Product available Ships in 3 days

MP 12x8/4x3 / N38 - ring 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

ring magnet

Catalog no 030395

GTIN: 5906301812326

5.00

Diameter

12 mm [±0,1 mm]

internal diameter Ø

8/4 mm [±0,1 mm]

Height

3 mm [±0,1 mm]

Weight

2.26 g

Magnetization Direction

↑ axial

Load capacity

1.49 kg / 14.65 N

Magnetic Induction

237.19 mT

Coating

[NiCuNi] Nickel

1.427 ZŁ with VAT / pcs + price for transport

1.160 ZŁ net + 23% VAT / pcs

bulk discounts:

Need more?

price from 1 pcs

1.160 ZŁ

1.427 ZŁ

price from 550 pcs

1.090 ZŁ

1.341 ZŁ

price from 2200 pcs

1.021 ZŁ

1.256 ZŁ

Carbon Footprint – environmental impact GPSR Regulation – product safety

Looking for a better price?

Give us a call +48 22 499 98 98 otherwise get in touch through our online form our website.
Force and appearance of magnetic components can be reviewed with our online calculation tool.

Order by 14:00 and we’ll ship today!

MP 12x8/4x3 / N38 - ring magnet

Specification / characteristics MP 12x8/4x3 / N38 - ring magnet

properties

properties	values
Cat. no.	030395
GTIN	5906301812326
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	12 mm [±0,1 mm]
internal diameter Ø	8/4 mm [±0,1 mm]
Height	3 mm [±0,1 mm]
Weight	2.26 g
Magnetization Direction	↑ axial
Load capacity ~ ?	1.49 kg / 14.65 N
Magnetic Induction ~ ?	237.19 mT
Coating	[NiCuNi] Nickel
Manufacturing Tolerance	±0.1 mm

Magnetic properties of material N38

Specification / characteristics MP 12x8/4x3 / 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 analysis of the assembly - technical parameters

The following information are the outcome of a mathematical calculation. Values are based on models for the class NdFeB. Real-world conditions might slightly deviate from the simulation results. Use these data as a supplementary guide for designers.

Table 1: Static force (pull vs gap) - characteristics
MP 12x8/4x3 / N38

Distance (mm)	Induction (Gauss) / mT	Pull Force (kg)	Risk Status
0 mm	2423 Gs 242.3 mT	1.49 kg / 1490.0 g 14.6 N	safe
1 mm	2138 Gs 213.8 mT	1.16 kg / 1160.1 g 11.4 N	safe
2 mm	1786 Gs 178.6 mT	0.81 kg / 809.4 g 7.9 N	safe
5 mm	885 Gs 88.5 mT	0.20 kg / 198.7 g 1.9 N	safe
10 mm	277 Gs 27.7 mT	0.02 kg / 19.5 g 0.2 N	safe
15 mm	110 Gs 11.0 mT	0.00 kg / 3.1 g 0.0 N	safe
20 mm	53 Gs 5.3 mT	0.00 kg / 0.7 g 0.0 N	safe
30 mm	18 Gs 1.8 mT	0.00 kg / 0.1 g 0.0 N	safe
50 mm	4 Gs 0.4 mT	0.00 kg / 0.0 g 0.0 N	safe

Magnetic force decreases drastically per each millimeter of spacing. Keep in mind that every additional insulation layer (e.g., dirt, varnish, dust) noticeably weakens the grip. Magnets hold most effectively at the point of direct contact; air break weakens the force. Observe how quickly the pull force fall, when the magnet does not adhere directly to the steel surface. When designing the mounting, eliminate additional spacers.

Table 2: Wall mounting (shearing) - vertical pull
MP 12x8/4x3 / N38

Surface type	Friction coefficient / % Mocy	Max load (kg)
Raw steel	µ = 0.3 30% Nominalnej Siły	0.45 kg / 447.0 g 4.4 N
Painted steel (standard)	µ = 0.2 20% Nominalnej Siły	0.30 kg / 298.0 g 2.9 N
Oily/slippery steel	µ = 0.1 10% Nominalnej Siły	0.15 kg / 149.0 g 1.5 N
Magnet with anti-slip rubber	µ = 0.5 50% Nominalnej Siły	0.75 kg / 745.0 g 7.3 N

When placing a element on a vertical plane (e.g., a fridge), it you can count on only approx. 20%-30% of nominal attraction strength. Gravity and a low friction coefficient cause that magnets slip faster than they detach. Planning a hanger? Consider that the shear force is much weaker than the maximum static pull force. On a painted metal, the element will give way down under a much lighter weight. Utilizing a rubberized layer can significantly increase the grip.

