MPL 10x10x4 / N38 - lamellar magnet

Strengths as well as weaknesses of NdFeB magnets.

In addition to their magnetic capacity, neodymium magnets provide the following advantages:

• They retain attractive force for nearly ten years – the drop is just ~1% (according to analyses),
• They maintain their magnetic properties even under close interference source,
• A magnet with a shiny gold surface looks better,
• Magnets are distinguished by very high magnetic induction on the active area,
• Thanks to resistance to high temperature, they are capable of working (depending on the form) even at temperatures up to 230°C and higher...
• Thanks to versatility in forming and the capacity to modify to specific needs,
• Huge importance in advanced technology sectors – they find application in computer drives, electric drive systems, advanced medical instruments, as well as modern systems.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in compact dimensions, which makes them useful in compact constructions

Problematic aspects of neodymium magnets and proposals for their use:

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth securing magnets using a steel holder. Such protection not only protects the magnet but also improves its resistance to damage
• 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 durability even at temperatures up to 230°C
• They oxidize in a humid environment - during use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• Due to limitations in creating threads and complicated shapes in magnets, we propose using cover - magnetic mechanism.
• Potential hazard related to microscopic parts of magnets can be dangerous, when accidentally swallowed, which is particularly important in the context of child safety. It is also worth noting that tiny parts of these magnets can disrupt the diagnostic process medical in case of swallowing.
• Due to neodymium price, their price exceeds standard values,

Highest magnetic holding force – what contributes to it?

Information about lifting capacity was defined for the most favorable conditions, assuming:

• on a plate made of mild steel, optimally conducting the magnetic field
• whose transverse dimension reaches at least 10 mm
• characterized by lack of roughness
• without the slightest clearance between the magnet and steel
• for force acting at a right angle (pull-off, not shear)
• at ambient temperature approx. 20 degrees Celsius

Practical lifting capacity: influencing factors

In practice, the actual holding force is determined by a number of factors, listed from crucial:

• Air gap (betwixt the magnet and the plate), because even a very small clearance (e.g. 0.5 mm) can cause a reduction in lifting capacity by up to 50% (this also applies to paint, rust or dirt).
• Force direction – declared lifting capacity refers to pulling vertically. When attempting to slide, the magnet exhibits significantly lower power (often approx. 20-30% of maximum force).
• Metal thickness – thin material does not allow full use of the magnet. Part of the magnetic field passes through the material instead of converting into lifting capacity.
• Steel grade – the best choice is pure iron steel. Stainless steels may generate lower lifting capacity.
• Surface finish – ideal contact is possible only on smooth steel. Rough texture reduce the real contact area, weakening the magnet.
• Heat – NdFeB sinters have a sensitivity to temperature. At higher temperatures they are weaker, and in frost they can be stronger (up to a certain limit).

* Lifting capacity testing was performed on a smooth plate of optimal thickness, under a perpendicular pulling force, whereas under attempts to slide the magnet the lifting capacity is smaller. Additionally, even a minimal clearance {between} the magnet’s surface and the plate decreases the holding force.