NCM 30x13.5x5 / N38 - channel magnetic holder

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their exceptional pulling force, neodymium magnets offer the following advantages:

• They have constant strength, and over nearly 10 years their performance decreases symbolically – ~1% (according to theory),
• They are highly resistant to demagnetization caused by external magnetic fields,
• Because of the reflective layer of nickel, the component looks aesthetically refined,
• Magnetic induction on the surface of these magnets is very strong,
• Neodymium magnets are known for very high magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the geometry),
• The ability for custom shaping as well as customization to custom needs – neodymium magnets can be manufactured in a wide range of shapes and sizes, which amplifies their functionality across industries,
• Key role in new technology industries – they are utilized in hard drives, electric motors, clinical machines along with other advanced devices,
• Relatively small size with high magnetic force – neodymium magnets offer strong power in compact dimensions, which allows for use in compact constructions

Disadvantages of NdFeB magnets:

• They are fragile when subjected to a heavy impact. If the magnets are exposed to mechanical hits, it is advisable to use in a metal holder. The steel housing, in the form of a holder, protects the magnet from damage while also enhances its overall robustness,
• Magnets lose power when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible power drop (influenced by the magnet’s form). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• They rust in a wet environment. For outdoor use, we recommend using encapsulated magnets, such as those made of polymer,
• Limited ability to create precision features in the magnet – the use of a external casing is recommended,
• Possible threat due to small fragments may arise, if ingested accidentally, which is important in the context of child safety. Furthermore, miniature parts from these products may interfere with diagnostics if inside the body,
• In cases of mass production, neodymium magnet cost is a challenge,

Detachment force of the magnet in optimal conditions – what affects it?

The given strength of the magnet corresponds to the optimal strength, assessed in the best circumstances, namely:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• with a thickness of minimum 10 mm
• with a polished side
• with zero air gap
• with vertical force applied
• in normal thermal conditions

Practical lifting capacity: influencing factors

In practice, the holding capacity of a magnet is affected by these factors, from crucial to less important:

• Air gap between the magnet and the plate, because even a very small distance (e.g. 0.5 mm) causes a drop in lifting force of up to 50%.
• Direction of applied force, because the maximum lifting capacity is achieved under perpendicular application. The force required to slide the magnet along the plate is usually several times lower.
• Thickness of the plate, as a plate that is too thin causes part of the magnetic flux not to be used and to remain wasted in the air.
• Material of the plate, because higher carbon content lowers holding force, while higher iron content increases it. The best choice is steel with high magnetic permeability and high saturation induction.
• Surface of the plate, because the more smooth and polished it is, the better the contact and consequently the greater the magnetic saturation.
• Operating temperature, since all permanent magnets have a negative temperature coefficient. This means that at high temperatures they are weaker, while at sub-zero temperatures they become slightly stronger.

* Lifting capacity testing was conducted on a smooth plate of optimal thickness, under a perpendicular pulling force, however under attempts to slide the magnet the holding force is lower. Additionally, even a small distance {between} the magnet and the plate lowers the load capacity.