UMH 20x7x35 [M4] / N38 - magnetic holder with hook
magnetic holder with hook
Catalog no 310425
GTIN: 5906301814542
Diameter Ø
20 mm [±1 mm]
Height
35 mm [±1 mm]
Height
7 mm [±1 mm]
Weight
21 g
Magnetization Direction
↑ axial
Load capacity
14.5 kg / 142.2 N
Coating
[NiCuNi] Nickel
8.59 ZŁ with VAT / pcs + price for transport
6.98 ZŁ net + 23% VAT / pcs
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UMH 20x7x35 [M4] / N38 - magnetic holder with hook
Specification / characteristics UMH 20x7x35 [M4] / N38 - magnetic holder with hook
| properties | values |
|---|---|
| Cat. no. | 310425 |
| GTIN | 5906301814542 |
| Production/Distribution | Dhit sp. z o.o. |
| Country of origin | Poland / China / Germany |
| Customs code | 85059029 |
| Diameter Ø | 20 mm [±1 mm] |
| Height | 35 mm [±1 mm] |
| Height | 7 mm [±1 mm] |
| Weight | 21 g |
| Magnetization Direction | ↑ axial |
| Load capacity ~ ? | 14.5 kg / 142.2 N |
| Coating | [NiCuNi] Nickel |
| Manufacturing Tolerance | ±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 | 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 |
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Pros and cons of neodymium magnets.
Besides their immense pulling force, neodymium magnets offer the following advantages:
- They retain attractive force for nearly 10 years – the loss is just ~1% (in theory),
- They possess excellent resistance to magnetism drop when exposed to external fields,
- Thanks to the shimmering finish, the surface of Ni-Cu-Ni, gold, or silver-plated gives an modern appearance,
- Neodymium magnets ensure maximum magnetic induction on a contact point, which ensures high operational effectiveness,
- Due to their durability and thermal resistance, neodymium magnets can operate (depending on the shape) even at high temperatures reaching 230°C or more...
- Thanks to freedom in forming and the ability to modify to complex applications,
- Wide application in high-tech industry – they are commonly used in computer drives, motor assemblies, diagnostic systems, and technologically advanced constructions.
- Thanks to concentrated force, small magnets offer high operating force, occupying minimum space,
Disadvantages of neodymium magnets:
- Brittleness is one of their disadvantages. Upon intense impact they can break. We recommend keeping them in a special holder, which not only protects them against impacts but also raises their 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.
- They rust in a humid environment - during use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
- We suggest cover - magnetic mount, due to difficulties in creating nuts inside the magnet and complex shapes.
- Possible danger to health – tiny shards of magnets are risky, if swallowed, which is particularly important in the aspect of protecting the youngest. It is also worth noting that small elements of these products can be problematic in diagnostics medical when they are in the body.
- Due to expensive raw materials, their price is relatively high,
Optimal lifting capacity of a neodymium magnet – what contributes to it?
Holding force of 14.5 kg is a result of laboratory testing executed under specific, ideal conditions:
- using a plate made of mild steel, functioning as a circuit closing element
- whose thickness is min. 10 mm
- with an polished contact surface
- with zero gap (without impurities)
- during pulling in a direction vertical to the mounting surface
- at temperature room level
Practical aspects of lifting capacity – factors
Holding efficiency is influenced by working environment parameters, including (from priority):
- Clearance – existence of any layer (rust, tape, air) interrupts the magnetic circuit, which reduces capacity rapidly (even by 50% at 0.5 mm).
- Direction of force – highest force is reached only during pulling at a 90° angle. The resistance to sliding of the magnet along the plate is typically many times smaller (approx. 1/5 of the lifting capacity).
- Wall thickness – thin material does not allow full use of the magnet. Magnetic flux penetrates through instead of converting into lifting capacity.
- Material type – the best choice is pure iron steel. Stainless steels may generate lower lifting capacity.
- Surface condition – ground elements guarantee perfect abutment, which improves force. Uneven metal reduce efficiency.
- Heat – NdFeB sinters 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).
* Holding force was tested on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, in contrast under shearing force the lifting capacity is smaller. Moreover, even a slight gap {between} the magnet and the plate reduces the load capacity.
Precautions when working with NdFeB magnets
Do not give to children
These products are not intended for children. Accidental ingestion of a few magnets can lead to them pinching intestinal walls, which constitutes a severe health hazard and necessitates urgent medical intervention.
Do not overheat magnets
Regular neodymium magnets (grade N) lose power when the temperature exceeds 80°C. The loss of strength is permanent.
ICD Warning
Warning for patients: Powerful magnets disrupt electronics. Maintain minimum 30 cm distance or ask another person to work with the magnets.
Keep away from computers
Data protection: Neodymium magnets can ruin data carriers and delicate electronics (pacemakers, medical aids, mechanical watches).
Metal Allergy
Allergy Notice: The Ni-Cu-Ni coating contains nickel. If redness happens, immediately stop handling magnets and wear gloves.
Safe operation
Exercise caution. Neodymium magnets act from a distance and connect with massive power, often faster than you can move away.
Impact on smartphones
Note: rare earth magnets generate a field that disrupts sensitive sensors. Maintain a safe distance from your mobile, device, and navigation systems.
Machining danger
Combustion risk: Rare earth powder is highly flammable. Do not process magnets in home conditions as this may cause fire.
Crushing risk
Risk of injury: The attraction force is so immense that it can result in blood blisters, pinching, and even bone fractures. Protective gloves are recommended.
Shattering risk
Watch out for shards. Magnets can fracture upon uncontrolled impact, ejecting shards into the air. Wear goggles.
Safety First!
Need more info? Read our article: Are neodymium magnets dangerous?
