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MP 40x10.4/5.5x5 / N38 - ring magnet

ring magnet

Catalog no 030249

GTIN/EAN: 5906301812258

5.00
Load capacity 9.47 kg / 92.86 N Magnetic Induction 150.36 mT / 1504 Gs
Diameter
40 mm [±0,1 mm]
internal diameter Ø
10.4/5.5 mm [±0,1 mm]
Height
5 mm [±0,1 mm]
Weight
46.23 g
Magnetization Direction
↑ axial
Coating
[NiCuNi] Nickel

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Engineering report for this magnet

Full PDF analysis: pull and shear force, effect of distance, temperature and plate thickness, safety distances and the demagnetization curve.

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Technical of the product - MP 40x10.4/5.5x5 / N38 - ring magnet

Specification / characteristics - MP 40x10.4/5.5x5 / N38 - ring magnet

properties
properties values
Cat. no. 030249
GTIN/EAN 5906301812258
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 40 mm [±0,1 mm]
internal diameter Ø 10.4/5.5 mm [±0,1 mm]
Height 5 mm [±0,1 mm]
Weight 46.23 g
Magnetization Direction ↑ axial
Load capacity ~ ? 9.47 kg / 92.86 N
Magnetic Induction ~ ? 150.36 mT / 1504 Gs
Coating [NiCuNi] Nickel
Manufacturing Tolerance ±0.1 mm

Magnetic properties of material N38

Specification / characteristics MP 40x10.4/5.5x5 / 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

Engineering analysis of the magnet - data

Presented values constitute the result of a mathematical simulation. Results were calculated on models for the material Nd2Fe14B. Operational performance may differ. Please consider these data as a supplementary guide when designing systems.

Table 1: Static force (pull vs distance) - characteristics
MP 40x10.4/5.5x5 / N38

Distance (mm) Induction (Gauss) / mT Pull Force (kg/lbs/g/N) Risk Status
0 mm 1289 Gs
128.9 mT
9.47 kg / 20.88 LBS
9470.0 g / 92.9 N
strong
1 mm 1265 Gs
126.5 mT
9.12 kg / 20.11 LBS
9120.9 g / 89.5 N
strong
2 mm 1232 Gs
123.2 mT
8.66 kg / 19.10 LBS
8662.7 g / 85.0 N
strong
3 mm 1193 Gs
119.3 mT
8.12 kg / 17.90 LBS
8121.3 g / 79.7 N
strong
5 mm 1099 Gs
109.9 mT
6.89 kg / 15.18 LBS
6887.8 g / 67.6 N
strong
10 mm 825 Gs
82.5 mT
3.88 kg / 8.56 LBS
3882.0 g / 38.1 N
strong
15 mm 580 Gs
58.0 mT
1.92 kg / 4.22 LBS
1915.5 g / 18.8 N
weak grip
20 mm 399 Gs
39.9 mT
0.91 kg / 2.00 LBS
908.3 g / 8.9 N
weak grip
30 mm 195 Gs
19.5 mT
0.22 kg / 0.48 LBS
217.6 g / 2.1 N
weak grip
50 mm 61 Gs
6.1 mT
0.02 kg / 0.05 LBS
21.0 g / 0.2 N
weak grip

Table 2: Sliding hold (vertical surface)
MP 40x10.4/5.5x5 / N38

Distance (mm) Friction coefficient Pull Force (kg/lbs/g/N)
0 mm Stal (~0.2) 1.89 kg / 4.18 LBS
1894.0 g / 18.6 N
1 mm Stal (~0.2) 1.82 kg / 4.02 LBS
1824.0 g / 17.9 N
2 mm Stal (~0.2) 1.73 kg / 3.82 LBS
1732.0 g / 17.0 N
3 mm Stal (~0.2) 1.62 kg / 3.58 LBS
1624.0 g / 15.9 N
5 mm Stal (~0.2) 1.38 kg / 3.04 LBS
1378.0 g / 13.5 N
10 mm Stal (~0.2) 0.78 kg / 1.71 LBS
776.0 g / 7.6 N
15 mm Stal (~0.2) 0.38 kg / 0.85 LBS
384.0 g / 3.8 N
20 mm Stal (~0.2) 0.18 kg / 0.40 LBS
182.0 g / 1.8 N
30 mm Stal (~0.2) 0.04 kg / 0.10 LBS
44.0 g / 0.4 N
50 mm Stal (~0.2) 0.00 kg / 0.01 LBS
4.0 g / 0.0 N

