220 883 938 2387 263 279 200
GSN-38EH 38EH/S 1220 1260 921 969 2387 279 303 200
GSN-28AH 28AH/S 1040 1080 785 831 2787 199 223 220
GSN-30AH 30AH/S 1080 1120 815 862 2787 223 239 220
GSN-25BH 25BH/S 980 1020 740 785 3000 183 199 240