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MP 12x8/4x3 / N38 - ring magnet

ring magnet

Catalog no 030395

GTIN/EAN: 5906301812326

5.00

Diameter

12 mm [±0,1 mm]

internal diameter Ø

8/4 mm [±0,1 mm]

Height

3 mm [±0,1 mm]

Weight

2.26 g

Magnetization Direction

↑ axial

Load capacity

2.21 kg / 21.72 N

Magnetic Induction

277.09 mT / 2771 Gs

Coating

[NiCuNi] Nickel

1.427 with VAT / pcs + price for transport

1.160 ZŁ net + 23% VAT / pcs

bulk discounts:

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Detailed specification - MP 12x8/4x3 / N38 - ring magnet

Specification / characteristics - MP 12x8/4x3 / N38 - ring magnet

properties
properties values
Cat. no. 030395
GTIN/EAN 5906301812326
Production/Distribution Dhit sp. z o.o.
ul. Zielona 14 05-850 Ożarów Mazowiecki PL
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 2.26 g
Magnetization Direction ↑ axial
Load capacity ~ ? 2.21 kg / 21.72 N
Magnetic Induction ~ ? 277.09 mT / 2771 Gs
Coating [NiCuNi] Nickel
Manufacturing Tolerance ±0.1 mm

Magnetic properties of material N38

Specification / characteristics MP 12x8/4x3 / N38 - ring magnet
properties values units
remenance Br [min. - max.] ? 12.2-12.6 kGs
remenance Br [min. - max.] ? 1220-1260 mT
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

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 10-6 °C-1
Thermal expansion perpendicular (⊥) to orientation (M) -(1-3) x 10-6 °C-1
Young's modulus 1.7 x 104 kg/mm²

Physical simulation of the assembly - technical parameters

Presented data are the outcome of a mathematical simulation. Results rely on models for the class Nd2Fe14B. Actual parameters may differ from theoretical values. Treat these data as a supplementary guide when designing systems.

Table 1: Static force (force vs gap) - power drop
MP 12x8/4x3 / N38

Distance (mm) Induction (Gauss) / mT Pull Force (kg/lbs/g/N) Risk Status
0 mm 2423 Gs
242.3 mT
2.21 kg / 4.87 lbs
2210.0 g / 21.7 N
medium risk
1 mm 2138 Gs
213.8 mT
1.72 kg / 3.79 lbs
1720.7 g / 16.9 N
weak grip
2 mm 1786 Gs
178.6 mT
1.20 kg / 2.65 lbs
1200.5 g / 11.8 N
weak grip
3 mm 1437 Gs
143.7 mT
0.78 kg / 1.71 lbs
777.8 g / 7.6 N
weak grip
5 mm 885 Gs
88.5 mT
0.29 kg / 0.65 lbs
294.7 g / 2.9 N
weak grip
10 mm 277 Gs
27.7 mT
0.03 kg / 0.06 lbs
28.9 g / 0.3 N
weak grip
15 mm 110 Gs
11.0 mT
0.00 kg / 0.01 lbs
4.6 g / 0.0 N
weak grip
20 mm 53 Gs
5.3 mT
0.00 kg / 0.00 lbs
1.1 g / 0.0 N
weak grip
30 mm 18 Gs
1.8 mT
0.00 kg / 0.00 lbs
0.1 g / 0.0 N
weak grip
50 mm 4 Gs
0.4 mT
0.00 kg / 0.00 lbs
0.0 g / 0.0 N
weak grip

