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MPL 30x20x20 / N38 - lamellar magnet

lamellar magnet

Catalog no 020142

GTIN/EAN: 5906301811480

5.00
Load capacity 24.27 kg / 238.07 N Magnetic Induction 512.53 mT / 5125 Gs
length
30 mm [±0,1 mm]
Width
20 mm [±0,1 mm]
Height
20 mm [±0,1 mm]
Weight
90 g
Magnetization Direction
↑ axial
Coating
[NiCuNi] Nickel

How we measure these parameters — certificates and measurements

product specifications »

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Frequently asked questions

How much will a block magnet really hold?
The catalogue force is measured in full contact with smooth steel at least 10 mm thick, pulled perpendicular, at about 20 °C. On 1 mm sheet about 50% of that value remains, on 0.5 mm about 25%. Mounted on a vertical wall the realistic figure is 20–30%, because the load is then in shear rather than in tension.
What is the maximum working temperature?
Standard N-series grades up to 80 °C, and N50, N52 and N54 up to 60 °C. Above the maximum working temperature the loss stops being reversible. The Curie temperature, at which magnetic properties are lost completely, is about 310 °C.
What safety factor should I allow?
At least twice the mass of the item, and three to five times for vertical mounting. The margin covers sheet thickness, surface condition, any layer of paint or rust, and vibration.

Guides from the knowledge base

Engineering report for this magnet

Full PDF analysis: pull and shear force, effect of distance, temperature and plate thickness, safety distances and the demagnetization curve.

PDF report Calculator
Want to talk magnets?

Call us now +48 888 99 98 98 alternatively let us know using contact form the contact section.
Specifications and structure of a neodymium magnet can be estimated using our power calculator.

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Technical parameters - MPL 30x20x20 / N38 - lamellar magnet

Specification / characteristics - MPL 30x20x20 / N38 - lamellar magnet

properties
properties values
Cat. no. 020142
GTIN/EAN 5906301811480
Production/Distribution Dhit sp. z o.o.
ul. Zielona 14 05-850 Ożarów Mazowiecki PL
Country of origin Poland / China / Germany
Customs code 85059029
length 30 mm [±0,1 mm]
Width 20 mm [±0,1 mm]
Height 20 mm [±0,1 mm]
Weight 90 g
Magnetization Direction ↑ axial
Load capacity ~ ? 24.27 kg / 238.07 N
Magnetic Induction ~ ? 512.53 mT / 5125 Gs
Coating [NiCuNi] Nickel
Manufacturing Tolerance ±0.1 mm

Magnetic properties of material N38

Specification / characteristics MPL 30x20x20 / N38 - lamellar magnet
properties values units
Remanence Br ? 12.2-12.6 kGs
Remanence Br ? 1220-1260 mT
Coercivity bHc ? 10.8-11.5 kOe
Coercivity bHc ? 860-915 kA/m
Intrinsic coercivity iHc ≥ 12 kOe
Intrinsic coercivity iHc ≥ 955 kA/m
Energy product BHmax ? 36-38 BH max MGOe
Energy product BHmax ? 287-303 BH max KJ/m
Maximum working temperature ? ≤ 80 °C

Physical properties of sintered neodymium magnets Nd2Fe14B at 20°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 310 °C
Curie Temperature TF 590 °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 modeling of the product - technical parameters

The following values are the result of a physical analysis. Results were calculated on models for the material Nd2Fe14B. Actual parameters may deviate from the simulation results. Use these data as a supplementary guide when designing systems.

