SMZR 32x225 / N52 - magnetic separator with handle

Strengths and weaknesses of neodymium magnets.

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

• Their strength is durable, and after around 10 years it decreases only by ~1% (according to research),
• Neodymium magnets are characterized by remarkably resistant to demagnetization caused by external magnetic fields,
• By covering with a lustrous layer of gold, the element has an proper look,
• They show high magnetic induction at the operating surface, making them more effective,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their shape) at temperatures up to 230°C and above...
• Considering the option of free shaping and customization to custom projects, magnetic components can be produced in a wide range of forms and dimensions, which expands the range of possible applications,
• Universal use in electronics industry – they serve a role in computer drives, motor assemblies, diagnostic systems, and complex engineering applications.
• Thanks to concentrated force, small magnets offer high operating force, in miniature format,

Problematic aspects of neodymium magnets and proposals for their use:

• Brittleness is one of their disadvantages. Upon strong impact they can break. We recommend keeping them in a steel housing, 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.
• Magnets exposed to a humid environment can rust. Therefore while using outdoors, we advise using water-impermeable magnets made of rubber, plastic or other material resistant to moisture
• Limited ability of producing nuts in the magnet and complex forms - preferred is casing - magnetic holder.
• Health risk related to microscopic parts of magnets are risky, when accidentally swallowed, which gains importance in the context of child health protection. Additionally, small components of these magnets are able to be problematic in diagnostics medical after entering the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Maximum holding power of the magnet – what it depends on?

Breakaway force is the result of a measurement for ideal contact conditions, including:

• on a block made of structural steel, perfectly concentrating the magnetic field
• possessing a thickness of min. 10 mm to avoid saturation
• with a plane cleaned and smooth
• without the slightest air gap between the magnet and steel
• under vertical force vector (90-degree angle)
• at room temperature

Determinants of lifting force in real conditions

Effective lifting capacity is influenced by specific conditions, mainly (from most important):

• Clearance – the presence of foreign body (rust, tape, gap) interrupts the magnetic circuit, which lowers capacity rapidly (even by 50% at 0.5 mm).
• Loading method – declared lifting capacity refers to detachment vertically. When applying parallel force, the magnet holds significantly lower power (often approx. 20-30% of nominal force).
• Element thickness – to utilize 100% power, the steel must be adequately massive. Thin sheet limits the attraction force (the magnet "punches through" it).
• Material type – the best choice is high-permeability steel. Stainless steels may have worse magnetic properties.
• Base smoothness – the smoother and more polished the plate, the better the adhesion and higher the lifting capacity. Roughness acts like micro-gaps.
• Thermal environment – temperature increase results in weakening of force. Check the maximum operating temperature for a given model.

* Holding force was checked on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, in contrast under parallel forces the lifting capacity is smaller. In addition, even a small distance {between} the magnet’s surface and the plate lowers the load capacity.