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MP 25x5x5 / N38 - ring magnet

ring magnet

Catalog no 030193

GTIN/EAN: 5906301812104

5.00

Diameter

25 mm [±0,1 mm]

internal diameter Ø

5 mm [±0,1 mm]

Height

5 mm [±0,1 mm]

Weight

17.67 g

Magnetization Direction

↑ axial

Load capacity

7.66 kg / 75.12 N

Magnetic Induction

230.20 mT / 2302 Gs

Coating

[NiCuNi] Nickel

6.00 with VAT / pcs + price for transport

4.88 ZŁ net + 23% VAT / pcs

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Technical specification of the product - MP 25x5x5 / N38 - ring magnet

Specification / characteristics - MP 25x5x5 / N38 - ring magnet

properties
properties values
Cat. no. 030193
GTIN/EAN 5906301812104
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 5 mm [±0,1 mm]
Weight 17.67 g
Magnetization Direction ↑ axial
Load capacity ~ ? 7.66 kg / 75.12 N
Magnetic Induction ~ ? 230.20 mT / 2302 Gs
Coating [NiCuNi] Nickel
Manufacturing Tolerance ±0.1 mm

Magnetic properties of material N38

Specification / characteristics MP 25x5x5 / 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

Engineering analysis of the assembly - data

Presented information represent the direct effect of a engineering calculation. Values rely on algorithms for the class Nd2Fe14B. Actual parameters may differ. Use these calculations as a reference point when designing systems.

Table 1: Static force (pull vs distance) - characteristics
MP 25x5x5 / N38

Distance (mm) Induction (Gauss) / mT Pull Force (kg/lbs/g/N) Risk Status
0 mm 5777 Gs
577.7 mT
7.66 kg / 16.89 lbs
7660.0 g / 75.1 N
medium risk
1 mm 5310 Gs
531.0 mT
6.47 kg / 14.27 lbs
6471.0 g / 63.5 N
medium risk
2 mm 4846 Gs
484.6 mT
5.39 kg / 11.88 lbs
5388.6 g / 52.9 N
medium risk
3 mm 4397 Gs
439.7 mT
4.44 kg / 9.78 lbs
4437.9 g / 43.5 N
medium risk
5 mm 3576 Gs
357.6 mT
2.93 kg / 6.47 lbs
2934.8 g / 28.8 N
medium risk
10 mm 2073 Gs
207.3 mT
0.99 kg / 2.17 lbs
985.9 g / 9.7 N
weak grip
15 mm 1231 Gs
123.1 mT
0.35 kg / 0.77 lbs
347.9 g / 3.4 N
weak grip
20 mm 773 Gs
77.3 mT
0.14 kg / 0.30 lbs
137.0 g / 1.3 N
weak grip
30 mm 356 Gs
35.6 mT
0.03 kg / 0.06 lbs
29.0 g / 0.3 N
weak grip
50 mm 115 Gs
11.5 mT
0.00 kg / 0.01 lbs
3.0 g / 0.0 N
weak grip

Table 2: Sliding capacity (wall)
MP 25x5x5 / N38

Distance (mm) Friction coefficient Pull Force (kg/lbs/g/N)
0 mm Stal (~0.2) 1.53 kg / 3.38 lbs
1532.0 g / 15.0 N
1 mm Stal (~0.2) 1.29 kg / 2.85 lbs
1294.0 g / 12.7 N
2 mm Stal (~0.2) 1.08 kg / 2.38 lbs
1078.0 g / 10.6 N
3 mm Stal (~0.2) 0.89 kg / 1.96 lbs
888.0 g / 8.7 N
5 mm Stal (~0.2) 0.59 kg / 1.29 lbs
586.0 g / 5.7 N
10 mm Stal (~0.2) 0.20 kg / 0.44 lbs
198.0 g / 1.9 N
15 mm Stal (~0.2) 0.07 kg / 0.15 lbs
70.0 g / 0.7 N
20 mm Stal (~0.2) 0.03 kg / 0.06 lbs
28.0 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: Wall mounting (shearing) - vertical pull
MP 25x5x5 / N38

Surface type Friction coefficient / % Mocy Max load (kg/lbs/g/N)
Raw steel
µ = 0.3 30% Nominalnej Siły
2.30 kg / 5.07 lbs
2298.0 g / 22.5 N
Painted steel (standard)
µ = 0.2 20% Nominalnej Siły
1.53 kg / 3.38 lbs
1532.0 g / 15.0 N
Oily/slippery steel
µ = 0.1 10% Nominalnej Siły
0.77 kg / 1.69 lbs
766.0 g / 7.5 N
Magnet with anti-slip rubber
µ = 0.5 50% Nominalnej Siły
3.83 kg / 8.44 lbs
3830.0 g / 37.6 N

