Product available Ships today (order by 14:00)

MP 15x7/3.5x5 / 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 030390

GTIN/EAN: 5906301812302

5.00

Diameter

15 mm [±0,1 mm]

internal diameter Ø

7/3.5 mm [±0,1 mm]

Height

5 mm [±0,1 mm]

Weight

6.27 g

Magnetization Direction

↑ axial

Load capacity

5.09 kg / 49.95 N

Magnetic Induction

343.70 mT / 3437 Gs

Coating

[NiCuNi] Nickel

3.44 ZŁ with VAT / pcs + price for transport

2.80 ZŁ net + 23% VAT / pcs

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MP 15x7/3.5x5 / N38 - ring magnet

Specification / characteristics MP 15x7/3.5x5 / N38 - ring magnet

properties

properties	values
Cat. no.	030390
GTIN/EAN	5906301812302
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	15 mm [±0,1 mm]
internal diameter Ø	7/3.5 mm [±0,1 mm]
Height	5 mm [±0,1 mm]
Weight	6.27 g
Magnetization Direction	↑ axial
Load capacity ~ ?	5.09 kg / 49.95 N
Magnetic Induction ~ ?	343.70 mT / 3437 Gs
Coating	[NiCuNi] Nickel
Manufacturing Tolerance	±0.1 mm

Magnetic properties of material N38

Specification / characteristics MP 15x7/3.5x5 / N38 - ring 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

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 - report

The following information constitute the outcome of a engineering simulation. Results are based on models for the class Nd₂Fe₁₄B. Actual parameters may deviate from the simulation results. Treat these calculations as a preliminary roadmap when designing systems.

Table 1: Static pull force (force vs distance) - interaction chart
MP 15x7/3.5x5 / N38

Distance (mm)	Induction (Gauss) / mT	Pull Force (kg)	Risk Status
0 mm	3054 Gs 305.4 mT	5.09 kg / 5090.0 g 49.9 N	strong
1 mm	2736 Gs 273.6 mT	4.09 kg / 4085.7 g 40.1 N	strong
2 mm	2372 Gs 237.2 mT	3.07 kg / 3069.9 g 30.1 N	strong
3 mm	2007 Gs 200.7 mT	2.20 kg / 2197.4 g 21.6 N	strong
5 mm	1377 Gs 137.7 mT	1.03 kg / 1034.5 g 10.1 N	safe
10 mm	526 Gs 52.6 mT	0.15 kg / 151.3 g 1.5 N	safe
15 mm	232 Gs 23.2 mT	0.03 kg / 29.3 g 0.3 N	safe
20 mm	118 Gs 11.8 mT	0.01 kg / 7.6 g 0.1 N	safe
30 mm	42 Gs 4.2 mT	0.00 kg / 0.9 g 0.0 N	safe
50 mm	10 Gs 1.0 mT	0.00 kg / 0.1 g 0.0 N	safe

Pulling power decreases drastically with every subsequent millimeter of gap. Note that even the smallest gap (e.g., contamination, paint, dust) noticeably weakens the grip. Neodymiums hold strongest during direct contact; gap weakens the power. See how flashily the pull force plummet, when the magnet does not touch tightly to the metal substrate. When planning the mounting, discard unnecessary gaps.

Table 2: Vertical load (vertical surface)
MP 15x7/3.5x5 / N38

Distance (mm)	Friction coefficient	Pull Force (kg)
0 mm	Stal (~0.2)	1.02 kg / 1018.0 g 10.0 N
1 mm	Stal (~0.2)	0.82 kg / 818.0 g 8.0 N
2 mm	Stal (~0.2)	0.61 kg / 614.0 g 6.0 N
3 mm	Stal (~0.2)	0.44 kg / 440.0 g 4.3 N
5 mm	Stal (~0.2)	0.21 kg / 206.0 g 2.0 N
10 mm	Stal (~0.2)	0.03 kg / 30.0 g 0.3 N
15 mm	Stal (~0.2)	0.01 kg / 6.0 g 0.1 N
20 mm	Stal (~0.2)	0.00 kg / 2.0 g 0.0 N
30 mm	Stal (~0.2)	0.00 kg / 0.0 g 0.0 N
50 mm	Stal (~0.2)	0.00 kg / 0.0 g 0.0 N

The table below indicates the approximate holding capacity required to initiate the sliding of the magnet downwards on a vertical steel wall (assuming typical friction). This parameter depends on the air gap between the magnet and the surface.

