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MP 15x7/3.5x3 / N38 - ring magnet

ring magnet

Catalog no 030182

GTIN: 5906301811992

Diameter [±0,1 mm]

15 mm

internal diameter Ø [±0,1 mm]

7/3.5 mm

Height [±0,1 mm]

3 mm

Weight

6.89 g

Magnetization Direction

↑ axial

Load capacity

0.9 kg / 8.83 N

Magnetic Induction

303.47 mT

Coating

[NiCuNi] nickel

1.747 ZŁ with VAT / pcs + price for transport

1.420 ZŁ net + 23% VAT / pcs

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MP 15x7/3.5x3 / N38 - ring magnet

Specification/characteristics MP 15x7/3.5x3 / N38 - ring magnet

properties

values

Cat. no.

030182

GTIN

5906301811992

Production/Distribution

Dhit sp. z o.o.

Country of origin

Poland / China / Germany

Customs code

85059029

Diameter

15 mm [±0,1 mm]

internal diameter Ø

7/3.5 mm [±0,1 mm]

Height

3 mm [±0,1 mm]

Weight

6.89 g [±0,1 mm]

Magnetization Direction

↑ axial

Load capacity ~ ?

0.9 kg / 8.83 N

Magnetic Induction ~ ?

303.47 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

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

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

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A neodymium ring magnet is created for screwing in. Thanks to the hole (often for a countersunk screw) enables easy screwing of the magnet to wood, walls, or plastic. Product MP 15x7/3.5x3 / N38 with a force of 0.9 kg works great as a door catch, hanger, or box closure. Its shape permits sliding it onto a rod or shaft.

This is very important. NdFeB sinters are extremely brittle. When tightening the screw, you must be careful. Use a hand screwdriver, not power tools, because too much force can shatter the ring. We suggest to use a washer to distribute the pressure. Remember: cracking during installation is not a product defect, but an installation error.

Most countersunk magnets have poles on flat faces. To create a closure, you need a pair where one magnet has the **N** pole on the countersunk side and the other has the **S** pole. With identical magnets, they might repel each other on the mounting sides. In the store, you can ask for complementary sets, or an alternative is to use one magnet and a metal plate as the second element.

Ring magnets come in two versions: with a straight hole and with a countersunk hole (chamfered). The countersunk hole allows the screw head to be hidden with the surface, which is key in furniture making. A ring without chamfer is better for sliding onto rods or separators. This product is the version MP 15x7/3.5x3 / N38 - check the hole type in the title or photo.

These magnets are coated with a standard anti-corrosion Ni-Cu-Ni coating. It protects the magnet in indoor conditions, but is not enough for rain. At the screw hole, the coating is thinner and can be damaged when tightening, becoming a focal point for corrosion. We recommend use for indoor use.

The declared pull force (0.9 kg) refers to ideal contact with a thick steel plate. In practice depends on contact area and air gap (e.g. paint layer). The ring has slightly less active surface than a solid cylinder, but still offers powerful force. When mounted on a wall (shear force), the magnet will hold approx. 20-30% of its nominal pull force.

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their immense pulling force, neodymium magnets offer the following advantages:

They virtually do not lose strength, because even after ten years, the performance loss is only ~1% (according to literature),
They are extremely resistant to demagnetization caused by external field interference,
Because of the lustrous layer of nickel, the component looks aesthetically refined,
They have exceptional magnetic induction on the surface of the magnet,
Neodymium magnets are known for strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the magnetic form),
Thanks to the possibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in different geometries, which expands their functional possibilities,
Important function in advanced technical fields – they are utilized in hard drives, rotating machines, medical equipment or even technologically developed systems,
Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in tiny dimensions, which allows for use in small systems

Disadvantages of neodymium magnets:

They are prone to breaking when subjected to a strong impact. If the magnets are exposed to external force, we recommend in a protective case. The steel housing, in the form of a holder, protects the magnet from fracture while also strengthens its overall resistance,
High temperatures may significantly reduce the magnetic power of neodymium magnets. Typically, above 80°C, they experience permanent weakening 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,
Due to corrosion risk in humid conditions, it is common to use sealed magnets made of plastic for outdoor use,
Using a cover – such as a magnetic holder – is advised due to the restrictions in manufacturing holes directly in the magnet,
Safety concern linked to microscopic shards may arise, especially if swallowed, which is significant in the family environments. Furthermore, tiny components from these magnets can interfere with diagnostics after being swallowed,
Due to expensive raw materials, their cost is above average,

Detachment force of the magnet in optimal conditions – what contributes to it?

The given holding capacity of the magnet corresponds to the highest holding force, calculated in the best circumstances, specifically:

with the use of low-carbon steel plate acting as a magnetic yoke
having a thickness of no less than 10 millimeters
with a polished side
with no separation
with vertical force applied
at room temperature

Practical aspects of lifting capacity – 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) 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 measured on the plate surface of 20 mm thickness, when the force acted perpendicularly, however under parallel forces the load capacity is reduced by as much as fivefold. Moreover, even a slight gap {between} the magnet and the plate reduces the holding force.

Handle Neodymium Magnets with Caution

The magnet coating is made of nickel, so be cautious if you have an 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, you can try wearing gloves or simply avoid direct contact with nickel-plated neodymium magnets.

Neodymium magnets can demagnetize at high temperatures.

Although magnets have demonstrated their effectiveness up to 80°C or 175°F, the temperature can vary depending on the type, shape, and intended use of the specific magnet.

People with pacemakers are advised to avoid neodymium magnets.

Neodymium magnets generate strong magnetic fields. As a result, they interfere with the operation of a pacemaker. This happens because such devices have a function to deactivate them in a magnetic field.

Neodymium magnets are the most powerful magnets ever invented. Their strength can surprise you.

Make sure to review all the information we have provided. This will help you avoid harm to your body and damage to the magnets.

Keep neodymium magnets as far away as possible 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.

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

Magnets will attract each other within a distance of several to around 10 cm from each other. Remember not to place fingers between magnets or alternatively in their path when they attract. Magnets, depending on their size, can even cut off a finger or alternatively there can be a significant pressure or even a fracture.

Dust and powder from neodymium magnets are flammable.

Avoid drilling or mechanical processing of neodymium magnets. If the magnet is crushed into fine powder or dust, it becomes highly flammable.

It is essential to keep neodymium magnets out of reach from children.

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.

Make sure not to bring neodymium magnets close to the TV, wallet, and computer HDD.

Strong magnetic fields emitted by neodymium magnets can destroy magnetic storage media such as floppy disks, credit cards, magnetic ID cards, cassette tapes, video tapes, or other devices. They can also damage televisions, VCRs, computer monitors, and CRT displays. You should especially avoid placing neodymium magnets near electronic devices.

Neodymium magnetic are highly fragile, they easily break as well as can crumble.

Neodymium magnets are delicate as well as will crack if allowed to collide with each other, even from a distance of a few centimeters. Despite being made of metal as well as coated with a shiny nickel plating, they are not as hard as steel. At the moment of collision between the magnets, tiny sharp metal pieces can be propelled in various directions at high speed. Eye protection is recommended.

Pay attention!

So you are aware of why neodymium magnets are so dangerous, read the article titled How dangerous are very powerful neodymium magnets?.