MP 15x7/3.5x3 / N38 - ring magnet
ring magnet
Catalog no 030182
GTIN/EAN: 5906301811992
Diameter
15 mm [±0,1 mm]
internal diameter Ø
7/3.5 mm [±0,1 mm]
Height
3 mm [±0,1 mm]
Weight
3.76 g
Magnetization Direction
↑ axial
Load capacity
2.71 kg / 26.61 N
Magnetic Induction
230.16 mT / 2302 Gs
Coating
[NiCuNi] Nickel
1.747 ZŁ with VAT / pcs + price for transport
1.420 ZŁ net + 23% VAT / pcs
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Technical of the product - MP 15x7/3.5x3 / N38 - ring magnet
Specification / characteristics - MP 15x7/3.5x3 / N38 - ring magnet
| properties | values |
|---|---|
| Cat. no. | 030182 |
| GTIN/EAN | 5906301811992 |
| Production/Distribution | Dhit sp. z o.o. |
| 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 | 3 mm [±0,1 mm] |
| Weight | 3.76 g |
| Magnetization Direction | ↑ axial |
| Load capacity ~ ? | 2.71 kg / 26.61 N |
| Magnetic Induction ~ ? | 230.16 mT / 2302 Gs |
| Coating | [NiCuNi] Nickel |
| Manufacturing Tolerance | ±0.1 mm |
Magnetic properties of material N38
| 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 |
Physical analysis of the product - technical parameters
These information are the direct effect of a mathematical analysis. Values are based on models for the material Nd2Fe14B. Operational parameters may differ from theoretical values. Use these data as a preliminary roadmap when designing systems.
Table 1: Static pull force (force vs gap) - power drop
MP 15x7/3.5x3 / N38
| Distance (mm) | Induction (Gauss) / mT | Pull Force (kg/lbs/g/N) | Risk Status |
|---|---|---|---|
| 0 mm |
1995 Gs
199.5 mT
|
2.71 kg / 5.97 LBS
2710.0 g / 26.6 N
|
warning |
| 1 mm |
1833 Gs
183.3 mT
|
2.29 kg / 5.05 LBS
2289.1 g / 22.5 N
|
warning |
| 2 mm |
1618 Gs
161.8 mT
|
1.78 kg / 3.93 LBS
1784.1 g / 17.5 N
|
low risk |
| 3 mm |
1385 Gs
138.5 mT
|
1.31 kg / 2.88 LBS
1307.5 g / 12.8 N
|
low risk |
| 5 mm |
959 Gs
95.9 mT
|
0.63 kg / 1.38 LBS
627.1 g / 6.2 N
|
low risk |
| 10 mm |
362 Gs
36.2 mT
|
0.09 kg / 0.20 LBS
89.3 g / 0.9 N
|
low risk |
| 15 mm |
156 Gs
15.6 mT
|
0.02 kg / 0.04 LBS
16.5 g / 0.2 N
|
low risk |
| 20 mm |
78 Gs
7.8 mT
|
0.00 kg / 0.01 LBS
4.1 g / 0.0 N
|
low risk |
| 30 mm |
27 Gs
2.7 mT
|
0.00 kg / 0.00 LBS
0.5 g / 0.0 N
|
low risk |
| 50 mm |
6 Gs
0.6 mT
|
0.00 kg / 0.00 LBS
0.0 g / 0.0 N
|
low risk |
Table 2: Sliding capacity (vertical surface)
MP 15x7/3.5x3 / N38
| Distance (mm) | Friction coefficient | Pull Force (kg/lbs/g/N) |
|---|---|---|
