SM 32x425 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of neodymium magnets.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• They retain attractive force for nearly ten years – the loss is just ~1% (based on simulations),
• They maintain their magnetic properties even under strong external field,
• A magnet with a shiny gold surface has better aesthetics,
• Neodymium magnets achieve maximum magnetic induction on a contact point, which increases force concentration,
• Through (adequate) combination of ingredients, they can achieve high thermal resistance, enabling action at temperatures reaching 230°C and above...
• Thanks to modularity in designing and the capacity to customize to complex applications,
• Fundamental importance in innovative solutions – they are commonly used in HDD drives, electromotive mechanisms, advanced medical instruments, also multitasking production systems.
• Thanks to efficiency per cm³, small magnets offer high operating force, in miniature format,

Disadvantages of neodymium magnets:

• Brittleness is one of their disadvantages. Upon intense impact they can break. We advise keeping them in a steel housing, which not only protects them against impacts but also increases their durability
• When exposed to high temperature, neodymium magnets suffer a drop in force. Often, when the temperature exceeds 80°C, their power decreases (depending on the size, as well as shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• Due to the susceptibility of magnets to corrosion in a humid environment, we recommend using waterproof magnets made of rubber, plastic or other material resistant to moisture, when using outdoors
• Limited ability of creating threads in the magnet and complex forms - recommended is a housing - mounting mechanism.
• Potential hazard to health – tiny shards of magnets can be dangerous, when accidentally swallowed, which becomes key in the context of child health protection. Additionally, small elements of these devices can be problematic in diagnostics medical in case of swallowing.
• With budget limitations the cost of neodymium magnets can be a barrier,

Magnetic strength at its maximum – what contributes to it?

Holding force of 0 kg is a theoretical maximum value conducted under specific, ideal conditions:

• using a sheet made of mild steel, serving as a magnetic yoke
• whose thickness equals approx. 10 mm
• with an ideally smooth touching surface
• without any air gap between the magnet and steel
• during pulling in a direction perpendicular to the plane
• at conditions approx. 20°C

Practical lifting capacity: influencing factors

Real force impacted by working environment parameters, including (from priority):

• Air gap (between the magnet and the plate), because even a microscopic clearance (e.g. 0.5 mm) leads to a reduction in lifting capacity by up to 50% (this also applies to paint, corrosion or dirt).
• Force direction – declared lifting capacity refers to pulling vertically. When slipping, the magnet exhibits significantly lower power (often approx. 20-30% of maximum force).
• Wall thickness – thin material does not allow full use of the magnet. Magnetic flux passes through the material instead of converting into lifting capacity.
• Steel grade – the best choice is pure iron steel. Cast iron may generate lower lifting capacity.
• Surface condition – ground elements guarantee perfect abutment, which improves force. Uneven metal weaken the grip.
• Thermal environment – temperature increase causes a temporary drop of force. It is worth remembering the thermal limit for a given model.

* Lifting capacity testing was conducted on a smooth plate of optimal thickness, under a perpendicular pulling force, in contrast under parallel forces the load capacity is reduced by as much as fivefold. In addition, even a small distance {between} the magnet and the plate reduces the lifting capacity.