Table 3: Vertical assembly (shearing) - vertical pull
MP 40x10.4/5.5x5 / N38

Surface type Friction coefficient / % Mocy Max load (kg/lbs/g/N)
Raw steel
µ = 0.3 30% Nominalnej Siły
2.84 kg / 6.26 LBS
2841.0 g / 27.9 N
Painted steel (standard)
µ = 0.2 20% Nominalnej Siły
1.89 kg / 4.18 LBS
1894.0 g / 18.6 N
Oily/slippery steel
µ = 0.1 10% Nominalnej Siły
0.95 kg / 2.09 LBS
947.0 g / 9.3 N
Magnet with anti-slip rubber
µ = 0.5 50% Nominalnej Siły
4.74 kg / 10.44 LBS
4735.0 g / 46.5 N

Table 4: Material efficiency (saturation) - sheet metal selection
MP 40x10.4/5.5x5 / N38

Steel thickness (mm) % power Real pull force (kg/lbs/g/N)
0.5 mm
10%
0.95 kg / 2.09 LBS
947.0 g / 9.3 N
1 mm
25%
2.37 kg / 5.22 LBS
2367.5 g / 23.2 N
2 mm
50%
4.74 kg / 10.44 LBS
4735.0 g / 46.5 N
3 mm
75%
7.10 kg / 15.66 LBS
7102.5 g / 69.7 N
5 mm
100%
9.47 kg / 20.88 LBS
9470.0 g / 92.9 N
10 mm
100%
9.47 kg / 20.88 LBS
9470.0 g / 92.9 N
11 mm
100%
9.47 kg / 20.88 LBS
9470.0 g / 92.9 N
12 mm
100%
9.47 kg / 20.88 LBS
9470.0 g / 92.9 N

Table 5: Thermal stability (stability) - power drop
MP 40x10.4/5.5x5 / N38

Ambient temp. (°C) Power loss Remaining pull (kg/lbs/g/N) Status
20 °C 0.0% 9.47 kg / 20.88 LBS
9470.0 g / 92.9 N
OK
40 °C -2.2% 9.26 kg / 20.42 LBS
9261.7 g / 90.9 N
OK
60 °C -4.4% 9.05 kg / 19.96 LBS
9053.3 g / 88.8 N
80 °C -6.6% 8.84 kg / 19.50 LBS
8845.0 g / 86.8 N
100 °C -28.8% 6.74 kg / 14.86 LBS
6742.6 g / 66.1 N

Table 6: Two magnets (repulsion) - field collision
MP 40x10.4/5.5x5 / N38

Gap (mm) Attraction (kg/lbs) (N-S) Lateral Force (kg/lbs/g/N) Repulsion (kg/lbs) (N-N)
0 mm 10.73 kg / 23.65 LBS
2 424 Gs
1.61 kg / 3.55 LBS
1609 g / 15.8 N
N/A
1 mm 10.55 kg / 23.25 LBS
2 555 Gs
1.58 kg / 3.49 LBS
1582 g / 15.5 N
9.49 kg / 20.93 LBS
~0 Gs
2 mm 10.33 kg / 22.78 LBS
2 529 Gs
1.55 kg / 3.42 LBS
1550 g / 15.2 N
9.30 kg / 20.50 LBS
~0 Gs
3 mm 10.09 kg / 22.23 LBS
2 499 Gs
1.51 kg / 3.34 LBS
1513 g / 14.8 N
9.08 kg / 20.01 LBS
~0 Gs
5 mm 9.52 kg / 20.98 LBS
2 427 Gs
1.43 kg / 3.15 LBS
1427 g / 14.0 N
8.56 kg / 18.88 LBS
~0 Gs
10 mm 7.80 kg / 17.20 LBS
2 198 Gs
1.17 kg / 2.58 LBS
1170 g / 11.5 N
7.02 kg / 15.48 LBS
~0 Gs
20 mm 4.40 kg / 9.69 LBS
1 650 Gs
0.66 kg / 1.45 LBS
660 g / 6.5 N
3.96 kg / 8.72 LBS
~0 Gs
50 mm 0.49 kg / 1.09 LBS
553 Gs
0.07 kg / 0.16 LBS
74 g / 0.7 N
0.44 kg / 0.98 LBS
~0 Gs
60 mm 0.25 kg / 0.54 LBS
391 Gs
0.04 kg / 0.08 LBS
37 g / 0.4 N
0.22 kg / 0.49 LBS
~0 Gs
70 mm 0.13 kg / 0.28 LBS
282 Gs
0.02 kg / 0.04 LBS
19 g / 0.2 N
0.12 kg / 0.26 LBS
~0 Gs
80 mm 0.07 kg / 0.15 LBS
209 Gs
0.01 kg / 0.02 LBS
11 g / 0.1 N
0.06 kg / 0.14 LBS
~0 Gs
90 mm 0.04 kg / 0.09 LBS
158 Gs
0.01 kg / 0.01 LBS
6 g / 0.1 N
0.04 kg / 0.08 LBS
~0 Gs
100 mm 0.02 kg / 0.05 LBS
121 Gs
0.00 kg / 0.01 LBS
4 g / 0.0 N
0.02 kg / 0.05 LBS
~0 Gs