Table 1: Static pull force (pull vs gap) - interaction chart
MPL 30x20x20 / N38

Distance (mm) Induction (Gauss) / mT Pull Force (kg/lbs/g/N) Risk Status
0 mm 5124 Gs
512.4 mT
 24.27 kg / 53.51 pounds
24270.0 g / 238.1 N
 crushing
1 mm 4730 Gs
473.0 mT
 20.68 kg / 45.60 pounds
20685.0 g / 202.9 N
 crushing
2 mm 4335 Gs
433.5 mT
 17.37 kg / 38.30 pounds
17370.7 g / 170.4 N
 crushing
3 mm 3950 Gs
395.0 mT
 14.43 kg / 31.80 pounds
14425.2 g / 141.5 N
 crushing
5 mm 3240 Gs
324.0 mT
 9.71 kg / 21.40 pounds
9706.2 g / 95.2 N
 medium risk
10 mm 1923 Gs
192.3 mT
 3.42 kg / 7.53 pounds
3417.4 g / 33.5 N
 medium risk
15 mm 1163 Gs
116.3 mT
 1.25 kg / 2.76 pounds
1250.2 g / 12.3 N
 weak grip
20 mm 736 Gs
73.6 mT
 0.50 kg / 1.10 pounds
500.4 g / 4.9 N
 weak grip
30 mm 338 Gs
33.8 mT
 0.11 kg / 0.23 pounds
105.3 g / 1.0 N
 weak grip
50 mm 106 Gs
10.6 mT
 0.01 kg / 0.02 pounds
10.3 g / 0.1 N
 weak grip
Grip strength weakens significantly with every subsequent millimeter of spacing. Remember that even a microscopic distance (e.g., contamination, varnish, rust) strongly reduces the pull force. Neodymiums work optimally at the point of direct contact; distance weakens the force. See how rapidly the load capacity plummet, when the product does not touch flatly to the metal substrate. When planning the assembly, eliminate additional spacers.

Table 2: Shear hold (vertical surface)
MPL 30x20x20 / N38

Distance (mm) Friction coefficient Pull Force (kg/lbs/g/N)
0 mm Stal (~0.2) 4.85 kg / 10.70 pounds
4854.0 g / 47.6 N
1 mm Stal (~0.2) 4.14 kg / 9.12 pounds
4136.0 g / 40.6 N
2 mm Stal (~0.2) 3.47 kg / 7.66 pounds
3474.0 g / 34.1 N
3 mm Stal (~0.2) 2.89 kg / 6.36 pounds
2886.0 g / 28.3 N
5 mm Stal (~0.2) 1.94 kg / 4.28 pounds
1942.0 g / 19.1 N
10 mm Stal (~0.2) 0.68 kg / 1.51 pounds
684.0 g / 6.7 N
15 mm Stal (~0.2) 0.25 kg / 0.55 pounds
250.0 g / 2.5 N
20 mm Stal (~0.2) 0.10 kg / 0.22 pounds
100.0 g / 1.0 N
30 mm Stal (~0.2) 0.02 kg / 0.05 pounds
22.0 g / 0.2 N
50 mm Stal (~0.2) 0.00 kg / 0.00 pounds
2.0 g / 0.0 N
The following data shows the estimated weight limit necessary to initiate the slippage of the magnet downwards on a vertical steel plate (considering typical friction). The holding force depends on the separation distance between the magnet and the surface.

Table 3: Wall mounting (sliding) - vertical pull
MPL 30x20x20 / N38

Surface type Friction coefficient / % Mocy Max load (kg/lbs/g/N)
Raw steel
µ = 0.3 30% Nominalnej Siły
7.28 kg / 16.05 pounds
7281.0 g / 71.4 N
Painted steel (standard)
µ = 0.2 20% Nominalnej Siły
4.85 kg / 10.70 pounds
4854.0 g / 47.6 N
Oily/slippery steel
µ = 0.1 10% Nominalnej Siły
2.43 kg / 5.35 pounds
2427.0 g / 23.8 N
Magnet with anti-slip rubber
µ = 0.5 50% Nominalnej Siły
12.14 kg / 26.75 pounds
12135.0 g / 119.0 N
When hanging a holder on a vertical surface (e.g., a car body), it will only hold barely about 20%-30% of its nominal power. Gravitational force and a weak degree of grip influence the fact that holders slide down faster than they detach. Planning a wall mount? Remember that the shear force is noticeably lower than the maximum static pull force. On a slippery surface, the holder will give way down under a noticeably lighter load. Utilizing a rubberized layer can drastically raise the stability.

