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MW 20x2.5 / N38 - cylindrical magnet

Name: Dhit sp. z o.o.
Address: Kościuszki 6A, Ożarów Mazowiecki, Poland, 05-850, PL
Telephone: +48 22 499 98 98
Price range: 1-6500
Rating: 5

cylindrical magnet

Catalog no 010042

GTIN: 5906301810414

5.00

Diameter Ø

20 mm [±0,1 mm]

Height

2.5 mm [±0,1 mm]

Weight

5.89 g

Magnetization Direction

↑ axial

Load capacity

1.95 kg / 19.09 N

Magnetic Induction

150.34 mT

Coating

[NiCuNi] Nickel

2.51 ZŁ with VAT / pcs + price for transport

2.04 ZŁ net + 23% VAT / pcs

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MW 20x2.5 / N38 - cylindrical magnet

Specification / characteristics MW 20x2.5 / N38 - cylindrical magnet

properties

properties	values
Cat. no.	010042
GTIN	5906301810414
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	2.5 mm [±0,1 mm]
Weight	5.89 g
Magnetization Direction	↑ axial
Load capacity ~ ?	1.95 kg / 19.09 N
Magnetic Induction ~ ?	150.34 mT
Coating	[NiCuNi] Nickel
Manufacturing Tolerance	±0.1 mm

Magnetic properties of material N38

Specification / characteristics MW 20x2.5 / N38 - cylindrical magnet

properties	values	units
remenance Br [Min. - Max.] ?	12.2-12.6	kGs
remenance Br [Min. - Max.] ?	1220-1260	T
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 106	°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 magnet - report

The following data are the outcome of a mathematical calculation. Values were calculated on algorithms for the class NdFeB. Operational parameters may differ. Please consider these calculations as a reference point during assembly planning.

Table 1: Static pull force (force vs distance) - characteristics
MW 20x2.5 / N38

Distance (mm)	Induction (Gauss) / mT	Pull Force (kg)	Risk Status
0 mm	1503 Gs 150.3 mT	1.95 kg / 1950.0 g 19.1 N	weak grip
1 mm	1431 Gs 143.1 mT	1.77 kg / 1767.8 g 17.3 N	weak grip
2 mm	1328 Gs 132.8 mT	1.52 kg / 1522.8 g 14.9 N	weak grip
5 mm	947 Gs 94.7 mT	0.77 kg / 774.4 g 7.6 N	weak grip
10 mm	457 Gs 45.7 mT	0.18 kg / 180.5 g 1.8 N	weak grip
15 mm	224 Gs 22.4 mT	0.04 kg / 43.5 g 0.4 N	weak grip
20 mm	120 Gs 12.0 mT	0.01 kg / 12.5 g 0.1 N	weak grip
30 mm	44 Gs 4.4 mT	0.00 kg / 1.7 g 0.0 N	weak grip
50 mm	11 Gs 1.1 mT	0.00 kg / 0.1 g 0.0 N	weak grip

Magnetic force drops sharply with every subsequent millimeter of gap. Note that even a microscopic distance (e.g., contamination, paint, rust) noticeably diminishes the holding power. Magnets work most effectively at the point of direct contact; distance weakens the power. Notice how quickly the parameters plummet, when the magnet does not touch tightly to the metal substrate. When planning the assembly, eliminate redundant distances.

Table 2: Wall mounting (shearing) - vertical pull
MW 20x2.5 / N38

Surface type	Friction coefficient / % Mocy	Max load (kg)
Raw steel	µ = 0.3 30% Nominalnej Siły	0.59 kg / 585.0 g 5.7 N
Painted steel (standard)	µ = 0.2 20% Nominalnej Siły	0.39 kg / 390.0 g 3.8 N
Oily/slippery steel	µ = 0.1 10% Nominalnej Siły	0.20 kg / 195.0 g 1.9 N
Magnet with anti-slip rubber	µ = 0.5 50% Nominalnej Siły	0.98 kg / 975.0 g 9.6 N

When hanging a element on a vertical surface (e.g., a fridge), it will maintain barely approx. 20%-30% of its maximum pull force. Gravitational force and a weak degree of grip cause that products slip easier than they detach. Planning a vertical fastening? Remember that the shear force is significantly lower than the maximum static pull force. On a painted metal, the magnet will slide down under a noticeably lighter cargo. Using a rubber coating can significantly increase the grip.

