MP 20x5x27 / N38 - ring magnet
ring magnet
Catalog no 030185
GTIN/EAN: 5906301812029
- Diameter
- 20 mm [±0,1 mm]
- internal diameter Ø
- 5 mm [±0,1 mm]
- Height
- 27 mm [±0,1 mm]
- Weight
- 59.64 g
- Magnetization Direction
- ↑ axial
- Coating
- [NiCuNi] Nickel
How we measure these parameters — certificates and measurements
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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 20x5x27 / N38 - ring magnet
Specification / characteristics - MP 20x5x27 / N38 - ring magnet
| properties | values |
|---|---|
| Cat. no. | 030185 |
| GTIN/EAN | 5906301812029 |
| Production/Distribution | Dhit sp. z o.o. |
| Country of origin | Poland / China / Germany |
| Customs code | 85059029 |
| Diameter | 20 mm [±0,1 mm] |
| internal diameter Ø | 5 mm [±0,1 mm] |
| Height | 27 mm [±0,1 mm] |
| Weight | 59.64 g |
| Magnetization Direction | ↑ axial |
| Load capacity ~ ? | 10.36 kg / 101.60 N |
| Magnetic Induction ~ ? | -34.79 mT / -348 Gs |
| Coating | [NiCuNi] Nickel |
| Manufacturing Tolerance | ±0.1 mm |
Magnetic properties of material N38
| properties | values | units |
|---|---|---|
| Remanence Br ? | 12.2-12.6 | kGs |
| Remanence Br ? | 1220-1260 | mT |
| Coercivity bHc ? | 10.8-11.5 | kOe |
| Coercivity bHc ? | 860-915 | kA/m |
| Intrinsic coercivity iHc | ≥ 12 | kOe |
| Intrinsic coercivity iHc | ≥ 955 | kA/m |
| Energy product BHmax ? | 36-38 | BH max MGOe |
| Energy product BHmax ? | 287-303 | BH max KJ/m |
| Maximum working 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 | 310 | °C |
| Curie Temperature TF | 590 | °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 modeling of the product - data
Presented information represent the outcome of a mathematical simulation. Values rely on models for the class Nd2Fe14B. Real-world parameters might slightly differ from theoretical values. Please consider these data as a preliminary roadmap for designers.
Table 1: Static pull force (pull vs gap) - characteristics
MP 20x5x27 / N38
| Distance (mm) | Induction (Gauss) / mT | Pull Force (kg/lbs/g/N) | Risk Status |
|---|---|---|---|
| 0 mm |
5716 Gs
571.6 mT
|
10.36 kg / 22.84 pounds
10360.0 g / 101.6 N
|
critical level |
| 1 mm |
5288 Gs
528.8 mT
|
8.87 kg / 19.55 pounds
8865.5 g / 87.0 N
|
medium risk |
| 2 mm |
4861 Gs
486.1 mT
|
7.49 kg / 16.51 pounds
7491.0 g / 73.5 N
|
medium risk |
| 3 mm |
4446 Gs
444.6 mT
|
6.27 kg / 13.82 pounds
6267.5 g / 61.5 N
|
medium risk |
| 5 mm |
3677 Gs
367.7 mT
|
4.29 kg / 9.45 pounds
4285.9 g / 42.0 N
|
medium risk |
| 10 mm |
2216 Gs
221.6 mT
|
1.56 kg / 3.43 pounds
1557.1 g / 15.3 N
|
safe |
| 15 mm |
1354 Gs
135.4 mT
|
0.58 kg / 1.28 pounds
580.9 g / 5.7 N
|
safe |
| 20 mm |
864 Gs
86.4 mT
|
0.24 kg / 0.52 pounds
236.9 g / 2.3 N
|
safe |
| 30 mm |
405 Gs
40.5 mT
|
0.05 kg / 0.11 pounds
52.1 g / 0.5 N
|
safe |
| 50 mm |
133 Gs
13.3 mT
|
