MP 40x20x5 / N38 - ring magnet
ring magnet
Catalog no 030199
GTIN/EAN: 5906301812166
- Diameter
- 40 mm [±0,1 mm]
- internal diameter Ø
- 20 mm [±0,1 mm]
- Height
- 5 mm [±0,1 mm]
- Weight
- 35.34 g
- Magnetization Direction
- ↑ axial
- Coating
- [NiCuNi] Nickel
9.95 zł net / pcs
12.24 zł with VAT (23% VAT) / pcs
bulk discounts:
Need more?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.
Call us now
+48 888 99 98 98
alternatively let us know using
contact form
the contact section.
Specifications and structure of a neodymium magnet can be estimated using our
power calculator.
Order by 14:00 and we’ll ship today!
Technical of the product - MP 40x20x5 / N38 - ring magnet
Specification / characteristics - MP 40x20x5 / N38 - ring magnet
| properties | values |
|---|---|
| Cat. no. | 030199 |
| GTIN/EAN | 5906301812166 |
| Production/Distribution | Dhit sp. z o.o. |
| Country of origin | Poland / China / Germany |
| Customs code | 85059029 |
| Diameter | 40 mm [±0,1 mm] |
| internal diameter Ø | 20 mm [±0,1 mm] |
| Height | 5 mm [±0,1 mm] |
| Weight | 35.34 g |
| Magnetization Direction | ↑ axial |
| Load capacity ~ ? | 7.24 kg / 70.98 N |
| Magnetic Induction ~ ? | 150.36 mT / 1504 Gs |
| Coating | [NiCuNi] Nickel |
| Manufacturing Tolerance | ±0.1 mm |
Magnetic properties of material N38
| 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
| 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 40x20x5 / N38
| Distance (mm) | Induction (Gauss) / mT | Pull Force (kg/lbs/g/N) | Risk Status |
|---|---|---|---|
| 0 mm |
5269 Gs
526.9 mT
|
7.24 kg / 15.96 LBS
7240.0 g / 71.0 N
|
strong |
| 1 mm |
5005 Gs
500.5 mT
|
6.53 kg / 14.41 LBS
6534.7 g / 64.1 N
|
strong |
| 2 mm |
4739 Gs
473.9 mT
|
5.86 kg / 12.91 LBS
5857.7 g / 57.5 N
|
strong |
| 3 mm |
4475 Gs
447.5 mT
|
5.22 kg / 11.51 LBS
5222.2 g / 51.2 N
|
strong |
| 5 mm |
3960 Gs
396.0 mT
|
4.09 kg / 9.02 LBS
4090.8 g / 40.1 N
|
strong |
| 10 mm |
2832 Gs
283.2 mT
|
2.09 kg / 4.61 LBS
2092.3 g / 20.5 N
|
strong |
| 15 mm |
1990 Gs
199.0 mT
|
1.03 kg / 2.28 LBS
1033.4 g / 10.1 N
|
weak grip |
| 20 mm |
1407 Gs
140.7 mT
|
0.52 kg / 1.14 LBS
516.3 g / 5.1 N
|
weak grip |
| 30 mm |
745 Gs
74.5 mT
|
0.14 kg / 0.32 LBS
144.6 g / 1.4 N
|
weak grip |
| 50 mm |
268 Gs
26.8 mT
|
0.02 kg / 0.04 LBS
18.7 g / 0.2 N
|
weak grip |
Table 2: Sliding hold (vertical surface)
MP 40x20x5 / N38
| Distance (mm) | Friction coefficient | Pull Force (kg/lbs/g/N) |
|---|---|---|
| 0 mm | Stal (~0.2) |
1.45 kg / 3.19 LBS
1448.0 g / 14.2 N
|
| 1 mm | Stal (~0.2) |
1.31 kg / 2.88 LBS
1306.0 g / 12.8 N
|
| 2 mm | Stal (~0.2) |
1.17 kg / 2.58 LBS
1172.0 g / 11.5 N
|
| 3 mm | Stal (~0.2) |
1.04 kg / 2.30 LBS
1044.0 g / 10.2 N
|
| 5 mm | Stal (~0.2) |
0.82 kg / 1.80 LBS
818.0 g / 8.0 N
|
| 10 mm | Stal (~0.2) |
0.42 kg / 0.92 LBS
418.0 g / 4.1 N
|
| 15 mm | Stal (~0.2) |
0.21 kg / 0.45 LBS
206.0 g / 2.0 N
|
| 20 mm | Stal (~0.2) |
0.10 kg / 0.23 LBS
104.0 g / 1.0 N
|
