MP 12x8/4x3 / N38 - ring magnet
ring magnet
Catalog no 030395
GTIN/EAN: 5906301812326
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 ZŁ with VAT / pcs + price for transport
1.160 ZŁ net + 23% VAT / pcs
bulk discounts:
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Product card - MP 12x8/4x3 / N38 - ring magnet
Specification / characteristics - MP 12x8/4x3 / N38 - ring magnet
| properties | values |
|---|---|
| Cat. no. | 030395 |
| GTIN/EAN | 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 | 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
| 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
| 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 analysis of the product - data
The following values represent the outcome of a engineering calculation. Values were calculated on models for the material Nd2Fe14B. Real-world conditions may differ. Please consider these data as a preliminary roadmap when designing systems.
Table 1: Static pull force (force vs distance) - power drop
MP 12x8/4x3 / N38
| Distance (mm) | Induction (Gauss) / mT | Pull Force (kg) | Risk Status |
|---|---|---|---|
| 0 mm |
2423 Gs
242.3 mT
|
2.21 kg / 2210.0 g
21.7 N
|
warning |
| 1 mm |
2138 Gs
213.8 mT
|
1.72 kg / 1720.7 g
16.9 N
|
weak grip |
| 2 mm |
1786 Gs
178.6 mT
|
1.20 kg / 1200.5 g
11.8 N
|
weak grip |
| 3 mm |
1437 Gs
143.7 mT
|
0.78 kg / 777.8 g
7.6 N
|
weak grip |
| 5 mm |
885 Gs
88.5 mT
|
0.29 kg / 294.7 g
2.9 N
|
weak grip |
| 10 mm |
277 Gs
27.7 mT
|
0.03 kg / 28.9 g
0.3 N
|
weak grip |
| 15 mm |
110 Gs
11.0 mT
|
0.00 kg / 4.6 g
0.0 N
|
weak grip |
| 20 mm |
53 Gs
5.3 mT
|
0.00 kg / 1.1 g
0.0 N
|
weak grip |
| 30 mm |
18 Gs
1.8 mT
|
0.00 kg / 0.1 g
0.0 N
|
weak grip |
| 50 mm |
4 Gs
0.4 mT
|
0.00 kg / 0.0 g
0.0 N
|
weak grip |
Table 2: Slippage load (wall)
MP 12x8/4x3 / N38
| Distance (mm) | Friction coefficient | Pull Force (kg) |
|---|---|---|
| 0 mm | Stal (~0.2) |
0.44 kg / 442.0 g
4.3 N
|
| 1 mm | Stal (~0.2) |
0.34 kg / 344.0 g
3.4 N
|
| 2 mm | Stal (~0.2) |
0.24 kg / 240.0 g
2.4 N
|
| 3 mm | Stal (~0.2) |
0.16 kg / 156.0 g
1.5 N
|
| 5 mm | Stal (~0.2) |
0.06 kg / 58.0 g
0.6 N
|
| 10 mm | Stal (~0.2) |
0.01 kg / 6.0 g
0.1 N
|
| 15 mm | Stal (~0.2) |
0.00 kg / 0.0 g
0.0 N
|
| 20 mm | Stal (~0.2) |
0.00 kg / 0.0 g
0.0 N
|
| 30 mm | Stal (~0.2) |
0.00 kg / 0.0 g
0.0 N
|
| 50 mm | Stal (~0.2) |
0.00 kg / 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) |
|---|---|---|
| Raw steel |
µ = 0.3
30% Nominalnej Siły
|
0.66 kg / 663.0 g
6.5 N
|
| Painted steel (standard) |
µ = 0.2
20% Nominalnej Siły
|
0.44 kg / 442.0 g
4.3 N
|
| Oily/slippery steel |
µ = 0.1
10% Nominalnej Siły
|
0.22 kg / 221.0 g
2.2 N
|
| Magnet with anti-slip rubber |
µ = 0.5
50% Nominalnej Siły
|
1.11 kg / 1105.0 g
10.8 N