0.01 kg / 0.01 pounds
5.6 g / 0.1 N
|
safe |
Table 2: Shear force (vertical surface)
MP 20x5x27 / N38
| Distance (mm) | Friction coefficient | Pull Force (kg/lbs/g/N) |
|---|---|---|
| 0 mm | Raw steel (µ ≈ 0.2) |
2.07 kg / 4.57 pounds
2072.0 g / 20.3 N
|
| 1 mm | Raw steel (µ ≈ 0.2) |
1.77 kg / 3.91 pounds
1774.0 g / 17.4 N
|
| 2 mm | Raw steel (µ ≈ 0.2) |
1.50 kg / 3.30 pounds
1498.0 g / 14.7 N
|
| 3 mm | Raw steel (µ ≈ 0.2) |
1.25 kg / 2.76 pounds
1254.0 g / 12.3 N
|
| 5 mm | Raw steel (µ ≈ 0.2) |
0.86 kg / 1.89 pounds
858.0 g / 8.4 N
|
| 10 mm | Raw steel (µ ≈ 0.2) |
0.31 kg / 0.69 pounds
312.0 g / 3.1 N
|
| 15 mm | Raw steel (µ ≈ 0.2) |
0.12 kg / 0.26 pounds
116.0 g / 1.1 N
|
| 20 mm | Raw steel (µ ≈ 0.2) |
0.05 kg / 0.11 pounds
48.0 g / 0.5 N
|
| 30 mm | Raw steel (µ ≈ 0.2) |
0.01 kg / 0.02 pounds
10.0 g / 0.1 N
|
| 50 mm | Raw steel (µ ≈ 0.2) |
0.00 kg / 0.00 pounds
2.0 g / 0.0 N
|
Table 3: Wall mounting (shearing) - vertical pull
MP 20x5x27 / N38
| Surface type | Friction coefficient / % | Max load (kg/lbs/g/N) |
|---|---|---|
| Raw steel |
µ = 0.3
30% of nominal force
|
3.11 kg / 6.85 pounds
3108.0 g / 30.5 N
|
| Painted steel (standard) |
µ = 0.2
20% of nominal force
|
2.07 kg / 4.57 pounds
2072.0 g / 20.3 N
|
| Oily/slippery steel |
µ = 0.1
10% of nominal force
|
1.04 kg / 2.28 pounds
1036.0 g / 10.2 N
|
| Magnet with anti-slip rubber |
µ = 0.5
50% of nominal force
|
5.18 kg / 11.42 pounds
5180.0 g / 50.8 N
|
Table 4: Steel thickness (saturation) - sheet metal selection
MP 20x5x27 / N38
| Steel thickness (mm) | % power | Real pull force (kg/lbs/g/N) |
|---|---|---|
| 0.5 mm |
|
0.52 kg / 1.14 pounds
518.0 g / 5.1 N
|
| 1 mm |
|
1.30 kg / 2.85 pounds
1295.0 g / 12.7 N
|
| 2 mm |
|
2.59 kg / 5.71 pounds
2590.0 g / 25.4 N
|
| 3 mm |
|
3.89 kg / 8.56 pounds
3885.0 g / 38.1 N
|
| 5 mm |
|
6.48 kg / 14.27 pounds
6475.0 g / 63.5 N
|
| 10 mm |
|
10.36 kg / 22.84 pounds
10360.0 g / 101.6 N
|
| 11 mm |
|
10.36 kg / 22.84 pounds
10360.0 g / 101.6 N
|
| 12 mm |
|
10.36 kg / 22.84 pounds
10360.0 g / 101.6 N
|
Table 5: Working in heat (stability) - resistance threshold
MP 20x5x27 / N38
| Magnet temperature (°C) | Force change relative to 20°C | Remaining pull (kg/lbs/g/N) | Status |
|---|---|---|---|
| 20 °C | 0.0% |
10.36 kg / 22.84 pounds
10360.0 g / 101.6 N
|
Estimate |
| 40 °C | -4.4% |
9.91 kg / 21.85 pounds
9909.2 g / 97.2 N
|
Estimate |
| 60 °C | -8.6% |
9.47 kg / 20.87 pounds
9468.4 g / 92.9 N
|
Estimate |
| 80 °C | -12.8% |
9.04 kg / 19.92 pounds
9037.6 g / 88.7 N
|
Material limit |
| 100 °C | — | — | Out of range — no model |
Table 6: Two magnets (repulsion) - field range
MP 20x5x27 / N38
| Gap (mm) | Attraction (kg/lbs) (N-S) | Lateral Force (kg/lbs/g/N) | Repulsion (kg/lbs) (N-N) |
|---|---|---|---|
| 0 mm |
44.24 kg / 97.54 pounds
6 064 Gs
|
6.64 kg / 14.63 pounds
6636 g / 65.1 N
|
N/A |
| 1 mm |
41.02 kg / 90.43 pounds
