¿What do the specifications N40, N42, N45, etc. mean?
The specifications N40, N42, N45, N45H etc. is a measurement for the quality of the magnet material. You can read two things from this:
1. How much "magnet energy" per volume is contained in this magnetic material
2. Up to what temperature the magnet can be used
The numbers (e.g., 40, 42, 45) are equivalent to approximately the maximum energy product of the magnet (in MGOe).
The letters N, M, H and respectively the letters SH, EH or UH say something about the maximum working temperature, which can be 80, 100, 120, 150, 180 or 200 °C. Most of our magnets begin with an "N" and should be used at 80 °C..
When we speak colloquially about the "power" of a magnet, we usually mean either the holding strength by direct contact with a metal plate or the attractive force to a piece of iron (or another magnet) at a certain range.
For this "power", the applied magnet material is not decisive in and of itself, but equally important is the volume of the magnet, the form of the magnet, the proportions of the magnet (e.g., the ratio between the diameter and the thickness of a disc magnet) and the combination with other materials, so e.g., the magnet is mounted on a piece of metal, in a metal pot, or is "free-standing".
This is similarly true in relationship to working temperature. The specified maximum temperature can only be used without a problem when the aspect ratio of the magnet is "optimal". If a magnet is, for example, too thin in relation to its diameter (or side length), the maximum temperature is reached earlier.;.
If you take any two magnets of differing size and magnetisation from our collection, the difference in their strength is more due to the differences in their volume than the differences in their magnetisation. For this reason, the larger magnet is the stronger magnet, even when its magnetisation classification is somewhat smaller.;.
You can find the exact associations between these classifications and the physical values of a magnet in the table 'Physical magnet data'. .;..
¿How strong are these magnets?
In the description of a few of our magnets, we indicate an approximate holding strength in grams or kilograms. Please note that this refers to a theoretically-attainable, maximum value that only applies under optimal conditions. The actual holding strength is dependent upon the following factors:
Distance between the magnet and the object it is attracted to:
If there is no direct contact, the holding strength reduces very quickly with increasing
distance. Even a half millimetre air gap can possibly reduce the holding strength by half. Even a thin coat of paint on a metallic object can cause a reduction in holding strength of the magnet.
Material of the object of magnetic attraction:
The theoretical holding strength is valid when the object of magnetic attraction consists of soft iron. This value reduces by 5% with structural steel ST37; with ST70 by approx. 30%.
Surface area of the object of magnetic attraction:
The smoother the surface, the greater the holding strength. For rougher surfaces, you should anticipate a considerable reduction in holding strength.
Direction of the force:
The theoretical holding strength is valid if a vertical force applies, that is, if the object of magnetic attraction is pulled vertically by the magnet. "óptimas". Thickness of the object of magnetic attraction:The object should not be too thin or a magnetic saturation will be achieved and part of the magnetic field will remain useless.
In principle, when planning a specific application of the magnets, you should not rely upon our holding strength specifications, but instead experiment first a bit of your own.
Incidentally: If you require the holding force in Newton, multiply our specifications in kg by 9,81 (a mass of 1 kg creates a downward force of 9,81 Newton).
¿Where are magnets manufactured?
Our magnets are produced in China. About 140 Chinese manufacturers produce approximately 60% of all neodymium magnets worldwide. We evaluated at least a dozen different manufacturers and checked the price/benefit-relationship. Our current supplier delivers magnets of constant quality at very reasonable prices. And since we purchase magnets in large amounts and have automated nearly 100% of the order process, we are fairly certain that, with us, you will find the very best price/benefit-relationship.
Can I drill a hole in a magnet?
Drilling (or sawing) of neodymium magnets is absolutely not recommended. First of all, the material is brittle and fragile. Secondly, drilling causes combustible dust and, thirdly, the heat caused by the drill can possibly demagnetise the material.
Specialists can work with the magnets with specialised diamond-tipped tools and constant water cooling. However, this normally occurs prior to magnetisation of the material. You should also note that magnets which have lost part of their coating due to drilling will no longer be corrosion-resistant.
Do magnets weaken over time?
Under normal conditions, neodymium magnets retain their magnetism nearly indefinitely. They differ in this case from conventional ferrite magnets that lose their magnetism over time, even without outside influences.
Influences that can lead to a loss of magnetic strength in neodymium magnets include:
Heat: most of our magnets should be exposed to a maximum of 80° C other strong magnetic fields.
How should I dispose of magnets?
Neodymium magnets should be taken to the old metal recycling centre.