MP 25x12.5x5 / N38 - ring magnet
ring magnet
Catalog no 030342
GTIN/EAN: 5906301812289
Diameter
25 mm [±0,1 mm]
internal diameter Ø
12.5 mm [±0,1 mm]
Height
5 mm [±0,1 mm]
Weight
13.81 g
Magnetization Direction
↑ axial
Load capacity
5.98 kg / 58.64 N
Magnetic Induction
230.20 mT / 2302 Gs
Coating
[NiCuNi] Nickel
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Technical of the product - MP 25x12.5x5 / N38 - ring magnet
Specification / characteristics - MP 25x12.5x5 / N38 - ring magnet
| properties | values |
|---|---|
| Cat. no. | 030342 |
| GTIN/EAN | 5906301812289 |
| 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 | 12.5 mm [±0,1 mm] |
| Height | 5 mm [±0,1 mm] |
| Weight | 13.81 g |
| Magnetization Direction | ↑ axial |
| Load capacity ~ ? | 5.98 kg / 58.64 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 |
Technical analysis of the magnet - data
Presented information are the result of a physical analysis. Values were calculated on algorithms for the class Nd2Fe14B. Real-world parameters may deviate from the simulation results. Please consider these data as a supplementary guide during assembly planning.
Table 1: Static pull force (pull vs distance) - interaction chart
MP 25x12.5x5 / N38
| Distance (mm) | Induction (Gauss) / mT | Pull Force (kg/lbs/g/N) | Risk Status |
|---|---|---|---|
| 0 mm |
5777 Gs
577.7 mT
|
5.98 kg / 13.18 pounds
5980.0 g / 58.7 N
|
strong |
| 1 mm |
5310 Gs
531.0 mT
|
5.05 kg / 11.14 pounds
5051.8 g / 49.6 N
|
strong |
| 2 mm |
4846 Gs
484.6 mT
|
4.21 kg / 9.27 pounds
4206.8 g / 41.3 N
|
strong |
| 3 mm |
4397 Gs
439.7 mT
|
3.46 kg / 7.64 pounds
3464.5 g / 34.0 N
|
strong |
| 5 mm |
3576 Gs
357.6 mT
|
2.29 kg / 5.05 pounds
2291.1 g / 22.5 N
|
strong |
| 10 mm |
2073 Gs
207.3 mT
|
0.77 kg / 1.70 pounds
769.7 g / 7.6 N
|
low risk |
| 15 mm |
1231 Gs
123.1 mT
|
0.27 kg / 0.60 pounds
271.6 g / 2.7 N
|
low risk |
| 20 mm |
773 Gs
77.3 mT
|
0.11 kg / 0.24 pounds
106.9 g / 1.0 N
|
low risk |
| 30 mm |
356 Gs
35.6 mT
|
0.02 kg / 0.05 pounds
22.7 g / 0.2 N
|
low risk |
| 50 mm |
115 Gs
11.5 mT
|
0.00 kg / 0.01 pounds
2.4 g / 0.0 N
|
low risk |
Table 2: Slippage load (wall)
MP 25x12.5x5 / N38
| Distance (mm) | Friction coefficient | Pull Force (kg/lbs/g/N) |
|---|---|---|
| 0 mm | Stal (~0.2) |
1.20 kg / 2.64 pounds
1196.0 g / 11.7 N
|
| 1 mm | Stal (~0.2) |
1.01 kg / 2.23 pounds
1010.0 g / 9.9 N
|
| 2 mm | Stal (~0.2) |
0.84 kg / 1.86 pounds
842.0 g / 8.3 N
|
| 3 mm | Stal (~0.2) |
0.69 kg / 1.53 pounds
692.0 g / 6.8 N
|
| 5 mm | Stal (~0.2) |
0.46 kg / 1.01 pounds
458.0 g / 4.5 N
|
| 10 mm | Stal (~0.2) |
0.15 kg / 0.34 pounds
154.0 g / 1.5 N
|
| 15 mm | Stal (~0.2) |
0.05 kg / 0.12 pounds
54.0 g / 0.5 N
|
| 20 mm | Stal (~0.2) |
0.02 kg / 0.05 pounds
22.0 g / 0.2 N
|
| 30 mm | Stal (~0.2) |