Table 3: Material efficiency (saturation) - power losses
MW 20x2.5 / N38

Steel thickness (mm)	% power	Real pull force (kg)
0.5 mm	10%	0.20 kg / 195.0 g 1.9 N
1 mm	25%	0.49 kg / 487.5 g 4.8 N
2 mm	50%	0.98 kg / 975.0 g 9.6 N
5 mm	100%	1.95 kg / 1950.0 g 19.1 N
10 mm	100%	1.95 kg / 1950.0 g 19.1 N

A thin metal plate is unable to absorb the entire magnetic field, which squanders power of the magnet. Should you install a neodymium to a thin surface, the flux will penetrate right through and the attraction force will be weaker. To utilize the maximum of this neodymium's power, you need a suitably thick element of metal. The material oversaturation causes that on sheet metal structures (e.g., thin profiles), the magnet holds weaker. We recommend selecting the steel dimension from these parameters.

Table 4: Working in heat (material behavior) - thermal limit
MW 20x2.5 / N38

Ambient temp. (°C)	Power loss	Remaining pull	Status
20 °C	0.0%	1.95 kg / 1950.0 g 19.1 N	OK
40 °C	-2.2%	1.91 kg / 1907.1 g 18.7 N	OK
60 °C	-4.4%	1.86 kg / 1864.2 g 18.3 N	OK
80 °C	-6.6%	1.82 kg / 1821.3 g 17.9 N
100 °C	-28.8%	1.39 kg / 1388.4 g 13.6 N

Ordinary NdFeB products lose strength above the temperature limit. Watch out for overheating – heat can permanently destroy this magnet. With every degree above norm, the magnet's power temporarily lowers. Refrain from using this product close to heaters exceeding its working range. Exceeding the critical threshold will cause permanent loss of magnetism.

Table 5: Magnet-Magnet interaction (attraction) - field range
MW 20x2.5 / N38

Gap (mm)	Attraction (kg) (N-S)	Repulsion (kg) (N-N)
0 mm	2.93 kg / 2925.0 g 28.7 N	N/A
2 mm	2.28 kg / 2280.0 g 22.4 N	2.13 kg / 2128.0 g 20.9 N
5 mm	1.16 kg / 1155.0 g 11.3 N	1.08 kg / 1078.0 g 10.6 N
10 mm	0.27 kg / 270.0 g 2.6 N	0.25 kg / 252.0 g 2.5 N
20 mm	0.02 kg / 15.0 g 0.1 N	0.01 kg / 14.0 g 0.1 N
50 mm	0.00 kg / 0.0 g 0.0 N	0.00 kg / 0.0 g 0.0 N

Two magnets attract each other from a wider radius than a magnet and sheet setup. The setup of two magnets creates a more powerful interaction and a wider radius of action. Planning to create a strong closure? Apply two magnets instead of a neodymium and a striker plate. Exercise caution that when bringing together two magnets, the impact force is extreme. The levitation is a bit weaker than the connection force, but still large.

Table 6: Hazards (implants) - precautionary measures
MW 20x2.5 / N38

Object / Device	Limit (Gauss) / mT	Safe distance
Pacemaker	5 Gs (0.5 mT)	7.0 cm
Hearing aid	10 Gs (1.0 mT)	5.5 cm
Timepiece	20 Gs (2.0 mT)	4.5 cm
Mobile device	40 Gs (4.0 mT)	3.5 cm
Car key	50 Gs (5.0 mT)	3.0 cm
Payment card	400 Gs (40.0 mT)	1.5 cm
HDD hard drive	600 Gs (60.0 mT)	1.0 cm

A strong magnetic field is a real danger to electronic devices as well as pacemakers. These magnets generate a field that disrupts operation of sensitive medical devices. Notice: the unseen radiation acts through matter and plastic. Exceptional care must be exercised by people with hearing aids and drug dispensers. Also at risk are: mechanical watches, remotes, speakers, and displays. Do not place the magnet near cards, HDD media, or sensitive navigation tools.

