MPL 40x10x4 / N38 - lamellar magnet

Strengths and weaknesses of NdFeB magnets.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• They retain attractive force for around 10 years – the drop is just ~1% (in theory),
• They possess excellent resistance to magnetic field loss as a result of opposing magnetic fields,
• The use of an shiny finish of noble metals (nickel, gold, silver) causes the element to have aesthetics,
• Neodymium magnets ensure maximum magnetic induction on a small surface, which allows for strong attraction,
• Through (adequate) combination of ingredients, they can achieve high thermal strength, enabling action at temperatures reaching 230°C and above...
• Considering the option of flexible forming and customization to individualized needs, magnetic components can be manufactured in a wide range of shapes and sizes, which amplifies use scope,
• Significant place in innovative solutions – they are commonly used in hard drives, motor assemblies, diagnostic systems, as well as modern systems.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Problematic aspects of neodymium magnets: application proposals

• Susceptibility to cracking is one of their disadvantages. Upon intense impact they can fracture. We recommend keeping them in a special holder, which not only protects them against impacts but also raises their durability
• We warn that neodymium magnets can lose their strength at high temperatures. To prevent this, we recommend our specialized [AH] magnets, which work effectively even at 230°C.
• When exposed to humidity, magnets usually rust. For applications outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which secure oxidation and corrosion.
• Due to limitations in realizing nuts and complicated forms in magnets, we recommend using cover - magnetic holder.
• Potential hazard related to microscopic parts of magnets can be dangerous, if swallowed, which gains importance in the aspect of protecting the youngest. Furthermore, small elements of these magnets are able to disrupt the diagnostic process medical in case of swallowing.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Maximum lifting force for a neodymium magnet – what contributes to it?

The declared magnet strength refers to the limit force, recorded under laboratory conditions, namely:

• on a block made of structural steel, effectively closing the magnetic flux
• possessing a massiveness of at least 10 mm to ensure full flux closure
• characterized by smoothness
• without any insulating layer between the magnet and steel
• for force acting at a right angle (pull-off, not shear)
• in neutral thermal conditions

Lifting capacity in practice – influencing factors

Holding efficiency impacted by working environment parameters, mainly (from priority):

• Gap between magnet and steel – even a fraction of a millimeter of separation (caused e.g. by veneer or dirt) drastically reduces the pulling force, often by half at just 0.5 mm.
• Loading method – catalog parameter refers to pulling vertically. When slipping, the magnet holds significantly lower power (often approx. 20-30% of maximum force).
• Substrate thickness – to utilize 100% power, the steel must be sufficiently thick. Thin sheet limits the attraction force (the magnet "punches through" it).
• Material type – the best choice is high-permeability steel. Stainless steels may generate lower lifting capacity.
• Surface condition – ground elements guarantee perfect abutment, which improves field saturation. Uneven metal reduce efficiency.
• Thermal conditions – neodymium magnets have a negative temperature coefficient. At higher temperatures they lose power, and in frost they can be stronger (up to a certain limit).

* Lifting capacity was assessed with the use of a polished steel plate of optimal thickness (min. 20 mm), under perpendicular pulling force, in contrast under shearing force the lifting capacity is smaller. In addition, even a small distance {between} the magnet’s surface and the plate reduces the lifting capacity.