Table 3: Material efficiency (saturation) - power losses
MP 12x8/4x3 / N38

Steel thickness (mm)	% power	Real pull force (kg)
0.5 mm	10%	0.15 kg / 149.0 g 1.5 N
1 mm	25%	0.37 kg / 372.5 g 3.7 N
2 mm	50%	0.75 kg / 745.0 g 7.3 N
5 mm	100%	1.49 kg / 1490.0 g 14.6 N
10 mm	100%	1.49 kg / 1490.0 g 14.6 N

A thin metal plate is unable to conduct the entire magnetic field, which squanders power of the magnet. If you install a neodymium to a too thin substrate, the field will penetrate right through and the pull force will drop sharply. To achieve full efficiency of this neodymium's potential, you need a suitably thick element of steel. The material oversaturation causes that on sheet metal structures (e.g., appliance housings), the holder works worse. We recommend selecting the steel thickness from these parameters.

Table 4: Thermal resistance (material behavior) - power drop
MP 12x8/4x3 / N38

Ambient temp. (°C)	Power loss	Remaining pull	Status
20 °C	0.0%	1.49 kg / 1490.0 g 14.6 N	OK
40 °C	-2.2%	1.46 kg / 1457.2 g 14.3 N	OK
60 °C	-4.4%	1.42 kg / 1424.4 g 14.0 N	OK
80 °C	-6.6%	1.39 kg / 1391.7 g 13.7 N
100 °C	-28.8%	1.06 kg / 1060.9 g 10.4 N

Ordinary NdFeB products lose strength past the thermal threshold. Protect against heat – excessive heat can permanently damage this product. As the temperature rises, the neodymium's capacity momentarily decreases. Do not use this magnet close to heaters higher than its operating temperature limit. Ignoring the limit will cause destruction of magnetism.

Table 5: Two magnets (repulsion) - forces in the system
MP 12x8/4x3 / N38

Gap (mm)	Attraction (kg) (N-S)	Repulsion (kg) (N-N)
0 mm	2.24 kg / 2235.0 g 21.9 N	N/A
2 mm	1.22 kg / 1215.0 g 11.9 N	1.13 kg / 1134.0 g 11.1 N
5 mm	0.30 kg / 300.0 g 2.9 N	0.28 kg / 280.0 g 2.7 N
10 mm	0.03 kg / 30.0 g 0.3 N	0.03 kg / 28.0 g 0.3 N
20 mm	0.00 kg / 0.0 g 0.0 N	0.00 kg / 0.0 g 0.0 N
50 mm	0.00 kg / 0.0 g 0.0 N	0.00 kg / 0.0 g 0.0 N

Two magnetic products interact from a wider radius than a magnet and sheet combination. Such a system of two magnets produces a massive flux and a wider radius of operation. Planning to create a strong closure? Utilize two neodymiums instead of a neodymium and a striker plate. Remember that when attracting two neodymiums, the impact force is huge. The repulsion force is marginally weaker than the connection force, but still significant.

Table 6: Protective zones (electronics) - warnings
MP 12x8/4x3 / N38

Object / Device	Limit (Gauss) / mT	Safe distance
Pacemaker	5 Gs (0.5 mT)	5.0 cm
Hearing aid	10 Gs (1.0 mT)	4.0 cm
Mechanical watch	20 Gs (2.0 mT)	3.0 cm
Mobile device	40 Gs (4.0 mT)	2.5 cm
Car key	50 Gs (5.0 mT)	2.5 cm
Payment card	400 Gs (40.0 mT)	1.0 cm
HDD hard drive	600 Gs (60.0 mT)	1.0 cm

Powerful magnet radiation is a large risk to electronic devices as well as medical implants. These magnets generate a flux that destroys function of digital equipment. Be aware: the invisible magnetic field penetrates the body and plastic. Increased vigilance must be exercised by people with cochlear implants and drug dispensers. Also at risk are: mechanical watches, car keys, membranes, and screens. Do not bring the product near payment cards, hard drives, or sensitive navigation tools.

