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neodymium magnets

We offer blue color magnetic Nd2Fe14B - our store's offer. All "magnets" in our store are available for immediate delivery (see the list). See the magnet price list for more details see the magnet price list

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MP 12x8/4x3 / N38 - ring magnet

ring magnet

Catalog no 030395

GTIN: 5906301812326

5

Diameter [±0,1 mm]

12 mm

internal diameter Ø [±0,1 mm]

8/4 mm

Height [±0,1 mm]

3 mm

Weight

4.24 g

Magnetization Direction

↑ axial

Load capacity

0.68 kg / 6.67 N

Magnetic Induction

237.19 mT

Coating

[NiCuNi] nickel

1.427 with VAT / pcs + price for transport

1.160 ZŁ net + 23% VAT / pcs

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MP 12x8/4x3 / N38 - ring magnet
Specification/characteristics MP 12x8/4x3 / N38 - ring magnet
properties
values
Cat. no.
030395
GTIN
5906301812326
Production/Distribution
Dhit sp. z o.o.
Country of origin
Poland / China / Germany
Customs code
85059029
Diameter
12 mm [±0,1 mm]
internal diameter Ø
8/4 mm [±0,1 mm]
Height
3 mm [±0,1 mm]
Weight
4.24 g [±0,1 mm]
Magnetization Direction
↑ axial
Load capacity ~ ?
0.68 kg / 6.67 N
Magnetic Induction ~ ?
237.19 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 sintered neodymium magnets Nd2Fe14B at 20°C

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

It is ideally suited for places where solid attachment of the magnet to the substrate is required without the risk of detachment. Thanks to the hole (often for a screw), this model enables easy screwing to wood, wall, plastic, or metal. It is also often used in advertising for fixing signs and in workshops for organizing tools.
This material behaves more like porcelain than steel, so it doesn't forgive mistakes during mounting. One turn too many can destroy the magnet, so do it slowly. It's a good idea to use a flexible washer under the screw head, which will cushion the stresses. Remember: cracking during assembly results from material properties, not a product defect.
Moisture can penetrate micro-cracks in the coating and cause oxidation of the magnet. Damage to the protective layer during assembly is the most common cause of rusting. If you must use it outside, paint it with anti-corrosion paint after mounting.
The inner hole diameter determines the maximum size of the mounting element. If the magnet does not have a chamfer (cone), we recommend using a screw with a flat or cylindrical head, or possibly using a washer. Aesthetic mounting requires selecting the appropriate head size.
This model is characterized by dimensions Ø12x3 mm and a weight of 4.24 g. The key parameter here is the lifting capacity amounting to approximately 0.68 kg (force ~6.67 N). The mounting hole diameter is precisely 8/4 mm.
These magnets are magnetized axially (through the thickness), which means one flat side is the N pole and the other is S. In the case of connecting two rings, make sure one is turned the right way. We do not offer paired sets with marked poles in this category, but they are easy to match manually.

Pros as well as cons of rare earth magnets.

Apart from their superior holding force, neodymium magnets have these key benefits:

  • They retain attractive force for almost ten years – the loss is just ~1% (based on simulations),
  • They have excellent resistance to weakening of magnetic properties as a result of external magnetic sources,
  • Thanks to the shimmering finish, the coating of Ni-Cu-Ni, gold, or silver gives an clean appearance,
  • Magnetic induction on the working layer of the magnet is strong,
  • Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and can work (depending on the shape) even at a temperature of 230°C or more...
  • Thanks to the possibility of precise forming and adaptation to specialized requirements, magnetic components can be created in a variety of shapes and sizes, which makes them more universal,
  • Fundamental importance in modern technologies – they find application in magnetic memories, electric drive systems, advanced medical instruments, also multitasking production systems.
  • Thanks to efficiency per cm³, small magnets offer high operating force, with minimal size,