| 0 mm | Stal (~0.2) |
0.54 kg / 1.19 LBS
542.0 g / 5.3 N
|
| 1 mm | Stal (~0.2) |
0.46 kg / 1.01 LBS
458.0 g / 4.5 N
|
| 2 mm | Stal (~0.2) |
0.36 kg / 0.78 LBS
356.0 g / 3.5 N
|
| 3 mm | Stal (~0.2) |
0.26 kg / 0.58 LBS
262.0 g / 2.6 N
|
| 5 mm | Stal (~0.2) |
0.13 kg / 0.28 LBS
126.0 g / 1.2 N
|
| 10 mm | Stal (~0.2) |
0.02 kg / 0.04 LBS
18.0 g / 0.2 N
|
| 15 mm | Stal (~0.2) |
0.00 kg / 0.01 LBS
4.0 g / 0.0 N
|
| 20 mm | Stal (~0.2) |
0.00 kg / 0.00 LBS
0.0 g / 0.0 N
|
| 30 mm | Stal (~0.2) |
0.00 kg / 0.00 LBS
0.0 g / 0.0 N
|
| 50 mm | Stal (~0.2) |
0.00 kg / 0.00 LBS
0.0 g / 0.0 N
|
Table 3: Vertical assembly (shearing) - vertical pull
MP 15x7/3.5x3 / N38
| Surface type | Friction coefficient / % Mocy | Max load (kg/lbs/g/N) |
|---|---|---|
| Raw steel |
µ = 0.3
30% Nominalnej Siły
|
0.81 kg / 1.79 LBS
813.0 g / 8.0 N
|
| Painted steel (standard) |
µ = 0.2
20% Nominalnej Siły
|
0.54 kg / 1.19 LBS
542.0 g / 5.3 N
|
| Oily/slippery steel |
µ = 0.1
10% Nominalnej Siły
|
0.27 kg / 0.60 LBS
271.0 g / 2.7 N
|
| Magnet with anti-slip rubber |
µ = 0.5
50% Nominalnej Siły
|
1.36 kg / 2.99 LBS
1355.0 g / 13.3 N
|
Table 4: Steel thickness (substrate influence) - power losses
MP 15x7/3.5x3 / N38
| Steel thickness (mm) | % power | Real pull force (kg/lbs/g/N) |
|---|---|---|
| 0.5 mm |
|
0.27 kg / 0.60 LBS
271.0 g / 2.7 N
|
| 1 mm |
|
0.68 kg / 1.49 LBS
677.5 g / 6.6 N
|
| 2 mm |
|
1.36 kg / 2.99 LBS
1355.0 g / 13.3 N
|
| 3 mm |
|
2.03 kg / 4.48 LBS
2032.5 g / 19.9 N
|
| 5 mm |
|
2.71 kg / 5.97 LBS
2710.0 g / 26.6 N
|
| 10 mm |
|
2.71 kg / 5.97 LBS
2710.0 g / 26.6 N
|
| 11 mm |
|
2.71 kg / 5.97 LBS
2710.0 g / 26.6 N
|
| 12 mm |
|
2.71 kg / 5.97 LBS
2710.0 g / 26.6 N
|
Table 5: Thermal resistance (material behavior) - thermal limit
MP 15x7/3.5x3 / N38
| Ambient temp. (°C) | Power loss | Remaining pull (kg/lbs/g/N) | Status |
|---|---|---|---|
| 20 °C | 0.0% |
2.71 kg / 5.97 LBS
2710.0 g / 26.6 N
|
OK |
| 40 °C | -2.2% |
2.65 kg / 5.84 LBS
2650.4 g / 26.0 N
|
OK |
| 60 °C | -4.4% |
2.59 kg / 5.71 LBS
2590.8 g / 25.4 N
|
|
| 80 °C | -6.6% |
2.53 kg / 5.58 LBS
2531.1 g / 24.8 N
|
|
| 100 °C | -28.8% |
1.93 kg / 4.25 LBS
1929.5 g / 18.9 N
|
Table 6: Two magnets (repulsion) - field range
MP 15x7/3.5x3 / N38
| Gap (mm) | Attraction (kg/lbs) (N-S) | Shear Strength (kg/lbs/g/N) | Repulsion (kg/lbs) (N-N) |
|---|---|---|---|
| 0 mm |
3.48 kg / 7.68 LBS
3 483 Gs
|
0.52 kg / 1.15 LBS
523 g / 5.1 N
|
N/A |
| 1 mm |
3.24 kg / 7.14 LBS
3 846 Gs
|
