SMZR 25x175 / N52 - magnetic separator with handle

Strengths and weaknesses of neodymium magnets.

In addition to their magnetic capacity, neodymium magnets provide the following advantages:

• They have unchanged lifting capacity, and over more than 10 years their attraction force decreases symbolically – ~1% (according to theory),
• Neodymium magnets remain remarkably resistant to magnetic field loss caused by magnetic disturbances,
• Thanks to the smooth finish, the plating of Ni-Cu-Ni, gold-plated, or silver-plated gives an clean appearance,
• The surface of neodymium magnets generates a intense magnetic field – this is a key feature,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and can work (depending on the form) even at a temperature of 230°C or more...
• Considering the option of flexible molding and adaptation to custom projects, neodymium magnets can be manufactured in a variety of forms and dimensions, which expands the range of possible applications,
• Universal use in advanced technology sectors – they are used in HDD drives, brushless drives, medical equipment, and other advanced devices.
• Thanks to concentrated force, small magnets offer high operating force, occupying minimum space,

Characteristics of disadvantages of neodymium magnets: application proposals

• At 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.
• We warn that neodymium magnets can lose their strength at high temperatures. To prevent this, we suggest our specialized [AH] magnets, which work effectively even at 230°C.
• When exposed to humidity, magnets usually rust. For applications outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which secure oxidation as well as corrosion.
• Due to limitations in realizing threads and complex forms in magnets, we recommend using casing - magnetic holder.
• Possible danger resulting from small fragments of magnets are risky, when accidentally swallowed, which gains importance in the context of child safety. Furthermore, tiny parts of these devices can be problematic in diagnostics medical in case of swallowing.
• Due to expensive raw materials, their price is higher than average,

Maximum lifting capacity of the magnet – what it depends on?

The force parameter is a measurement result conducted under specific, ideal conditions:

• on a block made of mild steel, effectively closing the magnetic field
• whose transverse dimension reaches at least 10 mm
• with an polished touching surface
• with total lack of distance (no paint)
• for force acting at a right angle (in the magnet axis)
• at ambient temperature approx. 20 degrees Celsius

Impact of factors on magnetic holding capacity in practice

Effective lifting capacity impacted by working environment parameters, mainly (from most important):

• Distance – the presence of foreign body (rust, tape, gap) interrupts the magnetic circuit, which lowers power steeply (even by 50% at 0.5 mm).
• Force direction – declared lifting capacity refers to detachment vertically. When applying parallel force, the magnet exhibits significantly lower power (often approx. 20-30% of maximum force).
• Steel thickness – too thin steel causes magnetic saturation, causing part of the flux to be escaped into the air.
• Material type – ideal substrate is pure iron steel. Stainless steels may generate lower lifting capacity.
• Surface structure – the smoother and more polished the plate, the better the adhesion and stronger the hold. Unevenness creates an air distance.
• Thermal conditions – neodymium magnets have a negative temperature coefficient. At higher temperatures they are weaker, and in frost they can be stronger (up to a certain limit).

* Lifting capacity testing was carried out on a smooth plate of suitable thickness, under a perpendicular pulling force, whereas under attempts to slide the magnet the lifting capacity is smaller. Moreover, even a small distance {between} the magnet’s surface and the plate decreases the lifting capacity.