0.00 kg / 0.01 pounds
4.0 g / 0.0 N
|
| 50 mm | Stal (~0.2) |
0.00 kg / 0.00 pounds
0.0 g / 0.0 N
|
Table 3: Wall mounting (shearing) - vertical pull
MP 25x12.5x5 / N38
| Surface type | Friction coefficient / % Mocy | Max load (kg/lbs/g/N) |
|---|---|---|
| Raw steel |
µ = 0.3
30% Nominalnej Siły
|
1.79 kg / 3.96 pounds
1794.0 g / 17.6 N
|
| Painted steel (standard) |
µ = 0.2
20% Nominalnej Siły
|
1.20 kg / 2.64 pounds
1196.0 g / 11.7 N
|
| Oily/slippery steel |
µ = 0.1
10% Nominalnej Siły
|
0.60 kg / 1.32 pounds
598.0 g / 5.9 N
|
| Magnet with anti-slip rubber |
µ = 0.5
50% Nominalnej Siły
|
2.99 kg / 6.59 pounds
2990.0 g / 29.3 N
|
Table 4: Material efficiency (substrate influence) - sheet metal selection
MP 25x12.5x5 / N38
| Steel thickness (mm) | % power | Real pull force (kg/lbs/g/N) |
|---|---|---|
| 0.5 mm |
|
0.60 kg / 1.32 pounds
598.0 g / 5.9 N
|
| 1 mm |
|
1.50 kg / 3.30 pounds
1495.0 g / 14.7 N
|
| 2 mm |
|
2.99 kg / 6.59 pounds
2990.0 g / 29.3 N
|
| 3 mm |
|
4.49 kg / 9.89 pounds
4485.0 g / 44.0 N
|
| 5 mm |
|
5.98 kg / 13.18 pounds
5980.0 g / 58.7 N
|
| 10 mm |
|
5.98 kg / 13.18 pounds
5980.0 g / 58.7 N
|
| 11 mm |
|
5.98 kg / 13.18 pounds
5980.0 g / 58.7 N
|
| 12 mm |
|
5.98 kg / 13.18 pounds
5980.0 g / 58.7 N
|
Table 5: Working in heat (stability) - thermal limit
MP 25x12.5x5 / N38
| Ambient temp. (°C) | Power loss | Remaining pull (kg/lbs/g/N) | Status |
|---|---|---|---|
| 20 °C | 0.0% |
5.98 kg / 13.18 pounds
5980.0 g / 58.7 N
|
OK |
| 40 °C | -2.2% |
5.85 kg / 12.89 pounds
5848.4 g / 57.4 N
|
OK |
| 60 °C | -4.4% |
5.72 kg / 12.60 pounds
5716.9 g / 56.1 N
|
OK |
| 80 °C | -6.6% |
5.59 kg / 12.31 pounds
5585.3 g / 54.8 N
|
|
| 100 °C | -28.8% |
4.26 kg / 9.39 pounds
4257.8 g / 41.8 N
|
Table 6: Two magnets (repulsion) - field range
MP 25x12.5x5 / N38
| Gap (mm) | Attraction (kg/lbs) (N-S) | Shear Force (kg/lbs/g/N) | Repulsion (kg/lbs) (N-N) |
|---|---|---|---|
| 0 mm |
82.42 kg / 181.72 pounds
6 082 Gs
|
12.36 kg / 27.26 pounds
12364 g / 121.3 N
|
N/A |
| 1 mm |
75.95 kg / 167.44 pounds
11 091 Gs
|
11.39 kg / 25.12 pounds
11392 g / 111.8 N
|
68.35 kg / 150.69 pounds
~0 Gs
|
| 2 mm |
69.63 kg / 153.51 pounds
10 620 Gs
|
10.44 kg / 23.03 pounds
10445 g / 102.5 N
|
62.67 kg / 138.16 pounds
~0 Gs
|
| 3 mm |
63.64 kg / 140.29 pounds
10 153 Gs
|
9.55 kg / 21.04 pounds
9545 g / 93.6 N
|
57.27 kg / 126.26 pounds
~0 Gs
|
| 5 mm |
52.69 kg / 116.16 pounds
9 238 Gs
|
7.90 kg / 17.42 pounds
7903 g / 77.5 N
|
47.42 kg / 104.54 pounds
~0 Gs
|
| 10 mm |
31.58 kg / 69.62 pounds
7 152 Gs
|
4.74 kg / 10.44 pounds
4737 g / 46.5 N
|
28.42 kg / 62.66 pounds
~0 Gs
|
| 20 mm |
10.61 kg / 23.39 pounds
4 145 Gs
|
1.59 kg / 3.51 pounds
1591 g / 15.6 N
|
9.55 kg / 21.05 pounds
~0 Gs
|
| 50 mm |
0.65 kg / 1.43 pounds
1 024 Gs
|
0.10 kg / 0.21 pounds
