UMT 11x17 colorless / N38 - board holder

Advantages as well as disadvantages of rare earth magnets.

Besides their stability, neodymium magnets are valued for these benefits:

• They virtually do not lose power, because even after 10 years the decline in efficiency is only ~1% (based on calculations),
• They are resistant to demagnetization induced by external field influence,
• A magnet with a shiny silver surface has better aesthetics,
• Magnets are distinguished by exceptionally strong magnetic induction on the working surface,
• Through (appropriate) combination of ingredients, they can achieve high thermal strength, enabling action at temperatures reaching 230°C and above...
• Considering the possibility of accurate forming and adaptation to unique needs, magnetic components can be created in a broad palette of forms and dimensions, which makes them more universal,
• Fundamental importance in innovative solutions – they serve a role in computer drives, brushless drives, medical equipment, also multitasking production systems.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Disadvantages of neodymium magnets:

• Brittleness is one of their disadvantages. Upon strong impact they can break. We advise keeping them in a steel housing, which not only secures them against impacts but also increases their durability
• Neodymium magnets decrease their power under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. Therefore, we recommend our special magnets marked [AH], which maintain durability even at temperatures up to 230°C
• 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 prevent oxidation as well as corrosion.
• Limited possibility of creating nuts in the magnet and complicated forms - preferred is a housing - mounting mechanism.
• Possible danger related to microscopic parts of magnets are risky, in case of ingestion, which gains importance in the context of child health protection. Additionally, small elements of these devices are able to be problematic in diagnostics medical after entering the body.
• With large orders the cost of neodymium magnets can be a barrier,

Magnetic strength at its maximum – what contributes to it?

Holding force of 0 kg is a measurement result executed under the following configuration:

• with the contact of a sheet made of special test steel, ensuring maximum field concentration
• whose transverse dimension is min. 10 mm
• with a surface free of scratches
• without the slightest insulating layer between the magnet and steel
• for force acting at a right angle (in the magnet axis)
• at conditions approx. 20°C

Determinants of lifting force in real conditions

Bear in mind that the working load will differ depending on the following factors, in order of importance:

• Distance – existence of any layer (rust, dirt, air) acts as an insulator, which reduces power steeply (even by 50% at 0.5 mm).
• Direction of force – maximum parameter is available only during perpendicular pulling. The shear force of the magnet along the surface is usually several times lower (approx. 1/5 of the lifting capacity).
• Plate thickness – insufficiently thick plate does not accept the full field, causing part of the flux to be escaped to the other side.
• Chemical composition of the base – mild steel gives the best results. Alloy steels reduce magnetic permeability and lifting capacity.
• Smoothness – full contact is possible only on smooth steel. Any scratches and bumps reduce the real contact area, reducing force.
• Thermal conditions – neodymium magnets have a sensitivity to temperature. When it is hot they lose power, and at low temperatures gain strength (up to a certain limit).

* Lifting capacity testing was conducted on plates with a smooth surface of optimal thickness, under a perpendicular pulling force, in contrast under shearing force 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.