MP 25x8x5 / N38 - ring magnet
ring magnet
Catalog no 030196
GTIN/EAN: 5906301812135
Diameter
25 mm [±0,1 mm]
internal diameter Ø
8 mm [±0,1 mm]
Height
5 mm [±0,1 mm]
Weight
16.52 g
Magnetization Direction
↑ axial
Load capacity
7.16 kg / 70.21 N
Magnetic Induction
230.20 mT / 2302 Gs
Coating
[NiCuNi] Nickel
5.90 ZŁ with VAT / pcs + price for transport
4.80 ZŁ net + 23% VAT / pcs
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Technical - MP 25x8x5 / N38 - ring magnet
Specification / characteristics - MP 25x8x5 / N38 - ring magnet
| properties | values |
|---|---|
| Cat. no. | 030196 |
| GTIN/EAN | 5906301812135 |
| Production/Distribution | Dhit sp. z o.o. |
| Country of origin | Poland / China / Germany |
| Customs code | 85059029 |
| Diameter | 25 mm [±0,1 mm] |
| internal diameter Ø | 8 mm [±0,1 mm] |
| Height | 5 mm [±0,1 mm] |
| Weight | 16.52 g |
| Magnetization Direction | ↑ axial |
| Load capacity ~ ? | 7.16 kg / 70.21 N |
| Magnetic Induction ~ ? | 230.20 mT / 2302 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 simulation of the magnet - technical parameters
These values represent the outcome of a engineering simulation. Values were calculated on algorithms for the material Nd2Fe14B. Real-world conditions might slightly differ from theoretical values. Treat these calculations as a supplementary guide during assembly planning.
Table 1: Static force (force vs distance) - power drop
MP 25x8x5 / N38
| Distance (mm) | Induction (Gauss) / mT | Pull Force (kg/lbs/g/N) | Risk Status |
|---|---|---|---|
| 0 mm |
5777 Gs
577.7 mT
|
7.16 kg / 15.79 lbs
7160.0 g / 70.2 N
|
warning |
| 1 mm |
5310 Gs
531.0 mT
|
6.05 kg / 13.33 lbs
6048.6 g / 59.3 N
|
warning |
| 2 mm |
4846 Gs
484.6 mT
|
5.04 kg / 11.10 lbs
5036.9 g / 49.4 N
|
warning |
| 3 mm |
4397 Gs
439.7 mT
|
4.15 kg / 9.15 lbs
4148.2 g / 40.7 N
|
warning |
| 5 mm |
3576 Gs
357.6 mT
|
2.74 kg / 6.05 lbs
2743.2 g / 26.9 N
|
warning |
| 10 mm |
2073 Gs
207.3 mT
|
0.92 kg / 2.03 lbs
921.6 g / 9.0 N
|
weak grip |
| 15 mm |
1231 Gs
123.1 mT
|
0.33 kg / 0.72 lbs
325.2 g / 3.2 N
|
weak grip |
| 20 mm |
773 Gs
77.3 mT
|
0.13 kg / 0.28 lbs
128.0 g / 1.3 N
|
weak grip |
| 30 mm |
356 Gs
35.6 mT
|
0.03 kg / 0.06 lbs
27.2 g / 0.3 N
|
weak grip |
| 50 mm |
115 Gs
11.5 mT
|
0.00 kg / 0.01 lbs
2.8 g / 0.0 N
|
weak grip |
Table 2: Shear hold (vertical surface)
MP 25x8x5 / N38
| Distance (mm) | Friction coefficient | Pull Force (kg/lbs/g/N) |
|---|---|---|
| 0 mm | Stal (~0.2) |
1.43 kg / 3.16 lbs
1432.0 g / 14.0 N
|
| 1 mm | Stal (~0.2) |
1.21 kg / 2.67 lbs
1210.0 g / 11.9 N
|