Table 3: Wall mounting (shearing) - behavior on slippery surfaces
MP 15x7/3.5x5 / N38

Surface type	Friction coefficient / % Mocy	Max load (kg)
Raw steel	µ = 0.3 30% Nominalnej Siły	1.53 kg / 1527.0 g 15.0 N
Painted steel (standard)	µ = 0.2 20% Nominalnej Siły	1.02 kg / 1018.0 g 10.0 N
Oily/slippery steel	µ = 0.1 10% Nominalnej Siły	0.51 kg / 509.0 g 5.0 N
Magnet with anti-slip rubber	µ = 0.5 50% Nominalnej Siły	2.55 kg / 2545.0 g 25.0 N

When mounting a holder on a upright surface (e.g., a car body), it you can count on barely approx. 20%-30% of nominal attraction strength. Gravitational force and a weak degree of grip mean that magnets move down easier than they pull off. Designing a hanger? Note that the shear force is significantly lower than the maximum static pull force. On a smooth steel, the element will slip down under a much lighter load. Utilizing a rubberized coating can effectively improve the result.

Table 4: Steel thickness (substrate influence) - power losses
MP 15x7/3.5x5 / N38

Steel thickness (mm)	% power	Real pull force (kg)
0.5 mm	10%	0.51 kg / 509.0 g 5.0 N
1 mm	25%	1.27 kg / 1272.5 g 12.5 N
2 mm	50%	2.55 kg / 2545.0 g 25.0 N
5 mm	100%	5.09 kg / 5090.0 g 49.9 N
10 mm	100%	5.09 kg / 5090.0 g 49.9 N

A thin sheet is unable to focus the full magnetic flux, which weakens actual performance of the holder. If you install a neodymium to a weak sheet, the magnetism will pass right through and the pull force will drop sharply. To utilize the maximum of this magnet's potential, you need a suitably thick backing of steel. The material oversaturation causes that on delicate walls (e.g., appliance housings), the product works worse. We advise picking the steel dimension according to the table below.

Table 5: Thermal stability (stability) - resistance threshold
MP 15x7/3.5x5 / N38

Ambient temp. (°C)	Power loss	Remaining pull	Status
20 °C	0.0%	5.09 kg / 5090.0 g 49.9 N	OK
40 °C	-2.2%	4.98 kg / 4978.0 g 48.8 N	OK
60 °C	-4.4%	4.87 kg / 4866.0 g 47.7 N
80 °C	-6.6%	4.75 kg / 4754.1 g 46.6 N
100 °C	-28.8%	3.62 kg / 3624.1 g 35.6 N

Standard neodymium magnets irreversibly lose parameters after exceeding the maximum temperature. Protect against heat – excessive heat can irreversibly demagnetize this product. As the temperature rises, the magnet's power temporarily lowers. Do not use this magnet in hot environments higher than its safe range. Too high temperature will cause permanent loss of magnetism.

*Engineering note: Heat tolerance is determined by both grade, as well as the dimension ratios. Thin magnets (low Pc) may lose charge permanently under lower heat stress than taller cylinders. Warning indicator in the table points to a risk of irreversible loss for this specific geometry.

Table 6: Magnet-Magnet interaction (attraction) - field collision
MP 15x7/3.5x5 / N38

Gap (mm)	Attraction (kg) (N-S)	Repulsion (kg) (N-N)
0 mm	8.17 kg / 8166 g 80.1 N 4 643 Gs	N/A
1 mm	7.39 kg / 7389 g 72.5 N 5 810 Gs	6.65 kg / 6650 g 65.2 N ~0 Gs
2 mm	6.55 kg / 6555 g 64.3 N 5 472 Gs	5.90 kg / 5899 g 57.9 N ~0 Gs
3 mm	5.72 kg / 5722 g 56.1 N 5 113 Gs	5.15 kg / 5150 g 50.5 N ~0 Gs
5 mm	4.19 kg / 4188 g 41.1 N 4 374 Gs	3.77 kg / 3769 g 37.0 N ~0 Gs
10 mm	1.66 kg / 1660 g 16.3 N 2 753 Gs	1.49 kg / 1494 g 14.7 N ~0 Gs
20 mm	0.24 kg / 243 g 2.4 N 1 053 Gs	0.22 kg / 218 g 2.1 N ~0 Gs
50 mm	0.00 kg / 4 g 0.0 N 134 Gs	0.00 kg / 0 g 0.0 N ~0 Gs

Two magnets attract each other from a much further distance than a magnet and sheet combination. The connection of magnet-to-magnet generates a stronger field and a further horizon of action. Want to build a powerful holder? Apply two magnets instead of a neodymium and a striker plate. Remember that when attracting two neodymiums, the impact force is massive. The repulsion force is slightly lower than the attraction, but still impressive.
*Field value for N-N configuration drops to ~0 Gs in the exact middle between the magnets (caused by magnetic field nullification).

