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neodymium magnets

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MP 25x7.5/4.5x5 / N38 - ring magnet

ring magnet

Catalog no 030194

GTIN: 5906301812111

5

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 with VAT / pcs + price for transport

6.50 ZŁ net + 23% VAT / pcs

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MP 25x7.5/4.5x5 / N38 - ring magnet

Specification/characteristics MP 25x7.5/4.5x5 / N38 - ring magnet
properties
values
Cat. no.
030194
GTIN
5906301812111
Production/Distribution
Dhit sp. z o.o.
Country of origin
Poland / China / Germany
Customs code
85059029
Diameter
25 mm [±0,1 mm]
internal diameter Ø
7.5/4.5 mm [±0,1 mm]
Height
5 mm [±0,1 mm]
Weight
22.38 g [±0,1 mm]
Magnetization Direction
↑ axial
Load capacity ~ ?
1.71 kg / 16.77 N
Magnetic Induction ~ ?
333.60 mT
Coating
[NiCuNi] nickel
Manufacturing Tolerance
± 0.1 mm

Magnetic properties of material N38

properties
values
units
remenance Br [Min. - Max.] ?
12.2-12.6
kGs
remenance Br [Min. - Max.] ?
1220-1260
T
coercivity bHc ?
10.8-11.5
kOe
coercivity bHc ?
860-915
kA/m
actual internal force iHc
≥ 12
kOe
actual internal force iHc
≥ 955
kA/m
energy density [Min. - Max.] ?
36-38
BH max MGOe
energy density [Min. - Max.] ?
287-303
BH max KJ/m
max. temperature ?
≤ 80
°C

Physical properties of NdFeB

properties
values
units
Vickers hardness
≥550
Hv
Density
≥7.4
g/cm3
Curie Temperature TC
312 - 380
°C
Curie Temperature TF
593 - 716
°F
Specific resistance
150
μΩ⋅Cm
Bending strength
250
Mpa
Compressive strength
1000~1100
Mpa
Thermal expansion parallel (∥) to orientation (M)
(3-4) x 106
°C-1
Thermal expansion perpendicular (⊥) to orientation (M)
-(1-3) x 10-6
°C-1
Young's modulus
1.7 x 104
kg/mm²

Shopping tips

Due to specific properties, neodymium element MP 25x7.5/4.5x5 / N38 in a ring-shaped form finds extensive use in various industries. Thanks to a powerful magnetic field of 1.71 kg, which can be described as force, they are key in applications that require high magnetic power in a relatively small area. Applications of MP 25x7.5/4.5x5 / N38 magnets include electrical mechanisms, generators, sound devices, and many other devices that use magnets for producing motion or storing energy. Despite their powerful strength, they have a comparatively low weight of 22.38 grams, which makes them more practical compared to bulkier alternatives.
Ring magnets work due to their atomic structure. In the production process, neodymium atoms are arranged appropriately, which allows for the creation of a concentrated magnetic field in a specific direction. This makes them perfect for devices such as stepper motors or industrial robots. Moreover, ring magnets are resistant to demagnetization.
They are used in various fields of technology and industry, such as electronics, e.g., in the production of speakers or electric motors, the automotive industry, e.g., in the construction of electric motors, and medicine, where they are used in precision diagnostic devices. Thanks to their temperature resistance and precision makes them ideal for technologically advanced applications.
Ring magnets stand out extraordinary pulling power, ability to work in extreme conditions, precise control of the magnetic field. Their unique ring form allows for application in devices requiring concentrated magnetic fields. Additionally, these magnets are significantly stronger and more versatile than ferrite counterparts, which has made them popular in advanced technologies and industrial applications.
Thanks to their resistance to high temperatures, ring magnets operate reliably even in tough conditions. Their magnetic properties remain stable, as long as the temperature does not exceed the Curie point. Compared to other types of magnets, ring magnets show greater resistance to demagnetization. For this reason, they are ideal for applications in the automotive industry, robotics, and devices requiring operation in changing or extreme environmental conditions.
A neodymium ring magnet in classes N50 and N52 is a strong and powerful magnetic piece in the form of a ring, that offers strong holding power and versatile application. Very good price, availability, stability and universal usability.

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 forcewhat 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?.

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