Table 4: Material efficiency (saturation) - power losses
MPL 30x20x20 / N38

Steel thickness (mm) % power Real pull force (kg/lbs/g/N)
0.5 mm
5%
 1.21 kg / 2.68 pounds
1213.5 g / 11.9 N
1 mm
13%
 3.03 kg / 6.69 pounds
3033.8 g / 29.8 N
2 mm
25%
 6.07 kg / 13.38 pounds
6067.5 g / 59.5 N
3 mm
38%
 9.10 kg / 20.06 pounds
9101.3 g / 89.3 N
5 mm
63%
 15.17 kg / 33.44 pounds
15168.8 g / 148.8 N
10 mm
100%
 24.27 kg / 53.51 pounds
24270.0 g / 238.1 N
11 mm
100%
 24.27 kg / 53.51 pounds
24270.0 g / 238.1 N
12 mm
100%
 24.27 kg / 53.51 pounds
24270.0 g / 238.1 N
A thin sheet is not enough to conduct the full magnetic flux, which weakens actual performance of the holder. If you mount a strong magnet to a too thin substrate, the flux will penetrate right through and the attraction force will be weaker. To utilize 100% of this neodymium's potential, you need a suitably thick element of metal. The material oversaturation causes that on thin elements (e.g., thin profiles), the product works worse. We advise picking the steel thickness based on the following data.

Table 5: Thermal resistance (stability) - power drop
MPL 30x20x20 / N38

Ambient temp. (°C) Power loss Remaining pull (kg/lbs/g/N) Status
20 °C 0.0% 24.27 kg / 53.51 pounds
24270.0 g / 238.1 N
 OK
40 °C -2.2% 23.74 kg / 52.33 pounds
23736.1 g / 232.9 N
 OK
60 °C -4.4% 23.20 kg / 51.15 pounds
23202.1 g / 227.6 N
 OK
80 °C -6.6% 22.67 kg / 49.97 pounds
22668.2 g / 222.4 N
100 °C -28.8% 17.28 kg / 38.10 pounds
17280.2 g / 169.5 N
Standard neodymium magnets lose power above the temperature limit. Avoid high temperatures – heat can irreversibly damage this product. With every degree above norm, the magnet's capacity briefly drops. Avoid using this product in hot environments higher than its operating temperature limit. Exceeding the critical threshold will cause permanent loss of magnetic properties.
*Important note: Thermal stability is determined by both grade, as well as the dimension ratios. Flat magnets (low permeance coefficient) risk losing magnetic properties sooner compared to rod magnets. Red status in the table signals a risk of irreversible loss for this particular item.

