MP 25x7.5/4.5x5 / N38 - ring magnet
ring magnet
Catalog no 030194
GTIN: 5906301812111
Diameter [±0,1 mm]
25 mm
internal diameter Ø [±0,1 mm]
7.5/4.5 mm
Height [±0,1 mm]
5 mm
Weight
22.38 g
Magnetization Direction
↑ axial
Load capacity
1.71 kg / 16.77 N
Magnetic Induction
333.60 mT
Coating
[NiCuNi] nickel
8.00 ZŁ with VAT / pcs + price for transport
6.50 ZŁ net + 23% VAT / pcs
bulk discounts:
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MP 25x7.5/4.5x5 / N38 - ring magnet
Magnetic properties of material N38
Physical properties of NdFeB
Shopping tips
Advantages and disadvantages of neodymium magnets NdFeB.
In addition to their tremendous field intensity, neodymium magnets offer the following advantages:
- They have stable power, and over more than ten years their performance decreases symbolically – ~1% (according to theory),
- Their ability to resist magnetic interference from external fields is notable,
- Thanks to the glossy finish and gold coating, they have an visually attractive appearance,
- Magnetic induction on the surface of these magnets is impressively powerful,
- With the right combination of compounds, they reach significant thermal stability, enabling operation at or above 230°C (depending on the structure),
- With the option for fine forming and personalized design, these magnets can be produced in various shapes and sizes, greatly improving application potential,
- Significant impact in new technology industries – they serve a purpose in hard drives, rotating machines, diagnostic apparatus along with technologically developed systems,
- Relatively small size with high magnetic force – neodymium magnets offer strong power in compact dimensions, which allows for use in miniature devices
Disadvantages of rare earth magnets:
- They can break when subjected to a sudden impact. If the magnets are exposed to external force, we recommend in a metal holder. The steel housing, in the form of a holder, protects the magnet from damage and increases its overall strength,
- High temperatures may significantly reduce the holding force of neodymium magnets. Typically, above 80°C, they experience permanent decline in performance (depending on shape). To prevent this, we offer heat-resistant magnets marked [AH], capable of working up to 230°C, which makes them perfect for high-temperature use,
- Magnets exposed to moisture can rust. Therefore, for outdoor applications, we suggest waterproof types made of plastic,
- Using a cover – such as a magnetic holder – is advised due to the limitations in manufacturing threads directly in the magnet,
- Possible threat from tiny pieces may arise, especially if swallowed, which is important in the context of child safety. It should also be noted that miniature parts from these devices can disrupt scanning once in the system,
- In cases of tight budgets, neodymium magnet cost may not be economically viable,
Maximum magnetic pulling force – what affects it?
The given holding capacity of the magnet corresponds to the highest holding force, assessed in the best circumstances, specifically:
- using a steel plate with low carbon content, serving as a magnetic circuit closure
- having a thickness of no less than 10 millimeters
- with a refined outer layer
- in conditions of no clearance
- in a perpendicular direction of force
- at room temperature
Determinants of practical lifting force of a magnet
The lifting capacity of a magnet is determined by in practice key elements, ordered from most important to least significant:
- Air gap between the magnet and the plate, because even a very small distance (e.g. 0.5 mm) causes a drop in lifting force of up to 50%.
- Direction of applied force, because the maximum lifting capacity is achieved under perpendicular application. The force required to slide the magnet along the plate is usually several times lower.
- Thickness of the plate, as a plate that is too thin causes part of the magnetic flux not to be used and to remain wasted in the air.
- Material of the plate, because higher carbon content lowers holding force, while higher iron content increases it. The best choice is steel with high magnetic permeability and high saturation induction.
- Surface of the plate, because the more smooth and polished it is, the better the contact and consequently the greater the magnetic saturation.
- Operating temperature, since all permanent magnets have a negative temperature coefficient. This means that at high temperatures they are weaker, while at sub-zero temperatures they become slightly stronger.
* Holding force was checked on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, however under attempts to slide the magnet the holding force is lower. In addition, even a small distance {between} the magnet’s surface and the plate decreases the load capacity.
Exercise Caution with Neodymium Magnets
Neodymium magnets can attract to each other, pinch the skin, and cause significant injuries.
If joining of neodymium magnets is not controlled, at that time they may crumble and crack. Remember not to move them to each other or have them firmly in hands at a distance less than 10 cm.
Magnets made of neodymium are known for being fragile, which can cause them to become damaged.
In the event of a collision between two neodymium magnets, it can result in them getting chipped. They are coated with a shiny nickel plating similar to steel, but they are not as hard. At the moment of connection between the magnets, small sharp metal fragments can be propelled in various directions at high speed. Eye protection is recommended.
The magnet is coated with nickel - be careful if you have an allergy.
Studies clearly indicate a small percentage of people who suffer from metal allergies such as nickel. An allergic reaction often manifests as skin redness and rash. If you have a nickel allergy, try wearing gloves or avoid direct contact with nickel-plated neodymium magnets.
You should maintain neodymium magnets at a safe distance from the wallet, computer, and TV.
Neodymium magnets generate strong magnetic fields that can damage magnetic media such as floppy disks, video tapes, HDDs, credit cards, magnetic ID cards, cassette tapes, etc. devices. They can also destroy devices like video players, televisions, CRT computer monitors. Do not forget to keep neodymium magnets at a safe distance from these electronic devices.
Neodymium magnets are the strongest magnets ever invented. Their strength can shock you.
To handle magnets properly, it is best to familiarize yourself with our information beforehand. This will help you avoid significant harm to your body and the magnets themselves.
Magnets should not be treated as toys. Therefore, it is not recommended for children to have access to them.
Not all neodymium magnets are toys, so do not let children play with them. Small magnets pose a serious choking hazard or can attract to each other in the intestines. In such cases, the only solution is to undergo surgery to remove the magnets, and otherwise, it can even lead to death.
Neodymium magnets can become demagnetized at high temperatures.
While Neodymium magnets can lose their magnetic properties at high temperatures, it's important to note that the extent of this effect can vary based on factors such as the magnet's material, shape, and intended application.
Dust and powder from neodymium magnets are highly flammable.
Avoid drilling or mechanical processing of neodymium magnets. If the magnet is crushed into fine powder or dust, it becomes highly flammable.
Avoid bringing neodymium magnets close to a phone or GPS.
Strong fields generated by neodymium magnets interfere with compasses and magnetometers used in navigation, as well as internal compasses of smartphones and GPS devices.
People with pacemakers are advised to avoid neodymium magnets.
In the case of neodymium magnets, there is a strong magnetic field. As a result, it interferes with the operation of a heart pacemaker. However, if the magnetic field does not affect the device, it can damage its components or deactivate the device when it is in a magnetic field.
Warning!
To raise awareness of why neodymium magnets are so dangerous, see the article titled How dangerous are powerful neodymium magnets?.