| 2 mm | Stal (~0.2) |
1.01 kg / 2.22 lbs
1008.0 g / 9.9 N
|
| 3 mm | Stal (~0.2) |
0.83 kg / 1.83 lbs
830.0 g / 8.1 N
|
| 5 mm | Stal (~0.2) |
0.55 kg / 1.21 lbs
548.0 g / 5.4 N
|
| 10 mm | Stal (~0.2) |
0.18 kg / 0.41 lbs
184.0 g / 1.8 N
|
| 15 mm | Stal (~0.2) |
0.07 kg / 0.15 lbs
66.0 g / 0.6 N
|
| 20 mm | Stal (~0.2) |
0.03 kg / 0.06 lbs
26.0 g / 0.3 N
|
| 30 mm | Stal (~0.2) |
0.01 kg / 0.01 lbs
6.0 g / 0.1 N
|
| 50 mm | Stal (~0.2) |
0.00 kg / 0.00 lbs
0.0 g / 0.0 N
|
Table 3: Vertical assembly (shearing) - behavior on slippery surfaces
MP 25x8x5 / N38
| Surface type | Friction coefficient / % Mocy | Max load (kg/lbs/g/N) |
|---|---|---|
| Raw steel |
µ = 0.3
30% Nominalnej Siły
|
2.15 kg / 4.74 lbs
2148.0 g / 21.1 N
|
| Painted steel (standard) |
µ = 0.2
20% Nominalnej Siły
|
1.43 kg / 3.16 lbs
1432.0 g / 14.0 N
|
| Oily/slippery steel |
µ = 0.1
10% Nominalnej Siły
|
0.72 kg / 1.58 lbs
716.0 g / 7.0 N
|
| Magnet with anti-slip rubber |
µ = 0.5
50% Nominalnej Siły
|
3.58 kg / 7.89 lbs
3580.0 g / 35.1 N
|
Table 4: Material efficiency (substrate influence) - power losses
MP 25x8x5 / N38
| Steel thickness (mm) | % power | Real pull force (kg/lbs/g/N) |
|---|---|---|
| 0.5 mm |
|
0.72 kg / 1.58 lbs
716.0 g / 7.0 N
|
| 1 mm |
|
1.79 kg / 3.95 lbs
1790.0 g / 17.6 N
|
| 2 mm |
|
3.58 kg / 7.89 lbs
3580.0 g / 35.1 N
|
| 3 mm |
|
5.37 kg / 11.84 lbs
5370.0 g / 52.7 N
|
| 5 mm |
|
7.16 kg / 15.79 lbs
7160.0 g / 70.2 N
|
| 10 mm |
|
7.16 kg / 15.79 lbs
7160.0 g / 70.2 N
|
| 11 mm |
|
7.16 kg / 15.79 lbs
7160.0 g / 70.2 N
|
| 12 mm |
|
7.16 kg / 15.79 lbs
7160.0 g / 70.2 N
|
Table 5: Working in heat (material behavior) - thermal limit
MP 25x8x5 / N38
| Ambient temp. (°C) | Power loss | Remaining pull (kg/lbs/g/N) | Status |
|---|---|---|---|
| 20 °C | 0.0% |
7.16 kg / 15.79 lbs
7160.0 g / 70.2 N
|
OK |
| 40 °C | -2.2% |
7.00 kg / 15.44 lbs
7002.5 g / 68.7 N
|
OK |
| 60 °C | -4.4% |
6.84 kg / 15.09 lbs
6845.0 g / 67.1 N
|
OK |
| 80 °C | -6.6% |
6.69 kg / 14.74 lbs
6687.4 g / 65.6 N
|
|
| 100 °C | -28.8% |
5.10 kg / 11.24 lbs
5097.9 g / 50.0 N
|
Table 6: Magnet-Magnet interaction (repulsion) - forces in the system
MP 25x8x5 / N38
| Gap (mm) | Attraction (kg/lbs) (N-S) | Lateral Force (kg/lbs/g/N) | Repulsion (kg/lbs) (N-N) |
|---|---|---|---|
| 0 mm |
82.42 kg / 181.72 lbs
6 082 Gs
|
12.36 kg / 27.26 lbs
12364 g / 121.3 N
|
N/A |
| 1 mm |
75.95 kg / 167.44 lbs
11 091 Gs
|
11.39 kg / 25.12 lbs
11392 g / 111.8 N
|
68.35 kg / 150.69 lbs
~0 Gs
|
| 2 mm |
69.63 kg / 153.51 lbs
10 620 Gs
|
10.44 kg / 23.03 lbs
10445 g / 102.5 N
|
62.67 kg / 138.16 lbs
