MW 40x8 / N38 - cylindrical magnet

Strengths and weaknesses of rare earth magnets.

Besides their remarkable magnetic power, neodymium magnets offer the following advantages:

• Their strength remains stable, and after approximately ten years it decreases only by ~1% (according to research),
• They are resistant to demagnetization induced by external magnetic fields,
• The use of an elegant coating of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• Magnetic induction on the working layer of the magnet turns out to be very high,
• Thanks to resistance to high temperature, they are capable of working (depending on the shape) even at temperatures up to 230°C and higher...
• Possibility of accurate creating as well as modifying to individual conditions,
• Huge importance in high-tech industry – they are used in HDD drives, motor assemblies, precision medical tools, also multitasking production systems.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Disadvantages of neodymium magnets:

• Susceptibility to cracking is one of their disadvantages. Upon intense impact they can break. We recommend keeping them in a steel housing, which not only protects them against impacts but also raises their durability
• We warn that neodymium magnets can reduce their power at high temperatures. To prevent this, we advise our specialized [AH] magnets, which work effectively even at 230°C.
• They oxidize in a humid environment. For use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• Due to limitations in realizing nuts and complex forms in magnets, we propose using casing - magnetic mechanism.
• Possible danger related to microscopic parts of magnets pose a threat, if swallowed, which gains importance in the context of child health protection. Additionally, tiny parts of these products can complicate diagnosis medical after entering the body.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which hinders application in large quantities

Maximum holding power of the magnet – what contributes to it?

Magnet power was determined for the most favorable conditions, taking into account:

• with the use of a sheet made of special test steel, guaranteeing maximum field concentration
• possessing a thickness of minimum 10 mm to avoid saturation
• with an polished touching surface
• with total lack of distance (no coatings)
• during pulling in a direction vertical to the plane
• at conditions approx. 20°C

Lifting capacity in practice – influencing factors

Bear in mind that the application force may be lower influenced by elements below, starting with the most relevant:

• Distance – existence of foreign body (rust, tape, gap) interrupts the magnetic circuit, which reduces capacity rapidly (even by 50% at 0.5 mm).
• Force direction – catalog parameter refers to detachment vertically. When applying parallel force, the magnet holds significantly lower power (often approx. 20-30% of nominal force).
• Steel thickness – insufficiently thick sheet does not accept the full field, causing part of the flux to be escaped to the other side.
• Material composition – different alloys attracts identically. Alloy additives worsen the interaction with the magnet.
• Base smoothness – the smoother and more polished the surface, the better the adhesion and stronger the hold. Unevenness acts like micro-gaps.
• Temperature influence – high temperature reduces magnetic field. Exceeding the limit temperature can permanently damage the magnet.

* Lifting capacity testing was carried out on a smooth plate of suitable thickness, under perpendicular forces, whereas under shearing force the holding force is lower. In addition, even a minimal clearance {between} the magnet’s surface and the plate lowers the lifting capacity.