Table 7: Safety (HSE) (implants) - warnings
MP 15x7/3.5x5 / N38

Object / Device	Limit (Gauss) / mT	Safe distance
Pacemaker	5 Gs (0.5 mT)	6.5 cm
Hearing aid	10 Gs (1.0 mT)	5.5 cm
Timepiece	20 Gs (2.0 mT)	4.0 cm
Phone / Smartphone	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

Powerful magnet radiation poses a serious hazard to IT equipment as well as pacemakers. These neodymiums produce a field that prevents correct functioning of sensitive medical devices. Be aware: the unseen radiation passes through tissues and housings. Exceptional care must be exercised by people with hearing aids and drug dispensers. Influence will be felt by: mechanical watches, remotes, speakers, and displays. Do not bring the product near payment cards, HDD media, or sensitive navigation tools.

Table 8: Collisions (cracking risk) - collision effects
MP 15x7/3.5x5 / N38

Start from (mm)	Speed (km/h)	Energy (J)
10 mm	29.26 km/h (8.13 m/s)	0.21 J
30 mm	49.78 km/h (13.83 m/s)	0.60 J
50 mm	64.25 km/h (17.85 m/s)	1.00 J
100 mm	90.87 km/h (25.24 m/s)	2.00 J

Neodymium magnets are delicate – a collision with steel can result in shattering. Control the attraction moment – a magnet released freely speeds with massive force. Impact energy can cause material chips or dangerous crushing to skin. Hold the magnet firmly during installation so it doesn't hit with great force against the steel surface. A collision at high speed ends with a crack of the magnet. Wear safety glasses when playing with large magnets.

Table 9: Anti-corrosion coating durability
MP 15x7/3.5x5 / 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. Moisture resistance is crucial for installations in bathrooms or outdoors.

Table 10: Electrical data (Flux)
MP 15x7/3.5x5 / N38

Parameter	Value	SI Unit / Description
Magnetic Flux	4 791 Mx	47.9 µWb
P_c Coefficient	0.39	Low (Flat)

Total magnetic flux emitted by the magnet pole. Key data in coil applications and motors. P_c value determines the working geometry.

Table 11: Underwater work (magnet fishing)
MP 15x7/3.5x5 / N38

Environment	Effective steel pull	Effect
Air (land)	5.09 kg	Standard
Water (riverbed)	5.83 kg (+0.74 kg Buoyancy gain)	+14.5%

Rust risk: Standard nickel requires drying after every contact with moisture; lack of maintenance will lead to rust spots.

Contrary to myths, water does not block the magnetic field. Note: for permanent underwater work, we recommend magnets with an anti-corrosive (epoxy) coating.

1. Wall mount (shear)

*Warning: On a vertical surface, the magnet holds just ~20% of its perpendicular strength.

2. Efficiency vs thickness

*Thin metal sheet (e.g. 0.5mm PC case) significantly limits the holding force.

3. Heat tolerance

*For N38 grade, the critical limit is 80°C.

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

chart generated for the permeance coefficient P_c (Permeance Coefficient) = 0.39

This simulation demonstrates the magnetic stability of the selected magnet under specific geometric conditions. 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 P_c (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 P_c 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 specification and ecology

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%

Environmental data

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: 030390-2025

Magnet Unit Converter

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Force (N)

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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 is a crucial issue when working with model MP 15x7/3.5x5 / N38. Neodymium magnets are sintered ceramics, which means they are hard but breakable and inelastic. One turn too many can destroy the magnet, so do it slowly. It's a good idea to use a rubber spacer under the screw head, which will cushion the stresses. 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 rubberized holders or additional protection with varnish.

The inner hole diameter determines the maximum size of the mounting element. 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 (15 mm), so it doesn't protrude beyond the outline.

It is a magnetic ring with a diameter of 15 mm and thickness 5 mm. The key parameter here is the holding force amounting to approximately 5.09 kg (force ~49.95 N). The product has a [NiCuNi] coating and is made of NdFeB material. Inner hole dimension: 7/3.5 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.

Pros as well as cons of neodymium magnets.