~0 Gs
|
| 3 mm |
63.64 kg / 140.29 lbs
10 153 Gs
|
9.55 kg / 21.04 lbs
9545 g / 93.6 N
|
57.27 kg / 126.26 lbs
~0 Gs
|
| 5 mm |
52.69 kg / 116.16 lbs
9 238 Gs
|
7.90 kg / 17.42 lbs
7903 g / 77.5 N
|
47.42 kg / 104.54 lbs
~0 Gs
|
| 10 mm |
31.58 kg / 69.62 lbs
7 152 Gs
|
4.74 kg / 10.44 lbs
4737 g / 46.5 N
|
28.42 kg / 62.66 lbs
~0 Gs
|
| 20 mm |
10.61 kg / 23.39 lbs
4 145 Gs
|
1.59 kg / 3.51 lbs
1591 g / 15.6 N
|
9.55 kg / 21.05 lbs
~0 Gs
|
| 50 mm |
0.65 kg / 1.43 lbs
1 024 Gs
|
0.10 kg / 0.21 lbs
97 g / 1.0 N
|
0.58 kg / 1.28 lbs
~0 Gs
|
| 60 mm |
0.31 kg / 0.69 lbs
712 Gs
|
0.05 kg / 0.10 lbs
47 g / 0.5 N
|
0.28 kg / 0.62 lbs
~0 Gs
|
| 70 mm |
0.16 kg / 0.36 lbs
514 Gs
|
0.02 kg / 0.05 lbs
24 g / 0.2 N
|
0.15 kg / 0.32 lbs
~0 Gs
|
| 80 mm |
0.09 kg / 0.20 lbs
383 Gs
|
0.01 kg / 0.03 lbs
14 g / 0.1 N
|
0.08 kg / 0.18 lbs
~0 Gs
|
| 90 mm |
0.05 kg / 0.12 lbs
293 Gs
|
0.01 kg / 0.02 lbs
8 g / 0.1 N
|
0.05 kg / 0.11 lbs
~0 Gs
|
| 100 mm |
0.03 kg / 0.07 lbs
230 Gs
|
0.00 kg / 0.01 lbs
5 g / 0.0 N
|
0.03 kg / 0.06 lbs
~0 Gs
|
Table 7: Protective zones (electronics) - precautionary measures
MP 25x8x5 / N38
| Object / Device | Limit (Gauss) / mT | Safe distance |
|---|---|---|
| Pacemaker | 5 Gs (0.5 mT) | 17.0 cm |
| Hearing aid | 10 Gs (1.0 mT) | 13.5 cm |
| Timepiece | 20 Gs (2.0 mT) | 10.5 cm |
| Mobile device | 40 Gs (4.0 mT) | 8.0 cm |
| Remote | 50 Gs (5.0 mT) | 7.5 cm |
| Payment card | 400 Gs (40.0 mT) | 3.0 cm |
| HDD hard drive | 600 Gs (60.0 mT) | 2.5 cm |
Table 8: Dynamics (kinetic energy) - collision effects
MP 25x8x5 / N38
| Start from (mm) | Speed (km/h) | Energy (J) | Predicted outcome |
|---|---|---|---|
| 10 mm |
22.62 km/h
(6.28 m/s)
|
0.33 J | |
| 30 mm |
36.45 km/h
(10.13 m/s)
|
0.85 J | |
| 50 mm |
46.96 km/h
(13.04 m/s)
|
1.41 J | |
| 100 mm |
66.40 km/h
(18.44 m/s)
|
2.81 J |
Table 9: Coating parameters (durability)
MP 25x8x5 / 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 (Flux)
MP 25x8x5 / N38
| Parameter | Value | SI Unit / Description |
|---|---|---|
| Magnetic Flux | 24 536 Mx | 245.4 µWb |
| Pc Coefficient | 1.03 | High (Stable) |
Table 11: Hydrostatics and buoyancy
MP 25x8x5 / N38
| Environment | Effective steel pull | Effect |
|---|---|---|
| Air (land) | 7.16 kg | Standard |
| Water (riverbed) |
8.20 kg
(+1.04 kg buoyancy gain)
|
+14.5% |
1. Shear force
*Caution: On a vertical surface, the magnet retains only a fraction of its max power.
2. Steel thickness impact
*Thin steel (e.g. 0.5mm PC case) drastically limits the holding force.
3. Power loss vs temp
*For N38 grade, the critical limit is 80°C.
