SM 32x225 [2xM8] / N42 - magnetic separator

Strengths as well as weaknesses of rare earth magnets.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They do not lose magnetism, even over nearly 10 years – the drop in lifting capacity is only ~1% (according to tests),
• They do not lose their magnetic properties even under external field action,
• By applying a shiny layer of nickel, the element presents an modern look,
• Neodymium magnets ensure maximum magnetic induction on a small area, which ensures high operational effectiveness,
• Through (adequate) combination of ingredients, they can achieve high thermal strength, enabling functioning at temperatures reaching 230°C and above...
• Due to the option of accurate shaping and customization to unique projects, magnetic components can be produced in a broad palette of shapes and sizes, which amplifies use scope,
• Versatile presence in advanced technology sectors – they are utilized in mass storage devices, drive modules, medical devices, also other advanced devices.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in compact dimensions, which makes them useful in miniature devices

Problematic aspects of neodymium magnets: application proposals

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth securing magnets using a steel holder. Such protection not only protects the magnet but also improves its resistance to damage
• When exposed to high temperature, neodymium magnets experience a drop in force. 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
• When exposed to humidity, magnets start to rust. To use them in conditions outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which prevent oxidation as well as corrosion.
• We recommend cover - magnetic mechanism, due to difficulties in creating threads inside the magnet and complicated forms.
• Possible danger related to microscopic parts of magnets are risky, in case of ingestion, which gains importance in the context of child health protection. Additionally, small components of these magnets can complicate diagnosis medical after entering the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Highest magnetic holding force – what affects it?

The specified lifting capacity concerns the limit force, obtained under laboratory conditions, specifically:

• using a plate made of mild steel, serving as a magnetic yoke
• with a cross-section no less than 10 mm
• characterized by lack of roughness
• without the slightest clearance between the magnet and steel
• under axial force vector (90-degree angle)
• in stable room temperature

Determinants of lifting force in real conditions

In real-world applications, the real power depends on a number of factors, ranked from the most important:

• Clearance – existence of foreign body (rust, tape, air) acts as an insulator, which reduces power steeply (even by 50% at 0.5 mm).
• Pull-off angle – note that the magnet has greatest strength perpendicularly. Under sliding down, the capacity drops significantly, often to levels of 20-30% of the nominal value.
• Element thickness – to utilize 100% power, the steel must be sufficiently thick. Paper-thin metal limits the attraction force (the magnet "punches through" it).
• Material type – ideal substrate is pure iron steel. Cast iron may generate lower lifting capacity.
• Smoothness – ideal contact is possible only on polished steel. Any scratches and bumps create air cushions, weakening the magnet.
• Heat – neodymium magnets have a sensitivity to temperature. At higher temperatures they lose power, and at low temperatures they can be stronger (up to a certain limit).

* Holding force was measured on the plate surface of 20 mm thickness, when the force acted perpendicularly, in contrast under parallel forces the holding force is lower. Moreover, even a slight gap {between} the magnet’s surface and the plate lowers the load capacity.