MW 9x3 / N38 - cylindrical magnet

Strengths as well as weaknesses of rare earth magnets.

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

• They do not lose power, even over approximately 10 years – the reduction in power is only ~1% (based on measurements),
• They show high resistance to demagnetization induced by external disturbances,
• By using a decorative coating of gold, the element has an modern look,
• Magnetic induction on the surface of the magnet is very high,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Considering the ability of accurate forming and customization to specialized solutions, magnetic components can be modeled in a broad palette of geometric configurations, which makes them more universal,
• Key role in modern technologies – they are commonly used in hard drives, electric motors, medical devices, also modern systems.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Drawbacks and weaknesses of neodymium magnets: application proposals

• Brittleness is one of their disadvantages. Upon strong impact they can break. We recommend keeping them in a strong case, which not only protects them against impacts but also increases their durability
• We warn that neodymium magnets can lose their strength at high temperatures. To prevent this, we suggest our specialized [AH] magnets, which work effectively even at 230°C.
• Due to the susceptibility of magnets to corrosion in a humid environment, we suggest using waterproof magnets made of rubber, plastic or other material immune to moisture, in case of application outdoors
• Due to limitations in producing threads and complex forms in magnets, we recommend using casing - magnetic mechanism.
• Possible danger to health – tiny shards of magnets are risky, if swallowed, which gains importance in the context of child safety. It is also worth noting that small elements of these devices are able to disrupt the diagnostic process medical after entering the body.
• Due to complex production process, their price exceeds standard values,

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

Information about lifting capacity was defined for optimal configuration, including:

• with the use of a sheet made of special test steel, ensuring maximum field concentration
• possessing a thickness of minimum 10 mm to ensure full flux closure
• with a surface perfectly flat
• without any air gap between the magnet and steel
• for force acting at a right angle (pull-off, not shear)
• at temperature approx. 20 degrees Celsius

Determinants of lifting force in real conditions

Please note that the application force may be lower influenced by elements below, starting with the most relevant:

• Gap between magnet and steel – every millimeter of separation (caused e.g. by veneer or unevenness) diminishes the magnet efficiency, often by half at just 0.5 mm.
• Direction of force – highest force is reached only during perpendicular pulling. The force required to slide of the magnet along the surface is usually several times lower (approx. 1/5 of the lifting capacity).
• Base massiveness – too thin steel causes magnetic saturation, causing part of the flux to be wasted to the other side.
• Material type – the best choice is high-permeability steel. Hardened steels may have worse magnetic properties.
• Surface quality – the more even the plate, the better the adhesion and stronger the hold. Roughness acts like micro-gaps.
• Heat – NdFeB sinters have a sensitivity to temperature. At higher temperatures they lose power, and in frost gain strength (up to a certain limit).

* Lifting capacity was determined using a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular pulling force, in contrast 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 holding force.