Table 7: Hazards (implants) - warnings
MP 40x10.4/5.5x5 / N38

Object / Device Limit (Gauss) / mT Safe distance
Pacemaker 5 Gs (0.5 mT) 12.5 cm
Hearing aid 10 Gs (1.0 mT) 10.0 cm
Mechanical watch 20 Gs (2.0 mT) 8.0 cm
Mobile device 40 Gs (4.0 mT) 6.0 cm
Remote 50 Gs (5.0 mT) 5.5 cm
Payment card 400 Gs (40.0 mT) 2.0 cm
HDD hard drive 600 Gs (60.0 mT) 1.5 cm

Table 8: Impact energy (kinetic energy) - warning
MP 40x10.4/5.5x5 / N38

Start from (mm) Speed (km/h) Energy (J) Predicted outcome
10 mm 19.38 km/h
(5.38 m/s)
0.67 J
30 mm 22.72 km/h
(6.31 m/s)
0.92 J
50 mm 22.91 km/h
(6.36 m/s)
0.94 J
100 mm 22.94 km/h
(6.37 m/s)
0.94 J

Table 9: Anti-corrosion coating durability
MP 40x10.4/5.5x5 / 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 40x10.4/5.5x5 / N38

Parameter Value SI Unit / Description
Magnetic Flux 17 767 Mx 177.7 µWb
Pc Coefficient 0.17 Low (Flat)

Table 11: Physics of underwater searching
MP 40x10.4/5.5x5 / N38

Environment Effective steel pull Effect
Air (land) 9.47 kg Standard
Water (riverbed) 10.84 kg
(+1.37 kg buoyancy gain)
+14.5%
Warning: This magnet has a standard nickel coating. After use in water, it must be dried and maintained immediately, otherwise it will rust!

1. Vertical hold

*Caution: On a vertical wall, the magnet retains merely approx. 20-30% of its nominal pull.

2. Steel thickness impact

*Thin metal sheet (e.g. computer case) severely limits the holding force.

3. Heat tolerance

*For N38 grade, the safety limit is 80°C.

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

chart generated for the permeance coefficient Pc (Permeance Coefficient) = 0.17

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.

Technical and environmental data

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: 030249-2026
Measurement Calculator

Magnet pull force


Magnetic Field

Other offers

The ring-shaped magnet MP 40x10.4/5.5x5 / N38 is created for mechanical fastening, where glue might fail or be insufficient. Mounting is clean and reversible, unlike gluing. It is also often used in advertising for fixing signs and in workshops for organizing tools.
This is a crucial issue when working with model MP 40x10.4/5.5x5 / N38. Neodymium magnets are sintered ceramics, which means they are very brittle and inelastic. One turn too many can destroy the magnet, so do it slowly. It's a good idea to use a rubber spacer under the screw head, which will cushion the stresses. 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 easily scratched when tightening the screw, which will become a corrosion focus. If you must use it outside, paint it with anti-corrosion paint after mounting.
A screw or bolt with a thread diameter smaller than 10.4/5.5 mm fits this model. For magnets with a straight hole, a conical head can act like a wedge and burst the magnet. Always check that the screw head is not larger than the outer diameter of the magnet (40 mm), so it doesn't protrude beyond the outline.
The presented product is a ring magnet with dimensions Ø40 mm (outer diameter) and height 5 mm. The pulling force of this model is an impressive 9.47 kg, which translates to 92.86 N in newtons. The product has a [NiCuNi] coating and is made of NdFeB material. Inner hole dimension: 10.4/5.5 mm.
The poles are located on the planes with holes, not on the sides of the ring. In the case of connecting two rings, make sure one is turned the right way. 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.