| 30 mm | Stal (~0.2) |
0.03 kg / 0.06 LBS
28.0 g / 0.3 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 40x20x5 / N38
| Surface type | Friction coefficient / % Mocy | Max load (kg/lbs/g/N) |
|---|---|---|
| Raw steel |
µ = 0.3
30% Nominalnej Siły
|
2.17 kg / 4.79 LBS
2172.0 g / 21.3 N
|
| Painted steel (standard) |
µ = 0.2
20% Nominalnej Siły
|
1.45 kg / 3.19 LBS
1448.0 g / 14.2 N
|
| Oily/slippery steel |
µ = 0.1
10% Nominalnej Siły
|
0.72 kg / 1.60 LBS
724.0 g / 7.1 N
|
| Magnet with anti-slip rubber |
µ = 0.5
50% Nominalnej Siły
|
3.62 kg / 7.98 LBS
3620.0 g / 35.5 N
|
Table 4: Material efficiency (saturation) - sheet metal selection
MP 40x20x5 / N38
| Steel thickness (mm) | % power | Real pull force (kg/lbs/g/N) |
|---|---|---|
| 0.5 mm |
|
0.72 kg / 1.60 LBS
724.0 g / 7.1 N
|
| 1 mm |
|
1.81 kg / 3.99 LBS
1810.0 g / 17.8 N
|
| 2 mm |
|
3.62 kg / 7.98 LBS
3620.0 g / 35.5 N
|
| 3 mm |
|
5.43 kg / 11.97 LBS
5430.0 g / 53.3 N
|
| 5 mm |
|
7.24 kg / 15.96 LBS
7240.0 g / 71.0 N
|
| 10 mm |
|
7.24 kg / 15.96 LBS
7240.0 g / 71.0 N
|
| 11 mm |
|
7.24 kg / 15.96 LBS
7240.0 g / 71.0 N
|
| 12 mm |
|
7.24 kg / 15.96 LBS
7240.0 g / 71.0 N
|
Table 5: Thermal stability (stability) - power drop
MP 40x20x5 / N38
| Ambient temp. (°C) | Power loss | Remaining pull (kg/lbs/g/N) | Status |
|---|---|---|---|
| 20 °C | 0.0% |
7.24 kg / 15.96 LBS
7240.0 g / 71.0 N
|
OK |
| 40 °C | -2.2% |
7.08 kg / 15.61 LBS
7080.7 g / 69.5 N
|
OK |
| 60 °C | -4.4% |
6.92 kg / 15.26 LBS
6921.4 g / 67.9 N
|
OK |
| 80 °C | -6.6% |
6.76 kg / 14.91 LBS
6762.2 g / 66.3 N
|
|
| 100 °C | -28.8% |
5.15 kg / 11.36 LBS
5154.9 g / 50.6 N
|
Table 6: Two magnets (repulsion) - field collision
MP 40x20x5 / N38
| Gap (mm) | Attraction (kg/lbs) (N-S) | Lateral Force (kg/lbs/g/N) | Repulsion (kg/lbs) (N-N) |
|---|---|---|---|
| 0 mm |
179.94 kg / 396.69 LBS
5 920 Gs
|
26.99 kg / 59.50 LBS
26991 g / 264.8 N
|
N/A |
| 1 mm |
171.16 kg / 377.35 LBS
10 277 Gs
|
25.67 kg / 56.60 LBS
25675 g / 251.9 N
|
154.05 kg / 339.62 LBS
~0 Gs
|
| 2 mm |
162.41 kg / 358.05 LBS
10 011 Gs
|
24.36 kg / 53.71 LBS
24361 g / 239.0 N
|
146.17 kg / 322.24 LBS
~0 Gs
|
| 3 mm |
153.87 kg / 339.24 LBS
9 744 Gs
|
23.08 kg / 50.89 LBS
23081 g / 226.4 N
|
138.49 kg / 305.31 LBS
~0 Gs
|
| 5 mm |
137.55 kg / 303.25 LBS
9 213 Gs
|
20.63 kg / 45.49 LBS
20633 g / 202.4 N
|
123.80 kg / 272.92 LBS
~0 Gs
|
| 10 mm |
101.67 kg / 224.14 LBS
7 921 Gs
|
15.25 kg / 33.62 LBS
15251 g / 149.6 N
|
91.50 kg / 201.73 LBS
~0 Gs
|
| 20 mm |
52.00 kg / 114.64 LBS
5 665 Gs
|
7.80 kg / 17.20 LBS
7800 g / 76.5 N
|
46.80 kg / 103.18 LBS
~0 Gs
|
| 50 mm |
6.64 kg / 14.64 LBS
2 025 Gs
|
1.00 kg / 2.20 LBS
996 g / 9.8 N
|
5.98 kg / 13.18 LBS
~0 Gs
|
| 60 mm |
3.59 kg / 7.92 LBS
1 489 Gs
|
0.54 kg / 1.19 LBS
539 g / 5.3 N
|
3.23 kg / 7.13 LBS
~0 Gs
|
| 70 mm |
2.03 kg / 4.48 LBS
1 120 Gs
|
0.30 kg / 0.67 LBS
305 g / 3.0 N
|
1.83 kg / 4.03 LBS
~0 Gs
|
| 80 mm |
1.20 kg / 2.64 LBS
860 Gs
|
0.18 kg / 0.40 LBS
