UMS 16x6.5x3.5x5 / N38 - conical magnetic holder

Strengths and weaknesses of rare earth magnets.

Besides their high retention, neodymium magnets are valued for these benefits:

• They do not lose strength, even over nearly ten years – the decrease in lifting capacity is only ~1% (according to tests),
• Neodymium magnets remain extremely resistant to loss of magnetic properties caused by external interference,
• A magnet with a smooth nickel surface has better aesthetics,
• Magnetic induction on the working part of the magnet remains impressive,
• Through (adequate) combination of ingredients, they can achieve high thermal resistance, enabling action at temperatures approaching 230°C and above...
• In view of the possibility of flexible molding and adaptation to unique solutions, NdFeB magnets can be produced in a variety of forms and dimensions, which expands the range of possible applications,
• Fundamental importance in advanced technology sectors – they are utilized in mass storage devices, brushless drives, medical devices, and multitasking production systems.
• Relatively small size with high pulling force – neodymium magnets offer high power in compact dimensions, which enables their usage in small systems

Cons of neodymium magnets and ways of using them

• They are fragile upon heavy impacts. To avoid cracks, it is worth securing magnets in special housings. Such protection not only shields the magnet but also increases its resistance to damage
• NdFeB magnets lose force when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of power (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 very 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 resistant to moisture, when using outdoors
• We recommend cover - magnetic holder, due to difficulties in creating threads inside the magnet and complicated shapes.
• Potential hazard to health – tiny shards of magnets can be dangerous, when accidentally swallowed, which is particularly important in the context of child health protection. It is also worth noting that tiny parts of these magnets are able to disrupt the diagnostic process medical in case of swallowing.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Maximum magnetic pulling force – what contributes to it?

Information about lifting capacity is the result of a measurement for ideal contact conditions, including:

• on a block made of mild steel, effectively closing the magnetic flux
• whose transverse dimension reaches at least 10 mm
• characterized by even structure
• under conditions of gap-free contact (surface-to-surface)
• during pulling in a direction vertical to the mounting surface
• at temperature room level

Lifting capacity in practice – influencing factors

Effective lifting capacity is influenced by working environment parameters, such as (from priority):

• Space between magnet and steel – even a fraction of a millimeter of separation (caused e.g. by veneer or dirt) significantly weakens the magnet efficiency, often by half at just 0.5 mm.
• Force direction – note that the magnet has greatest strength perpendicularly. Under sliding down, the capacity drops drastically, often to levels of 20-30% of the maximum value.
• Plate thickness – insufficiently thick steel causes magnetic saturation, causing part of the flux to be wasted into the air.
• Chemical composition of the base – mild steel gives the best results. Alloy steels decrease magnetic permeability and holding force.
• Smoothness – full contact is obtained only on smooth steel. Rough texture reduce the real contact area, weakening the magnet.
• Thermal factor – hot environment reduces magnetic field. Too high temperature can permanently damage the magnet.

* Lifting capacity was assessed by applying a polished steel plate of suitable thickness (min. 20 mm), under vertically applied force, whereas under shearing force the load capacity is reduced by as much as 75%. Additionally, even a minimal clearance {between} the magnet and the plate lowers the holding force.