Advantages

Besides their exceptional strength, neodymium magnets offer the following advantages:
  • Their magnetic field is durable, and after around ten years it decreases only by ~1% (according to research),
  • They maintain their magnetic properties even under external field action,
  • In other words, due to the shiny finish of nickel, the element gains visual value,
  • Magnets are characterized by maximum magnetic induction on the outer side,
  • Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their form) at temperatures up to 230°C and above...
  • Thanks to flexibility in constructing and the ability to customize to specific needs,
  • Significant place in high-tech industry – they are commonly used in computer drives, motor assemblies, advanced medical instruments, and technologically advanced constructions.
  • Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in tiny dimensions, which allows their use in compact constructions

Weaknesses

Disadvantages of neodymium magnets:
  • They are prone to damage upon heavy impacts. To avoid cracks, it is worth protecting magnets in special housings. Such protection not only protects the magnet but also improves its resistance to damage
  • Neodymium magnets decrease their power under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
  • They oxidize in a humid environment. For use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
  • We suggest cover - magnetic mechanism, due to difficulties in producing threads inside the magnet and complicated shapes.
  • Health risk resulting from small fragments of magnets are risky, if swallowed, which becomes key in the context of child safety. It is also worth noting that small elements of these devices are able to complicate diagnosis medical after entering the body.
  • Due to neodymium price, their price is higher than average,

Lifting parameters

Optimal lifting capacity of a neodymium magnetwhat contributes to it?

Information about lifting capacity is the result of a measurement for optimal configuration, assuming:
  • on a block made of structural steel, effectively closing the magnetic field
  • whose transverse dimension reaches at least 10 mm
  • with a surface cleaned and smooth
  • without the slightest clearance between the magnet and steel
  • under axial force direction (90-degree angle)
  • at standard ambient temperature

Lifting capacity in real conditions – factors

Real force impacted by specific conditions, such as (from priority):
  • Space between surfaces – even a fraction of a millimeter of distance (caused e.g. by veneer or dirt) diminishes the magnet efficiency, often by half at just 0.5 mm.
  • Loading method – declared lifting capacity refers to detachment vertically. When attempting to slide, the magnet exhibits much less (often approx. 20-30% of nominal force).
  • Element thickness – to utilize 100% power, the steel must be adequately massive. Thin sheet limits the attraction force (the magnet "punches through" it).
  • Metal type – different alloys reacts the same. Alloy additives worsen the attraction effect.
  • Surface condition – ground elements guarantee perfect abutment, which increases force. Rough surfaces reduce efficiency.
  • Temperature – temperature increase results in weakening of induction. It is worth remembering the maximum operating temperature for a given model.

Holding force was checked on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, whereas under attempts to slide the magnet the load capacity is reduced by as much as fivefold. In addition, even a minimal clearance between the magnet and the plate lowers the holding force.

Precautions when working with neodymium magnets
Shattering risk

Beware of splinters. Magnets can explode upon violent connection, launching shards into the air. Wear goggles.

Pinching danger

Protect your hands. Two powerful magnets will join instantly with a force of massive weight, destroying everything in their path. Exercise extreme caution!

Product not for children

These products are not toys. Eating a few magnets may result in them attracting across intestines, which poses a direct threat to life and requires urgent medical intervention.

Compass and GPS

A strong magnetic field negatively affects the functioning of compasses in phones and GPS navigation. Maintain magnets close to a device to avoid breaking the sensors.

Handling guide

Handle magnets consciously. Their immense force can surprise even professionals. Stay alert and do not underestimate their power.

Warning for allergy sufferers

Warning for allergy sufferers: The Ni-Cu-Ni coating consists of nickel. If redness occurs, immediately stop handling magnets and wear gloves.

Dust is flammable

Combustion risk: Rare earth powder is highly flammable. Avoid machining magnets in home conditions as this may cause fire.

Safe distance

Intense magnetic fields can corrupt files on credit cards, hard drives, and storage devices. Stay away of at least 10 cm.

Maximum temperature

Avoid heat. NdFeB magnets are sensitive to temperature. If you require resistance above 80°C, look for special high-temperature series (H, SH, UH).

Health Danger

Life threat: Neodymium magnets can turn off pacemakers and defibrillators. Stay away if you have medical devices.

Warning! Details about risks in the article: Safety of working with magnets.