SMZR 32x200 / N52 - magnetic separator with handle

Strengths as well as weaknesses of rare earth magnets.

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

• They retain magnetic properties for nearly ten years – the drop is just ~1% (based on simulations),
• Neodymium magnets remain highly resistant to loss of magnetic properties caused by external field sources,
• A magnet with a smooth gold surface has an effective appearance,
• Magnetic induction on the top side of the magnet remains very high,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the form) even at high temperatures reaching 230°C or more...
• Thanks to versatility in designing and the ability to customize to complex applications,
• Significant place in electronics industry – they are utilized in data components, brushless drives, medical equipment, as well as complex engineering applications.
• Thanks to concentrated force, small magnets offer high operating force, with minimal size,

Problematic aspects of neodymium magnets: tips and applications.

• Susceptibility to cracking is one of their disadvantages. Upon intense impact they can break. We recommend keeping them in a strong case, which not only secures them against impacts but also increases their durability
• Neodymium magnets decrease their strength under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
• They oxidize in a humid environment - during use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• Limited ability of producing nuts in the magnet and complicated shapes - preferred is cover - magnet mounting.
• Possible danger resulting from small fragments of magnets are risky, if swallowed, which gains importance in the context of child safety. Additionally, small elements of these magnets can be problematic in diagnostics medical when they are in the body.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Highest magnetic holding force – what it depends on?

Magnet power was determined for the most favorable conditions, including:

• using a sheet made of low-carbon steel, serving as a magnetic yoke
• possessing a thickness of min. 10 mm to avoid saturation
• characterized by smoothness
• under conditions of no distance (surface-to-surface)
• during detachment in a direction vertical to the mounting surface
• in temp. approx. 20°C

Determinants of lifting force in real conditions

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

• Space between magnet and steel – every millimeter of distance (caused e.g. by veneer or unevenness) diminishes the magnet efficiency, often by half at just 0.5 mm.
• Pull-off angle – remember that the magnet holds strongest perpendicularly. Under shear forces, the holding force drops significantly, often to levels of 20-30% of the maximum value.
• Metal thickness – thin material does not allow full use of the magnet. Part of the magnetic field penetrates through instead of converting into lifting capacity.
• Steel grade – ideal substrate is high-permeability steel. Cast iron may attract less.
• Smoothness – full contact is possible only on polished steel. Any scratches and bumps reduce the real contact area, weakening the magnet.
• Temperature – temperature increase results in weakening of induction. It is worth remembering the thermal limit for a given model.

* Lifting capacity testing was carried out on a smooth plate of optimal thickness, under perpendicular forces, whereas under attempts to slide the magnet the holding force is lower. Moreover, even a slight gap {between} the magnet’s surface and the plate decreases the lifting capacity.