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MP 25x5x27 / N38 - ring magnet

ring magnet

Catalog no 030192

GTIN/EAN: 5906301812098

5.00

Diameter

25 mm [±0,1 mm]

internal diameter Ø

5 mm [±0,1 mm]

Height

27 mm [±0,1 mm]

Weight

95.43 g

Magnetization Direction

↑ axial

Load capacity

18.51 kg / 181.54 N

Magnetic Induction

562.34 mT / 5623 Gs

Coating

[NiCuNi] Nickel

47.18 with VAT / pcs + price for transport

38.36 ZŁ net + 23% VAT / pcs

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Technical data of the product - MP 25x5x27 / N38 - ring magnet

Specification / characteristics - MP 25x5x27 / N38 - ring magnet

properties
properties values
Cat. no. 030192
GTIN/EAN 5906301812098
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 5 mm [±0,1 mm]
Height 27 mm [±0,1 mm]
Weight 95.43 g
Magnetization Direction ↑ axial
Load capacity ~ ? 18.51 kg / 181.54 N
Magnetic Induction ~ ? 562.34 mT / 5623 Gs
Coating [NiCuNi] Nickel
Manufacturing Tolerance ±0.1 mm

Magnetic properties of material N38

Specification / characteristics MP 25x5x27 / 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 analysis of the magnet - technical parameters

The following values are the direct effect of a mathematical simulation. Results are based on algorithms for the material Nd2Fe14B. Operational parameters might slightly differ. Use these data as a preliminary roadmap during assembly planning.

Table 1: Static force (pull vs distance) - power drop
MP 25x5x27 / N38

Distance (mm) Induction (Gauss) / mT Pull Force (kg/lbs/g/N) Risk Status
0 mm 5716 Gs
571.6 mT
18.51 kg / 40.81 lbs
18510.0 g / 181.6 N
critical level
1 mm 5288 Gs
528.8 mT
15.84 kg / 34.92 lbs
15839.8 g / 155.4 N
critical level
2 mm 4861 Gs
486.1 mT
13.38 kg / 29.51 lbs
13384.0 g / 131.3 N
critical level
3 mm 4446 Gs
444.6 mT
11.20 kg / 24.69 lbs
11198.0 g / 109.9 N
critical level
5 mm 3677 Gs
367.7 mT
7.66 kg / 16.88 lbs
7657.5 g / 75.1 N
medium risk
10 mm 2216 Gs
221.6 mT
2.78 kg / 6.13 lbs
2782.1 g / 27.3 N
medium risk
15 mm 1354 Gs
135.4 mT
1.04 kg / 2.29 lbs
1037.8 g / 10.2 N
weak grip
20 mm 864 Gs
86.4 mT
0.42 kg / 0.93 lbs
423.3 g / 4.2 N
weak grip
30 mm 405 Gs
40.5 mT
0.09 kg / 0.21 lbs
93.1 g / 0.9 N
weak grip
50 mm 133 Gs
13.3 mT
0.01 kg / 0.02 lbs
10.0 g / 0.1 N
weak grip

Table 2: Sliding capacity (vertical surface)
MP 25x5x27 / N38

Distance (mm) Friction coefficient Pull Force (kg/lbs/g/N)
0 mm Stal (~0.2) 3.70 kg / 8.16 lbs
3702.0 g / 36.3 N
1 mm Stal (~0.2) 3.17 kg / 6.98 lbs
3168.0 g / 31.1 N
2 mm Stal (~0.2) 2.68 kg / 5.90 lbs
2676.0 g / 26.3 N
3 mm Stal (~0.2) 2.24 kg / 4.94 lbs
2240.0 g / 22.0 N
5 mm Stal (~0.2) 1.53 kg / 3.38 lbs
1532.0 g / 15.0 N
10 mm Stal (~0.2) 0.56 kg / 1.23 lbs
556.0 g / 5.5 N
15 mm Stal (~0.2) 0.21 kg / 0.46 lbs
208.0 g / 2.0 N
20 mm Stal (~0.2) 0.08 kg / 0.19 lbs
84.0 g / 0.8 N
30 mm Stal (~0.2) 0.02 kg / 0.04 lbs
18.0 g / 0.2 N
50 mm Stal (~0.2) 0.00 kg / 0.00 lbs
2.0 g / 0.0 N