0.49 kg / 1.07 LBS
486 g / 4.8 N
|
2.91 kg / 6.43 LBS
~0 Gs
|
| 2 mm |
2.94 kg / 6.49 LBS
3 666 Gs
|
0.44 kg / 0.97 LBS
441 g / 4.3 N
|
2.65 kg / 5.84 LBS
~0 Gs
|
| 3 mm |
2.62 kg / 5.78 LBS
3 460 Gs
|
0.39 kg / 0.87 LBS
393 g / 3.9 N
|
2.36 kg / 5.20 LBS
~0 Gs
|
| 5 mm |
1.98 kg / 4.36 LBS
3 004 Gs
|
0.30 kg / 0.65 LBS
296 g / 2.9 N
|
1.78 kg / 3.92 LBS
~0 Gs
|
| 10 mm |
0.81 kg / 1.78 LBS
1 919 Gs
|
0.12 kg / 0.27 LBS
121 g / 1.2 N
|
0.73 kg / 1.60 LBS
~0 Gs
|
| 20 mm |
0.11 kg / 0.25 LBS
724 Gs
|
0.02 kg / 0.04 LBS
17 g / 0.2 N
|
0.10 kg / 0.23 LBS
~0 Gs
|
| 50 mm |
0.00 kg / 0.00 LBS
88 Gs
|
0.00 kg / 0.00 LBS
0 g / 0.0 N
|
0.00 kg / 0.00 LBS
~0 Gs
|
| 60 mm |
0.00 kg / 0.00 LBS
54 Gs
|
0.00 kg / 0.00 LBS
0 g / 0.0 N
|
0.00 kg / 0.00 LBS
~0 Gs
|
| 70 mm |
0.00 kg / 0.00 LBS
35 Gs
|
0.00 kg / 0.00 LBS
0 g / 0.0 N
|
0.00 kg / 0.00 LBS
~0 Gs
|
| 80 mm |
0.00 kg / 0.00 LBS
24 Gs
|
0.00 kg / 0.00 LBS
0 g / 0.0 N
|
0.00 kg / 0.00 LBS
~0 Gs
|
| 90 mm |
0.00 kg / 0.00 LBS
17 Gs
|
0.00 kg / 0.00 LBS
0 g / 0.0 N
|
0.00 kg / 0.00 LBS
~0 Gs
|
| 100 mm |
0.00 kg / 0.00 LBS
13 Gs
|
0.00 kg / 0.00 LBS
0 g / 0.0 N
|
0.00 kg / 0.00 LBS
~0 Gs
|
Table 7: Hazards (electronics) - warnings
MP 15x7/3.5x3 / N38
| Object / Device | Limit (Gauss) / mT | Safe distance |
|---|---|---|
| Pacemaker | 5 Gs (0.5 mT) | 5.5 cm |
| Hearing aid | 10 Gs (1.0 mT) | 4.5 cm |
| Timepiece | 20 Gs (2.0 mT) | 3.5 cm |
| Mobile device | 40 Gs (4.0 mT) | 3.0 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 |
Table 8: Collisions (kinetic energy) - warning
MP 15x7/3.5x3 / N38
| Start from (mm) | Speed (km/h) | Energy (J) | Predicted outcome |
|---|---|---|---|
| 10 mm |
27.63 km/h
(7.67 m/s)
|
0.11 J | |
| 30 mm |
46.90 km/h
(13.03 m/s)
|
0.32 J | |
| 50 mm |
60.54 km/h
(16.82 m/s)
|
0.53 J | |
| 100 mm |
85.62 km/h
(23.78 m/s)
|
1.06 J |
Table 9: Coating parameters (durability)
MP 15x7/3.5x3 / 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: Electrical data (Flux)
MP 15x7/3.5x3 / N38
| Parameter | Value | SI Unit / Description |
|---|---|---|
| Magnetic Flux | 3 461 Mx | 34.6 µWb |
| Pc Coefficient | 0.26 | Low (Flat) |
Table 11: Underwater work (magnet fishing)
MP 15x7/3.5x3 / N38
| Environment | Effective steel pull | Effect |
|---|---|---|
| Air (land) | 2.71 kg | Standard |
| Water (riverbed) |
3.10 kg
(+0.39 kg buoyancy gain)
|
+14.5% |
1. Sliding resistance
*Warning: On a vertical surface, the magnet holds only a fraction of its perpendicular strength.