Table 7: Collisions (cracking risk) - warning
MW 20x2.5 / N38

Start from (mm)	Speed (km/h)	Energy (J)
10 mm	19.38 km/h (5.38 m/s)	0.09 J
30 mm	31.80 km/h (8.83 m/s)	0.23 J
50 mm	41.03 km/h (11.40 m/s)	0.38 J
100 mm	58.03 km/h (16.12 m/s)	0.77 J

NdFeB products are prone to chipping – a strong collision with metal causes immediate chipping. Watch the impact speed – a neodymium left loose turns into a projectile. Striking energy can trigger coating fragments or painful pinches to fingers. Hold the magnet firmly during installation so it doesn't hit with great force against the steel surface. A collision at high speed almost guarantees destruction of the magnet. Use safety goggles when playing with powerful specimens.

Table 8: Anti-corrosion coating durability
MW 20x2.5 / 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)

The following table defines the conditions under which this product can be safely used. Moisture resistance is crucial for installations in bathrooms or outdoors.

Table 9: Physics of underwater searching
MW 20x2.5 / N38

Environment	Effective steel pull	Effect
Air (land)	1.95 kg	Standard
Water (riverbed)	2.23 kg (+0.28 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!

Contrary to myths, water does not block the magnetic field. Buoyancy helps in lifting finds.

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This product is an incredibly powerful cylindrical magnet, composed of advanced NdFeB material, which, at dimensions of Ø20x2.5 mm, guarantees the highest energy density. The MW 20x2.5 / N38 component features an accuracy of ±0.1mm and professional build quality, making it an excellent solution for the most demanding engineers and designers. As a magnetic rod with significant force (approx. 1.95 kg), this product is in stock from our European logistics center, ensuring rapid order fulfillment. Moreover, its Ni-Cu-Ni coating secures it against corrosion in standard operating conditions, ensuring an aesthetic appearance and durability for years.

It successfully proves itself in DIY projects, advanced robotics, and broadly understood industry, serving as a positioning or actuating element. Thanks to the pull force of 19.09 N with a weight of only 5.89 g, this rod is indispensable in electronics and wherever low weight is crucial.

Since our magnets have a very precise dimensions, 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 long-term durability in automation, specialized industrial adhesives are used, which do not react with the nickel coating and fill the gap, guaranteeing high repeatability of the connection.

Magnets N38 are suitable for the majority of applications in automation and machine building, where excessive miniaturization with maximum force is not required. If you need the strongest magnets in the same volume (Ø20x2.5), contact us regarding higher grades (e.g., N50, N52), however, N38 is the standard available off-the-shelf in our warehouse.

This model is characterized by dimensions Ø20x2.5 mm, which, at a weight of 5.89 g, makes it an element with high magnetic energy density. The key parameter here is the lifting capacity amounting to approximately 1.95 kg (force ~19.09 N), which, with such compact dimensions, proves the high grade of the NdFeB material. The product has a [NiCuNi] coating, which secures it against oxidation, giving it an aesthetic, silvery shine.

Standardly, the magnetic axis runs through the center of the cylinder, causing the greatest attraction force to occur on the bases with a diameter of 20 mm. 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 diametrically if your project requires it.

Strengths as well as weaknesses of NdFeB magnets.

Apart from their strong magnetic energy, neodymium magnets have these key benefits:

Their magnetic field remains stable, and after around ten years it decreases only by ~1% (according to research),
Magnets effectively protect themselves against loss of magnetization caused by external fields,
The use of an elegant finish of noble metals (nickel, gold, silver) causes the element to present itself better,
Neodymium magnets deliver maximum magnetic induction on a small area, which increases force concentration,
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...
Possibility of detailed forming and optimizing to specific conditions,
Fundamental importance in innovative solutions – they serve a role in magnetic memories, electric drive systems, diagnostic systems, also other advanced devices.
Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in small dimensions, which makes them useful in miniature devices

Problematic aspects of neodymium magnets: tips and applications.