|
Table 4: Material efficiency (substrate influence) - power losses
MP 12x8/4x3 / N38
| Steel thickness (mm) | % power | Real pull force (kg) |
|---|---|---|
| 0.5 mm |
|
0.22 kg / 221.0 g
2.2 N
|
| 1 mm |
|
0.55 kg / 552.5 g
5.4 N
|
| 2 mm |
|
1.11 kg / 1105.0 g
10.8 N
|
| 5 mm |
|
2.21 kg / 2210.0 g
21.7 N
|
| 10 mm |
|
2.21 kg / 2210.0 g
21.7 N
|
Table 5: Thermal resistance (material behavior) - thermal limit
MP 12x8/4x3 / N38
| Ambient temp. (°C) | Power loss | Remaining pull | Status |
|---|---|---|---|
| 20 °C | 0.0% |
2.21 kg / 2210.0 g
21.7 N
|
OK |
| 40 °C | -2.2% |
2.16 kg / 2161.4 g
21.2 N
|
OK |
| 60 °C | -4.4% |
2.11 kg / 2112.8 g
20.7 N
|
|
| 80 °C | -6.6% |
2.06 kg / 2064.1 g
20.2 N
|
|
| 100 °C | -28.8% |
1.57 kg / 1573.5 g
15.4 N
|
Table 6: Magnet-Magnet interaction (attraction) - field range
MP 12x8/4x3 / N38
| Gap (mm) | Attraction (kg) (N-S) | Repulsion (kg) (N-N) |
|---|---|---|
| 0 mm |
3.09 kg / 3092 g
30.3 N
4 010 Gs
|
N/A |
| 1 mm |
2.77 kg / 2774 g
27.2 N
4 589 Gs
|
2.50 kg / 2496 g
24.5 N
~0 Gs
|
| 2 mm |
2.41 kg / 2408 g
23.6 N
4 276 Gs
|
2.17 kg / 2167 g
21.3 N
~0 Gs
|
| 3 mm |
2.03 kg / 2034 g
20.0 N
3 930 Gs
|
1.83 kg / 1831 g
18.0 N
~0 Gs
|
| 5 mm |
1.36 kg / 1362 g
13.4 N
3 216 Gs
|
1.23 kg / 1226 g
12.0 N
~0 Gs
|
| 10 mm |
0.41 kg / 412 g
4.0 N
1 770 Gs
|
0.37 kg / 371 g
3.6 N
~0 Gs
|
| 20 mm |
0.04 kg / 40 g
0.4 N
554 Gs
|
0.04 kg / 36 g
0.4 N
~0 Gs
|
| 50 mm |
0.00 kg / 0 g
0.0 N
58 Gs
|
0.00 kg / 0 g
0.0 N
~0 Gs
|
Table 7: Protective zones (implants) - 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 |
| Phone / Smartphone | 40 Gs (4.0 mT) | 2.5 cm |
| Remote | 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: Impact energy (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: Construction 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% |
1. Vertical hold
*Warning: On a vertical wall, the magnet retains just a fraction of its nominal pull.
2. Efficiency vs thickness
*Thin steel (e.g. 0.5mm PC case) drastically weakens the holding force.
3. Heat tolerance
*For standard magnets, the safety limit is 80°C.
4. Demagnetization curve and operating point (B-H)
chart generated for the permeance coefficient Pc (Permeance Coefficient) = 0.32
The chart above illustrates the magnetic characteristics of the material within the second quadrant of the hysteresis loop. 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.
Chemical composition
| 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% |
Sustainability
| recyclability (EoL) | 100% |
| recycled raw materials | ~10% (pre-cons) |
| carbon footprint | low / zredukowany |
| waste code (EWC) | 16 02 16 |
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Advantages and disadvantages of neodymium magnets.