Table 2: Slippage force (vertical surface)
MP 12x8/4x3 / N38

Distance (mm) Friction coefficient Pull Force (kg/lbs/g/N)
0 mm Stal (~0.2) 0.44 kg / 0.97 lbs
442.0 g / 4.3 N
1 mm Stal (~0.2) 0.34 kg / 0.76 lbs
344.0 g / 3.4 N
2 mm Stal (~0.2) 0.24 kg / 0.53 lbs
240.0 g / 2.4 N
3 mm Stal (~0.2) 0.16 kg / 0.34 lbs
156.0 g / 1.5 N
5 mm Stal (~0.2) 0.06 kg / 0.13 lbs
58.0 g / 0.6 N
10 mm Stal (~0.2) 0.01 kg / 0.01 lbs
6.0 g / 0.1 N
15 mm Stal (~0.2) 0.00 kg / 0.00 lbs
0.0 g / 0.0 N
20 mm Stal (~0.2) 0.00 kg / 0.00 lbs
0.0 g / 0.0 N
30 mm Stal (~0.2) 0.00 kg / 0.00 lbs
0.0 g / 0.0 N
50 mm Stal (~0.2) 0.00 kg / 0.00 lbs
0.0 g / 0.0 N

Table 3: Vertical assembly (sliding) - vertical pull
MP 12x8/4x3 / N38

Surface type Friction coefficient / % Mocy Max load (kg/lbs/g/N)
Raw steel
µ = 0.3 30% Nominalnej Siły
0.66 kg / 1.46 lbs
663.0 g / 6.5 N
Painted steel (standard)
µ = 0.2 20% Nominalnej Siły
0.44 kg / 0.97 lbs
442.0 g / 4.3 N
Oily/slippery steel
µ = 0.1 10% Nominalnej Siły
0.22 kg / 0.49 lbs
221.0 g / 2.2 N
Magnet with anti-slip rubber
µ = 0.5 50% Nominalnej Siły
1.11 kg / 2.44 lbs
1105.0 g / 10.8 N

Table 4: Material efficiency (saturation) - power losses
MP 12x8/4x3 / N38

Steel thickness (mm) % power Real pull force (kg/lbs/g/N)
0.5 mm
10%
0.22 kg / 0.49 lbs
221.0 g / 2.2 N
1 mm
25%
0.55 kg / 1.22 lbs
552.5 g / 5.4 N
2 mm
50%
1.11 kg / 2.44 lbs
1105.0 g / 10.8 N
3 mm
75%
1.66 kg / 3.65 lbs
1657.5 g / 16.3 N
5 mm
100%
2.21 kg / 4.87 lbs
2210.0 g / 21.7 N
10 mm
100%
2.21 kg / 4.87 lbs
2210.0 g / 21.7 N
11 mm
100%
2.21 kg / 4.87 lbs
2210.0 g / 21.7 N
12 mm
100%
2.21 kg / 4.87 lbs
2210.0 g / 21.7 N

Table 5: Thermal resistance (stability) - power drop
MP 12x8/4x3 / N38

Ambient temp. (°C) Power loss Remaining pull (kg/lbs/g/N) Status
20 °C 0.0% 2.21 kg / 4.87 lbs
2210.0 g / 21.7 N
OK
40 °C -2.2% 2.16 kg / 4.77 lbs
2161.4 g / 21.2 N
OK
60 °C -4.4% 2.11 kg / 4.66 lbs
2112.8 g / 20.7 N
80 °C -6.6% 2.06 kg / 4.55 lbs
2064.1 g / 20.2 N
100 °C -28.8% 1.57 kg / 3.47 lbs
1573.5 g / 15.4 N

Table 6: Magnet-Magnet interaction (attraction) - field collision
MP 12x8/4x3 / N38