Table 6: Magnet-Magnet interaction (repulsion) - field range
MPL 30x20x20 / N38

Gap (mm) Attraction (kg/lbs) (N-S) Shear Force (kg/lbs/g/N) Repulsion (kg/lbs) (N-N)
0 mm 97.11 kg / 214.09 pounds
5 859 Gs
14.57 kg / 32.11 pounds
14567 g / 142.9 N
 N/A
1 mm 89.88 kg / 198.15 pounds
9 859 Gs
13.48 kg / 29.72 pounds
13482 g / 132.3 N
 80.89 kg / 178.34 pounds
~0 Gs
2 mm 82.77 kg / 182.47 pounds
9 461 Gs
12.42 kg / 27.37 pounds
12415 g / 121.8 N
 74.49 kg / 164.22 pounds
~0 Gs
3 mm 75.96 kg / 167.47 pounds
9 063 Gs
11.39 kg / 25.12 pounds
11394 g / 111.8 N
 68.37 kg / 150.72 pounds
~0 Gs
5 mm 63.42 kg / 139.81 pounds
8 281 Gs
9.51 kg / 20.97 pounds
9513 g / 93.3 N
 57.08 kg / 125.83 pounds
~0 Gs
10 mm 38.84 kg / 85.62 pounds
6 481 Gs
5.83 kg / 12.84 pounds
5826 g / 57.1 N
 34.95 kg / 77.06 pounds
~0 Gs
20 mm 13.67 kg / 30.15 pounds
3 845 Gs
2.05 kg / 4.52 pounds
2051 g / 20.1 N
 12.31 kg / 27.13 pounds
~0 Gs
50 mm 0.88 kg / 1.94 pounds
976 Gs
0.13 kg / 0.29 pounds
132 g / 1.3 N
 0.79 kg / 1.75 pounds
~0 Gs
60 mm 0.42 kg / 0.93 pounds
675 Gs
0.06 kg / 0.14 pounds
63 g / 0.6 N
 0.38 kg / 0.84 pounds
~0 Gs
70 mm 0.22 kg / 0.48 pounds
484 Gs
0.03 kg / 0.07 pounds
33 g / 0.3 N
 0.20 kg / 0.43 pounds
~0 Gs
80 mm 0.12 kg / 0.26 pounds
358 Gs
0.02 kg / 0.04 pounds
18 g / 0.2 N
 0.11 kg / 0.24 pounds
~0 Gs
90 mm 0.07 kg / 0.15 pounds
272 Gs
0.01 kg / 0.02 pounds
10 g / 0.1 N
 0.06 kg / 0.14 pounds
~0 Gs
100 mm 0.04 kg / 0.09 pounds
211 Gs
0.01 kg / 0.01 pounds
6 g / 0.1 N
 0.04 kg / 0.08 pounds
~0 Gs
Two strong neodymiums interact from a much further distance than a magnet and steel setup. The setup of magnet-to-magnet produces a massive flux and a larger range of performance. Designing a powerful holder? Utilize two neodymiums instead of a neodymium and a striker plate. Exercise caution that when attracting two neodymiums, the collision energy is huge. The repulsion force is marginally weaker than the connection force, but still large.
*The magnetic induction for N-N configuration drops to ~0 Gs at the geometric center of the gap (caused by magnetic field nullification).
* Results show sliding force of dual matching neodymium magnets (friction coefficient ~0.15 for Ni-Ni coating).

Table 7: Protective zones (electronics) - warnings
MPL 30x20x20 / N38

Object / Device Limit (Gauss) / mT Safe distance
Pacemaker 5 Gs (0.5 mT) 16.0 cm
Hearing aid 10 Gs (1.0 mT) 12.5 cm
Timepiece 20 Gs (2.0 mT) 10.0 cm
Phone / Smartphone 40 Gs (4.0 mT) 7.5 cm
Car key 50 Gs (5.0 mT) 7.0 cm
Payment card 400 Gs (40.0 mT) 3.0 cm
HDD hard drive 600 Gs (60.0 mT) 2.5 cm
A strong magnetic field poses a large risk to electronics and medical implants. These neodymiums generate a flux that destroys function of sensitive medical devices. Notice: the unseen radiation passes through tissues and housings. Special caution must be exercised by people with cochlear implants and drug dispensers. Also at risk are: automatic timepieces, car keys, speakers, and screens. Do not bring the product near payment cards, hard drives, or precise measuring instruments.

Table 8: Dynamics (kinetic energy) - warning
MPL 30x20x20 / N38

Start from (mm) Speed (km/h) Energy (J) Predicted outcome
10 mm 17.74 km/h
(4.93 m/s)
 1.09 J
30 mm 19.06 km/h
(5.30 m/s)
 1.26 J
50 mm 19.12 km/h
(5.31 m/s)
 1.27 J
100 mm 19.13 km/h
(5.31 m/s)
 1.27 J
Magnetic elements are prone to chipping – a strong collision with metal causes immediate chipping. Watch the impact speed – a neodymium left loose turns into a projectile. Impact energy can cause material chips or injury to skin. Always hold the magnet during bringing near metal so it doesn't hit with great force against the metal. A collision at high speed ends with a crack of the magnet. Wear eye protection when handling with large magnets.

