SM 32x275 [2xM8] / N52 - magnetic separator

Strengths as well as weaknesses of NdFeB magnets.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• They virtually do not lose power, because even after ten years the performance loss is only ~1% (in laboratory conditions),
• They retain their magnetic properties even under external field action,
• A magnet with a metallic nickel surface has better aesthetics,
• Magnetic induction on the top side of the magnet remains maximum,
• Through (adequate) combination of ingredients, they can achieve high thermal resistance, allowing for operation at temperatures approaching 230°C and above...
• Possibility of custom modeling and adjusting to precise applications,
• Significant place in advanced technology sectors – they are commonly used in hard drives, drive modules, diagnostic systems, also multitasking production systems.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Characteristics of disadvantages of neodymium magnets: weaknesses and usage proposals

• At very strong impacts they can crack, therefore we recommend placing them in special holders. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
• When exposed to high temperature, neodymium magnets suffer a drop in strength. Often, when the temperature exceeds 80°C, their power decreases (depending on the size and 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. For applications outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which prevent oxidation and corrosion.
• Due to limitations in producing threads and complicated forms in magnets, we propose using casing - magnetic mount.
• Possible danger related to microscopic parts of magnets are risky, if swallowed, which becomes key in the context of child safety. Additionally, tiny parts of these magnets are able to complicate diagnosis medical in case of swallowing.
• With mass production the cost of neodymium magnets is a challenge,

Maximum magnetic pulling force – what it depends on?

The specified lifting capacity concerns the maximum value, obtained under optimal environment, namely:

• on a block made of mild steel, effectively closing the magnetic field
• with a cross-section minimum 10 mm
• with a plane free of scratches
• with direct contact (without coatings)
• under vertical force direction (90-degree angle)
• in temp. approx. 20°C

Determinants of practical lifting force of a magnet

Effective lifting capacity is affected by specific conditions, including (from priority):

• Gap between magnet and steel – every millimeter of separation (caused e.g. by veneer or dirt) drastically reduces the magnet efficiency, often by half at just 0.5 mm.
• Load vector – maximum parameter is obtained only during perpendicular pulling. The shear force of the magnet along the surface is standardly several times lower (approx. 1/5 of the lifting capacity).
• Plate thickness – too thin plate does not close the flux, causing part of the flux to be wasted into the air.
• Metal type – different alloys reacts the same. Alloy additives worsen the interaction with the magnet.
• Smoothness – full contact is obtained only on smooth steel. Rough texture reduce the real contact area, reducing force.
• Thermal conditions – neodymium magnets have a sensitivity to temperature. When it is hot they are weaker, and at low temperatures they can be stronger (up to a certain limit).

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