Gap (mm) Attraction (kg/lbs) (N-S) Sliding Force (kg/lbs/g/N) Repulsion (kg/lbs) (N-N)
0 mm 3.09 kg / 6.82 lbs
4 010 Gs
0.46 kg / 1.02 lbs
464 g / 4.6 N
N/A
1 mm 2.77 kg / 6.12 lbs
4 589 Gs
0.42 kg / 0.92 lbs
416 g / 4.1 N
2.50 kg / 5.50 lbs
~0 Gs
2 mm 2.41 kg / 5.31 lbs
4 276 Gs
0.36 kg / 0.80 lbs
361 g / 3.5 N
2.17 kg / 4.78 lbs
~0 Gs
3 mm 2.03 kg / 4.48 lbs
3 930 Gs
0.31 kg / 0.67 lbs
305 g / 3.0 N
1.83 kg / 4.04 lbs
~0 Gs
5 mm 1.36 kg / 3.00 lbs
3 216 Gs
0.20 kg / 0.45 lbs
204 g / 2.0 N
1.23 kg / 2.70 lbs
~0 Gs
10 mm 0.41 kg / 0.91 lbs
1 770 Gs
0.06 kg / 0.14 lbs
62 g / 0.6 N
0.37 kg / 0.82 lbs
~0 Gs
20 mm 0.04 kg / 0.09 lbs
554 Gs
0.01 kg / 0.01 lbs
6 g / 0.1 N
0.04 kg / 0.08 lbs
~0 Gs
50 mm 0.00 kg / 0.00 lbs
58 Gs
0.00 kg / 0.00 lbs
0 g / 0.0 N
0.00 kg / 0.00 lbs
~0 Gs
60 mm 0.00 kg / 0.00 lbs
35 Gs
0.00 kg / 0.00 lbs
0 g / 0.0 N
0.00 kg / 0.00 lbs
~0 Gs
70 mm 0.00 kg / 0.00 lbs
23 Gs
0.00 kg / 0.00 lbs
0 g / 0.0 N
0.00 kg / 0.00 lbs
~0 Gs
80 mm 0.00 kg / 0.00 lbs
16 Gs
0.00 kg / 0.00 lbs
0 g / 0.0 N
0.00 kg / 0.00 lbs
~0 Gs
90 mm 0.00 kg / 0.00 lbs
11 Gs
0.00 kg / 0.00 lbs
0 g / 0.0 N
0.00 kg / 0.00 lbs
~0 Gs
100 mm 0.00 kg / 0.00 lbs
8 Gs
0.00 kg / 0.00 lbs
0 g / 0.0 N
0.00 kg / 0.00 lbs
~0 Gs

Table 7: Hazards (electronics) - warnings
MP 12x8/4x3 / N38

Object / Device Limit (Gauss) / mT Safe distance
Pacemaker 5 Gs (0.5 mT) 5.0 cm
Hearing aid 10 Gs (1.0 mT) 4.0 cm
Timepiece 20 Gs (2.0 mT) 3.0 cm
Mobile device 40 Gs (4.0 mT) 2.5 cm
Car key 50 Gs (5.0 mT) 2.5 cm
Payment card 400 Gs (40.0 mT) 1.0 cm
HDD hard drive 600 Gs (60.0 mT) 1.0 cm

Table 8: Dynamics (cracking risk) - warning
MP 12x8/4x3 / N38

Start from (mm) Speed (km/h) Energy (J) Predicted outcome
10 mm 31.79 km/h
(8.83 m/s)
0.09 J
30 mm 54.63 km/h
(15.17 m/s)
0.26 J
50 mm 70.52 km/h
(19.59 m/s)
0.43 J
100 mm 99.73 km/h
(27.70 m/s)
0.87 J

Table 9: Anti-corrosion coating durability
MP 12x8/4x3 / N38

Technical parameter Value / Description
Coating type [NiCuNi] Nickel
Layer structure Nickel - Copper - Nickel
Layer thickness 10-20 µm
Salt spray test (SST) ? 24 h
Recommended environment Indoors only (dry)

Table 10: Electrical data (Pc)
MP 12x8/4x3 / N38

Parameter Value SI Unit / Description
Magnetic Flux 2 466 Mx 24.7 µWb
Pc Coefficient 0.32 Low (Flat)

Table 11: Underwater work (magnet fishing)
MP 12x8/4x3 / N38

Environment Effective steel pull Effect
Air (land) 2.21 kg Standard
Water (riverbed) 2.53 kg
(+0.32 kg buoyancy gain)
+14.5%
Rust risk: Standard nickel requires drying after every contact with moisture; lack of maintenance will lead to rust spots.
1. Sliding resistance

*Note: On a vertical surface, the magnet retains only a fraction of its perpendicular strength.

