MPL 30x15x2 / N38 - lamellar magnet

Strengths and weaknesses of rare earth magnets.

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

• They do not lose magnetism, even during approximately 10 years – the drop in lifting capacity is only ~1% (based on measurements),
• They are extremely resistant to demagnetization induced by presence of other magnetic fields,
• Thanks to the reflective finish, the coating of nickel, gold-plated, or silver-plated gives an aesthetic appearance,
• They show high magnetic induction at the operating surface, which improves attraction properties,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their form) at temperatures up to 230°C and above...
• Thanks to freedom in designing and the capacity to adapt to individual projects,
• Versatile presence in high-tech industry – they find application in HDD drives, electric motors, diagnostic systems, as well as technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer high power in tiny dimensions, which enables their usage in compact constructions

Problematic aspects of neodymium magnets: application proposals

• At strong impacts they can crack, therefore we advise placing them in steel cases. A metal housing provides additional protection against damage and increases the magnet's durability.
• Neodymium magnets lose their force 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 stability even at temperatures up to 230°C
• Due to the susceptibility of magnets to corrosion in a humid environment, we recommend using waterproof magnets made of rubber, plastic or other material resistant to moisture, in case of application outdoors
• Due to limitations in realizing threads and complex forms in magnets, we propose using casing - magnetic holder.
• Potential hazard to health – tiny shards 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 when they are in the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Highest magnetic holding force – what contributes to it?

The declared magnet strength represents the limit force, obtained under laboratory conditions, specifically:

• on a base made of mild steel, perfectly concentrating the magnetic field
• possessing a thickness of minimum 10 mm to ensure full flux closure
• with a surface cleaned and smooth
• without any insulating layer between the magnet and steel
• during detachment in a direction perpendicular to the mounting surface
• at standard ambient temperature

Practical aspects of lifting capacity – factors

During everyday use, the real power is determined by a number of factors, ranked from the most important:

• Distance – the presence of any layer (rust, tape, gap) interrupts the magnetic circuit, which reduces capacity steeply (even by 50% at 0.5 mm).
• Pull-off angle – remember that the magnet has greatest strength perpendicularly. Under sliding down, the capacity drops drastically, often to levels of 20-30% of the nominal value.
• Metal thickness – thin material does not allow full use of the magnet. Magnetic flux penetrates through instead of generating force.
• Material type – ideal substrate is pure iron steel. Hardened steels may attract less.
• Surface quality – the more even the surface, the better the adhesion and higher the lifting capacity. Unevenness acts like micro-gaps.
• Heat – neodymium magnets have a negative temperature coefficient. When it is hot they lose power, and at low temperatures they can be stronger (up to a certain limit).

* Lifting capacity testing was carried out on plates with a smooth surface of optimal thickness, under perpendicular forces, however under shearing force the load capacity is reduced by as much as 75%. In addition, even a minimal clearance {between} the magnet and the plate lowers the holding force.