SM 25x275 [2xM8] / N52 - magnetic separator

Strengths as well as weaknesses of neodymium magnets.

Apart from their strong power, neodymium magnets have these key benefits:

• Their strength is durable, and after around ten years it decreases only by ~1% (according to research),
• They are extremely resistant to demagnetization induced by presence of other magnetic fields,
• The use of an metallic finish of noble metals (nickel, gold, silver) causes the element to look better,
• The surface of neodymium magnets generates a intense magnetic field – this is a distinguishing feature,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can work (depending on the form) even at a temperature of 230°C or more...
• Thanks to the ability of precise forming and customization to individualized projects, NdFeB magnets can be manufactured in a variety of geometric configurations, which increases their versatility,
• Universal use in innovative solutions – they are utilized in mass storage devices, drive modules, diagnostic systems, also industrial machines.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in compact dimensions, which enables their usage in miniature devices

Drawbacks and weaknesses of neodymium magnets: application proposals

• They are fragile upon heavy impacts. To avoid cracks, it is worth securing magnets in a protective case. Such protection not only shields the magnet but also increases its resistance to damage
• Neodymium magnets decrease their power 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 durability even at temperatures up to 230°C
• They rust in a humid environment. For use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• Due to limitations in creating threads and complex shapes in magnets, we recommend using a housing - magnetic holder.
• Potential hazard 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 small components of these devices can complicate diagnosis medical in case of swallowing.
• With large orders the cost of neodymium magnets is a challenge,

Detachment force of the magnet in optimal conditions – what contributes to it?

Holding force of 0 kg is a result of laboratory testing conducted under standard conditions:

• with the contact of a yoke made of special test steel, ensuring maximum field concentration
• with a cross-section minimum 10 mm
• with an polished contact surface
• without any air gap between the magnet and steel
• under axial force direction (90-degree angle)
• at ambient temperature room level

What influences lifting capacity in practice

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

• Clearance – the presence of foreign body (paint, dirt, air) acts as an insulator, which lowers power rapidly (even by 50% at 0.5 mm).
• Angle of force application – highest force is available only during pulling at a 90° angle. The shear force of the magnet along the surface is usually many times smaller (approx. 1/5 of the lifting capacity).
• Wall thickness – the thinner the sheet, the weaker the hold. Part of the magnetic field passes through the material instead of generating force.
• Metal type – different alloys reacts the same. High carbon content weaken the interaction with the magnet.
• Smoothness – ideal contact is obtained only on smooth steel. Any scratches and bumps reduce the real contact area, weakening the magnet.
• Heat – neodymium magnets have a negative temperature coefficient. At higher temperatures they lose power, and in frost they can be stronger (up to a certain limit).

* Lifting capacity testing was carried out on a smooth plate of optimal thickness, under a perpendicular pulling force, however under attempts to slide the magnet the holding force is lower. Moreover, even a minimal clearance {between} the magnet’s surface and the plate reduces the lifting capacity.