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MP 20x10x5 / N38 - ring magnet

ring magnet

Catalog no 030184

GTIN: 5906301812012

5.00

Diameter

20 mm [±0,1 mm]

internal diameter Ø

10 mm [±0,1 mm]

Height

5 mm [±0,1 mm]

Weight

8.84 g

Magnetization Direction

↑ axial

Load capacity

5.20 kg / 50.97 N

Magnetic Induction

0.28 mT / 3 Gs

Coating

[NiCuNi] Nickel

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MP 20x10x5 / N38 - ring magnet

Specification / characteristics MP 20x10x5 / N38 - ring magnet

properties

properties	values
Cat. no.	030184
GTIN	5906301812012
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	20 mm [±0,1 mm]
internal diameter Ø	10 mm [±0,1 mm]
Height	5 mm [±0,1 mm]
Weight	8.84 g
Magnetization Direction	↑ axial
Load capacity ~ ?	5.20 kg / 50.97 N
Magnetic Induction ~ ?	0.28 mT / 3 Gs
Coating	[NiCuNi] Nickel
Manufacturing Tolerance	±0.1 mm

Magnetic properties of material N38

Specification / characteristics MP 20x10x5 / N38 - ring 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 product - data

These information are the direct effect of a engineering analysis. Results are based on models for the material NdFeB. Operational conditions may differ from theoretical values. Use these data as a reference point when designing systems.

Table 1: Static force (force vs distance) - interaction chart
MP 20x10x5 / N38

Distance (mm)	Induction (Gauss) / mT	Pull Force (kg)	Risk Status
0 mm	5917 Gs 591.7 mT	5.20 kg / 5200.0 g 51.0 N	warning
1 mm	5321 Gs 532.1 mT	4.21 kg / 4205.9 g 41.3 N	warning
2 mm	4736 Gs 473.6 mT	3.33 kg / 3332.2 g 32.7 N	warning
5 mm	3216 Gs 321.6 mT	1.54 kg / 1536.2 g 15.1 N	safe
10 mm	1650 Gs 165.0 mT	0.40 kg / 404.2 g 4.0 N	safe
15 mm	907 Gs 90.7 mT	0.12 kg / 122.3 g 1.2 N	safe
20 mm	544 Gs 54.4 mT	0.04 kg / 44.0 g 0.4 N	safe
30 mm	240 Gs 24.0 mT	0.01 kg / 8.5 g 0.1 N	safe
50 mm	75 Gs 7.5 mT	0.00 kg / 0.8 g 0.0 N	safe

Grip strength decreases significantly with every subsequent millimeter of distance. Keep in mind that even a very thin break (e.g., contamination, paint, rust) strongly diminishes the holding power. Neodymiums hold strongest during direct contact; gap drastically cuts the power. Observe how rapidly the parameters plummet, when the magnet does not touch flatly to the metal substrate. When planning the assembly, avoid additional spacers.

Table 2: Wall mounting (sliding) - behavior on slippery surfaces
MP 20x10x5 / N38

Surface type	Friction coefficient / % Mocy	Max load (kg)
Raw steel	µ = 0.3 30% Nominalnej Siły	1.56 kg / 1560.0 g 15.3 N
Painted steel (standard)	µ = 0.2 20% Nominalnej Siły	1.04 kg / 1040.0 g 10.2 N
Oily/slippery steel	µ = 0.1 10% Nominalnej Siły	0.52 kg / 520.0 g 5.1 N
Magnet with anti-slip rubber	µ = 0.5 50% Nominalnej Siły	2.60 kg / 2600.0 g 25.5 N

When placing a element on a upright wall (e.g., a fridge), it will maintain only approx. 1/5 of nominal attraction strength. Gravity and a weak degree of grip influence the fact that holders move down faster than they pop off the substrate. Planning a vertical fastening? Consider that the shear force is noticeably lower than the perpendicular breakaway force. On a painted metal, the element will slide down under a much lighter weight. Utilizing a rubberized layer can significantly increase the grip.