Table 4: Steel thickness (substrate influence) - sheet metal selection
MP 25x5x5 / N38

Steel thickness (mm) % power Real pull force (kg/lbs/g/N)
0.5 mm
10%
0.77 kg / 1.69 lbs
766.0 g / 7.5 N
1 mm
25%
1.92 kg / 4.22 lbs
1915.0 g / 18.8 N
2 mm
50%
3.83 kg / 8.44 lbs
3830.0 g / 37.6 N
3 mm
75%
5.75 kg / 12.67 lbs
5745.0 g / 56.4 N
5 mm
100%
7.66 kg / 16.89 lbs
7660.0 g / 75.1 N
10 mm
100%
7.66 kg / 16.89 lbs
7660.0 g / 75.1 N
11 mm
100%
7.66 kg / 16.89 lbs
7660.0 g / 75.1 N
12 mm
100%
7.66 kg / 16.89 lbs
7660.0 g / 75.1 N

Table 5: Thermal stability (material behavior) - power drop
MP 25x5x5 / N38

Ambient temp. (°C) Power loss Remaining pull (kg/lbs/g/N) Status
20 °C 0.0% 7.66 kg / 16.89 lbs
7660.0 g / 75.1 N
OK
40 °C -2.2% 7.49 kg / 16.52 lbs
7491.5 g / 73.5 N
OK
60 °C -4.4% 7.32 kg / 16.14 lbs
7323.0 g / 71.8 N
OK
80 °C -6.6% 7.15 kg / 15.77 lbs
7154.4 g / 70.2 N
100 °C -28.8% 5.45 kg / 12.02 lbs
5453.9 g / 53.5 N

Table 6: Magnet-Magnet interaction (attraction) - field range
MP 25x5x5 / 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 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 (implants) - precautionary measures
MP 25x5x5 / 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
Mechanical watch 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 (kinetic energy) - collision effects
MP 25x5x5 / N38

Start from (mm) Speed (km/h) Energy (J) Predicted outcome
10 mm 22.62 km/h
(6.28 m/s)
0.35 J
30 mm 36.46 km/h
(10.13 m/s)
0.91 J
50 mm 46.96 km/h
(13.05 m/s)
1.50 J
100 mm 66.40 km/h
(18.45 m/s)
3.01 J

Table 9: Anti-corrosion coating durability
MP 25x5x5 / 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 25x5x5 / N38

Parameter Value SI Unit / Description
Magnetic Flux 24 536 Mx 245.4 µWb
Pc Coefficient 1.03 High (Stable)

Table 11: Physics of underwater searching
MP 25x5x5 / N38

Environment Effective steel pull Effect
Air (land) 7.66 kg Standard
Water (riverbed) 8.77 kg
(+1.11 kg buoyancy gain)
+14.5%
Rust risk: Remember to wipe the magnet thoroughly after removing it from water and apply a protective layer (e.g., oil) to avoid corrosion.
1. Vertical hold

*Caution: On a vertical wall, the magnet holds merely approx. 20-30% of its perpendicular strength.

2. Steel thickness impact

*Thin metal sheet (e.g. 0.5mm PC case) significantly weakens the holding force.

3. Power loss vs temp

*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) = 1.03

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.

Technical and environmental data
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: 030193-2026
Magnet Unit Converter
Magnet pull force

Field Strength

Other deals

The ring-shaped magnet MP 25x5x5 / 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 7.66 kg works great as a cabinet closure, speaker holder, or spacer element in devices.
This is a crucial issue when working with model MP 25x5x5 / N38. Neodymium magnets are sintered ceramics, which means they are very brittle and inelastic. 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.
These magnets are coated with standard Ni-Cu-Ni plating, which protects them in indoor conditions, but is not sufficient for rain. In the place of the mounting hole, the coating is thinner and easily scratched when tightening the screw, which will become a corrosion focus. 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.
This model is characterized by dimensions Ø25x5 mm and a weight of 17.67 g. The key parameter here is the lifting capacity amounting to approximately 7.66 kg (force ~75.12 N). The mounting hole diameter is precisely 5 mm.
These magnets are magnetized axially (through the thickness), which means one flat side is the N pole and the other is S. 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.

Advantages as well as disadvantages of Nd2Fe14B magnets.

