UMS 20x8.6x4.5x7 / N38 - conical magnetic holder

Pros as well as cons of rare earth magnets.

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

• They retain full power for almost ten years – the drop is just ~1% (in theory),
• Neodymium magnets are highly resistant to demagnetization caused by external magnetic fields,
• A magnet with a metallic silver surface has an effective appearance,
• Magnetic induction on the working layer of the magnet is exceptional,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their form) at temperatures up to 230°C and above...
• Thanks to the possibility of accurate molding and customization to custom requirements, NdFeB magnets can be modeled in a wide range of shapes and sizes, which expands the range of possible applications,
• Significant place in high-tech industry – they serve a role in mass storage devices, electromotive mechanisms, advanced medical instruments, also other advanced devices.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in tiny dimensions, which enables their usage in compact constructions

Characteristics of disadvantages of neodymium magnets and proposals for their use:

• 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 protects them against impacts but also raises their durability
• NdFeB magnets lose power when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of strength (a factor is the shape and 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 suggest using waterproof magnets made of rubber, plastic or other material stable to moisture, in case of application outdoors
• Due to limitations in producing threads and complex forms in magnets, we propose using casing - magnetic holder.
• Potential hazard to health – tiny shards of magnets pose a threat, when accidentally swallowed, which gains importance in the context of child health protection. It is also worth noting that small elements of these magnets are able to complicate diagnosis 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

Breakaway strength of the magnet in ideal conditions – what contributes to it?

The force parameter is a result of laboratory testing conducted under specific, ideal conditions:

• using a sheet made of low-carbon steel, functioning as a ideal flux conductor
• whose transverse dimension is min. 10 mm
• with a plane cleaned and smooth
• without any air gap between the magnet and steel
• for force acting at a right angle (in the magnet axis)
• at standard ambient temperature

Determinants of practical lifting force of a magnet

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

• Space between surfaces – even a fraction of a millimeter of separation (caused e.g. by varnish or dirt) significantly weakens the magnet efficiency, often by half at just 0.5 mm.
• Loading method – declared lifting capacity refers to detachment vertically. When applying parallel force, the magnet holds much less (typically approx. 20-30% of nominal force).
• Steel thickness – insufficiently thick sheet causes magnetic saturation, causing part of the power to be wasted to the other side.
• Material composition – different alloys attracts identically. High carbon content weaken the attraction effect.
• Surface quality – the smoother and more polished the surface, the larger the contact zone and stronger the hold. Roughness creates an air distance.
• Thermal conditions – NdFeB sinters have a negative temperature coefficient. At higher temperatures they are weaker, and at low temperatures they can be stronger (up to a certain limit).

* Holding force was checked on the plate surface of 20 mm thickness, when the force acted perpendicularly, however under parallel forces the load capacity is reduced by as much as fivefold. In addition, even a small distance {between} the magnet and the plate decreases the holding force.