Table 3: Material efficiency (substrate influence) - sheet metal selection
MP 20x10x5 / N38

Steel thickness (mm)	% power	Real pull force (kg)
0.5 mm	10%	0.52 kg / 520.0 g 5.1 N
1 mm	25%	1.30 kg / 1300.0 g 12.8 N
2 mm	50%	2.60 kg / 2600.0 g 25.5 N
5 mm	100%	5.20 kg / 5200.0 g 51.0 N
10 mm	100%	5.20 kg / 5200.0 g 51.0 N

A thin metal plate is unable to absorb the entire magnetic field, which weakens actual performance of the holder. Should you install a neodymium to a weak sheet, the field will pass right through and the attraction force will be weaker. To squeeze full efficiency of this neodymium's potential, you need a suitably thick piece of steel. The saturation effect causes that on delicate walls (e.g., appliance housings), the holder works worse. We advise picking the steel cross-section according to the table below.

Table 4: Thermal resistance (material behavior) - power drop
MP 20x10x5 / N38

Ambient temp. (°C)	Power loss	Remaining pull	Status
20 °C	0.0%	5.20 kg / 5200.0 g 51.0 N	OK
40 °C	-2.2%	5.09 kg / 5085.6 g 49.9 N	OK
60 °C	-4.4%	4.97 kg / 4971.2 g 48.8 N	OK
80 °C	-6.6%	4.86 kg / 4856.8 g 47.6 N
100 °C	-28.8%	3.70 kg / 3702.4 g 36.3 N

Classic neodymiums irreversibly lose power above the temperature limit. Protect against heat – heat can permanently damage this product. With increasing heat, the neodymium's power momentarily lowers. Avoid using this magnet close to heaters exceeding its working range. Exceeding the critical threshold will cause permanent loss of magnetic properties.

Table 5: Magnet-Magnet interaction (repulsion) - field collision
MP 20x10x5 / N38

Gap (mm)	Attraction (kg) (N-S)	Repulsion (kg) (N-N)
0 mm	7.80 kg / 7800.0 g 76.5 N	N/A
2 mm	5.00 kg / 4995.0 g 49.0 N	4.66 kg / 4662.0 g 45.7 N
5 mm	2.31 kg / 2310.0 g 22.7 N	2.16 kg / 2156.0 g 21.2 N
10 mm	0.60 kg / 600.0 g 5.9 N	0.56 kg / 560.0 g 5.5 N
20 mm	0.06 kg / 60.0 g 0.6 N	0.06 kg / 56.0 g 0.5 N
50 mm	0.00 kg / 0.0 g 0.0 N	0.00 kg / 0.0 g 0.0 N

Two magnetic products attract each other from a significantly greater distance than a magnet and steel setup. The connection of magnet-to-magnet produces a massive flux and a larger range of action. Want to build a powerful holder? Apply two magnets instead of a neodymium and a steel. Be careful that when attracting two neodymiums, the impact force is extreme. The repulsion force is a bit weaker than the connection force, but still significant.

Table 6: Hazards (implants) - precautionary measures
MP 20x10x5 / N38

Object / Device	Limit (Gauss) / mT	Safe distance
Pacemaker	5 Gs (0.5 mT)	14.5 cm
Hearing aid	10 Gs (1.0 mT)	11.5 cm
Timepiece	20 Gs (2.0 mT)	9.0 cm
Phone / Smartphone	40 Gs (4.0 mT)	6.5 cm
Car key	50 Gs (5.0 mT)	6.0 cm
Payment card	400 Gs (40.0 mT)	2.5 cm
HDD hard drive	600 Gs (60.0 mT)	2.0 cm

A strong magnetic field is a serious hazard to electronics and medical implants. These NdFeB products produce a flux that destroys function of digital equipment. Remember: the invisible magnetic field penetrates the body and housings. Exceptional care must be taken by people with cochlear implants and drug dispensers. Also at risk are: mechanical watches, remotes, speakers, and screens. Do not place the magnet near cards, HDD media, or sensitive navigation tools.