Table 3: Wall mounting (shearing) - behavior on slippery surfaces
MP 25x5x27 / N38

Surface type Friction coefficient / % Mocy Max load (kg/lbs/g/N)
Raw steel
µ = 0.3 30% Nominalnej Siły
5.55 kg / 12.24 lbs
5553.0 g / 54.5 N
Painted steel (standard)
µ = 0.2 20% Nominalnej Siły
3.70 kg / 8.16 lbs
3702.0 g / 36.3 N
Oily/slippery steel
µ = 0.1 10% Nominalnej Siły
1.85 kg / 4.08 lbs
1851.0 g / 18.2 N
Magnet with anti-slip rubber
µ = 0.5 50% Nominalnej Siły
9.26 kg / 20.40 lbs
9255.0 g / 90.8 N

Table 4: Steel thickness (substrate influence) - power losses
MP 25x5x27 / N38

Steel thickness (mm) % power Real pull force (kg/lbs/g/N)
0.5 mm
5%
0.93 kg / 2.04 lbs
925.5 g / 9.1 N
1 mm
13%
2.31 kg / 5.10 lbs
2313.8 g / 22.7 N
2 mm
25%
4.63 kg / 10.20 lbs
4627.5 g / 45.4 N
3 mm
38%
6.94 kg / 15.30 lbs
6941.3 g / 68.1 N
5 mm
63%
11.57 kg / 25.50 lbs
11568.8 g / 113.5 N
10 mm
100%
18.51 kg / 40.81 lbs
18510.0 g / 181.6 N
11 mm
100%
18.51 kg / 40.81 lbs
18510.0 g / 181.6 N
12 mm
100%
18.51 kg / 40.81 lbs
18510.0 g / 181.6 N

Table 5: Thermal resistance (stability) - power drop
MP 25x5x27 / N38

Ambient temp. (°C) Power loss Remaining pull (kg/lbs/g/N) Status
20 °C 0.0% 18.51 kg / 40.81 lbs
18510.0 g / 181.6 N
OK
40 °C -2.2% 18.10 kg / 39.91 lbs
18102.8 g / 177.6 N
OK
60 °C -4.4% 17.70 kg / 39.01 lbs
17695.6 g / 173.6 N
OK
80 °C -6.6% 17.29 kg / 38.11 lbs
17288.3 g / 169.6 N
100 °C -28.8% 13.18 kg / 29.05 lbs
13179.1 g / 129.3 N

Table 6: Two magnets (repulsion) - forces in the system
MP 25x5x27 / N38

Gap (mm) Attraction (kg/lbs) (N-S) Shear Strength (kg/lbs/g/N) Repulsion (kg/lbs) (N-N)
0 mm 13.99 kg / 30.83 lbs
6 064 Gs
2.10 kg / 4.62 lbs
2098 g / 20.6 N
N/A
1 mm 12.97 kg / 28.59 lbs
11 008 Gs
1.94 kg / 4.29 lbs
1945 g / 19.1 N
11.67 kg / 25.73 lbs
~0 Gs
2 mm 11.97 kg / 26.39 lbs
10 576 Gs
1.80 kg / 3.96 lbs
1795 g / 17.6 N
10.77 kg / 23.75 lbs
~0 Gs
3 mm 11.02 kg / 24.29 lbs
10 146 Gs
1.65 kg / 3.64 lbs
1652 g / 16.2 N
9.91 kg / 21.86 lbs
~0 Gs
5 mm 9.26 kg / 20.42 lbs
9 303 Gs
1.39 kg / 3.06 lbs
1389 g / 13.6 N
8.33 kg / 18.37 lbs
~0 Gs
10 mm 5.79 kg / 12.76 lbs
7 353 Gs
0.87 kg / 1.91 lbs
868 g / 8.5 N
5.21 kg / 11.48 lbs
~0 Gs
20 mm 2.10 kg / 4.63 lbs
4 432 Gs
0.32 kg / 0.70 lbs
315 g / 3.1 N
1.89 kg / 4.17 lbs
~0 Gs
50 mm 0.14 kg / 0.32 lbs
1 159 Gs
0.02 kg / 0.05 lbs
22 g / 0.2 N
0.13 kg / 0.29 lbs
~0 Gs
60 mm 0.07 kg / 0.16 lbs
811 Gs
0.01 kg / 0.02 lbs
11 g / 0.1 N
0.06 kg / 0.14 lbs
~0 Gs
70 mm 0.04 kg / 0.08 lbs
589 Gs
0.01 kg / 0.01 lbs
6 g / 0.1 N
0.03 kg / 0.07 lbs
~0 Gs
80 mm 0.02 kg / 0.05 lbs
440 Gs
0.00 kg / 0.01 lbs
3 g / 0.0 N
0.02 kg / 0.04 lbs
~0 Gs
90 mm 0.01 kg / 0.03 lbs
338 Gs
0.00 kg / 0.00 lbs
2 g / 0.0 N
0.01 kg / 0.02 lbs
~0 Gs
100 mm 0.01 kg / 0.02 lbs
265 Gs
0.00 kg / 0.00 lbs
1 g / 0.0 N
0.00 kg / 0.00 lbs
~0 Gs