180 g / 1.8 N
|
1.08 kg / 2.38 LBS
~0 Gs
|
| 90 mm |
0.73 kg / 1.62 LBS
673 Gs
|
0.11 kg / 0.24 LBS
110 g / 1.1 N
|
0.66 kg / 1.46 LBS
~0 Gs
|
| 100 mm |
0.47 kg / 1.03 LBS
536 Gs
|
0.07 kg / 0.15 LBS
70 g / 0.7 N
|
0.42 kg / 0.92 LBS
~0 Gs
|
Table 7: Hazards (implants) - warnings
MP 40x20x5 / N38
| Object / Device | Limit (Gauss) / mT | Safe distance |
|---|---|---|
| Pacemaker | 5 Gs (0.5 mT) | 24.0 cm |
| Hearing aid | 10 Gs (1.0 mT) | 18.5 cm |
| Mechanical watch | 20 Gs (2.0 mT) | 14.5 cm |
| Mobile device | 40 Gs (4.0 mT) | 11.0 cm |
| Remote | 50 Gs (5.0 mT) | 10.5 cm |
| Payment card | 400 Gs (40.0 mT) | 4.5 cm |
| HDD hard drive | 600 Gs (60.0 mT) | 3.5 cm |
Table 8: Impact energy (kinetic energy) - warning
MP 40x20x5 / N38
| Start from (mm) | Speed (km/h) | Energy (J) | Predicted outcome |
|---|---|---|---|
| 10 mm |
17.57 km/h
(4.88 m/s)
|
0.42 J | |
| 30 mm |
20.25 km/h
(5.62 m/s)
|
0.56 J | |
| 50 mm |
20.46 km/h
(5.68 m/s)
|
0.57 J | |
| 100 mm |
20.50 km/h
(5.69 m/s)
|
0.57 J |
Table 9: Anti-corrosion coating durability
MP 40x20x5 / 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 40x20x5 / N38
| Parameter | Value | SI Unit / Description |
|---|---|---|
| Magnetic Flux | 56 325 Mx | 563.3 µWb |
| Pc Coefficient | 0.80 | High (Stable) |
Table 11: Physics of underwater searching
MP 40x20x5 / N38
| Environment | Effective steel pull | Effect |
|---|---|---|
| Air (land) | 7.24 kg | Standard |
| Water (riverbed) |
8.29 kg
(+1.05 kg buoyancy gain)
|
+14.5% |
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) = 0.80
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.
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 |
Other offers
Advantages as well as disadvantages of Nd2Fe14B magnets.
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
- 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 magnet – what contributes to it?
- 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
- 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
Safe distance
Intense magnetic fields can corrupt files on credit cards, hard drives, and storage devices. Stay away of at least 10 cm.
Health Danger
Life threat: Neodymium magnets can turn off pacemakers and defibrillators. Stay away if you have medical devices.
Shattering risk
Beware of splinters. Magnets can explode upon violent connection, launching shards into the air. Wear goggles.
Handling guide
Handle magnets consciously. Their immense force can surprise even professionals. Stay alert and do not underestimate their power.
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).
Dust is flammable
Combustion risk: Rare earth powder is highly flammable. Avoid machining magnets in home conditions as this may cause fire.
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.
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!
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.
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.
