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 high retention, neodymium magnets are valued for these benefits:
- Their magnetic field remains stable, and after approximately ten years it drops only by ~1% (according to research),
- They feature excellent resistance to magnetic field loss when exposed to opposing magnetic fields,
- Thanks to the shiny finish, the layer of nickel, gold-plated, or silver gives an clean appearance,
- They show high magnetic induction at the operating surface, which affects their effectiveness,
- Thanks to resistance to high temperature, they can operate (depending on the form) even at temperatures up to 230°C and higher...
- Considering the potential of precise molding and customization to individualized needs, NdFeB magnets can be created in a broad palette of forms and dimensions, which amplifies use scope,
- Universal use in innovative solutions – they are used in computer drives, drive modules, diagnostic systems, and modern systems.
- Thanks to their power density, small magnets offer high operating force, in miniature format,
Drawbacks and weaknesses of neodymium magnets and ways of using them
- Susceptibility to cracking is one of their disadvantages. Upon strong impact they can break. We advise keeping them in a strong case, which not only secures them against impacts but also increases their durability
- When exposed to high temperature, neodymium magnets suffer a drop in force. Often, when the temperature exceeds 80°C, their strength 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
- Magnets exposed to a humid environment can rust. Therefore during using outdoors, we suggest using waterproof magnets made of rubber, plastic or other material resistant to moisture
- Limited possibility of creating nuts in the magnet and complicated forms - preferred is cover - magnetic holder.
- Potential hazard to health – tiny shards of magnets pose a threat, if swallowed, which gains importance in the context of child safety. It is also worth noting that tiny parts of these products are able to complicate diagnosis medical in case of swallowing.
- Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications
Detachment force of the magnet in optimal conditions – what affects it?
Holding force of 14.5 kg is a result of laboratory testing performed under specific, ideal conditions:
- with the use of a sheet made of special test steel, ensuring maximum field concentration
- whose thickness reaches at least 10 mm
- with an polished touching surface
- without the slightest insulating layer between the magnet and steel
- during pulling in a direction perpendicular to the mounting surface
- at conditions approx. 20°C
Practical lifting capacity: influencing factors
In real-world applications, the actual lifting capacity results from a number of factors, ranked from the most important:
- Air gap (betwixt the magnet and the plate), as even a microscopic distance (e.g. 0.5 mm) leads to a decrease in lifting capacity by up to 50% (this also applies to paint, corrosion or debris).
- Angle of force application – highest force is reached only during pulling at a 90° angle. The shear force of the magnet along the plate is typically several times smaller (approx. 1/5 of the lifting capacity).
- Substrate thickness – for full efficiency, the steel must be adequately massive. Thin sheet limits the attraction force (the magnet "punches through" it).
- Material composition – not every steel reacts the same. Alloy additives worsen the attraction effect.
- Smoothness – ideal contact is possible only on smooth steel. Rough texture reduce the real contact area, reducing force.
- Temperature influence – high temperature weakens pulling force. Too high temperature can permanently damage the magnet.
* Lifting capacity testing was carried out on a smooth plate of optimal thickness, under perpendicular forces, however under parallel forces the load capacity is reduced by as much as 75%. Moreover, even a small distance {between} the magnet’s surface and the plate reduces the load capacity.
Safety rules for work with neodymium magnets
GPS Danger
Remember: rare earth magnets generate a field that disrupts sensitive sensors. Keep a safe distance from your phone, tablet, and GPS.
Medical implants
Health Alert: Strong magnets can deactivate pacemakers and defibrillators. Do not approach if you have medical devices.
Swallowing risk
NdFeB magnets are not intended for children. Eating a few magnets can lead to them attracting across intestines, which constitutes a critical condition and necessitates immediate surgery.
Avoid contact if allergic
It is widely known that nickel (standard magnet coating) is a potent allergen. If you have an allergy, avoid direct skin contact and opt for versions in plastic housing.
Serious injuries
Big blocks can smash fingers instantly. Under no circumstances place your hand betwixt two attracting surfaces.
Data carriers
Very strong magnetic fields can corrupt files on credit cards, HDDs, and storage devices. Stay away of min. 10 cm.
Magnet fragility
Despite the nickel coating, neodymium is brittle and not impact-resistant. Do not hit, as the magnet may shatter into sharp, dangerous pieces.
Powerful field
Exercise caution. Rare earth magnets act from a distance and snap with massive power, often faster than you can react.
Heat sensitivity
Regular neodymium magnets (N-type) lose power when the temperature exceeds 80°C. The loss of strength is permanent.
Fire warning
Powder created during cutting of magnets is flammable. Do not drill into magnets unless you are an expert.
Important!
Learn more about hazards in the article: Magnet Safety Guide.
