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MW 20x18 / N38 - cylindrical magnet

cylindrical magnet

Catalog no 010040

GTIN/EAN: 5906301810391

Diameter Ø

20 mm [±0,1 mm]

Height

18 mm [±0,1 mm]

Weight

42.41 g

Magnetization Direction

↑ axial

Load capacity

13.19 kg / 129.35 N

Magnetic Induction

541.64 mT / 5416 Gs

Coating

[NiCuNi] Nickel

23.54 with VAT / pcs + price for transport

19.14 ZŁ net + 23% VAT / pcs

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Technical details - MW 20x18 / N38 - cylindrical magnet

Specification / characteristics - MW 20x18 / N38 - cylindrical magnet

properties
properties values
Cat. no. 010040
GTIN/EAN 5906301810391
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 Ø 20 mm [±0,1 mm]
Height 18 mm [±0,1 mm]
Weight 42.41 g
Magnetization Direction ↑ axial
Load capacity ~ ? 13.19 kg / 129.35 N
Magnetic Induction ~ ? 541.64 mT / 5416 Gs
Coating [NiCuNi] Nickel
Manufacturing Tolerance ±0.1 mm

Magnetic properties of material N38

Specification / characteristics MW 20x18 / N38 - cylindrical 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 simulation of the product - data

The following information constitute the outcome of a mathematical calculation. Results were calculated on models for the material Nd2Fe14B. Actual conditions may deviate from the simulation results. Please consider these calculations as a supplementary guide when designing systems.

Table 1: Static pull force (force vs gap) - characteristics
MW 20x18 / N38

Distance (mm) Induction (Gauss) / mT Pull Force (kg/lbs/g/N) Risk Status
0 mm 5414 Gs
541.4 mT
13.19 kg / 29.08 pounds
13190.0 g / 129.4 N
critical level
1 mm 4870 Gs
487.0 mT
10.67 kg / 23.52 pounds
10669.5 g / 104.7 N
critical level
2 mm 4330 Gs
433.0 mT
8.43 kg / 18.59 pounds
8434.2 g / 82.7 N
strong
3 mm 3816 Gs
381.6 mT
6.55 kg / 14.45 pounds
6552.7 g / 64.3 N
strong
5 mm 2913 Gs
291.3 mT
3.82 kg / 8.42 pounds
3818.4 g / 37.5 N
strong
10 mm 1455 Gs
145.5 mT
0.95 kg / 2.10 pounds
952.2 g / 9.3 N
safe
15 mm 775 Gs
77.5 mT
0.27 kg / 0.60 pounds
270.1 g / 2.7 N
safe
20 mm 450 Gs
45.0 mT
0.09 kg / 0.20 pounds
91.3 g / 0.9 N
safe
30 mm 188 Gs
18.8 mT
0.02 kg / 0.04 pounds
15.9 g / 0.2 N
safe
50 mm 54 Gs
5.4 mT
0.00 kg / 0.00 pounds
1.3 g / 0.0 N
safe

Table 2: Sliding load (wall)
MW 20x18 / N38

Distance (mm) Friction coefficient Pull Force (kg/lbs/g/N)
0 mm Stal (~0.2) 2.64 kg / 5.82 pounds
2638.0 g / 25.9 N
1 mm Stal (~0.2) 2.13 kg / 4.70 pounds
2134.0 g / 20.9 N
2 mm Stal (~0.2) 1.69 kg / 3.72 pounds
1686.0 g / 16.5 N
3 mm Stal (~0.2) 1.31 kg / 2.89 pounds
1310.0 g / 12.9 N
5 mm Stal (~0.2) 0.76 kg / 1.68 pounds
764.0 g / 7.5 N
10 mm Stal (~0.2) 0.19 kg / 0.42 pounds
190.0 g / 1.9 N
15 mm Stal (~0.2) 0.05 kg / 0.12 pounds
54.0 g / 0.5 N
20 mm Stal (~0.2) 0.02 kg / 0.04 pounds
18.0 g / 0.2 N
30 mm Stal (~0.2) 0.00 kg / 0.01 pounds
4.0 g / 0.0 N
50 mm Stal (~0.2) 0.00 kg / 0.00 pounds
0.0 g / 0.0 N