Problematic aspects of neodymium magnets and ways of using them

  • To avoid cracks upon strong impacts, we suggest using special steel holders. Such a solution protects the magnet and simultaneously improves its durability.
  • We warn that neodymium magnets can reduce their power at high temperatures. To prevent this, we recommend our specialized [AH] magnets, which work effectively even at 230°C.
  • Magnets exposed to a humid environment can rust. Therefore when using outdoors, we recommend using water-impermeable magnets made of rubber, plastic or other material resistant to moisture
  • Due to limitations in creating nuts and complicated shapes in magnets, we propose using a housing - magnetic mechanism.
  • Possible danger resulting from small fragments of magnets pose a threat, when accidentally swallowed, which is particularly important in the context of child health protection. Additionally, small elements of these products are able to disrupt the diagnostic process medical after entering the body.
  • Due to expensive raw materials, their price is higher than average,

Magnetic strength at its maximum – what affects it?

The declared magnet strength refers to the maximum value, obtained under optimal environment, meaning:

  • with the contact of a sheet made of special test steel, guaranteeing full magnetic saturation
  • whose thickness reaches at least 10 mm
  • characterized by lack of roughness
  • with total lack of distance (no coatings)
  • for force applied at a right angle (pull-off, not shear)
  • at temperature approx. 20 degrees Celsius

What influences lifting capacity in practice

Holding efficiency impacted by working environment parameters, mainly (from priority):

  • Space between magnet and steel – even a fraction of a millimeter of separation (caused e.g. by varnish or dirt) drastically reduces the pulling force, often by half at just 0.5 mm.
  • Loading method – catalog parameter refers to pulling vertically. When attempting to slide, the magnet exhibits much less (often approx. 20-30% of maximum force).
  • Metal thickness – the thinner the sheet, the weaker the hold. Part of the magnetic field penetrates through instead of converting into lifting capacity.
  • Metal type – different alloys attracts identically. High carbon content worsen the attraction effect.
  • Surface finish – ideal contact is possible only on polished steel. Rough texture create air cushions, reducing force.
  • Thermal conditions – NdFeB sinters have a sensitivity to temperature. At higher temperatures they are weaker, and at low temperatures gain strength (up to a certain limit).

* Lifting capacity testing was carried out on a smooth plate of optimal thickness, under perpendicular forces, however under attempts to slide the magnet the load capacity is reduced by as much as 75%. In addition, even a small distance {between} the magnet’s surface and the plate decreases the holding force.

Precautions when working with neodymium magnets

Adults only

Only for adults. Tiny parts pose a choking risk, causing serious injuries. Store away from kids and pets.

Do not overheat magnets

Standard neodymium magnets (N-type) lose magnetization when the temperature exceeds 80°C. The loss of strength is permanent.

Warning for heart patients

Life threat: Neodymium magnets can turn off heart devices and defibrillators. Do not approach if you have medical devices.

Mechanical processing

Dust created during cutting of magnets is flammable. Do not drill into magnets without proper cooling and knowledge.

Allergy Warning

Some people experience a contact allergy to nickel, which is the typical protective layer for NdFeB magnets. Prolonged contact might lead to an allergic reaction. We suggest use safety gloves.

Cards and drives

Data protection: Strong magnets can damage data carriers and delicate electronics (heart implants, hearing aids, timepieces).

Risk of cracking

Protect your eyes. Magnets can explode upon violent connection, ejecting sharp fragments into the air. Wear goggles.

Bodily injuries

Danger of trauma: The pulling power is so great that it can result in blood blisters, crushing, and even bone fractures. Use thick gloves.

Caution required

Be careful. Neodymium magnets attract from a distance and snap with huge force, often faster than you can move away.

Threat to navigation

GPS units and mobile phones are extremely sensitive to magnetic fields. Close proximity with a powerful NdFeB magnet can permanently damage the internal compass in your phone.

Caution!

Details about risks in the article: Magnet Safety Guide.

Dhit sp. z o.o.

e-mail: bok@dhit.pl

tel: +48 888 99 98 98