Table 9: Coating parameters (durability)
MPL 30x20x20 / 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. Improper coating selection is the most common cause of magnet failure over time.

Table 10: Construction data (Pc)
MPL 30x20x20 / N38

Parameter Value SI Unit / Description
Magnetic Flux 30 878 Mx 308.8 µWb
Pc Coefficient 0.74 High (Stable)
Flux value emitted by the magnet pole. Essential parameter when building generators and motors. Pc value defines the working geometry.

Table 11: Underwater work (magnet fishing)
MPL 30x20x20 / N38

Environment Effective steel pull Effect
Air (land) 24.27 kg Standard
Water (riverbed) 27.79 kg
(+3.52 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. Sliding resistance

*Note: On a vertical wall, the magnet holds only approx. 20-30% of its perpendicular strength.

2. Plate thickness effect

*Thin steel (e.g. 0.5mm PC case) significantly weakens the holding force.

3. Temperature resistance

*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) = 0.74

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.

Technical specification and ecology

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%

Sustainability

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: 020142-2026
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Component MPL 30x20x20 / N38 features a low profile and professional pulling force, making it a perfect solution for building separators and machines. As a block magnet with high power (approx. 24.27 kg), this product is available immediately from our warehouse in Poland. The durable anti-corrosion layer ensures a long lifespan in a dry environment, protecting the core from oxidation.
The key to success is shifting the magnets along their largest connection plane (using e.g., the edge of a table), which is easier than trying to tear them apart directly. Watch your fingers! Magnets with a force of 24.27 kg can pinch very hard and cause hematomas. Never use metal tools for prying, as the brittle NdFeB material may chip and damage your eyes.
They constitute a key element in the production of wind generators and material handling systems. They work great as fasteners under tiles, wood, or glass. Customers often choose this model for workshop organization on strips and for advanced DIY and modeling projects, where precision and power count.
Cyanoacrylate glues (super glue type) are good only for small magnets; for larger plates, we recommend resins. Double-sided tape cushions vibrations, which is an advantage when mounting in moving elements. Remember to clean and degrease the magnet surface before gluing, which significantly increases the adhesion of the glue to the nickel coating.
The magnetic axis runs through the shortest dimension, which is typical for gripper magnets. In practice, this means that this magnet has the greatest attraction force on its main planes (30x20 mm), which is ideal for flat mounting. This is the most popular configuration for block magnets used in separators and holders.
This model is characterized by dimensions 30x20x20 mm, which, at a weight of 90 g, makes it an element with high energy density. The key parameter here is the holding force amounting to approximately 24.27 kg (force ~238.07 N), which, with such a flat shape, proves the high power of the material. The protective [NiCuNi] coating secures the magnet against corrosion.

Advantages and disadvantages of rare earth magnets.

Pros

Apart from their consistent magnetism, neodymium magnets have these key benefits:
  • They do not lose strength, even during approximately 10 years – the reduction in power is only ~1% (theoretically),
  • Magnets effectively defend themselves against loss of magnetization caused by external fields,
  • In other words, due to the metallic layer of silver, the element looks attractive,
  • Neodymium magnets deliver maximum magnetic induction on a their surface, which ensures high operational effectiveness,
  • Neodymium magnets are characterized by very high magnetic induction on the magnet surface and are able to act (depending on the form) even at a temperature of 230°C or more...
  • Due to the possibility of precise molding and adaptation to individualized requirements, NdFeB magnets can be created in a broad palette of geometric configurations, which makes them more universal,
  • Universal use in electronics industry – they serve a role in mass storage devices, electric drive systems, medical devices, as well as modern systems.
  • Relatively small size with high pulling force – neodymium magnets offer high power in small dimensions, which enables their usage in small systems