Table 7: Dynamics (cracking risk) - warning
MP 20x10x5 / N38

Start from (mm)	Speed (km/h)	Energy (J)
10 mm	25.62 km/h (7.12 m/s)	0.22 J
30 mm	42.41 km/h (11.78 m/s)	0.61 J
50 mm	54.70 km/h (15.19 m/s)	1.02 J
100 mm	77.35 km/h (21.49 m/s)	2.04 J

NdFeB products are very brittle – a strong collision with metal risks their cracking. Control the attraction moment – a magnet released freely becomes dangerous. Impact energy can trigger coating fragments or dangerous crushing to fingers. Always hold the magnet during mounting so it doesn't hit violently against the metal. A contact at a velocity of dozens of km/h ends with a crack of the neodymium. Use safety goggles when working with powerful specimens.

Table 8: Surface protection spec
MP 20x10x5 / 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: Underwater work (magnet fishing)
MP 20x10x5 / N38

Environment	Effective steel pull	Effect
Air (land)	5.20 kg	Standard
Water (riverbed)	5.95 kg (+0.75 kg Buoyancy gain)	+14.5%

Warning: Remember to wipe the magnet thoroughly after removing it from water and apply a protective layer (e.g., oil) to avoid corrosion.

Contrary to myths, water does not block the magnetic field. However, remember the water resistance when pulling the rope quickly.

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The ring-shaped magnet MP 20x10x5 / N38 is created for mechanical fastening, where glue might fail or be insufficient. Mounting is clean and reversible, unlike gluing. It is also often used in advertising for fixing signs and in workshops for organizing tools.

This material behaves more like porcelain than steel, so it doesn't forgive mistakes during mounting. When tightening the screw, you must maintain great sensitivity. We recommend tightening manually with a screwdriver, not an impact driver, because too much pressure will cause the ring to crack. The flat screw head should evenly press the magnet. Remember: cracking during assembly results from material properties, not a product defect.

Moisture can penetrate micro-cracks in the coating and cause oxidation of the magnet. In the place of the mounting hole, the coating is thinner and easily scratched when tightening the screw, which will become a corrosion focus. This product is dedicated for inside building use. For outdoor applications, we recommend choosing rubberized holders or additional protection with varnish.

A screw or bolt with a thread diameter smaller than 10 mm fits this model. 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 (20 mm), so it doesn't protrude beyond the outline.

It is a magnetic ring with a diameter of 20 mm and thickness 5 mm. The pulling force of this model is an impressive 5.20 kg, which translates to 50.97 N in newtons. The product has a [NiCuNi] coating and is made of NdFeB material. Inner hole dimension: 10 mm.

These magnets are magnetized axially (through the thickness), which means one flat side is the N pole and the other is S. 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 and disadvantages of NdFeB magnets.

Besides their immense strength, neodymium magnets offer the following advantages:

They do not lose power, even over nearly 10 years – the reduction in power is only ~1% (based on measurements),
They do not lose their magnetic properties even under close interference source,
The use of an shiny finish of noble metals (nickel, gold, silver) causes the element to have aesthetics,
Magnetic induction on the surface of the magnet is exceptional,
Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and can work (depending on the form) even at a temperature of 230°C or more...
Thanks to the ability of free shaping and adaptation to custom needs, magnetic components can be created in a wide range of forms and dimensions, which amplifies use scope,
Fundamental importance in modern technologies – they find application in computer drives, brushless drives, diagnostic systems, and complex engineering applications.
Thanks to concentrated force, small magnets offer high operating force, in miniature format,

