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

ring magnet

Catalog no 030249

GTIN/EAN: 5906301812258

5.00

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

27.00 with VAT / pcs + price for transport

21.95 ZŁ net + 23% VAT / pcs

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Product card - 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

Technical modeling of the product - report

These information constitute the direct effect of a mathematical simulation. Values were calculated on algorithms for the material Nd2Fe14B. Actual parameters might slightly differ. Please consider these calculations as a supplementary guide during assembly planning.

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

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

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

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

Table 3: Vertical assembly (sliding) - behavior on slippery surfaces
MP 40x10.4/5.5x5 / N38

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

Table 4: Steel thickness (saturation) - power losses
MP 40x10.4/5.5x5 / N38

Steel thickness (mm) % power Real pull force (kg)
0.5 mm
10%
0.95 kg / 947.0 g
9.3 N
1 mm
25%
2.37 kg / 2367.5 g
23.2 N
2 mm
50%
4.74 kg / 4735.0 g
46.5 N
5 mm
100%
9.47 kg / 9470.0 g
92.9 N
10 mm
100%
9.47 kg / 9470.0 g
92.9 N

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

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

Table 6: Two magnets (attraction) - forces in the system
MP 40x10.4/5.5x5 / N38

Gap (mm) Attraction (kg) (N-S) Repulsion (kg) (N-N)
0 mm 10.73 kg / 10727 g
105.2 N
2 424 Gs
N/A
1 mm 10.55 kg / 10547 g
103.5 N
2 555 Gs
9.49 kg / 9492 g
93.1 N
~0 Gs
2 mm 10.33 kg / 10331 g
101.3 N
2 529 Gs
9.30 kg / 9298 g
91.2 N
~0 Gs
3 mm 10.09 kg / 10085 g
98.9 N
2 499 Gs
9.08 kg / 9077 g
89.0 N
~0 Gs
5 mm 9.52 kg / 9516 g
93.3 N
2 427 Gs
8.56 kg / 8564 g
84.0 N
~0 Gs
10 mm 7.80 kg / 7802 g
76.5 N
2 198 Gs
7.02 kg / 7022 g
68.9 N
~0 Gs
20 mm 4.40 kg / 4397 g
43.1 N
1 650 Gs
3.96 kg / 3957 g
38.8 N
~0 Gs
50 mm 0.49 kg / 494 g
4.8 N
553 Gs
0.44 kg / 445 g
4.4 N
~0 Gs

Table 7: Protective zones (electronics) - precautionary measures
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
Timepiece 20 Gs (2.0 mT) 8.0 cm
Phone / Smartphone 40 Gs (4.0 mT) 6.0 cm
Car key 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 (cracking risk) - warning
MP 40x10.4/5.5x5 / N38

Start from (mm) Speed (km/h) Energy (J) Predicted outcome
10 mm 17.75 km/h
(4.93 m/s)
0.56 J
30 mm 25.36 km/h
(7.04 m/s)
1.15 J
50 mm 32.32 km/h
(8.98 m/s)
1.86 J
100 mm 45.65 km/h
(12.68 m/s)
3.72 J

Table 9: Coating parameters (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: Hydrostatics and buoyancy
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%
Rust risk: This magnet has a standard nickel coating. After use in water, it must be dried and maintained immediately, otherwise it will rust!
1. Sliding resistance

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

2. Plate thickness effect

*Thin steel (e.g. 0.5mm PC case) drastically limits the holding force.

3. Heat tolerance

*For standard magnets, the max working temp is 80°C.

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

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

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
Chemical composition
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: 030249-2025
Measurement Calculator
Magnet pull force

Magnetic Induction

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The ring magnet with a hole 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. This product with a force of 9.47 kg works great as a cabinet closure, speaker holder, or mounting element in devices.
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. 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.
These magnets are coated with standard Ni-Cu-Ni plating, which protects them in indoor conditions, but does not ensure full waterproofing. Damage to the protective layer during assembly is the most common cause of rusting. If you must use it outside, paint it with anti-corrosion paint after mounting.
The inner hole diameter determines the maximum size of the mounting element. 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.
This model is characterized by dimensions Ø40x5 mm and a weight of 46.23 g. The key parameter here is the holding force amounting to approximately 9.47 kg (force ~92.86 N). 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. 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.

Advantages as well as disadvantages of neodymium magnets.

