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neodymium magnets

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MP 25x13x4 / N38 - ring magnet

ring magnet

Catalog no 030190

GTIN: 5906301812074

5

Diameter [±0,1 mm]

25 mm

internal diameter Ø [±0,1 mm]

13 mm

Height [±0,1 mm]

4 mm

Weight

11.31 g

Magnetization Direction

↑ axial

Load capacity

2.96 kg / 29.03 N

Magnetic Induction

135.80 mT

Coating

[NiCuNi] nickel

6.77 with VAT / pcs + price for transport

5.50 ZŁ net + 23% VAT / pcs

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MP 25x13x4 / N38 - ring magnet

Specification/characteristics MP 25x13x4 / N38 - ring magnet
properties
values
Cat. no.
030190
GTIN
5906301812074
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
13 mm [±0,1 mm]
Height
4 mm [±0,1 mm]
Weight
11.31 g [±0,1 mm]
Magnetization Direction
↑ axial
Load capacity ~ ?
2.96 kg / 29.03 N
Magnetic Induction ~ ?
135.80 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 25x13x4 / N38 in a ring-shaped form finds extensive use in various industries. Thanks to a powerful magnetic field of 2.96 kg, which can be described as force, they are key in applications that require strong magnetism in a compact space. Applications of MP 25x13x4 / N38 magnets include electrical mechanisms, generators, audio systems, and several other devices that use magnets for producing motion or storing energy. Despite their powerful strength, they have a relatively low weight of 11.31 grams, which makes them more practical compared to heavier alternatives.
The operation of ring magnets results from their unique atomic structure. In the production process, neodymium atoms are arranged appropriately, which allows for generating a strong and precise magnetic field. This makes them perfect for devices such as stepper motors or industrial robots. Moreover, ring magnets are resistant to demagnetization.
Ring magnets have a wide range of applications in many industries, such as production of electronic devices, such as speakers and electric motors, the automotive industry, e.g., in the construction of electric motors, and medicine, where they are used in precision diagnostic devices. Their ability to work in high temperatures and precise magnetic field control makes them indispensable in challenging industrial conditions.
Ring magnets stand out extraordinary pulling power, ability to work in extreme conditions, precise control of the magnetic field. Thanks to their ring shape allows for effective use in devices such as motors or speakers. Additionally, these magnets are more durable than traditional ferrite magnets, making them an ideal choice in the automotive, electronics, and medical industries.
Ring magnets perform excellently across a wide range of temperatures. 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 of class N50 and N52 is a strong and powerful metal object shaped like a ring, featuring high force and universal applicability. Very good price, 24h delivery, ruggedness and versatility.

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their exceptional strength, neodymium magnets offer the following advantages:

  • They have constant strength, and over nearly 10 years their performance decreases symbolically – ~1% (in testing),
  • They remain magnetized despite exposure to magnetic noise,
  • Because of the lustrous layer of nickel, the component looks visually appealing,
  • The outer field strength of the magnet shows remarkable magnetic properties,
  • With the right combination of materials, they reach significant thermal stability, enabling operation at or above 230°C (depending on the design),
  • Thanks to the freedom in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in different geometries, which expands their application range,
  • Wide application in cutting-edge sectors – they find application in computer drives, rotating machines, clinical machines as well as sophisticated instruments,
  • Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in tiny dimensions, which makes them useful in compact constructions

Disadvantages of NdFeB magnets:

  • They can break when subjected to a powerful impact. If the magnets are exposed to external force, it is suggested to place them in a protective case. The steel housing, in the form of a holder, protects the magnet from breakage while also reinforces its overall strength,
  • Magnets lose pulling force when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible field weakening (influenced by the magnet’s structure). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
  • Due to corrosion risk in humid conditions, it is common to use sealed magnets made of rubber for outdoor use,
  • Using a cover – such as a magnetic holder – is advised due to the restrictions in manufacturing complex structures directly in the magnet,
  • Possible threat from tiny pieces may arise, in case of ingestion, which is notable in the context of child safety. Additionally, tiny components from these products may complicate medical imaging when ingested,
  • In cases of large-volume purchasing, neodymium magnet cost may be a barrier,

Maximum lifting capacity of the magnetwhat affects it?

The given pulling force of the magnet represents the maximum force, calculated under optimal conditions, specifically:

  • with mild steel, used as a magnetic flux conductor
  • of a thickness of at least 10 mm
  • with a polished side
  • with zero air gap
  • with vertical force applied
  • in normal thermal conditions

Lifting capacity in practice – influencing factors

In practice, the holding capacity of a magnet is affected by the following aspects, in descending order of importance:

  • Air gap between the magnet and the plate, since even a very small distance (e.g. 0.5 mm) can cause 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 measured on the plate surface of 20 mm thickness, when a perpendicular force was applied, whereas under parallel forces the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet’s surface and the plate reduces the lifting capacity.

Caution with Neodymium Magnets

Keep neodymium magnets away from people with pacemakers.

Neodymium magnets generate strong magnetic fields. As a result, they interfere with the operation of a pacemaker. This is because many of these devices are equipped with a function that deactivates the device in a magnetic field.

If you have a nickel allergy, avoid contact with neodymium magnets.

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, you can try wearing gloves or simply avoid direct contact with nickel-plated neodymium magnets.

Keep neodymium magnets away from GPS and smartphones.

Magnetic fields generated by neodymium magnets interfere with compasses and magnetometers used in navigation, as well as internal compasses of smartphones and GPS devices.

Comparing neodymium magnets to ferrite magnets (found in speakers), they are 10 times stronger, and their strength can shock you.

Familiarize yourself with our information to properly handle these magnets and avoid significant swellings to your body and prevent disruption to the magnets.

Neodymium magnets can become demagnetized at high temperatures.

Although magnets are generally resilient, their ability to maintain their magnetic potency can be influenced by factors like the type of material used, the magnet's shape, and the intended purpose for which it is employed.

Neodymium magnets are known for being fragile, which can cause them to crumble.

Neodymium magnets are characterized by significant fragility. Neodymium magnets are made of metal and coated with a shiny nickel, but they are not as durable as steel. At the moment of connection between the magnets, sharp metal fragments can be dispersed in different directions.

Do not place neodymium magnets near a computer HDD, TV, and wallet.

Strong fields generated by neodymium magnets can damage magnetic storage media such as floppy disks, credit cards, magnetic ID cards, cassette tapes, video tapes, or other similar devices. They can also damage televisions, VCRs, computer monitors, and CRT displays. Avoid placing neodymium magnets in close proximity to electronic devices.

  Magnets are not toys, children should not play with 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.

Dust and powder from neodymium magnets are highly flammable.

Do not attempt to drill into neodymium magnets. Mechanical processing is also not recommended. If the magnet is crushed into fine powder or dust, it becomes highly flammable.

Neodymium Magnets can attract to each other due to their immense internal force, causing the skin and other body parts to get pinched and resulting in significant swellings.

Magnets attract each other within a distance of several to about 10 cm from each other. Don't put your fingers in the path of magnet attraction, as a serious injury may occur. Magnets, depending on their size, are able even cut off a finger or alternatively there can be a serious pressure or even a fracture.

Warning!

To illustrate why neodymium magnets are so dangerous, see the article - How very dangerous are very powerful neodymium magnets?.

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tel: +48 888 99 98 98