4. Demagnetization curve and operating point (B-H)
chart generated for the permeance coefficient Pc (Permeance Coefficient) = 1.03
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% |
Ecology and recycling (GPSR)
| recyclability (EoL) | 100% |
| recycled raw materials | ~10% (pre-cons) |
| carbon footprint | low / zredukowany |
| waste code (EWC) | 16 02 16 |
View also deals
Pros as well as cons of Nd2Fe14B magnets.
Benefits
- They have unchanged lifting capacity, and over around ten years their performance decreases symbolically – ~1% (in testing),
- They possess excellent resistance to magnetic field loss due to opposing magnetic fields,
- By applying a reflective coating of nickel, the element has an proper look,
- The surface of neodymium magnets generates a strong magnetic field – this is a key feature,
- Thanks to resistance to high temperature, they are capable of working (depending on the shape) even at temperatures up to 230°C and higher...
- Thanks to flexibility in forming and the capacity to adapt to unusual requirements,
- Key role in innovative solutions – they are used in data components, drive modules, diagnostic systems, as well as complex engineering applications.
- Compactness – despite small sizes they generate large force, making them ideal for precision applications
Disadvantages
- They are prone to damage upon heavy impacts. To avoid cracks, it is worth protecting magnets in special housings. Such protection not only shields 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 power. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
- They rust in a humid environment. For use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
- Limited possibility of producing threads in the magnet and complex forms - recommended is cover - magnetic holder.
- Health risk to health – tiny shards of magnets can be dangerous, when accidentally swallowed, which gains importance in the aspect of protecting the youngest. It is also worth noting that small components of these magnets are able to be problematic in diagnostics medical in case of swallowing.
- Due to complex production process, their price is higher than average,
Lifting parameters
Maximum lifting capacity of the magnet – what affects it?
- with the application of a yoke made of low-carbon steel, ensuring maximum field concentration
- whose thickness is min. 10 mm
- with an ground touching surface
- without any air gap between the magnet and steel
- for force applied at a right angle (in the magnet axis)
- at room temperature
Practical lifting capacity: influencing factors
- Clearance – the presence of foreign body (rust, dirt, gap) interrupts the magnetic circuit, which reduces power rapidly (even by 50% at 0.5 mm).
- Force direction – declared lifting capacity refers to detachment vertically. When slipping, the magnet holds significantly lower power (typically approx. 20-30% of nominal force).
- Wall thickness – the thinner the sheet, the weaker the hold. Part of the magnetic field penetrates through instead of generating force.
- Steel type – mild steel attracts best. Higher carbon content reduce magnetic properties and holding force.
- Smoothness – ideal contact is possible only on polished steel. Rough texture reduce the real contact area, weakening the magnet.
- Operating temperature – neodymium magnets have a sensitivity to temperature. When it is hot they lose power, and in frost gain strength (up to a certain limit).
Lifting capacity testing was conducted on a smooth plate of optimal thickness, under a perpendicular pulling force, however under shearing force the holding force is lower. Additionally, even a slight gap between the magnet and the plate reduces the lifting capacity.
Warnings
Magnetic media
Powerful magnetic fields can erase data on credit cards, hard drives, and storage devices. Keep a distance of at least 10 cm.
Nickel coating and allergies
Medical facts indicate that the nickel plating (the usual finish) is a strong allergen. If your skin reacts to metals, prevent direct skin contact or choose versions in plastic housing.
GPS and phone interference
Be aware: rare earth magnets produce a field that interferes with sensitive sensors. Maintain a separation from your phone, tablet, and navigation systems.
Dust is flammable
Dust produced during grinding of magnets is combustible. Avoid drilling into magnets unless you are an expert.
Implant safety
People with a pacemaker have to keep an absolute distance from magnets. The magnetism can interfere with the operation of the life-saving device.
Crushing force
Big blocks can crush fingers in a fraction of a second. Do not place your hand betwixt two attracting surfaces.
Heat warning
Standard neodymium magnets (grade N) lose power when the temperature exceeds 80°C. This process is irreversible.
Immense force
Exercise caution. Neodymium magnets act from a distance and connect with huge force, often quicker than you can react.
Eye protection
Neodymium magnets are ceramic materials, meaning they are prone to chipping. Impact of two magnets will cause them breaking into small pieces.
Choking Hazard
Strictly store magnets away from children. Ingestion danger is high, and the consequences of magnets clamping inside the body are fatal.