Table 3: Vertical assembly (sliding) - vertical pull
MW 20x18 / N38

Surface type Friction coefficient / % Mocy Max load (kg/lbs/g/N)
Raw steel
µ = 0.3 30% Nominalnej Siły
3.96 kg / 8.72 pounds
3957.0 g / 38.8 N
Painted steel (standard)
µ = 0.2 20% Nominalnej Siły
2.64 kg / 5.82 pounds
2638.0 g / 25.9 N
Oily/slippery steel
µ = 0.1 10% Nominalnej Siły
1.32 kg / 2.91 pounds
1319.0 g / 12.9 N
Magnet with anti-slip rubber
µ = 0.5 50% Nominalnej Siły
6.60 kg / 14.54 pounds
6595.0 g / 64.7 N

Table 4: Steel thickness (substrate influence) - sheet metal selection
MW 20x18 / N38

Steel thickness (mm) % power Real pull force (kg/lbs/g/N)
0.5 mm
5%
0.66 kg / 1.45 pounds
659.5 g / 6.5 N
1 mm
13%
1.65 kg / 3.63 pounds
1648.8 g / 16.2 N
2 mm
25%
3.30 kg / 7.27 pounds
3297.5 g / 32.3 N
3 mm
38%
4.95 kg / 10.90 pounds
4946.3 g / 48.5 N
5 mm
63%
8.24 kg / 18.17 pounds
8243.8 g / 80.9 N
10 mm
100%
13.19 kg / 29.08 pounds
13190.0 g / 129.4 N
11 mm
100%
13.19 kg / 29.08 pounds
13190.0 g / 129.4 N
12 mm
100%
13.19 kg / 29.08 pounds
13190.0 g / 129.4 N

Table 5: Thermal stability (stability) - power drop
MW 20x18 / N38

Ambient temp. (°C) Power loss Remaining pull (kg/lbs/g/N) Status
20 °C 0.0% 13.19 kg / 29.08 pounds
13190.0 g / 129.4 N
OK
40 °C -2.2% 12.90 kg / 28.44 pounds
12899.8 g / 126.5 N
OK
60 °C -4.4% 12.61 kg / 27.80 pounds
12609.6 g / 123.7 N
OK
80 °C -6.6% 12.32 kg / 27.16 pounds
12319.5 g / 120.9 N
100 °C -28.8% 9.39 kg / 20.70 pounds
9391.3 g / 92.1 N

Table 6: Two magnets (repulsion) - field range
MW 20x18 / N38

Gap (mm) Attraction (kg/lbs) (N-S) Sliding Force (kg/lbs/g/N) Repulsion (kg/lbs) (N-N)
0 mm 56.78 kg / 125.17 pounds
5 968 Gs
8.52 kg / 18.78 pounds
8516 g / 83.5 N
N/A
1 mm 51.26 kg / 113.01 pounds
10 289 Gs
7.69 kg / 16.95 pounds
7689 g / 75.4 N
46.13 kg / 101.71 pounds
~0 Gs
2 mm 45.93 kg / 101.25 pounds
9 739 Gs
6.89 kg / 15.19 pounds
6889 g / 67.6 N
41.33 kg / 91.13 pounds
~0 Gs
3 mm 40.93 kg / 90.24 pounds
9 194 Gs
6.14 kg / 13.54 pounds
6140 g / 60.2 N
36.84 kg / 81.22 pounds
~0 Gs
5 mm 32.06 kg / 70.68 pounds
8 137 Gs
4.81 kg / 10.60 pounds
4809 g / 47.2 N
28.86 kg / 63.62 pounds
~0 Gs
10 mm 16.44 kg / 36.24 pounds
5 826 Gs
2.47 kg / 5.44 pounds
2465 g / 24.2 N
14.79 kg / 32.61 pounds
~0 Gs
20 mm 4.10 kg / 9.04 pounds
2 909 Gs
0.61 kg / 1.36 pounds
615 g / 6.0 N
3.69 kg / 8.13 pounds
~0 Gs
50 mm 0.15 kg / 0.34 pounds
565 Gs
0.02 kg / 0.05 pounds
23 g / 0.2 N
0.14 kg / 0.31 pounds
~0 Gs
60 mm 0.07 kg / 0.15 pounds
376 Gs
0.01 kg / 0.02 pounds
10 g / 0.1 N
0.06 kg / 0.14 pounds
~0 Gs
70 mm 0.03 kg / 0.07 pounds
262 Gs
0.00 kg / 0.01 pounds
5 g / 0.0 N
0.03 kg / 0.07 pounds
~0 Gs
80 mm 0.02 kg / 0.04 pounds
190 Gs
0.00 kg / 0.01 pounds
3 g / 0.0 N
0.02 kg / 0.03 pounds
~0 Gs
90 mm 0.01 kg / 0.02 pounds
142 Gs
0.00 kg / 0.00 pounds
1 g / 0.0 N
0.00 kg / 0.00 pounds
~0 Gs
100 mm 0.01 kg / 0.01 pounds
109 Gs
0.00 kg / 0.00 pounds
1 g / 0.0 N
0.00 kg / 0.00 pounds
~0 Gs