Benefits
- They virtually do not lose strength, because even after 10 years the decline in efficiency is only ~1% (based on calculations),
- They have excellent resistance to magnetic field loss due to external fields,
- In other words, due to the reflective surface of silver, the element looks attractive,
- They are known for high magnetic induction at the operating surface, making them more effective,
- Thanks to resistance to high temperature, they can operate (depending on the form) even at temperatures up to 230°C and higher...
- Thanks to the ability of free forming and adaptation to individualized projects, neodymium magnets can be produced in a broad palette of shapes and sizes, which makes them more universal,
- Significant place in electronics industry – they are commonly used in data components, electric motors, precision medical tools, as well as technologically advanced constructions.
- Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications
Limitations
- They are prone to damage upon heavy impacts. To avoid cracks, it is worth securing magnets in a protective case. Such protection not only protects the magnet but also increases its resistance to damage
- Neodymium magnets decrease their force under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
- They oxidize in a humid environment - during use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
- We recommend a housing - magnetic holder, due to difficulties in creating threads inside the magnet and complicated shapes.
- Possible danger related to microscopic parts of magnets can be dangerous, when accidentally swallowed, which becomes key in the context of child safety. Additionally, small elements of these devices can be problematic in diagnostics medical in case of swallowing.
- With large orders the cost of neodymium magnets is a challenge,
Pull force analysis
Optimal lifting capacity of a neodymium magnet – what it depends on?
- with the application of a sheet made of low-carbon steel, guaranteeing full magnetic saturation
- whose transverse dimension is min. 10 mm
- characterized by smoothness
- under conditions of gap-free contact (surface-to-surface)
- during pulling in a direction perpendicular to the plane
- in temp. approx. 20°C
Magnet lifting force in use – key factors
- Clearance – existence of foreign body (paint, dirt, air) interrupts the magnetic circuit, which lowers capacity rapidly (even by 50% at 0.5 mm).
- Force direction – catalog parameter refers to detachment vertically. When slipping, the magnet holds significantly lower power (often approx. 20-30% of nominal force).
- Plate thickness – too thin plate causes magnetic saturation, causing part of the flux to be escaped to the other side.
- Metal type – different alloys attracts identically. Alloy additives worsen the interaction with the magnet.
- Surface condition – ground elements ensure maximum contact, which increases force. Rough surfaces weaken the grip.
- Temperature influence – hot environment weakens magnetic field. Exceeding the limit temperature can permanently damage the magnet.
Lifting capacity was assessed using a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, in contrast under parallel forces the lifting capacity is smaller. In addition, even a small distance between the magnet and the plate lowers the holding force.
Warnings
This is not a toy
NdFeB magnets are not toys. Accidental ingestion of a few magnets can lead to them pinching intestinal walls, which constitutes a critical condition and necessitates urgent medical intervention.
Handling rules
Be careful. Rare earth magnets act from a distance and snap with huge force, often quicker than you can move away.
Risk of cracking
Despite metallic appearance, neodymium is delicate and cannot withstand shocks. Avoid impacts, as the magnet may shatter into sharp, dangerous pieces.
Physical harm
Pinching hazard: The attraction force is so immense that it can result in hematomas, crushing, and broken bones. Protective gloves are recommended.
Implant safety
Individuals with a pacemaker should keep an absolute distance from magnets. The magnetism can disrupt the functioning of the life-saving device.
Do not overheat magnets
Monitor thermal conditions. Heating the magnet above 80 degrees Celsius will ruin its properties and pulling force.
Precision electronics
A powerful magnetic field disrupts the operation of compasses in smartphones and GPS navigation. Keep magnets near a smartphone to prevent breaking the sensors.
Do not drill into magnets
Machining of NdFeB material carries a risk of fire hazard. Neodymium dust oxidizes rapidly with oxygen and is hard to extinguish.
Cards and drives
Very strong magnetic fields can erase data on payment cards, hard drives, and storage devices. Keep a distance of min. 10 cm.
Metal Allergy
Studies show that nickel (the usual finish) is a potent allergen. If you have an allergy, avoid direct skin contact or opt for coated magnets.
