Permanent Magnets

MagDev Ltd can supply all commercially available Permanent Magnetic Materials ( NdFeB , SmCo , Ferrite , ALNiCo with Bonded variations also available ) for all your applications ( Lifting, Sensing, Filtering and Motors/Generators) . We have extensive stocks and so we may even have the shape and size you require (Shopping Cart )

Not sure which material you want, follow our ‘Material Selection Guide’ before moving on to the more detailed description of each material. If your still not clear give our teama call and let them talk you through your requirement( +44 (0) 1793 425600 )

Material Selection Guide

Magdev Ltd magnets are used in a variety of Lifting, Switching, Motor/Generator, and Filtering applications.

Selecting a Magnet

  • Stage 1 - Which Material - Choose the best material for your Application.
  • Stage 2 - What Shape - Choose a shape which suits your design.
  • Stage 3 - What Size - Use the web site to find the product code of the exact size or nearest we have in Stock.

Which Material?


Choice of magnetic materials is dependent on :

  • Magnetic Strength
  • Operating Temperature
  • Corrosion Resistance
  • Cost
  • Stability

For each of the categories above we will compare the four main material groups Ferrite, ALNICO, Samarium Cobalt (SmCo), Neodymium Iron Boron ( NdFeB ).

  • The Energy stored in the material
  • Flux Density on the surface of the magnet
  • Pull required to remove the magnet from a flat piece of steel
MaterialEnergy ( MGOe )Flux Density (Gauss)Pull ( kg/cm2 )
Ferrite 3.3 1400 0.25
ALNICO 5.0 1300 0.20
Sm Co 26.0 3500 1.5
NdFeB 35.0 4500 2.5

Operating Temperature


All magnet materials lose magnetism as temperature rises :

Reversible Losses will return as the magnet cools as long as the working Temperatures are not exceeded. Exceeding working temperatures will mean that the magnet needs to be re-magnetised on cooling. Exceeding Curie temperatures will damage the magnet beyond repair.

Sub zero temperature affects are detailed below :

MaterialReversible Losses / Deg CWorking Temperature Deg CCurie Temperature Deg C 
Ferrite 0.19% 250 460 Large irreversible losses below -40 deg C
ALNICO 0.02% 550 860 Losses < 10% down to 4 K
Sm Co 0.03% 300 750 Minimal loses down to 4 K
NdFeB 0.12% 120 320 No losses down to 77 K


Material        Resistance to CorrosionAdditional Comments
Ferrite Excellent  
Sm Co Excellent Will break down if exposed to Hydrogen
NdFeB Poor Ni,Zn coatings protect in stores conditions. Will break down if exposed to Hydrogen


MaterialCost Comparison
Ferrite Low ( x 1 )
ALNICO Medium ( x 5 )
Sm Co Very High ( x 20 )
NdFeB High ( x 10 )



External magnetic fields

External magnetic fields can demagnetise materials to different degrees.

MaterialEase of DemagnetisationComments
Ferrite Low Pushing magnets together in repulsion can demagnetise by 10%
ALNICO High Pushing magnets together in repulsion can demagnetise by 50%
Sm Co Very Low  
NdFeB Very Low  


With modern materials magnetic losses with time and vibration are minimal. All magnet materials are brittle if subjected to impact, especially SmCo.


It is recommended that magnets used in particle deflection systems have high Hci values. Tests have shown that SmCo shows significant losses when exposed to high levels of radiation ( 109 1010 rads ) and NdFeB also has high losses at 4 x 106 rads ( 50% ) and 7 x 107 rads ( 100 % ) Cobalt will also retain radiation after exposure.


For optimum performance it is recommended that you use the magnet materials in excess of the following Length to Diameter ratios. At ratios below this Gauss levels and pull could be reduced.

MaterialLength to Diameter Ratio
Ferrite 1
Sm Co 0.7
NdFeB 0.7

Sintered Neodymium Iron Boron (NdFeB )

Sintered Samarium Colbalt (SmCo)


AluminiumNickel Colbalt ( AlNiCo )

Having selected your Magnet why not let our Technical team improve the whole system and even build the assembly for you ( +44 (0) 1793 425600 ). Pot magnets can pull 5 times what a plain magnet can with the advantage of protection for the brittle magnet material and easier ways of fixing the magnet. Pot magnets