Table 7: Safety (HSE) (implants) - warnings
MW 20x18 / N38

Object / Device Limit (Gauss) / mT Safe distance
Pacemaker 5 Gs (0.5 mT) 12.5 cm
Hearing aid 10 Gs (1.0 mT) 9.5 cm
Mechanical watch 20 Gs (2.0 mT) 7.5 cm
Mobile device 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) 2.5 cm
HDD hard drive 600 Gs (60.0 mT) 2.0 cm

Table 8: Impact energy (cracking risk) - warning
MW 20x18 / N38

Start from (mm) Speed (km/h) Energy (J) Predicted outcome
10 mm 18.57 km/h
(5.16 m/s)
0.56 J
30 mm 30.83 km/h
(8.56 m/s)
1.56 J
50 mm 39.77 km/h
(11.05 m/s)
2.59 J
100 mm 56.24 km/h
(15.62 m/s)
5.18 J

Table 9: Surface protection spec
MW 20x18 / 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)
MW 20x18 / N38

Parameter Value SI Unit / Description
Magnetic Flux 17 374 Mx 173.7 µWb
Pc Coefficient 0.85 High (Stable)

Table 11: Submerged application
MW 20x18 / N38

Environment Effective steel pull Effect
Air (land) 13.19 kg Standard
Water (riverbed) 15.10 kg
(+1.91 kg buoyancy gain)
+14.5%
Rust risk: Standard nickel requires drying after every contact with moisture; lack of maintenance will lead to rust spots.
1. Vertical hold

*Warning: On a vertical wall, the magnet retains only approx. 20-30% of its max power.

2. Steel thickness impact

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

3. Heat tolerance

*For N38 grade, the max working temp is 80°C.

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

chart generated for the permeance coefficient Pc (Permeance Coefficient) = 0.85

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
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%
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: 010040-2026
Magnet Unit Converter
Magnet pull force

Magnetic Field

Other products

The presented product is an exceptionally strong rod magnet, composed of advanced NdFeB material, which, with dimensions of Ø20x18 mm, guarantees optimal power. The MW 20x18 / N38 model is characterized by high dimensional repeatability and industrial build quality, making it a perfect solution for the most demanding engineers and designers. As a magnetic rod with significant force (approx. 13.19 kg), this product is in stock from our warehouse in Poland, ensuring quick order fulfillment. Moreover, its Ni-Cu-Ni coating shields it against corrosion in typical operating conditions, ensuring an aesthetic appearance and durability for years.
It finds application in DIY projects, advanced robotics, and broadly understood industry, serving as a fastening or actuating element. Thanks to the high power of 129.35 N with a weight of only 42.41 g, this cylindrical magnet is indispensable in miniature devices and wherever low weight is crucial.
Since our magnets have a tolerance of ±0.1mm, the recommended way is to glue them into holes with a slightly larger diameter (e.g., 20.1 mm) using two-component epoxy glues. To ensure stability in automation, specialized industrial adhesives are used, which are safe for nickel and fill the gap, guaranteeing durability of the connection.
Grade N38 is the most popular standard for industrial neodymium magnets, offering a great economic balance and high resistance to demagnetization. If you need even stronger magnets in the same volume (Ø20x18), contact us regarding higher grades (e.g., N50, N52), however, N38 is the standard in continuous sale in our store.
The presented product is a neodymium magnet with precisely defined parameters: diameter 20 mm and height 18 mm. The value of 129.35 N means that the magnet is capable of holding a weight many times exceeding its own mass of 42.41 g. The product has a [NiCuNi] coating, which protects the surface against external factors, giving it an aesthetic, silvery shine.
This rod magnet is magnetized axially (along the height of 18 mm), which means that the N and S poles are located on the flat, circular surfaces. Such an arrangement is standard when connecting magnets in stacks (e.g., in filters) or when mounting in sockets at the bottom of a hole. On request, we can also produce versions magnetized through the diameter if your project requires it.

Pros as well as cons of neodymium magnets.

