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neodymium magnets

We provide blue color magnets Nd2Fe14B - our store's offer. Practically all "neodymium magnets" in our store are in stock for immediate delivery (check the list). See the magnet pricing for more details check 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

bulk discounts:

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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

The ring-shaped magnet MP 12x8/4x3 / N38 is created for mechanical fastening, where glue might fail or be insufficient. Mounting is clean and reversible, unlike gluing. This product with a force of 0.68 kg works great as a cabinet closure, speaker holder, or mounting element in devices.
This is a crucial issue when working with model MP 12x8/4x3 / N38. Neodymium magnets are sintered ceramics, which means they are hard but breakable and inelastic. When tightening the screw, you must maintain great sensitivity. We recommend tightening manually with a screwdriver, not an impact driver, because too much pressure will cause the ring to crack. The flat screw head should evenly press the magnet. Remember: cracking during assembly results from material properties, not a product defect.
These magnets are coated with standard Ni-Cu-Ni plating, which protects them in indoor conditions, but does not ensure full waterproofing. In the place of the mounting hole, the coating is thinner and easily scratched when tightening the screw, which will become a corrosion focus. This product is dedicated for inside building use. For outdoor applications, we recommend choosing magnets in hermetic housing or additional protection with varnish.
A screw or bolt with a thread diameter smaller than 8/4 mm fits this model. For magnets with a straight hole, a conical head can act like a wedge and burst the magnet. Always check that the screw head is not larger than the outer diameter of the magnet (12 mm), so it doesn't protrude beyond the outline.
This model is characterized by dimensions Ø12x3 mm and a weight of 4.24 g. The pulling force of this model is an impressive 0.68 kg, which translates to 6.67 N in newtons. 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. If you want two such magnets screwed with cones facing each other (faces) to attract, you must connect them with opposite poles (N to S). When ordering a larger quantity, magnets are usually packed in stacks, where they are already naturally paired.

Pros as well as cons of rare earth magnets.

Apart from their consistent power, neodymium magnets have these key benefits:

  • They have constant strength, and over around ten years their attraction force decreases symbolically – ~1% (in testing),
  • Neodymium magnets are remarkably resistant to loss of magnetic properties caused by external interference,
  • In other words, due to the metallic layer of nickel, the element looks attractive,
  • The surface of neodymium magnets generates a strong magnetic field – this is a key feature,
  • Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can work (depending on the form) even at a temperature of 230°C or more...
  • Due to the possibility of precise molding and customization to individualized requirements, NdFeB magnets can be created in a variety of shapes and sizes, which amplifies use scope,
  • Versatile presence in high-tech industry – they are used in HDD drives, electric motors, advanced medical instruments, and technologically advanced constructions.
  • Thanks to concentrated force, small magnets offer high operating force, with minimal size,

Disadvantages of neodymium magnets:

  • To avoid cracks upon strong impacts, we suggest using special steel housings. Such a solution protects the magnet and simultaneously improves its durability.
  • When exposed to high temperature, neodymium magnets experience a drop in force. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size and shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 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 protecting against moisture
  • We recommend cover - magnetic mechanism, due to difficulties in realizing nuts inside the magnet and complicated forms.
  • Possible danger related to microscopic parts of magnets pose a threat, if swallowed, which gains importance in the context of child health protection. Furthermore, small elements of these magnets can be problematic in diagnostics medical when they are in the body.
  • Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Maximum magnetic pulling forcewhat affects it?

The specified lifting capacity refers to the peak performance, obtained under laboratory conditions, meaning:

  • with the application of a sheet made of special test steel, ensuring maximum field concentration
  • possessing a massiveness of at least 10 mm to ensure full flux closure
  • characterized by smoothness
  • under conditions of gap-free contact (metal-to-metal)
  • during pulling in a direction vertical to the mounting surface
  • at conditions approx. 20°C

Impact of factors on magnetic holding capacity in practice

In real-world applications, the actual lifting capacity results from a number of factors, listed from crucial:

  • Gap between magnet and steel – every millimeter of distance (caused e.g. by varnish or unevenness) diminishes the pulling force, often by half at just 0.5 mm.
  • Loading method – declared lifting capacity refers to detachment vertically. When attempting to slide, the magnet exhibits significantly lower power (often approx. 20-30% of maximum force).
  • Metal thickness – thin material does not allow full use of the magnet. Part of the magnetic field passes through the material instead of generating force.
  • Material type – ideal substrate is pure iron steel. Hardened steels may have worse magnetic properties.
  • Smoothness – full contact is obtained only on polished steel. Rough texture reduce the real contact area, weakening the magnet.
  • Temperature – heating the magnet results in weakening of force. It is worth remembering the thermal limit for a given model.

* Lifting capacity testing was carried out on plates with a smooth surface of suitable thickness, under perpendicular forces, whereas under parallel forces the load capacity is reduced by as much as 5 times. Additionally, even a small distance {between} the magnet’s surface and the plate decreases the load capacity.

Safe handling of NdFeB magnets

Permanent damage

Keep cool. NdFeB magnets are sensitive to temperature. If you require resistance above 80°C, look for HT versions (H, SH, UH).

Medical interference

Individuals with a ICD should keep an absolute distance from magnets. The magnetism can interfere with the operation of the implant.

Bodily injuries

Big blocks can break fingers in a fraction of a second. Under no circumstances place your hand betwixt two attracting surfaces.

Dust is flammable

Combustion risk: Rare earth powder is highly flammable. Avoid machining magnets in home conditions as this may cause fire.

Adults only

Neodymium magnets are not toys. Swallowing multiple magnets can lead to them attracting across intestines, which poses a critical condition and necessitates immediate surgery.

GPS and phone interference

A strong magnetic field interferes with the functioning of magnetometers in smartphones and GPS navigation. Keep magnets close to a smartphone to prevent damaging the sensors.

Keep away from computers

Powerful magnetic fields can erase data on payment cards, HDDs, and storage devices. Maintain a gap of at least 10 cm.

Allergy Warning

Warning for allergy sufferers: The Ni-Cu-Ni coating consists of nickel. If an allergic reaction appears, cease working with magnets and wear gloves.

Conscious usage

Before use, check safety instructions. Sudden snapping can destroy the magnet or hurt your hand. Think ahead.

Eye protection

Neodymium magnets are ceramic materials, meaning they are prone to chipping. Impact of two magnets leads to them shattering into shards.

Attention!

Learn more about risks in the article: Safety of working with magnets.

Dhit sp. z o.o.

e-mail: bok@dhit.pl

tel: +48 888 99 98 98