97 g / 1.0 N
|
0.58 kg / 1.28 pounds
~0 Gs
|
| 60 mm |
0.31 kg / 0.69 pounds
712 Gs
|
0.05 kg / 0.10 pounds
47 g / 0.5 N
|
0.28 kg / 0.62 pounds
~0 Gs
|
| 70 mm |
0.16 kg / 0.36 pounds
514 Gs
|
0.02 kg / 0.05 pounds
24 g / 0.2 N
|
0.15 kg / 0.32 pounds
~0 Gs
|
| 80 mm |
0.09 kg / 0.20 pounds
383 Gs
|
0.01 kg / 0.03 pounds
14 g / 0.1 N
|
0.08 kg / 0.18 pounds
~0 Gs
|
| 90 mm |
0.05 kg / 0.12 pounds
293 Gs
|
0.01 kg / 0.02 pounds
8 g / 0.1 N
|
0.05 kg / 0.11 pounds
~0 Gs
|
| 100 mm |
0.03 kg / 0.07 pounds
230 Gs
|
0.00 kg / 0.01 pounds
5 g / 0.0 N
|
0.03 kg / 0.06 pounds
~0 Gs
|
Table 7: Hazards (implants) - warnings
MP 25x12.5x5 / 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 |
| Car key | 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: Collisions (cracking risk) - collision effects
MP 25x12.5x5 / N38
| Start from (mm) | Speed (km/h) | Energy (J) | Predicted outcome |
|---|---|---|---|
| 10 mm |
22.61 km/h
(6.28 m/s)
|
0.27 J | |
| 30 mm |
36.44 km/h
(10.12 m/s)
|
0.71 J | |
| 50 mm |
46.94 km/h
(13.04 m/s)
|
1.17 J | |
| 100 mm |
66.37 km/h
(18.43 m/s)
|
2.35 J |
Table 9: Coating parameters (durability)
MP 25x12.5x5 / 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 (Flux)
MP 25x12.5x5 / N38
| Parameter | Value | SI Unit / Description |
|---|---|---|
| Magnetic Flux | 24 536 Mx | 245.4 µWb |
| Pc Coefficient | 1.03 | High (Stable) |
Table 11: Underwater work (magnet fishing)
MP 25x12.5x5 / N38
| Environment | Effective steel pull | Effect |
|---|---|---|
| Air (land) | 5.98 kg | Standard |
| Water (riverbed) |
6.85 kg
(+0.87 kg buoyancy gain)
|
+14.5% |
1. Sliding resistance
*Warning: On a vertical wall, the magnet holds merely a fraction of its nominal pull.
2. Steel saturation
*Thin steel (e.g. 0.5mm PC case) drastically weakens the holding force.
3. Temperature resistance
*For N38 material, the safety limit is 80°C.
4. Demagnetization curve and operating point (B-H)
chart generated for the permeance coefficient Pc (Permeance Coefficient) = 1.03
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.
Elemental analysis
| 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 |
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Pros and cons of rare earth magnets.
Benefits
- They virtually do not lose power, because even after ten years the decline in efficiency is only ~1% (in laboratory conditions),
- They do not lose their magnetic properties even under strong external field,
- Thanks to the shiny finish, the surface of Ni-Cu-Ni, gold-plated, or silver gives an elegant appearance,
- Magnets have excellent magnetic induction on the active area,
- Through (appropriate) combination of ingredients, they can achieve high thermal strength, enabling functioning at temperatures approaching 230°C and above...
