SM 25x350 [2xM8] / N52 - magnetic separator

Advantages and disadvantages of rare earth magnets.

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

• Their magnetic field remains stable, and after approximately 10 years it drops only by ~1% (according to research),
• Magnets effectively defend themselves against demagnetization caused by ambient magnetic noise,
• A magnet with a metallic silver surface looks better,
• Magnetic induction on the top side of the magnet remains maximum,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and are able to act (depending on the form) even at a temperature of 230°C or more...
• Possibility of accurate modeling as well as adjusting to precise applications,
• Key role in future technologies – they are used in computer drives, electromotive mechanisms, advanced medical instruments, as well as multitasking production systems.
• Thanks to concentrated force, small magnets offer high operating force, with minimal size,

What to avoid - cons of neodymium magnets and proposals for their use:

• 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
• We warn that neodymium magnets can lose their power at high temperatures. To prevent this, we suggest our specialized [AH] magnets, which work effectively even at 230°C.
• Due to the susceptibility of magnets to corrosion in a humid environment, we suggest using waterproof magnets made of rubber, plastic or other material stable to moisture, in case of application outdoors
• Limited ability of creating threads in the magnet and complicated shapes - recommended is a housing - magnetic holder.
• Possible danger resulting from small fragments of magnets are risky, when accidentally swallowed, which gains importance in the context of child health protection. It is also worth noting that tiny parts of these devices are able to complicate diagnosis medical in case of swallowing.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Highest magnetic holding force – what it depends on?

The load parameter shown concerns the maximum value, measured under optimal environment, namely:

• on a block made of mild steel, optimally conducting the magnetic field
• whose transverse dimension equals approx. 10 mm
• characterized by lack of roughness
• with direct contact (no impurities)
• for force acting at a right angle (in the magnet axis)
• at ambient temperature approx. 20 degrees Celsius

Practical lifting capacity: influencing factors

It is worth knowing that the magnet holding will differ depending on elements below, in order of importance:

• Gap (betwixt the magnet and the metal), because even a very small clearance (e.g. 0.5 mm) leads to a decrease in force by up to 50% (this also applies to varnish, corrosion or debris).
• Force direction – declared lifting capacity refers to detachment vertically. When attempting to slide, the magnet exhibits much less (often approx. 20-30% of nominal force).
• Metal thickness – thin material does not allow full use of the magnet. Magnetic flux penetrates through instead of converting into lifting capacity.
• Steel type – mild steel gives the best results. Higher carbon content lower magnetic permeability and lifting capacity.
• Smoothness – full contact is possible only on polished steel. Rough texture create air cushions, reducing force.
• Temperature influence – high temperature weakens magnetic field. Exceeding the limit temperature can permanently damage the magnet.

* Lifting capacity testing was performed on plates with a smooth surface of suitable thickness, under perpendicular forces, whereas under parallel forces the lifting capacity is smaller. Moreover, even a small distance {between} the magnet’s surface and the plate decreases the load capacity.