MP 62x42x25 / N38 - ring magnet

Pros and cons of rare earth magnets.

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

• Their power is maintained, and after approximately ten years it decreases only by ~1% (according to research),
• They have excellent resistance to magnetism drop as a result of external fields,
• By covering with a shiny layer of gold, the element gains an aesthetic look,
• They show high magnetic induction at the operating surface, which affects their effectiveness,
• Through (appropriate) combination of ingredients, they can achieve high thermal strength, enabling operation at temperatures reaching 230°C and above...
• Possibility of accurate shaping as well as modifying to atypical applications,
• Universal use in innovative solutions – they are commonly used in magnetic memories, drive modules, diagnostic systems, and multitasking production systems.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in small dimensions, which allows their use in miniature devices

Disadvantages of NdFeB magnets:

• Brittleness is one of their disadvantages. Upon strong impact they can fracture. We advise keeping them in a strong case, which not only protects them against impacts but also raises their durability
• Neodymium magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of strength (a factor is the shape as well as dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are extremely resistant to heat
• Due to the susceptibility of magnets to corrosion in a humid environment, we recommend using waterproof magnets made of rubber, plastic or other material stable to moisture, in case of application outdoors
• Limited possibility of producing threads in the magnet and complex forms - preferred is a housing - magnetic holder.
• Potential hazard related to microscopic parts of magnets are risky, if swallowed, which is particularly important in the aspect of protecting the youngest. Additionally, tiny parts of these magnets can be problematic in diagnostics medical in case of swallowing.
• Due to neodymium price, their price is relatively high,

Optimal lifting capacity of a neodymium magnet – what affects it?

The load parameter shown represents the peak performance, recorded under ideal test conditions, namely:

• using a sheet made of low-carbon steel, serving as a circuit closing element
• with a thickness of at least 10 mm
• characterized by smoothness
• with zero gap (no coatings)
• under vertical application of breakaway force (90-degree angle)
• in neutral thermal conditions

Practical lifting capacity: influencing factors

It is worth knowing that the application force will differ depending on the following factors, starting with the most relevant:

• Space between surfaces – every millimeter of separation (caused e.g. by varnish or unevenness) significantly weakens the magnet efficiency, often by half at just 0.5 mm.
• Pull-off angle – note that the magnet holds strongest perpendicularly. Under shear forces, the capacity drops drastically, often to levels of 20-30% of the maximum value.
• Substrate thickness – for full efficiency, the steel must be sufficiently thick. Paper-thin metal restricts the lifting capacity (the magnet "punches through" it).
• Metal type – not every steel attracts identically. High carbon content worsen the interaction with the magnet.
• Plate texture – smooth surfaces ensure maximum contact, which improves field saturation. Rough surfaces weaken the grip.
• Temperature – temperature increase results in weakening of force. It is worth remembering the thermal limit for a given model.

* Lifting capacity was determined using a polished steel plate of optimal thickness (min. 20 mm), under vertically applied force, in contrast under parallel forces the holding force is lower. In addition, even a minimal clearance {between} the magnet and the plate lowers the load capacity.