Table 7: Hazards (electronics) - warnings
MP 25x5x27 / N38

Object / Device Limit (Gauss) / mT Safe distance
Pacemaker 5 Gs (0.5 mT) 18.0 cm
Hearing aid 10 Gs (1.0 mT) 14.0 cm
Mechanical watch 20 Gs (2.0 mT) 11.0 cm
Mobile device 40 Gs (4.0 mT) 8.5 cm
Car key 50 Gs (5.0 mT) 7.5 cm
Payment card 400 Gs (40.0 mT) 3.5 cm
HDD hard drive 600 Gs (60.0 mT) 2.5 cm

Table 8: Dynamics (cracking risk) - warning
MP 25x5x27 / N38

Start from (mm) Speed (km/h) Energy (J) Predicted outcome
10 mm 15.31 km/h
(4.25 m/s)
0.86 J
30 mm 24.40 km/h
(6.78 m/s)
2.19 J
50 mm 31.42 km/h
(8.73 m/s)
3.63 J
100 mm 44.42 km/h
(12.34 m/s)
7.26 J

Table 9: Corrosion resistance
MP 25x5x27 / 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 25x5x27 / N38

Parameter Value SI Unit / Description
Magnetic Flux 4 917 Mx 49.2 µWb
Pc Coefficient 1.40 High (Stable)

Table 11: Hydrostatics and buoyancy
MP 25x5x27 / N38

Environment Effective steel pull Effect
Air (land) 18.51 kg Standard
Water (riverbed) 21.19 kg
(+2.68 kg buoyancy gain)
+14.5%
Corrosion warning: Standard nickel requires drying after every contact with moisture; lack of maintenance will lead to rust spots.
1. Sliding resistance

*Note: On a vertical wall, the magnet holds merely ~20% of its perpendicular strength.

2. Steel thickness impact

*Thin steel (e.g. computer case) drastically weakens the holding force.

3. Heat tolerance

*For standard magnets, the critical limit is 80°C.

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

chart generated for the permeance coefficient Pc (Permeance Coefficient) = 1.40

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
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%
Ecology and recycling (GPSR)
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: 030192-2026
Measurement Calculator
Pulling force

Magnetic Induction

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It is ideally suited for places where solid attachment of the magnet to the substrate is required without the risk of detachment. Mounting is clean and reversible, unlike gluing. It is also often used in advertising for fixing signs and in workshops for organizing tools.
This material behaves more like porcelain than steel, so it doesn't forgive mistakes during mounting. When tightening the screw, you must maintain caution. We recommend tightening manually with a screwdriver, not an impact driver, because too much pressure will cause the ring to crack. 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. 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. This product is dedicated for indoor use. For outdoor applications, we recommend choosing magnets in hermetic housing 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.
This model is characterized by dimensions Ø25x27 mm and a weight of 95.43 g. The key parameter here is the holding force amounting to approximately 18.51 kg (force ~181.54 N). The mounting hole diameter is precisely 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). When ordering a larger quantity, magnets are usually packed in stacks, where they are already naturally paired.

Pros and cons of neodymium magnets.

