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.
Choice of magnetic materials is dependent on :
- Magnetic Strength
- Operating Temperature
- Corrosion Resistance
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
|Material||Energy ( MGOe )||Flux Density (Gauss)||Pull ( kg/cm2 )|
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 :
|Material||Reversible Losses / Deg C||Working Temperature Deg C||Curie 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 Corrosion||Additional Comments|
|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|
|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.
|Material||Ease of Demagnetisation||Comments|
|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|
With modern materials magnetic losses with time and vibration are minimal. All magnet materials are brittle if subjected to impact, especially SmCo.Radiation
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.
|Material||Length to Diameter Ratio|
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