2. Steel saturation

*Thin steel (e.g. 0.5mm PC case) significantly weakens the holding force.

3. Power loss vs temp

*For N38 grade, the max working temp is 80°C.

4. Demagnetization curve and operating point (B-H)

chart generated for the permeance coefficient Pc (Permeance Coefficient) = 0.32

This simulation demonstrates the magnetic stability of the selected magnet under specific geometric conditions. The solid red line represents the demagnetization curve (material potential), while the dashed blue line is the load line based on the magnet's geometry. The Pc (Permeance Coefficient), also known as the load line slope, is a dimensionless value that describes the relationship between the magnet's shape and its magnetic stability. The intersection of these two lines (the black dot) is the operating point — it determines the actual magnetic flux density generated by the magnet in this specific configuration. A higher Pc value means the magnet is more 'slender' (tall relative to its area), resulting in a higher operating point and better resistance to irreversible demagnetization caused by external fields or temperature. A value of 0.42 is relatively low (typical for flat magnets), meaning the operating point is closer to the 'knee' of the curve — caution is advised when operating at temperatures near the maximum limit to avoid strength loss.

Technical specification and ecology
Material specification
iron (Fe) 64% – 68%
neodymium (Nd) 29% – 32%
boron (B) 1.1% – 1.2%
dysprosium (Dy) 0.5% – 2.0%
coating (Ni-Cu-Ni) < 0.05%
Environmental data
recyclability (EoL) 100%
recycled raw materials ~10% (pre-cons)
carbon footprint low / zredukowany
waste code (EWC) 16 02 16
Safety card (GPSR)
responsible entity
Dhit sp. z o.o.
ul. Kościuszki 6A, 05-850 Ożarów Mazowiecki
tel: +48 22 499 98 98 | e-mail: bok@dhit.pl
batch number/type
id: 030395-2026
Measurement Calculator
Magnet pull force

Field Strength

Other products

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. This product with a force of 2.21 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. One turn too many can destroy the magnet, so do it slowly. It's a good idea to use a rubber spacer under the screw head, which will cushion the stresses. 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 is not sufficient for rain. In the place of the mounting hole, the coating is thinner and can be damaged when tightening the screw, which will become a corrosion focus. If you must use it outside, paint it with anti-corrosion paint after mounting.
A screw or bolt with a thread diameter smaller than 8/4 mm fits this model. 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 2.26 g. The pulling force of this model is an impressive 2.21 kg, which translates to 21.72 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. In the case of connecting two rings, make sure one is turned the right way. When ordering a larger quantity, magnets are usually packed in stacks, where they are already naturally paired.

Strengths as well as weaknesses of Nd2Fe14B magnets.

Strengths

Besides their magnetic performance, neodymium magnets are valued for these benefits:
  • They have unchanged lifting capacity, and over more than ten years their attraction force decreases symbolically – ~1% (according to theory),
  • They are extremely resistant to demagnetization induced by external field influence,
  • The use of an aesthetic finish of noble metals (nickel, gold, silver) causes the element to have aesthetics,
  • They are known for high magnetic induction at the operating surface, which affects their effectiveness,
  • Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their shape) at temperatures up to 230°C and above...
  • Thanks to freedom in shaping and the ability to customize to individual projects,
  • Significant place in future technologies – they serve a role in hard drives, brushless drives, medical devices, and other advanced devices.
  • Compactness – despite small sizes they generate large force, making them ideal for precision applications