To avoid cracks upon strong impacts, we suggest using special steel housings. Such a solution protects the magnet and simultaneously increases its durability.
NdFeB magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of strength (a factor is the shape as well as 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 rust. Therefore while using outdoors, we suggest using water-impermeable magnets made of rubber, plastic or other material resistant to moisture
We suggest cover - magnetic mount, due to difficulties in realizing threads inside the magnet and complex forms.
Potential hazard resulting from small fragments of magnets can be dangerous, when accidentally swallowed, which becomes key in the context of child safety. Furthermore, small elements of these magnets can disrupt the diagnostic process medical after entering the body.
High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which hinders application in large quantities

Highest magnetic holding force – what contributes to it?

Magnet power was determined for optimal configuration, including:

on a base made of mild steel, optimally conducting the magnetic flux
whose transverse dimension equals approx. 10 mm
characterized by even structure
with direct contact (no coatings)
under axial application of breakaway force (90-degree angle)
at room temperature

Lifting capacity in practice – influencing factors

During everyday use, the actual lifting capacity is determined by several key aspects, ranked from crucial:

Distance – existence of any layer (paint, dirt, gap) interrupts the magnetic circuit, which reduces capacity rapidly (even by 50% at 0.5 mm).
Angle of force application – highest force is reached only during perpendicular pulling. The resistance to sliding of the magnet along the plate is standardly many times lower (approx. 1/5 of the lifting capacity).
Substrate thickness – for full efficiency, the steel must be adequately massive. Thin sheet restricts the attraction force (the magnet "punches through" it).
Chemical composition of the base – low-carbon steel gives the best results. Higher carbon content lower magnetic properties and lifting capacity.
Surface structure – the more even the surface, the better the adhesion and stronger the hold. Unevenness acts like micro-gaps.
Temperature – temperature increase results in weakening of force. Check the thermal limit for a given model.

* Lifting capacity testing was conducted on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, in contrast under shearing force the load capacity is reduced by as much as 75%. Additionally, even a minimal clearance {between} the magnet’s surface and the plate decreases the lifting capacity.

Safe handling of neodymium magnets

Conscious usage

Handle magnets consciously. Their huge power can surprise even professionals. Be vigilant and do not underestimate their power.

Magnets are brittle

Watch out for shards. Magnets can fracture upon violent connection, ejecting sharp fragments into the air. Eye protection is mandatory.

Physical harm

Large magnets can smash fingers in a fraction of a second. Never place your hand betwixt two attracting surfaces.

Magnetic interference

An intense magnetic field interferes with the operation of magnetometers in phones and navigation systems. Keep magnets close to a smartphone to prevent damaging the sensors.

Electronic hazard

Equipment safety: Neodymium magnets can ruin payment cards and delicate electronics (pacemakers, medical aids, timepieces).

Heat warning

Regular neodymium magnets (grade N) lose magnetization when the temperature goes above 80°C. The loss of strength is permanent.

Fire risk

Machining of NdFeB material carries a risk of fire hazard. Neodymium dust oxidizes rapidly with oxygen and is difficult to extinguish.

Product not for children

Neodymium magnets are not toys. Eating several magnets may result in them attracting across intestines, which poses a severe health hazard and requires urgent medical intervention.

Metal Allergy

Allergy Notice: The nickel-copper-nickel coating consists of nickel. If redness happens, cease handling magnets and wear gloves.

Life threat

Warning for patients: Powerful magnets affect electronics. Maintain minimum 30 cm distance or ask another person to handle the magnets.

Caution!

More info about hazards in the article: Magnet Safety Guide.

MW 20x2.5 / N38 - cylindrical magnet

MW 20x2.5 / N38 - cylindrical magnet

Magnetic properties of material N38

Physical properties of sintered neodymium magnets Nd2Fe14B at 20°C

Technical modeling of the magnet - report

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Strengths as well as weaknesses of NdFeB magnets.

Highest magnetic holding force – what contributes to it?

Lifting capacity in practice – influencing factors

Safe handling of neodymium magnets

Physical properties of sintered neodymium magnets Nd₂Fe₁₄B at 20°C