- Possibility of detailed shaping and adjusting to precise requirements,
- Fundamental importance in modern technologies – they are utilized in magnetic memories, drive modules, medical equipment, as well as modern systems.
- Compactness – despite small sizes they provide effective action, making them ideal for precision applications
Limitations
- Brittleness is one of their disadvantages. Upon intense impact they can fracture. We advise keeping them in a steel housing, which not only secures them against impacts but also raises their durability
- NdFeB magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of strength (a factor is the shape as well as dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are very resistant to heat
- Due to the susceptibility of magnets to corrosion in a humid environment, we advise using waterproof magnets made of rubber, plastic or other material immune to moisture, when using outdoors
- Limited possibility of creating threads in the magnet and complicated shapes - recommended is a housing - mounting mechanism.
- Potential hazard related to microscopic parts of magnets are risky, in case of ingestion, which becomes key in the context of child health protection. It is also worth noting that small elements of these products can disrupt the diagnostic process medical when they are in the body.
- With large orders the cost of neodymium magnets is economically unviable,
Holding force characteristics
Best holding force of the magnet in ideal parameters – what affects it?
- using a sheet made of high-permeability steel, functioning as a magnetic yoke
- whose transverse dimension is min. 10 mm
- with a surface free of scratches
- with zero gap (no paint)
- under vertical application of breakaway force (90-degree angle)
- at conditions approx. 20°C
Lifting capacity in practice – influencing factors
- Gap between surfaces – every millimeter of separation (caused e.g. by veneer or unevenness) drastically reduces the pulling force, often by half at just 0.5 mm.
- Force direction – remember that the magnet holds strongest perpendicularly. Under sliding down, the holding force drops significantly, often to levels of 20-30% of the maximum value.
- Wall thickness – thin material does not allow full use of the magnet. Magnetic flux penetrates through instead of generating force.
- Plate material – low-carbon steel attracts best. Higher carbon content lower magnetic properties and holding force.
- Smoothness – ideal contact is obtained only on polished steel. Rough texture create air cushions, reducing force.
- Heat – NdFeB sinters have a sensitivity to temperature. At higher temperatures they lose power, and at low temperatures they can be stronger (up to a certain limit).
Lifting capacity testing was performed on a smooth plate of suitable thickness, under perpendicular forces, whereas under parallel forces the load capacity is reduced by as much as fivefold. Moreover, even a slight gap between the magnet’s surface and the plate decreases the holding force.
Safety rules for work with neodymium magnets
Dust is flammable
Fire warning: Rare earth powder is highly flammable. Avoid machining magnets without safety gear as this may cause fire.
Impact on smartphones
GPS units and mobile phones are highly susceptible to magnetic fields. Close proximity with a powerful NdFeB magnet can permanently damage the internal compass in your phone.
Warning for allergy sufferers
Some people experience a sensitization to nickel, which is the typical protective layer for NdFeB magnets. Prolonged contact may cause dermatitis. We recommend wear protective gloves.
Handling guide
Exercise caution. Rare earth magnets attract from a long distance and connect with huge force, often quicker than you can move away.
This is not a toy
Strictly store magnets out of reach of children. Ingestion danger is significant, and the consequences of magnets clamping inside the body are fatal.
Serious injuries
Watch your fingers. Two powerful magnets will snap together immediately with a force of several hundred kilograms, crushing anything in their path. Exercise extreme caution!
Health Danger
Warning for patients: Strong magnetic fields disrupt medical devices. Maintain minimum 30 cm distance or request help to handle the magnets.
Thermal limits
Monitor thermal conditions. Exposing the magnet to high heat will ruin its magnetic structure and strength.
Data carriers
Device Safety: Neodymium magnets can damage data carriers and delicate electronics (heart implants, medical aids, mechanical watches).
Eye protection
NdFeB magnets are ceramic materials, which means they are prone to chipping. Clashing of two magnets will cause them shattering into small pieces.
