What are special features of a pot magnet?
Table of Contents
Important features of pot magnets
Key points: When handling pot magnets,
keep the following in mind:
Principle
A pot magnet is embedded in a steel pot. The steel pot increases the adhesive force of the magnet on direct contact with a thick iron surface. If there is no direct contact with the counterpart, or if the steel plate is thin, painted or rough, you won’t be able to put as much strain on it.Displacement force
The indicated adhesive force was measured perpendicular to the surface to which the magnet should stick. It takes a lot less strength to move the magnet sideways. Therefore, you won’t be able to put as much strain on a pot magnet if you use it on a wall as opposed to using it on the ceiling. Please note our FAQ regarding displacement force. By using appropriate rubber caps on the bottom side of pot magnets, you can enhance the adhesive force in shear direction considerably. Or you can use magnet systems with rubber coating: They adhere much more strongly in shear direction.Rust
Neodymium pot magnets are not rust-proof and therefore intended for dry indoor use. Our ferrite pot magnets, on the other hand, are rust-proof.Please note that over time, (flash) rust may develop on both neodymium pot magnets and ferrite pot magnets, but this does not affect the function of the magnets.
Maximum working temperature
Most pot magnets can be heated to a temperature of up to 80°C without losing their magnetisation (ferrite magnets and certain CSN-types even higher). The adhesive that connects the magnet and the steel pot can, however, become brittle if continuously heated to this temperature. Hence, it is recommended to use pot magnets only at room temperature.Magnetic flux lines of raw magnets vs. pot magnets
Raw magnet
With a "naked" magnet (raw magnet) the field lines move freely through the air. They surround the magnet widely in all directions and can therefore attract a counterpart from a distance of a few millimetres.
Disc magnet in free space
Disc magnet on iron contact surface
Pot magnet
The field lines move even easier through iron than through the air. The steel pot of a pot magnet directs the magnetic field lines downward to the contact surface. This causes the magnetic force to be bundled at the contact surface (see picture below).
Pot magnet in free space
Pot magnet on iron contact surface
Adhesion diagram of article CSN-16
Such a strong adhesive force occurs only with direct contact to the counterpart.
A pot magnet is not suitable for attracting an iron subject over a distance of several millimetres, since the field lines don't cover this distance.
Example adhesion diagram of article CSN-16 (max.
adhesive force: 4 kg): At a distance of 1 mm between pot magnet and steel plate, the max.
adhesive force is still 1 kg, at a distance of 4 mm and more there is no more adhesive force left.
Why can't I put two pot magnets flush on top of each other?
Unfortunately it is true: You can't stack two pot magnets
exactly on top of each other, because they will strongly repel each other.
Pot magnets can only be arranged side by side and staggered.
The reason is that all our pot magnets have the same pole on the adhesive surface, e.g.
always the north pole.
The steel pot is the south pole of this system.
If two pot magnets are near each other, the north pole of one pot magnet attracts the south pole (=steel pot) of the other.
Hence, the pot magnets arrange themselves next to each other.
It is not possible to put them on top of each other, because the same poles repel each other.
Offset
To protect the magnet and ensure maximum adhesive force, the magnet must not protrude from the pot. In practice the magnet is slightly recessed in the pot. The offset varies from magnet to magnet, but the adhesive force indicated in the online shop is guaranteed.Suitable counterparts to pot magnets
Screw-on metal discs
We recommend inexpensive and practical countersunk metal discs as an ideal surface for pot magnets. They can easily be screwed onto non-magnetic surfaces with a countersunk head screw. They are also suitable counterparts for disc magnets (available with or without hole).Select a counterpart that is slightly larger than the diameter of the pot magnet, which ensures that the magnet has some leeway on the disc and still achieves its full adhesive force.
Glue-on metal discs
We also recommend self-adhesive metal discs as counterparts to pot magnets (available untreated or with white coating). They are only suitable for pot magnets and disc magnets with a diameter of up to 20 mm.Combination of pot magnet with raw magnet
Normally you place a pot magnet on an iron counterpart.
This results in a very high adhesive force (see explanation above).
If you combine a pot magnet with a raw magnet, however, the magnetic flux lines are not bundled downwards but distributed in a large area.
The adhesive force is only a fraction of the indicated maximum adhesive force.
If you want to combine pot and raw magnets, you have to use magnets with a significantly higher adhesive force.
Pot magnets on iron
Pot magnet on raw magnet
Pot magnet application areas
Pot magnets are especially suitable for use in the following industries:
- Booth construction, store construction, interior fittings
- Bath and kitchen installations
- Cabinetry, furniture construction
- Metal construction
- Machine and plant construction
- Lighting industry