SMZR 25x225 / N52 - magnetic separator with handle

Pros as well as cons of rare earth magnets.

Besides their durability, neodymium magnets are valued for these benefits:

• They have stable power, and over more than 10 years their performance decreases symbolically – ~1% (according to theory),
• They retain their magnetic properties even under external field action,
• By covering with a shiny layer of nickel, the element presents an aesthetic look,
• The surface of neodymium magnets generates a strong magnetic field – this is a distinguishing feature,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can work (depending on the shape) even at a temperature of 230°C or more...
• Possibility of accurate creating as well as adapting to atypical needs,
• Fundamental importance in future technologies – they find application in computer drives, electromotive mechanisms, medical equipment, as well as industrial machines.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

What to avoid - cons of neodymium magnets: weaknesses and usage proposals

• To avoid cracks upon strong impacts, we recommend using special steel holders. Such a solution secures the magnet and simultaneously improves its durability.
• When exposed to high temperature, neodymium magnets suffer a drop in power. Often, when the temperature exceeds 80°C, their strength 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
• They rust in a humid environment - during use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• We suggest a housing - magnetic mechanism, due to difficulties in producing nuts inside the magnet and complex forms.
• Potential hazard to health – tiny shards of magnets are risky, when accidentally swallowed, which gains importance in the context of child health protection. It is also worth noting that small elements of these magnets can be problematic in diagnostics medical after entering the body.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which can limit application in large quantities

Maximum lifting capacity of the magnet – what contributes to it?

Breakaway force is the result of a measurement for ideal contact conditions, taking into account:

• with the use of a sheet made of special test steel, guaranteeing maximum field concentration
• with a cross-section of at least 10 mm
• characterized by even structure
• under conditions of gap-free contact (surface-to-surface)
• during detachment in a direction perpendicular to the mounting surface
• at ambient temperature approx. 20 degrees Celsius

Key elements affecting lifting force

During everyday use, the actual lifting capacity depends on many variables, listed from crucial:

• Space between surfaces – every millimeter of distance (caused e.g. by veneer or unevenness) diminishes the pulling force, often by half at just 0.5 mm.
• Force direction – remember that the magnet holds strongest perpendicularly. Under sliding down, the capacity drops drastically, often to levels of 20-30% of the maximum value.
• Element thickness – for full efficiency, the steel must be adequately massive. Paper-thin metal restricts the attraction force (the magnet "punches through" it).
• Steel grade – the best choice is high-permeability steel. Cast iron may attract less.
• Surface structure – the smoother and more polished the surface, the larger the contact zone and stronger the hold. Roughness creates an air distance.
• Temperature – heating the magnet results in weakening of force. It is worth remembering the thermal limit for a given model.

* Lifting capacity was determined by applying a polished steel plate of optimal thickness (min. 20 mm), under perpendicular detachment force, whereas under shearing force the holding force is lower. Moreover, even a slight gap {between} the magnet’s surface and the plate decreases the holding force.