11 008 Gs
|
6.15 kg / 13.56 pounds
6153 g / 60.4 N
|
36.92 kg / 81.39 pounds
~0 Gs
|
| 2 mm |
37.86 kg / 83.47 pounds
10 576 Gs
|
5.68 kg / 12.52 pounds
5679 g / 55.7 N
|
34.07 kg / 75.12 pounds
~0 Gs
|
| 3 mm |
34.85 kg / 76.83 pounds
10 146 Gs
|
5.23 kg / 11.52 pounds
5227 g / 51.3 N
|
31.36 kg / 69.14 pounds
~0 Gs
|
| 5 mm |
29.30 kg / 64.58 pounds
9 303 Gs
|
4.39 kg / 9.69 pounds
4394 g / 43.1 N
|
26.37 kg / 58.13 pounds
~0 Gs
|
| 10 mm |
18.30 kg / 40.35 pounds
7 353 Gs
|
2.75 kg / 6.05 pounds
2745 g / 26.9 N
|
16.47 kg / 36.32 pounds
~0 Gs
|
| 20 mm |
6.65 kg / 14.66 pounds
4 432 Gs
|
1.00 kg / 2.20 pounds
997 g / 9.8 N
|
5.98 kg / 13.19 pounds
~0 Gs
|
| 50 mm |
0.45 kg / 1.00 pounds
1 159 Gs
|
0.07 kg / 0.15 pounds
68 g / 0.7 N
|
0.41 kg / 0.90 pounds
~0 Gs
|
| 60 mm |
0.22 kg / 0.49 pounds
811 Gs
|
0.03 kg / 0.07 pounds
33 g / 0.3 N
|
0.20 kg / 0.44 pounds
~0 Gs
|
| 70 mm |
0.12 kg / 0.26 pounds
589 Gs
|
0.02 kg / 0.04 pounds
18 g / 0.2 N
|
0.11 kg / 0.23 pounds
~0 Gs
|
| 80 mm |
0.07 kg / 0.14 pounds
440 Gs
|
0.01 kg / 0.02 pounds
10 g / 0.1 N
|
0.06 kg / 0.13 pounds
~0 Gs
|
| 90 mm |
0.04 kg / 0.09 pounds
338 Gs
|
0.01 kg / 0.01 pounds
6 g / 0.1 N
|
0.03 kg / 0.08 pounds
~0 Gs
|
| 100 mm |
0.02 kg / 0.05 pounds
265 Gs
|
0.00 kg / 0.01 pounds
4 g / 0.0 N
|
0.02 kg / 0.05 pounds
~0 Gs
|
Table 7: Axial field levels — not safety zones
MP 20x5x27 / N38
| Field level (Gs) | mT | Model distance (cm) |
|---|---|---|
| < 5 Gs | < 0.5 mT | 18.0 cm |
| < 10 Gs | < 1.0 mT | 14.0 cm |
| < 20 Gs | < 2.0 mT | 11.0 cm |
| < 40 Gs | < 4.0 mT | 8.5 cm |
| < 50 Gs | < 5.0 mT | 7.5 cm |
| < 400 Gs | < 40.0 mT | 3.5 cm |
| < 600 Gs | < 60.0 mT | 2.5 cm |
Table 8: Collisions (cracking risk) - collision effects
MP 20x5x27 / N38
| Start from (mm) | Speed (km/h) | Energy (J) | Predicted outcome |
|---|---|---|---|
| 10 mm |
14.40 km/h
(4.00 m/s)
|
0.48 J | |
| 30 mm |
15.54 km/h
(4.32 m/s)
|
0.56 J | |
| 50 mm |
15.59 km/h
(4.33 m/s)
|
0.56 J | |
| 100 mm |
15.60 km/h
(4.33 m/s)
|
0.56 J |
Table 9: Coating parameters (durability)
MP 20x5x27 / 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 20x5x27 / N38
| Parameter | Value | SI Unit / Description |
|---|---|---|
| Magnetic Flux | 14 314 Mx | 143.1 µWb |
| Pc Coefficient | 1.16 | High (Stable) |
Table 11: Underwater work (magnet fishing)
MP 20x5x27 / N38
| Environment | Effective steel pull | Effect |
|---|---|---|
| Air (land) | 10.36 kg | Standard |
| Water (riverbed) |
11.86 kg
(+1.50 kg buoyancy gain)
|
+14.5% |
1. Wall mount (shear)
*Warning: On a vertical wall, the magnet holds just a fraction of its perpendicular strength.
2. Steel saturation
*Thin metal sheet (e.g. computer case) drastically reduces the holding force.
3. Power loss vs temp
N38: the maximum material working temperature is 80°C. Permitted conditions also depend on the shape and magnetic circuit.