Weaknesses

Disadvantages of neodymium magnets:
  • At very strong impacts they can crack, therefore we recommend placing them in steel cases. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
  • When exposed to high temperature, neodymium magnets suffer a drop in strength. Often, when the temperature exceeds 80°C, their power 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
  • Due to the susceptibility of magnets to corrosion in a humid environment, we advise using waterproof magnets made of rubber, plastic or other material stable to moisture, in case of application outdoors
  • We suggest cover - magnetic mount, due to difficulties in realizing nuts inside the magnet and complicated shapes.
  • Potential hazard related to microscopic parts of magnets can be dangerous, in case of ingestion, which is particularly important in the context of child health protection. Furthermore, small elements of these products are able to complicate diagnosis medical when they are in the body.
  • Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Pull force analysis

Maximum lifting force for a neodymium magnet – what affects it?

The load parameter shown represents the maximum value, obtained under optimal environment, namely:
  • with the use of a sheet made of low-carbon steel, guaranteeing maximum field concentration
  • possessing a thickness of at least 10 mm to avoid saturation
  • with a surface cleaned and smooth
  • under conditions of no distance (surface-to-surface)
  • under perpendicular force direction (90-degree angle)
  • at temperature room level

What influences lifting capacity in practice

In real-world applications, the actual lifting capacity results from a number of factors, presented from the most important:
  • Clearance – existence of any layer (paint, dirt, gap) interrupts the magnetic circuit, which lowers power rapidly (even by 50% at 0.5 mm).
  • Direction of force – maximum parameter is obtained only during pulling at a 90° angle. The resistance to sliding of the magnet along the plate is usually several times lower (approx. 1/5 of the lifting capacity).
  • Wall thickness – thin material does not allow full use of the magnet. Part of the magnetic field passes through the material instead of converting into lifting capacity.
  • Steel type – low-carbon steel attracts best. Alloy admixtures decrease magnetic properties and lifting capacity.
  • Surface quality – the more even the plate, the larger the contact zone and higher the lifting capacity. Unevenness acts like micro-gaps.
  • Thermal factor – hot environment weakens magnetic field. Exceeding the limit temperature can permanently damage the magnet.

Holding force was checked on the plate surface of 20 mm thickness, when a perpendicular force was applied, whereas under parallel forces the load capacity is reduced by as much as 5 times. In addition, even a slight gap between the magnet’s surface and the plate lowers the lifting capacity.

Warnings
Finger safety

Pinching hazard: The attraction force is so great that it can cause hematomas, crushing, and even bone fractures. Protective gloves are recommended.

Choking Hazard

Only for adults. Small elements pose a choking risk, causing intestinal necrosis. Keep away from kids and pets.

Fire risk

Powder produced during machining of magnets is combustible. Avoid drilling into magnets unless you are an expert.

GPS and phone interference

Be aware: rare earth magnets generate a field that interferes with precision electronics. Maintain a separation from your mobile, device, and navigation systems.

ICD Warning

Warning for patients: Strong magnetic fields disrupt medical devices. Keep minimum 30 cm distance or request help to handle the magnets.

Caution required

Before use, check safety instructions. Sudden snapping can destroy the magnet or injure your hand. Be predictive.

Thermal limits

Watch the temperature. Heating the magnet above 80 degrees Celsius will ruin its properties and strength.

Skin irritation risks

Studies show that nickel (standard magnet coating) is a potent allergen. If you have an allergy, refrain from touching magnets with bare hands or choose versions in plastic housing.

Threat to electronics

Data protection: Strong magnets can damage data carriers and sensitive devices (pacemakers, hearing aids, timepieces).

Beware of splinters

Neodymium magnets are ceramic materials, which means they are fragile like glass. Impact of two magnets will cause them shattering into shards.

Attention! More info about hazards in the article: Magnet Safety Guide.
Dhit sp. z o.o.

e-mail: bok@dhit.pl

tel: +48 888 99 98 98