SM 32x225 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their exceptional magnetic power, neodymium magnets offer the following advantages:

• They do not lose their strength nearly ten years – the reduction of power is only ~1% (according to tests),
• They are very resistant to demagnetization caused by external magnetic fields,
• By applying a reflective layer of gold, the element gains a modern look,
• Magnetic induction on the surface of these magnets is impressively powerful,
• These magnets tolerate high temperatures, often exceeding 230°C, when properly designed (in relation to form),
• The ability for custom shaping and customization to custom needs – neodymium magnets can be manufactured in many forms and dimensions, which amplifies their functionality across industries,
• Key role in modern technologies – they are utilized in HDDs, electric drives, healthcare devices as well as high-tech tools,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in compact dimensions, which makes them useful in small systems

Disadvantages of NdFeB magnets:

• They may fracture when subjected to a sudden impact. If the magnets are exposed to external force, it is advisable to use in a protective case. The steel housing, in the form of a holder, protects the magnet from fracture and additionally increases its overall robustness,
• Magnets lose magnetic efficiency when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible power drop (influenced by the magnet’s structure). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• They rust in a humid environment, especially when used outside, we recommend using encapsulated magnets, such as those made of polymer,
• The use of a protective casing or external holder is recommended, since machining fine details in neodymium magnets is difficult,
• Safety concern due to small fragments may arise, in case of ingestion, which is notable in the context of child safety. Additionally, minuscule fragments from these assemblies may interfere with diagnostics when ingested,
• In cases of mass production, neodymium magnet cost is a challenge,

Maximum lifting force for a neodymium magnet – what it depends on?

The given strength of the magnet corresponds to the optimal strength, measured under optimal conditions, namely:

• with the use of low-carbon steel plate serving as a magnetic yoke
• with a thickness of minimum 10 mm
• with a refined outer layer
• with no separation
• under perpendicular detachment force
• in normal thermal conditions

Practical aspects of lifting capacity – factors

The lifting capacity of a magnet is determined by in practice key elements, according to their importance:

• Air gap between the magnet and the plate, as even a very small distance (e.g. 0.5 mm) can cause a drop in lifting force of up to 50%.
• Direction of applied force, because the maximum lifting capacity is achieved under perpendicular application. The force required to slide the magnet along the plate is usually several times lower.
• Thickness of the plate, as a plate that is too thin causes part of the magnetic flux not to be used and to remain wasted in the air.
• Material of the plate, because higher carbon content lowers holding force, while higher iron content increases it. The best choice is steel with high magnetic permeability and high saturation induction.
• Surface of the plate, because the more smooth and polished it is, the better the contact and consequently the greater the magnetic saturation.
• Operating temperature, since all permanent magnets have a negative temperature coefficient. This means that at high temperatures they are weaker, while at sub-zero temperatures they become slightly stronger.

* Holding force was checked on the plate surface of 20 mm thickness, when the force acted perpendicularly, whereas under parallel forces the load capacity is reduced by as much as 5 times. In addition, even a minimal clearance {between} the magnet and the plate lowers the holding force.