Strengths

Besides their high retention, neodymium magnets are valued for these benefits:
  • Their magnetic field is durable, and after around ten years it decreases only by ~1% (theoretically),
  • They are noted for resistance to demagnetization induced by external magnetic fields,
  • The use of an elegant finish of noble metals (nickel, gold, silver) causes the element to look better,
  • Magnetic induction on the working part of the magnet turns out to be strong,
  • Neodymium magnets are characterized by very high magnetic induction on the magnet surface and are able to act (depending on the shape) even at a temperature of 230°C or more...
  • Due to the ability of precise molding and adaptation to custom projects, magnetic components can be modeled in a broad palette of shapes and sizes, which makes them more universal,
  • Huge importance in electronics industry – they find application in magnetic memories, electromotive mechanisms, advanced medical instruments, as well as industrial machines.
  • Compactness – despite small sizes they generate large force, making them ideal for precision applications

Disadvantages

Drawbacks and weaknesses of neodymium magnets and ways of using them
  • They are fragile upon heavy impacts. To avoid cracks, it is worth protecting magnets using a steel holder. Such protection not only protects the magnet but also increases its resistance to damage
  • Neodymium 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 very resistant to heat
  • When exposed to humidity, magnets usually rust. For applications outside, it is recommended to use protective magnets, such as those in rubber or plastics, which secure oxidation as well as corrosion.
  • Limited ability of making nuts in the magnet and complicated shapes - preferred is casing - magnetic holder.
  • Health risk to health – tiny shards of magnets are risky, if swallowed, which is particularly important in the aspect of protecting the youngest. Furthermore, tiny parts of these devices are able to disrupt the diagnostic process medical after entering the body.
  • Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Holding force characteristics

Magnetic strength at its maximum – what it depends on?

Magnet power was determined for the most favorable conditions, taking into account:
  • using a base made of mild steel, serving as a ideal flux conductor
  • with a thickness of at least 10 mm
  • with a surface free of scratches
  • with total lack of distance (without impurities)
  • during pulling in a direction vertical to the mounting surface
  • at standard ambient temperature

Lifting capacity in real conditions – factors

Effective lifting capacity impacted by working environment parameters, including (from priority):
  • Clearance – existence of foreign body (rust, dirt, gap) acts as an insulator, which lowers power rapidly (even by 50% at 0.5 mm).
  • Angle of force application – highest force is available only during pulling at a 90° angle. The force required to slide of the magnet along the plate is usually several times smaller (approx. 1/5 of the lifting capacity).
  • Metal thickness – the thinner the sheet, the weaker the hold. Part of the magnetic field passes through the material instead of generating force.
  • Plate material – mild steel attracts best. Alloy admixtures decrease magnetic properties and lifting capacity.
  • Smoothness – ideal contact is possible only on smooth steel. Rough texture create air cushions, weakening the magnet.
  • Thermal factor – high temperature weakens magnetic field. Too high temperature can permanently demagnetize the magnet.

Holding force was tested on the plate surface of 20 mm thickness, when a perpendicular force was applied, in contrast under shearing force the lifting capacity is smaller. In addition, even a small distance between the magnet and the plate lowers the holding force.

H&S for magnets
Operating temperature

Regular neodymium magnets (N-type) undergo demagnetization when the temperature goes above 80°C. This process is irreversible.

Threat to electronics

Equipment safety: Strong magnets can ruin data carriers and delicate electronics (heart implants, hearing aids, timepieces).

Dust is flammable

Fire hazard: Neodymium dust is highly flammable. Avoid machining magnets in home conditions as this risks ignition.

Product not for children

Neodymium magnets are not intended for children. Accidental ingestion of a few magnets can lead to them pinching intestinal walls, which poses a severe health hazard and requires immediate surgery.

Warning for allergy sufferers

It is widely known that the nickel plating (the usual finish) is a potent allergen. If your skin reacts to metals, refrain from touching magnets with bare hands or opt for coated magnets.

Life threat

People with a heart stimulator have to maintain an absolute distance from magnets. The magnetic field can interfere with the operation of the implant.

Material brittleness

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

Caution required

Use magnets with awareness. Their powerful strength can surprise even experienced users. Stay alert and do not underestimate their force.

Keep away from electronics

A strong magnetic field negatively affects the operation of compasses in smartphones and GPS navigation. Keep magnets close to a device to prevent damaging the sensors.

Bone fractures

Danger of trauma: The attraction force is so great that it can result in blood blisters, crushing, and broken bones. Use thick gloves.

Caution! Looking for details? Read our article: Are neodymium magnets dangerous?
Dhit sp. z o.o.

e-mail: bok@dhit.pl

tel: +48 888 99 98 98