Strengths

Besides their high retention, neodymium magnets are valued for these benefits:
  • They have constant strength, and over around ten years their performance decreases symbolically – ~1% (according to theory),
  • They show high resistance to demagnetization induced by presence of other magnetic fields,
  • A magnet with a shiny gold surface looks better,
  • The surface of neodymium magnets generates a intense magnetic field – this is a distinguishing feature,
  • Through (appropriate) combination of ingredients, they can achieve high thermal resistance, allowing for action at temperatures reaching 230°C and above...
  • Thanks to the ability of free shaping and customization to specialized needs, neodymium magnets can be created in a broad palette of shapes and sizes, which amplifies use scope,
  • Key role in future technologies – they find application in magnetic memories, motor assemblies, medical equipment, and other advanced devices.
  • Compactness – despite small sizes they generate large force, making them ideal for precision applications

Weaknesses

Drawbacks and weaknesses of neodymium magnets: tips and applications.
  • They are fragile upon too strong 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
  • When exposed to high temperature, neodymium magnets suffer a drop in force. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size, as well as shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
  • They rust in a humid environment. For use outdoors we advise using waterproof magnets e.g. in rubber, plastic
  • We recommend a housing - magnetic holder, due to difficulties in producing nuts inside the magnet and complicated shapes.
  • Possible danger to health – tiny shards of magnets can be dangerous, if swallowed, which becomes key in the aspect of protecting the youngest. It is also worth noting that small elements of these devices can be problematic in diagnostics medical when they are in the body.
  • High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which hinders application in large quantities

Lifting parameters

Breakaway strength of the magnet in ideal conditionswhat affects it?

Magnet power was determined for ideal contact conditions, taking into account:
  • using a base made of high-permeability steel, serving as a ideal flux conductor
  • possessing a massiveness of minimum 10 mm to ensure full flux closure
  • with an ideally smooth touching surface
  • with direct contact (no coatings)
  • under perpendicular force vector (90-degree angle)
  • in temp. approx. 20°C

Determinants of lifting force in real conditions

Holding efficiency impacted by working environment parameters, mainly (from most important):
  • Gap between magnet and steel – every millimeter of separation (caused e.g. by veneer or unevenness) significantly weakens the pulling force, often by half at just 0.5 mm.
  • Direction of force – highest force is reached only during pulling at a 90° angle. The resistance to sliding of the magnet along the plate is usually many times lower (approx. 1/5 of the lifting capacity).
  • Substrate thickness – to utilize 100% power, the steel must be adequately massive. Thin sheet restricts the lifting capacity (the magnet "punches through" it).
  • Material type – the best choice is pure iron steel. Hardened steels may have worse magnetic properties.
  • Plate texture – smooth surfaces ensure maximum contact, which increases field saturation. Uneven metal weaken the grip.
  • Thermal factor – high temperature reduces magnetic field. Too high temperature can permanently demagnetize the magnet.

Holding force was checked on the plate surface of 20 mm thickness, when the force acted perpendicularly, however under shearing force the lifting capacity is smaller. In addition, even a slight gap between the magnet’s surface and the plate reduces the load capacity.

Precautions when working with NdFeB magnets
Serious injuries

Protect your hands. Two powerful magnets will snap together instantly with a force of several hundred kilograms, destroying anything in their path. Be careful!

This is not a toy

Strictly store magnets out of reach of children. Ingestion danger is high, and the effects of magnets connecting inside the body are life-threatening.

Heat sensitivity

Regular neodymium magnets (N-type) lose magnetization when the temperature surpasses 80°C. Damage is permanent.

Allergy Warning

Studies show that the nickel plating (standard magnet coating) is a common allergen. If your skin reacts to metals, prevent touching magnets with bare hands and select versions in plastic housing.

Threat to navigation

Note: rare earth magnets produce a field that interferes with precision electronics. Keep a safe distance from your phone, device, and GPS.

Implant safety

Individuals with a heart stimulator should keep an absolute distance from magnets. The magnetism can stop the functioning of the life-saving device.

Fragile material

Despite the nickel coating, neodymium is brittle and not impact-resistant. Do not hit, as the magnet may crumble into hazardous fragments.

Handling guide

Handle magnets consciously. Their powerful strength can surprise even experienced users. Stay alert and respect their force.

Magnetic media

Device Safety: Neodymium magnets can damage payment cards and delicate electronics (pacemakers, medical aids, timepieces).

Fire risk

Fire hazard: Neodymium dust is highly flammable. Do not process magnets without safety gear as this may cause fire.

Attention! Looking for details? Check our post: Are neodymium magnets dangerous?
Dhit sp. z o.o.

e-mail: bok@dhit.pl

tel: +48 888 99 98 98