Benefits

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

They do not lose magnetism, even after nearly ten years – the decrease in strength is only ~1% (according to tests),
Neodymium magnets are highly resistant to magnetic field loss caused by magnetic disturbances,
The use of an refined coating of noble metals (nickel, gold, silver) causes the element to present itself better,
The surface of neodymium magnets generates a strong magnetic field – this is a key feature,
Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and can work (depending on the shape) even at a temperature of 230°C or more...
Possibility of exact modeling and adjusting to atypical needs,
Fundamental importance in electronics industry – they are commonly used in HDD drives, electric drive systems, advanced medical instruments, as well as technologically advanced constructions.
Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Limitations

Disadvantages of NdFeB magnets:

To avoid cracks under impact, we suggest using special steel holders. Such a solution protects the magnet and simultaneously improves its durability.
Neodymium magnets lose their strength under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
Due to the susceptibility of magnets to corrosion in a humid environment, we suggest using waterproof magnets made of rubber, plastic or other material stable to moisture, in case of application outdoors
We suggest cover - magnetic mechanism, due to difficulties in realizing nuts inside the magnet and complicated forms.
Possible danger to health – tiny shards of magnets are risky, if swallowed, which is particularly important in the context of child safety. It is also worth noting that small components of these products are able to be problematic in diagnostics medical when they are in the body.
With large orders the cost of neodymium magnets can be a barrier,

Holding force characteristics

Optimal lifting capacity of a neodymium magnet – what contributes to it?

Breakaway force was defined for optimal configuration, assuming:

on a plate made of mild steel, perfectly concentrating the magnetic field
with a thickness no less than 10 mm
with an polished touching surface
with direct contact (without coatings)
under perpendicular application of breakaway force (90-degree angle)
at room temperature

Lifting capacity in real conditions – factors

Bear in mind that the working load will differ influenced by the following factors, starting with the most relevant:

Gap between magnet and steel – every millimeter of distance (caused e.g. by veneer or unevenness) significantly weakens the pulling force, often by half at just 0.5 mm.
Force direction – note that the magnet has greatest strength perpendicularly. Under shear forces, the capacity drops drastically, often to levels of 20-30% of the nominal value.
Base massiveness – insufficiently thick sheet does not accept the full field, causing part of the power to be escaped to the other side.
Material composition – not every steel attracts identically. High carbon content weaken the attraction effect.
Surface condition – smooth surfaces guarantee perfect abutment, which increases field saturation. Rough surfaces reduce efficiency.
Temperature influence – high temperature reduces magnetic field. Too high temperature can permanently damage the magnet.

Lifting capacity testing was conducted on a smooth plate of optimal thickness, under a perpendicular pulling force, whereas under parallel forces the lifting capacity is smaller. In addition, even a small distance between the magnet and the plate decreases the load capacity.

Safety rules for work with neodymium magnets

Impact on smartphones

A strong magnetic field negatively affects the operation of magnetometers in smartphones and navigation systems. Do not bring magnets close to a smartphone to prevent damaging the sensors.

Thermal limits

Standard neodymium magnets (grade N) undergo demagnetization when the temperature surpasses 80°C. The loss of strength is permanent.

Implant safety

Life threat: Neodymium magnets can deactivate pacemakers and defibrillators. Do not approach if you have electronic implants.

Data carriers

Powerful magnetic fields can destroy records on credit cards, HDDs, and other magnetic media. Maintain a gap of at least 10 cm.

Do not drill into magnets

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

Choking Hazard

NdFeB magnets are not intended for children. Eating a few magnets may result in them pinching intestinal walls, which poses a severe health hazard and necessitates urgent medical intervention.

Metal Allergy

Medical facts indicate that the nickel plating (the usual finish) is a potent allergen. If you have an allergy, avoid touching magnets with bare hands or opt for coated magnets.

Magnets are brittle

Neodymium magnets are sintered ceramics, which means they are prone to chipping. Collision of two magnets leads to them cracking into small pieces.

Pinching danger

Big blocks can smash fingers in a fraction of a second. Never put your hand between two attracting surfaces.

Caution required

Before starting, read the rules. Uncontrolled attraction can break the magnet or hurt your hand. Think ahead.

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

MP 15x7/3.5x5 / N38 - ring magnet

Not sure what to buy?

MP 15x7/3.5x5 / N38 - ring magnet

Magnetic properties of material N38

Physical properties of sintered neodymium magnets Nd2Fe14B at 20°C

Engineering simulation of the product - report

1. Wall mount (shear)

2. Efficiency vs thickness

3. Heat tolerance

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

Chemical composition

Environmental data

Force (pull)

Magnetic Induction

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Pros as well as cons of neodymium magnets.

Benefits

Limitations

Holding force characteristics

Optimal lifting capacity of a neodymium magnet – what contributes to it?

Lifting capacity in real conditions – factors

Impact on smartphones

Thermal limits

Implant safety

Data carriers

Do not drill into magnets

Choking Hazard

Metal Allergy

Magnets are brittle

Pinching danger

Caution required

Physical properties of sintered neodymium magnets Nd₂Fe₁₄B at 20°C