Table 7: Impact energy (cracking risk) - warning
MP 12x8/4x3 / N38

Start from (mm)	Speed (km/h)	Energy (J)
10 mm	26.11 km/h (7.25 m/s)	0.06 J
30 mm	44.85 km/h (12.46 m/s)	0.18 J
50 mm	57.90 km/h (16.08 m/s)	0.29 J
100 mm	81.89 km/h (22.75 m/s)	0.58 J

NdFeB products are prone to chipping – a strong collision with metal risks their cracking. Watch the impact speed – a neodymium left loose speeds with massive force. Striking energy can cause material chips or dangerous crushing to fingers. Always hold the magnet during mounting so it doesn't hit with great force against the metal. A collision at high speed almost guarantees destruction of the neodymium. Use safety goggles when working with large magnets.

Table 8: Coating parameters (durability)
MP 12x8/4x3 / 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 SST (salt spray test) is an industry standard for determining coating lifespan in harsh conditions. The silver nickel coating also serves an aesthetic function but is not fully waterproof.

Table 9: Underwater work (magnet fishing)
MP 12x8/4x3 / N38

Environment	Effective steel pull	Effect
Air (land)	1.49 kg	Standard
Water (riverbed)	1.71 kg (+0.22 kg Buoyancy gain)	+14.5%

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

Water displaces steel, making heavy objects slightly lighter. Buoyancy helps in lifting finds.

View more offers

Product available Ships in 3 days

MP 10x4.3x4 / N38 - ring magnet

1.045 ZŁ brutto / pcs

Product available Ships in 3 days

MPL 40x10x4 / N38 - lamellar magnet

4.87 ZŁ brutto / pcs

Product available Ships in 3 days

MW 10x6 / N38 - cylindrical magnet

1.045 ZŁ brutto / pcs

Product available Ships in 3 days

SMZR 25x125 / N52 - magnetic separator with handle

369.00 ZŁ brutto / pcs

It is ideally suited for places where solid attachment of the magnet to the substrate is required without the risk of detachment. 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. One turn too many can destroy the magnet, so do it slowly. 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 indoor use. For outdoor applications, we recommend choosing magnets in hermetic housing or additional protection with varnish.

A screw or bolt with a thread diameter smaller than 8/4 mm fits this model. If the magnet does not have a chamfer (cone), we recommend using a screw with a flat or cylindrical head, or possibly using a washer. Always check that the screw head is not larger than the outer diameter of the magnet (12 mm), so it doesn't protrude beyond the outline.

This model is characterized by dimensions Ø12x3 mm and a weight of 2.26 g. The key parameter here is the holding force amounting to approximately 1.49 kg (force ~14.65 N). The product has a [NiCuNi] coating and is made of NdFeB material. Inner hole dimension: 8/4 mm.

The poles are located on the planes with holes, not on the sides of the ring. 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.

Pros as well as cons of neodymium magnets.

Besides their exceptional magnetic power, neodymium magnets offer the following advantages:

They have stable power, and over more than 10 years their attraction force decreases symbolically – ~1% (according to theory),
They feature excellent resistance to magnetic field loss when exposed to external fields,
Thanks to the shiny finish, the surface of nickel, gold-plated, or silver gives an elegant appearance,
They are known for high magnetic induction at the operating surface, which affects their effectiveness,
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...
In view of the possibility of precise shaping and adaptation to custom solutions, neodymium magnets can be modeled in a variety of forms and dimensions, which expands the range of possible applications,
Huge importance in modern technologies – they serve a role in data components, brushless drives, medical devices, also industrial machines.
Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in small dimensions, which enables their usage in small systems

Disadvantages of neodymium magnets:

To avoid cracks upon strong impacts, we suggest using special steel housings. Such a solution protects the magnet and simultaneously increases its durability.
Neodymium magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of strength (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 extremely resistant to heat
They rust in a humid environment. For use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
Due to limitations in realizing nuts and complex shapes in magnets, we propose using casing - magnetic mechanism.
Possible danger related to microscopic parts of magnets pose a threat, when accidentally swallowed, which gains importance in the context of child safety. Furthermore, small elements of these magnets are able to be problematic in diagnostics medical in case of swallowing.
With large orders the cost of neodymium magnets is a challenge,

Maximum lifting capacity of the magnet – what contributes to it?