Benefits

Besides their remarkable field intensity, neodymium magnets offer the following advantages:
  • They do not lose magnetism, even during around ten years – the decrease in lifting capacity is only ~1% (theoretically),
  • They are resistant to demagnetization induced by external field influence,
  • Thanks to the shimmering finish, the coating of Ni-Cu-Ni, gold-plated, or silver-plated gives an clean appearance,
  • The surface of neodymium magnets generates a concentrated magnetic field – this is one of their assets,
  • Due to their durability and thermal resistance, neodymium magnets can operate (depending on the shape) even at high temperatures reaching 230°C or more...
  • Possibility of precise shaping and adjusting to defined needs,
  • Wide application in modern industrial fields – they are utilized in hard drives, electric drive systems, medical devices, and technologically advanced constructions.
  • Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Weaknesses

Cons of neodymium magnets and proposals for their use:
  • Susceptibility to cracking is one of their disadvantages. Upon strong impact they can fracture. We advise keeping them in a strong case, which not only secures them against impacts but also increases their durability
  • When exposed to high temperature, neodymium magnets experience a drop in force. 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
  • Magnets exposed to a humid environment can rust. Therefore during using outdoors, we recommend using waterproof magnets made of rubber, plastic or other material protecting against moisture
  • We recommend casing - magnetic mechanism, due to difficulties in realizing threads inside the magnet and complicated shapes.
  • Possible danger to health – tiny shards of magnets are risky, when accidentally swallowed, which gains importance in the aspect of protecting the youngest. Furthermore, small components of these devices can complicate diagnosis medical after entering the body.
  • Due to expensive raw materials, their price is higher than average,

Lifting parameters

Breakaway strength of the magnet in ideal conditionswhat affects it?

Breakaway force was defined for optimal configuration, assuming:
  • with the application of a yoke made of low-carbon steel, ensuring maximum field concentration
  • with a cross-section minimum 10 mm
  • with an polished touching surface
  • with direct contact (no coatings)
  • during pulling in a direction perpendicular to the mounting surface
  • at temperature approx. 20 degrees Celsius

Determinants of lifting force in real conditions

Bear in mind that the working load will differ depending on the following factors, in order of importance:
  • Clearance – existence of foreign body (paint, dirt, air) interrupts the magnetic circuit, which lowers capacity steeply (even by 50% at 0.5 mm).
  • Force direction – declared lifting capacity refers to pulling vertically. When applying parallel force, the magnet exhibits much less (typically approx. 20-30% of maximum force).
  • Metal thickness – thin material does not allow full use of the magnet. Magnetic flux penetrates through instead of generating force.
  • Material composition – different alloys reacts the same. High carbon content weaken the attraction effect.
  • Plate texture – ground elements ensure maximum contact, which increases field saturation. Rough surfaces weaken the grip.
  • Heat – NdFeB sinters have a sensitivity to temperature. At higher temperatures they lose power, and in frost gain strength (up to a certain limit).

Lifting capacity testing was conducted on a smooth plate of suitable thickness, under a perpendicular pulling force, however under parallel forces the lifting capacity is smaller. Moreover, even a small distance between the magnet’s surface and the plate reduces the holding force.

Safety rules for work with NdFeB magnets
Skin irritation risks

Nickel alert: The Ni-Cu-Ni coating contains nickel. If an allergic reaction happens, cease working with magnets and use protective gear.

Powerful field

Before starting, check safety instructions. Sudden snapping can break the magnet or hurt your hand. Be predictive.

Medical implants

Health Alert: Neodymium magnets can deactivate pacemakers and defibrillators. Stay away if you have electronic implants.

Magnetic interference

A powerful magnetic field interferes with the operation of magnetometers in phones and navigation systems. Maintain magnets near a device to prevent damaging the sensors.

Do not give to children

These products are not intended for children. Eating a few magnets can lead to them pinching intestinal walls, which constitutes a direct threat to life and necessitates immediate surgery.

Electronic hazard

Do not bring magnets close to a wallet, laptop, or screen. The magnetic field can irreversibly ruin these devices and erase data from cards.

Heat sensitivity

Standard neodymium magnets (N-type) lose magnetization when the temperature goes above 80°C. The loss of strength is permanent.

Pinching danger

Danger of trauma: The attraction force is so immense that it can result in hematomas, pinching, and even bone fractures. Use thick gloves.

Risk of cracking

Neodymium magnets are ceramic materials, meaning they are fragile like glass. Collision of two magnets leads to them cracking into shards.

Fire warning

Fire warning: Neodymium dust is explosive. Do not process magnets without safety gear as this risks ignition.

Security! Need more info? Check our post: Why are neodymium magnets dangerous?