Pros

Besides their stability, neodymium magnets are valued for these benefits:
  • Their strength is durable, and after approximately ten years it drops only by ~1% (theoretically),
  • They are resistant to demagnetization induced by external magnetic fields,
  • By using a reflective coating of silver, the element acquires an proper look,
  • Magnetic induction on the surface of the magnet turns out to be very high,
  • Through (adequate) combination of ingredients, they can achieve high thermal resistance, allowing for operation at temperatures reaching 230°C and above...
  • Thanks to freedom in forming and the ability to adapt to complex applications,
  • Universal use in high-tech industry – they serve a role in computer drives, electric drive systems, medical equipment, as well as modern systems.
  • Thanks to concentrated force, small magnets offer high operating force, with minimal size,

Cons

Disadvantages of NdFeB magnets:
  • At very strong impacts they can break, therefore we advise placing them in steel cases. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
  • NdFeB magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of power (a factor is the shape and dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are extremely resistant to heat
  • Magnets exposed to a humid environment can corrode. Therefore during using outdoors, we suggest using waterproof magnets made of rubber, plastic or other material resistant to moisture
  • Limited ability of making threads in the magnet and complicated shapes - preferred is casing - magnet mounting.
  • Possible danger resulting from small fragments of magnets are risky, when accidentally swallowed, which gains importance in the context of child health protection. Additionally, small elements of these devices are able to disrupt the diagnostic process medical in case of swallowing.
  • Due to expensive raw materials, their price is higher than average,

Lifting parameters

Maximum lifting capacity of the magnetwhat it depends on?

Holding force of 9.47 kg is a theoretical maximum value conducted under standard conditions:
  • on a block made of mild steel, effectively closing the magnetic flux
  • whose transverse dimension reaches at least 10 mm
  • characterized by smoothness
  • under conditions of no distance (metal-to-metal)
  • under perpendicular application of breakaway force (90-degree angle)
  • at standard ambient temperature

Determinants of lifting force in real conditions

In practice, the real power depends on several key aspects, presented from most significant:
  • Distance – the presence of foreign body (paint, dirt, air) interrupts the magnetic circuit, which reduces power rapidly (even by 50% at 0.5 mm).
  • Force direction – catalog parameter refers to pulling vertically. When slipping, the magnet holds significantly lower power (often approx. 20-30% of maximum force).
  • Metal thickness – thin material does not allow full use of the magnet. Part of the magnetic field passes through the material instead of converting into lifting capacity.
  • Material composition – not every steel reacts the same. Alloy additives worsen the interaction with the magnet.
  • Surface finish – full contact is possible only on smooth steel. Rough texture reduce the real contact area, reducing force.
  • Thermal conditions – NdFeB sinters have a sensitivity to temperature. When it is hot they lose power, and at low temperatures they can be stronger (up to a certain limit).

Holding force was checked on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, whereas under shearing force the holding force is lower. Moreover, even a small distance between the magnet and the plate decreases the lifting capacity.

Safety rules for work with neodymium magnets
Finger safety

Mind your fingers. Two large magnets will snap together instantly with a force of several hundred kilograms, destroying everything in their path. Exercise extreme caution!

Do not give to children

Product intended for adults. Small elements can be swallowed, causing intestinal necrosis. Store away from kids and pets.

Nickel coating and allergies

Warning for allergy sufferers: The nickel-copper-nickel coating consists of nickel. If an allergic reaction appears, immediately stop handling magnets and wear gloves.

Conscious usage

Be careful. Rare earth magnets attract from a distance and connect with huge force, often quicker than you can react.

Keep away from computers

Equipment safety: Neodymium magnets can damage payment cards and sensitive devices (heart implants, medical aids, mechanical watches).

Mechanical processing

Dust generated during cutting of magnets is self-igniting. Avoid drilling into magnets without proper cooling and knowledge.

Permanent damage

Watch the temperature. Exposing the magnet above 80 degrees Celsius will ruin its properties and pulling force.

Material brittleness

Despite metallic appearance, neodymium is delicate and cannot withstand shocks. Avoid impacts, as the magnet may crumble into sharp, dangerous pieces.

Implant safety

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

GPS and phone interference

Navigation devices and smartphones are highly sensitive to magnetic fields. Close proximity with a powerful NdFeB magnet can ruin the sensors in your phone.

Warning! More info about risks in the article: Magnet Safety Guide.
Dhit sp. z o.o.

e-mail: bok@dhit.pl

tel: +48 888 99 98 98