4. Demagnetization curve and operating point (B-H)
chart generated for the permeance coefficient Pc (Permeance Coefficient) = 1.16
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% |
Sustainability
| recyclability (EoL) | 100% |
| recycled raw materials | ~10% (pre-cons) |
| carbon footprint | low / zredukowany |
| waste code (EWC) | 16 02 16 |
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Advantages as well as disadvantages of rare earth magnets.
Benefits
- They have constant strength, and over nearly 10 years their attraction force decreases symbolically – ~1% (in testing),
- Magnets perfectly protect themselves against demagnetization caused by ambient magnetic noise,
- The use of an refined layer of noble metals (nickel, gold, silver) causes the element to look better,
- Magnetic induction on the working layer of the magnet turns out to be very high,
- Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their shape) at temperatures up to 230°C and above...
- Thanks to flexibility in designing and the capacity to modify to complex applications,
- Versatile presence in high-tech industry – they are used in HDD drives, brushless drives, medical devices, also complex engineering applications.
- Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications
Cons
- Susceptibility to cracking is one of their disadvantages. Upon strong impact they can break. We recommend keeping them in a special holder, which not only protects them against impacts but also increases their durability
- Do not exceed this material temperature limit: 80°C. Overheating may permanently weaken the magnet.
- Due to the susceptibility of magnets to corrosion in a humid environment, we recommend using waterproof magnets made of rubber, plastic or other material stable to moisture, in case of application outdoors
- Limited ability of making threads in the magnet and complicated shapes - recommended is casing - mounting mechanism.
- Potential hazard resulting from small fragments of magnets are risky, when accidentally swallowed, which becomes key in the context of child health protection. Additionally, small elements of these devices can complicate diagnosis medical when they are in the body.
- Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications
Pull force analysis
Maximum magnetic pulling force – what affects it?
- on a plate made of structural steel, effectively closing the magnetic field
- with a cross-section minimum 10 mm
- with a plane perfectly flat
- with total lack of distance (no coatings)
- for force acting at a right angle (pull-off, not shear)
- in stable room temperature
Practical aspects of lifting capacity – factors
- Air gap (between the magnet and the plate), because even a tiny distance (e.g. 0.5 mm) leads to a drastic drop in force by up to 50% (this also applies to varnish, rust or dirt).
- Force direction – remember that the magnet has greatest strength perpendicularly. Under shear forces, the capacity drops drastically, often to levels of 20-30% of the nominal value.
- Plate thickness – too thin plate does not accept the full field, causing part of the power to be wasted into the air.
- Metal type – not every steel reacts the same. Alloy additives weaken the interaction with the magnet.
- Surface finish – full contact is obtained only on polished steel. Any scratches and bumps create air cushions, weakening the magnet.
- Temperature influence – hot environment weakens magnetic field. Exceeding the limit temperature can permanently demagnetize the magnet.
Holding force was checked on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, in contrast under parallel forces the holding force is lower. Moreover, even a minimal clearance between the magnet and the plate decreases the load capacity.
Precautions when working with neodymium magnets
Serious injuries
Big blocks can smash fingers instantly. Do not place your hand betwixt two attracting surfaces.
Phone sensors
A strong magnetic field disrupts the functioning of magnetometers in phones and GPS navigation. Keep magnets close to a smartphone to avoid damaging the sensors.
Data carriers
Equipment safety: Neodymium magnets can damage data carriers and sensitive devices (pacemakers, medical aids, mechanical watches).
Maximum temperature
Do not exceed the maximum operating temperature stated in the specifications of the particular product. The limit depends on the material, geometry and operating arrangement; there is no single threshold for all neodymium magnets. Overheating can permanently weaken a magnet.
Metal Allergy
Certain individuals suffer from a hypersensitivity to Ni, which is the common plating for NdFeB magnets. Extended handling might lead to an allergic reaction. We strongly advise wear protective gloves.
Fire risk
Machining of NdFeB material carries a risk of fire hazard. Magnetic powder oxidizes rapidly with oxygen and is difficult to extinguish.
Warning for heart patients
Medical warning: Neodymium magnets can deactivate pacemakers and defibrillators. Do not approach if you have medical devices.
Adults only
Always store magnets out of reach of children. Risk of swallowing is high, and the consequences of magnets connecting inside the body are life-threatening.
Protective goggles
NdFeB magnets are ceramic materials, meaning they are very brittle. Impact of two magnets leads to them cracking into small pieces.
Safe operation
Exercise caution. Rare earth magnets act from a long distance and snap with massive power, often quicker than you can react.