Cons of neodymium magnets and ways of using them

At strong impacts they can break, therefore we recommend placing them in special holders. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
We warn that neodymium magnets can lose their power at high temperatures. To prevent this, we recommend our specialized [AH] magnets, which work effectively even at 230°C.
When exposed to humidity, magnets usually rust. For applications outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which prevent oxidation and corrosion.
We recommend a housing - magnetic mount, due to difficulties in creating threads inside the magnet and complicated shapes.
Health risk related to microscopic parts of magnets can be dangerous, when accidentally swallowed, which becomes key in the context of child safety. Additionally, small components of these magnets can be problematic in diagnostics medical when they are in the body.
Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Breakaway strength of the magnet in ideal conditions – what affects it?

The load parameter shown refers to the peak performance, measured under ideal test conditions, specifically:

on a base made of mild steel, optimally conducting the magnetic flux
possessing a massiveness of at least 10 mm to avoid saturation
with a plane free of scratches
without the slightest air gap between the magnet and steel
for force acting at a right angle (pull-off, not shear)
in neutral thermal conditions

Practical lifting capacity: influencing factors

It is worth knowing that the magnet holding will differ depending on the following factors, starting with the most relevant:

Distance (between the magnet and the metal), because even a microscopic distance (e.g. 0.5 mm) results in a drastic drop in force by up to 50% (this also applies to varnish, rust or debris).
Force direction – catalog parameter refers to detachment vertically. When applying parallel force, the magnet exhibits much less (typically approx. 20-30% of maximum force).
Wall 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.
Steel grade – the best choice is pure iron steel. Stainless steels may attract less.
Surface finish – ideal contact is possible only on smooth steel. Rough texture create air cushions, weakening the magnet.
Thermal conditions – neodymium magnets have a sensitivity to temperature. When it is hot they are weaker, and at low temperatures they can be stronger (up to a certain limit).

* Lifting capacity was assessed with the use of a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular pulling force, in contrast under attempts to slide the magnet the holding force is lower. Additionally, even a slight gap {between} the magnet’s surface and the plate decreases the lifting capacity.

Safety rules for work with NdFeB magnets

Warning for allergy sufferers

Medical facts indicate that the nickel plating (the usual finish) is a potent allergen. If you have an allergy, refrain from touching magnets with bare hands and choose coated magnets.

Cards and drives

Data protection: Strong magnets can ruin payment cards and sensitive devices (heart implants, medical aids, mechanical watches).

Serious injuries

Watch your fingers. Two large magnets will snap together immediately with a force of massive weight, destroying anything in their path. Be careful!

Combustion hazard

Combustion risk: Rare earth powder is highly flammable. Avoid machining magnets in home conditions as this risks ignition.

Choking Hazard

Absolutely keep magnets out of reach of children. Risk of swallowing is high, and the consequences of magnets clamping inside the body are very dangerous.

Medical implants

For implant holders: Strong magnetic fields affect electronics. Maintain minimum 30 cm distance or request help to handle the magnets.

Precision electronics

Remember: neodymium magnets produce a field that confuses precision electronics. Maintain a separation from your phone, device, and GPS.

Material brittleness

Beware of splinters. Magnets can fracture upon uncontrolled impact, launching shards into the air. Eye protection is mandatory.

Heat sensitivity

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

Do not underestimate power

Use magnets consciously. Their powerful strength can shock even experienced users. Be vigilant and do not underestimate their power.

Danger!

Looking for details? Check our post: Are neodymium magnets dangerous?

MP 20x10x5 / N38 - ring magnet

MP 20x10x5 / N38 - ring magnet

Magnetic properties of material N38

Physical properties of sintered neodymium magnets Nd2Fe14B at 20°C

Technical modeling of the product - data

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Advantages and disadvantages of NdFeB magnets.

Breakaway strength of the magnet in ideal conditions – what affects it?

Practical lifting capacity: influencing factors

Safety rules for work with NdFeB magnets

Physical properties of sintered neodymium magnets Nd₂Fe₁₄B at 20°C