Weaknesses

Disadvantages of NdFeB magnets:
  • At very strong impacts they can crack, therefore we recommend placing them in steel cases. A metal housing provides additional protection against damage and increases the magnet's durability.
  • When exposed to high temperature, neodymium magnets experience a drop in power. Often, when the temperature exceeds 80°C, their power decreases (depending on the size, as well as shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
  • They oxidize in a humid environment - during use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
  • We recommend casing - magnetic holder, due to difficulties in creating threads inside the magnet and complicated shapes.
  • Potential hazard related to microscopic parts of magnets pose a threat, in case of ingestion, which is particularly important in the context of child health protection. It is also worth noting that tiny parts of these magnets can be problematic in diagnostics medical in case of swallowing.
  • Due to expensive raw materials, their price is higher than average,

Lifting parameters

Highest magnetic holding force – what it depends on?

Holding force of 24.27 kg is a theoretical maximum value conducted under specific, ideal conditions:
  • with the contact of a yoke made of low-carbon steel, ensuring full magnetic saturation
  • possessing a thickness of minimum 10 mm to avoid saturation
  • with a plane free of scratches
  • without the slightest clearance between the magnet and steel
  • under vertical application of breakaway force (90-degree angle)
  • in neutral thermal conditions

Lifting capacity in real conditions – factors

Holding efficiency is affected by specific conditions, including (from priority):
  • Air gap (betwixt the magnet and the metal), because even a very small clearance (e.g. 0.5 mm) results in a reduction in force by up to 50% (this also applies to paint, rust or debris).
  • Direction of force – maximum parameter is reached only during perpendicular pulling. The resistance to sliding of the magnet along the plate is usually many times smaller (approx. 1/5 of the lifting capacity).
  • Metal thickness – thin material does not allow full use of the magnet. Part of the magnetic field penetrates through instead of generating force.
  • Material composition – not every steel attracts identically. Alloy additives worsen the attraction effect.
  • Smoothness – full contact is obtained only on smooth steel. Rough texture reduce the real contact area, weakening the magnet.
  • Thermal environment – heating the magnet results in weakening of force. It is worth remembering the maximum operating temperature for a given model.

Lifting capacity testing was performed on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, in contrast under shearing force the lifting capacity is smaller. Additionally, even a minimal clearance between the magnet’s surface and the plate decreases the lifting capacity.

Safety rules for work with neodymium magnets
This is not a toy

Neodymium magnets are not toys. Swallowing several magnets can lead to them pinching intestinal walls, which poses a severe health hazard and requires urgent medical intervention.

Combustion hazard

Powder generated during grinding of magnets is self-igniting. Avoid drilling into magnets unless you are an expert.

Powerful field

Before use, check safety instructions. Sudden snapping can break the magnet or hurt your hand. Think ahead.

Thermal limits

Control the heat. Heating the magnet above 80 degrees Celsius will permanently weaken its magnetic structure and pulling force.

Safe distance

Very strong magnetic fields can erase data on credit cards, hard drives, and storage devices. Keep a distance of min. 10 cm.

Fragile material

Neodymium magnets are ceramic materials, which means they are fragile like glass. Clashing of two magnets will cause them cracking into shards.

Warning for heart patients

People with a pacemaker have to keep an absolute distance from magnets. The magnetism can disrupt the functioning of the life-saving device.

Pinching danger

Big blocks can break fingers in a fraction of a second. Never place your hand betwixt two strong magnets.

Allergic reactions

A percentage of the population experience a contact allergy to Ni, which is the standard coating for neodymium magnets. Prolonged contact can result in a rash. It is best to use safety gloves.

Compass and GPS

An intense magnetic field negatively affects the functioning of compasses in phones and GPS navigation. Maintain magnets near a device to prevent breaking the sensors.

Danger! Details about hazards in the article: Safety of working with magnets.