2. Plate thickness effect
*Thin metal sheet (e.g. 0.5mm PC case) severely weakens 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) = 0.26
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.
Elemental analysis
| 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 |
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Advantages as well as disadvantages of neodymium magnets.
Advantages
- Their power is maintained, and after around ten years it decreases only by ~1% (theoretically),
- They do not lose their magnetic properties even under close interference source,
- In other words, due to the reflective layer of silver, the element gains a professional look,
- They feature high magnetic induction at the operating surface, which increases their power,
- Through (appropriate) combination of ingredients, they can achieve high thermal strength, allowing for operation at temperatures reaching 230°C and above...
- Thanks to flexibility in designing and the ability to adapt to complex applications,
- Key role in innovative solutions – they are commonly used in HDD drives, motor assemblies, medical devices, and complex engineering applications.
- Thanks to efficiency per cm³, small magnets offer high operating force, occupying minimum space,
Cons
- To avoid cracks under impact, we suggest using special steel housings. Such a solution protects the magnet and simultaneously increases its durability.
- NdFeB magnets lose force when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening 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 start to 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.
- Due to limitations in creating nuts and complicated shapes in magnets, we recommend using casing - magnetic holder.
- Potential hazard to health – tiny shards of magnets are risky, in case of ingestion, which is particularly important in the aspect of protecting the youngest. It is also worth noting that small elements of these devices are able to 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
Lifting parameters
Best holding force of the magnet in ideal parameters – what contributes to it?
- with the contact of a yoke made of low-carbon steel, guaranteeing full magnetic saturation
- with a thickness minimum 10 mm
- with an polished contact surface
- with total lack of distance (without coatings)
- during pulling in a direction perpendicular to the plane
- in neutral thermal conditions
Practical aspects of lifting capacity – factors
- Clearance – the presence of foreign body (rust, tape, air) acts as an insulator, which lowers capacity steeply (even by 50% at 0.5 mm).
- Force direction – remember that the magnet holds strongest perpendicularly. Under shear forces, the holding force drops significantly, often to levels of 20-30% of the nominal value.
- Substrate thickness – for full efficiency, the steel must be adequately massive. Paper-thin metal limits the lifting capacity (the magnet "punches through" it).
- Metal type – different alloys reacts the same. Alloy additives weaken the attraction effect.
- Surface quality – the more even the surface, the better the adhesion and higher the lifting capacity. Roughness creates an air distance.
- Thermal conditions – neodymium magnets have a sensitivity to temperature. When it is hot they lose power, and at low temperatures they can be stronger (up to a certain limit).
Lifting capacity testing was carried out on a smooth plate of optimal thickness, under a perpendicular pulling force, whereas under shearing force the lifting capacity is smaller. Additionally, even a slight gap between the magnet and the plate lowers the lifting capacity.
H&S for magnets
Protective goggles
Watch out for shards. Magnets can fracture upon violent connection, launching sharp fragments into the air. Wear goggles.
Operating temperature
Standard neodymium magnets (N-type) lose power when the temperature exceeds 80°C. This process is irreversible.
Compass and GPS
GPS units and mobile phones are extremely susceptible to magnetic fields. Close proximity with a strong magnet can ruin the internal compass in your phone.
Data carriers
Data protection: Strong magnets can damage data carriers and delicate electronics (heart implants, hearing aids, mechanical watches).
ICD Warning
Warning for patients: Strong magnetic fields affect medical devices. Maintain minimum 30 cm distance or request help to handle the magnets.
Avoid contact if allergic
Some people have a sensitization to nickel, which is the typical protective layer for NdFeB magnets. Frequent touching may cause a rash. We recommend use protective gloves.
Respect the power
Handle with care. Neodymium magnets attract from a long distance and snap with huge force, often faster than you can react.
Dust explosion hazard
Drilling and cutting of NdFeB material poses a fire risk. Neodymium dust reacts violently with oxygen and is hard to extinguish.
Product not for children
Always keep magnets away from children. Choking hazard is significant, and the consequences of magnets clamping inside the body are tragic.
Finger safety
Risk of injury: The attraction force is so immense that it can result in hematomas, pinching, and even bone fractures. Use thick gloves.
