MW 8x20 / N38 - cylindrical magnet

Strengths as well as weaknesses of NdFeB magnets.

Apart from their notable power, neodymium magnets have these key benefits:

• They retain attractive force for almost 10 years – the drop is just ~1% (based on simulations),
• They do not lose their magnetic properties even under close interference source,
• By covering with a smooth coating of gold, the element gains an professional look,
• They feature high magnetic induction at the operating surface, which affects their effectiveness,
• 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...
• Possibility of precise machining and adapting to atypical requirements,
• Wide application in future technologies – they are used in computer drives, brushless drives, medical devices, and complex engineering applications.
• Thanks to concentrated force, small magnets offer high operating force, in miniature format,

What to avoid - cons of neodymium magnets and proposals for their use:

• Brittleness is one of their disadvantages. Upon strong impact they can fracture. We recommend keeping them in a steel housing, which not only secures them against impacts but also raises their durability
• We warn that neodymium magnets can lose their power at high temperatures. To prevent this, we recommend our specialized [AH] magnets, which work effectively even at 230°C.
• When exposed to humidity, magnets start to rust. For applications outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which secure oxidation as well as corrosion.
• Due to limitations in creating nuts and complicated shapes in magnets, we recommend using cover - magnetic holder.
• Potential hazard related to microscopic parts of magnets pose a threat, when accidentally swallowed, which gains importance in the context of child health protection. Additionally, small elements of these magnets can complicate diagnosis medical when they are in the body.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which hinders application in large quantities

Maximum magnetic pulling force – what affects it?

The load parameter shown refers to the peak performance, recorded under optimal environment, specifically:

• on a block made of mild steel, effectively closing the magnetic field
• possessing a thickness of min. 10 mm to avoid saturation
• with an polished touching surface
• without the slightest insulating layer between the magnet and steel
• for force acting at a right angle (pull-off, not shear)
• at conditions approx. 20°C

Determinants of lifting force in real conditions

Real force is affected by working environment parameters, such as (from most important):

• Gap (betwixt the magnet and the metal), since even a very small clearance (e.g. 0.5 mm) leads to a reduction in force by up to 50% (this also applies to paint, rust or dirt).
• Force direction – declared lifting capacity refers to detachment vertically. When slipping, the magnet holds significantly lower power (often approx. 20-30% of nominal force).
• Metal thickness – thin material does not allow full use of the magnet. Part of the magnetic field passes through the material instead of generating force.
• Material type – ideal substrate is high-permeability steel. Hardened steels may have worse magnetic properties.
• Smoothness – full contact is possible only on polished steel. Rough texture create air cushions, reducing force.
• Temperature – temperature increase causes a temporary drop of induction. It is worth remembering the thermal limit for a given model.

* Lifting capacity was measured with the use of a smooth steel plate of optimal thickness (min. 20 mm), under vertically applied force, whereas under parallel forces the load capacity is reduced by as much as 5 times. Additionally, even a slight gap {between} the magnet’s surface and the plate reduces the load capacity.