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neodymium magnets

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MP 20x8/4x5 / N38 - ring magnet

ring magnet

Catalog no 030333

GTIN: 5906301812272

5

Diameter [±0,1 mm]

20 mm

internal diameter Ø [±0,1 mm]

8/4 mm

Height [±0,1 mm]

5 mm

Weight

16.49 g

Magnetization Direction

↑ axial

Load capacity

1.71 kg / 16.77 N

Magnetic Induction

296.67 mT

Coating

[NiCuNi] nickel

7.75 with VAT / pcs + price for transport

6.30 ZŁ net + 23% VAT / pcs

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MP 20x8/4x5 / N38 - ring magnet

Specification/characteristics MP 20x8/4x5 / N38 - ring magnet
properties
values
Cat. no.
030333
GTIN
5906301812272
Production/Distribution
Dhit sp. z o.o.
Country of origin
Poland / China / Germany
Customs code
85059029
Diameter
20 mm [±0,1 mm]
internal diameter Ø
8/4 mm [±0,1 mm]
Height
5 mm [±0,1 mm]
Weight
16.49 g [±0,1 mm]
Magnetization Direction
↑ axial
Load capacity ~ ?
1.71 kg / 16.77 N
Magnetic Induction ~ ?
296.67 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

Neodymium magnets MP 20x8/4x5 / N38 in a ring form are regularly used in various industries due to their specific properties. 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 compact space. Usage of MP 20x8/4x5 / N38 magnets include electric motors, generating systems, sound devices, and several other devices that use magnets for producing motion or storing energy. Despite their significant strength, they have a relatively low weight of 16.49 grams, which makes them more convenient to use compared to heavier alternatives.
The operation of ring magnets results from their unique atomic structure. Their properties arise from a controlled production process, including sintering and magnetization, 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. Additionally, their resistance to high temperatures and demagnetization makes them indispensable in industry.
Ring magnets have a wide range of applications in many industries, 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 medical equipment, e.g., in scanning devices. Their ability to work in high temperatures and precise magnetic field control makes them indispensable in challenging industrial conditions.
Their uniqueness comes from high magnetic strength, resistance to high temperatures, precise control of the magnetic field. Their unique ring form allows for application in devices requiring concentrated magnetic fields. Moreover, these magnets are significantly stronger and more versatile than ferrite counterparts, which has made them popular in advanced technologies and industrial applications.
Ring magnets perform excellently across a wide range of temperatures. They do not lose their magnetic properties, as long as the temperature does not exceed the Curie point. Compared to other types of magnets, ring magnets show greater resistance to demagnetization. Because of this, they are ideal for applications in the automotive industry, robotics, and devices requiring operation in changing or extreme environmental conditions.
A ring magnet of class N50 and N52 is a powerful and highly strong magnetic product shaped like a ring, featuring high force and broad usability. Attractive price, availability, durability and versatility.

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their pulling strength, neodymium magnets provide the following advantages:

  • They have constant strength, and over more than 10 years their performance decreases symbolically – ~1% (according to theory),
  • They remain magnetized despite exposure to magnetic surroundings,
  • By applying a shiny layer of silver, the element gains a clean look,
  • The outer field strength of the magnet shows advanced magnetic properties,
  • Thanks to their enhanced temperature resistance, they can operate (depending on the shape) even at temperatures up to 230°C or more,
  • With the option for tailored forming and personalized design, these magnets can be produced in numerous shapes and sizes, greatly improving engineering flexibility,
  • Important function in new technology industries – they find application in hard drives, rotating machines, medical equipment along with technologically developed systems,
  • Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of neodymium magnets:

  • They can break when subjected to a powerful impact. If the magnets are exposed to mechanical hits, it is advisable to use in a steel housing. The steel housing, in the form of a holder, protects the magnet from cracks , and at the same time reinforces its overall strength,
  • They lose power at increased temperatures. Most neodymium magnets experience permanent reduction in strength when heated above 80°C (depending on the form and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
  • Magnets exposed to wet conditions can corrode. Therefore, for outdoor applications, it's best to use waterproof types made of rubber,
  • Limited ability to create internal holes in the magnet – the use of a external casing is recommended,
  • Potential hazard from tiny pieces may arise, especially if swallowed, which is crucial in the context of child safety. Furthermore, miniature parts from these devices might hinder health screening once in the system,
  • High unit cost – neodymium magnets are pricier than other types of magnets (e.g., ferrite), which may limit large-scale applications

Maximum lifting force for a neodymium magnet – what contributes to it?

The given lifting capacity of the magnet represents the maximum lifting force, measured under optimal conditions, that is:

  • with mild steel, serving as a magnetic flux conductor
  • of a thickness of at least 10 mm
  • with a polished side
  • in conditions of no clearance
  • with vertical force applied
  • in normal thermal conditions

Key elements affecting lifting force

Practical lifting force is determined by factors, by priority:

  • 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 the plate surface of 20 mm thickness, when the force acted perpendicularly, however under attempts to slide the magnet the lifting capacity is smaller. Moreover, even a slight gap {between} the magnet’s surface and the plate lowers the load capacity.

Handle Neodymium Magnets with Caution

Neodymium magnets should not be near people with pacemakers.

Neodymium magnets generate very strong magnetic fields that can 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.

The magnet coating contains nickel, so be cautious if you have a nickel allergy.

Studies show a small percentage of people have allergies to certain metals, including 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.

Neodymium magnets are over 10 times more powerful than ferrite magnets (the ones in speakers), and their power can shock you.

Please review the information on how to handle neodymium magnets and avoid significant harm to your body, as well as prevent unintentional damage to the magnets.

Dust and powder from neodymium magnets are highly flammable.

Do not attempt to drill into neodymium magnets. Mechanical processing is also not recommended. Once crushed into fine powder or dust, this material becomes highly flammable.

Neodymium magnets can become demagnetized at high temperatures.

Despite the general resilience of magnets, their ability to retain their magnetic strength can be influenced by factors like the type of material used, the magnet's shape, and the intended purpose for which it is employed.

  Magnets should not be treated as toys. Therefore, it is not recommended for children to have access to them.

Remember that neodymium magnets are not toys. Do not allow children to play with them. Small magnets can pose a serious choking hazard. If multiple magnets are swallowed, they can attract to each other through the intestinal walls, causing significant injuries, and even death.

Magnets made of neodymium are highly susceptible to damage, resulting in their cracking.

Neodymium magnets are characterized by significant fragility. Magnets made of neodymium 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.

You should maintain neodymium magnets at a safe distance from the wallet, computer, and TV.

The strong magnetic field generated by neodymium magnets can damage magnetic media such as floppy disks, video tapes, HDDs, credit cards, magnetic ID cards, cassette tapes, etc. devices. They can also damage devices like video players, televisions, CRT computer monitors. Do not forget to keep neodymium magnets away from these electronic devices.

Neodymium Magnets can attract to each other, pinch the skin, and cause significant injuries.

If have a finger between or on the path of attracting magnets, there may be a large cut or a fracture.

Do not bring neodymium magnets close to GPS and smartphones.

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

Be careful!

Please see the article - What danger lies in neodymium magnets? You will learn how to handle them properly.

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