Breakaway force was defined for ideal contact conditions, taking into account:

using a base made of low-carbon steel, serving as a ideal flux conductor
possessing a thickness of min. 10 mm to ensure full flux closure
characterized by even structure
without any insulating layer between the magnet and steel
during pulling in a direction perpendicular to the plane
in stable room temperature

Practical lifting capacity: influencing factors

Effective lifting capacity impacted by specific conditions, including (from priority):

Clearance – the presence of foreign body (paint, dirt, air) interrupts the magnetic circuit, which lowers capacity steeply (even by 50% at 0.5 mm).
Pull-off angle – note that the magnet holds strongest perpendicularly. Under shear forces, the holding force drops significantly, often to levels of 20-30% of the maximum value.
Base massiveness – too thin steel causes magnetic saturation, causing part of the power to be escaped to the other side.
Steel grade – ideal substrate is pure iron steel. Stainless steels may attract less.
Surface finish – full contact is possible only on polished steel. Any scratches and bumps create air cushions, weakening the magnet.
Heat – NdFeB sinters have a negative temperature coefficient. At higher temperatures they lose power, and at low temperatures gain strength (up to a certain limit).

* Lifting capacity testing was conducted on a smooth plate of optimal thickness, under a perpendicular pulling force, whereas under attempts to slide the magnet the load capacity is reduced by as much as fivefold. Additionally, even a minimal clearance {between} the magnet’s surface and the plate reduces the lifting capacity.

Safety rules for work with NdFeB magnets

Combustion hazard

Powder created during cutting of magnets is self-igniting. Do not drill into magnets without proper cooling and knowledge.

Health Danger

Health Alert: Neodymium magnets can deactivate heart devices and defibrillators. Do not approach if you have electronic implants.

Magnet fragility

Despite the nickel coating, the material is brittle and not impact-resistant. Do not hit, as the magnet may crumble into sharp, dangerous pieces.

GPS and phone interference

Navigation devices and smartphones are extremely susceptible to magnetic fields. Close proximity with a powerful NdFeB magnet can permanently damage the internal compass in your phone.

Respect the power

Handle with care. Rare earth magnets act from a distance and snap with massive power, often faster than you can react.

Swallowing risk

NdFeB magnets are not suitable for play. Swallowing several magnets may result in them connecting inside the digestive tract, which constitutes a severe health hazard and requires immediate surgery.

Serious injuries

Watch your fingers. Two powerful magnets will join instantly with a force of massive weight, crushing everything in their path. Be careful!

Maximum temperature

Regular neodymium magnets (N-type) undergo demagnetization when the temperature goes above 80°C. The loss of strength is permanent.

Data carriers

Do not bring magnets close to a purse, laptop, or TV. The magnetic field can destroy these devices and wipe information from cards.

Nickel allergy

Warning for allergy sufferers: The nickel-copper-nickel coating consists of nickel. If an allergic reaction happens, cease handling magnets and wear gloves.

Security!

Learn more about risks in the article: Safety of working with magnets.

MP 12x8/4x3 / N38 - ring magnet

MP 12x8/4x3 / N38 - ring magnet

Magnetic properties of material N38

Physical properties of sintered neodymium magnets Nd2Fe14B at 20°C

Technical analysis of the assembly - technical parameters

View more offers

MP 10x4.3x4 / N38 - ring magnet

MPL 40x10x4 / N38 - lamellar magnet

MW 10x6 / N38 - cylindrical magnet

SMZR 25x125 / N52 - magnetic separator with handle

Pros as well as cons of neodymium magnets.

Maximum lifting capacity of the magnet – what contributes to it?

Practical lifting capacity: influencing factors

Safety rules for work with NdFeB magnets

Physical properties of sintered neodymium magnets Nd₂Fe₁₄B at 20°C