AM Magnetyczny zbieracz / N38 - magnetic accessories

Strengths as well as weaknesses of rare earth magnets.

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

• They retain magnetic properties for almost ten years – the loss is just ~1% (in theory),
• They are resistant to demagnetization induced by external magnetic fields,
• In other words, due to the shiny surface of gold, the element is aesthetically pleasing,
• Magnets are characterized by maximum magnetic induction on the active area,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their shape) at temperatures up to 230°C and above...
• Thanks to flexibility in forming and the ability to adapt to unusual requirements,
• Significant place in innovative solutions – they find application in HDD drives, brushless drives, advanced medical instruments, and multitasking production systems.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in tiny dimensions, which makes them useful in miniature devices

Cons of neodymium magnets and proposals for their use:

• Brittleness is one of their disadvantages. Upon intense impact they can fracture. We recommend keeping them in a strong case, which not only protects them against impacts but also increases their durability
• Neodymium magnets lose 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 durability even at temperatures up to 230°C
• They rust in a humid environment - during use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• Due to limitations in realizing nuts and complicated shapes in magnets, we propose using cover - magnetic holder.
• Health risk to health – tiny shards of magnets pose a threat, if swallowed, which gains importance in the context of child safety. It is also worth noting that small components of these products are able to be problematic in diagnostics 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

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

Information about lifting capacity was defined for optimal configuration, assuming:

• using a base made of mild steel, acting as a ideal flux conductor
• with a cross-section no less than 10 mm
• with an polished contact surface
• with direct contact (without paint)
• under perpendicular force direction (90-degree angle)
• at conditions approx. 20°C

Lifting capacity in practice – influencing factors

In real-world applications, the actual holding force results from a number of factors, ranked from most significant:

• Distance (betwixt the magnet and the plate), since even a tiny distance (e.g. 0.5 mm) can cause a drastic drop in lifting capacity by up to 50% (this also applies to varnish, corrosion or dirt).
• Force direction – catalog parameter refers to pulling vertically. When attempting to slide, the magnet holds much less (typically approx. 20-30% of nominal force).
• Substrate thickness – to utilize 100% power, the steel must be sufficiently thick. Thin sheet restricts the attraction force (the magnet "punches through" it).
• Material composition – not every steel reacts the same. High carbon content weaken the interaction with the magnet.
• Surface condition – ground elements ensure maximum contact, which improves force. Rough surfaces weaken the grip.
• Temperature influence – high temperature weakens pulling force. Too high temperature can permanently damage the magnet.

* Lifting capacity testing was performed on a smooth plate of suitable thickness, under perpendicular forces, in contrast under shearing force the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet and the plate decreases the lifting capacity.