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MP 25x12.5x5 / N38 - ring magnet

ring magnet

Catalog no 030342

GTIN/EAN: 5906301812289

5.00

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

6.20 with VAT / pcs + price for transport

5.04 ZŁ net + 23% VAT / pcs

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Technical of the product - MP 25x12.5x5 / N38 - ring magnet

Specification / characteristics - MP 25x12.5x5 / N38 - ring magnet

properties
properties values
Cat. no. 030342
GTIN/EAN 5906301812289
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 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

Specification / characteristics MP 25x12.5x5 / 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

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
10%
0.60 kg / 1.32 pounds
598.0 g / 5.9 N
1 mm
25%
1.50 kg / 3.30 pounds
1495.0 g / 14.7 N
2 mm
50%
2.99 kg / 6.59 pounds
2990.0 g / 29.3 N
3 mm
75%
4.49 kg / 9.89 pounds
4485.0 g / 44.0 N
5 mm
100%
5.98 kg / 13.18 pounds
5980.0 g / 58.7 N
10 mm
100%
5.98 kg / 13.18 pounds
5980.0 g / 58.7 N
11 mm
100%
5.98 kg / 13.18 pounds
5980.0 g / 58.7 N
12 mm
100%
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%
Corrosion warning: Remember to wipe the magnet thoroughly after removing it from water and apply a protective layer (e.g., oil) to avoid corrosion.
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.

Engineering data and GPSR
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
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: 030342-2026
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Magnet pull force

Magnetic Field

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The ring-shaped magnet MP 25x12.5x5 / N38 is created for permanent mounting, where glue might fail or be insufficient. Mounting is clean and reversible, unlike gluing. This product with a force of 5.98 kg works great as a cabinet closure, speaker holder, or mounting element in devices.
This is a crucial issue when working with model MP 25x12.5x5 / 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. The flat screw head should evenly press the magnet. Remember: cracking during assembly results from material properties, not a product defect.
Moisture can penetrate micro-cracks in the coating and cause oxidation of the magnet. Damage to the protective layer during assembly is the most common cause of rusting. This product is dedicated for indoor use. For outdoor applications, we recommend choosing rubberized holders or additional protection with varnish.
The inner hole diameter determines the maximum size of the mounting element. 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. Always check that the screw head is not larger than the outer diameter of the magnet (25 mm), so it doesn't protrude beyond the outline.
It is a magnetic ring with a diameter of 25 mm and thickness 5 mm. The key parameter here is the lifting capacity amounting to approximately 5.98 kg (force ~58.67 N). The mounting hole diameter is precisely 12.5 mm.
The poles are located on the planes with holes, not on the sides of the ring. 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). We do not offer paired sets with marked poles in this category, but they are easy to match manually.

Pros and cons of rare earth magnets.

Benefits

In addition to their magnetic capacity, neodymium magnets provide the following advantages:
  • 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

Disadvantages of NdFeB magnets:
  • 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 parameterswhat affects it?

Breakaway force was defined for the most favorable conditions, including:
  • 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

Real force impacted by working environment parameters, mainly (from priority):
  • 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.

Attention! Learn more about risks in the article: Magnet Safety Guide.