UMGW 20x15x7 [M4] GW / N38 - magnetic holder internal thread

Strengths and weaknesses of rare earth magnets.

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

• They virtually do not lose power, because even after ten years the performance loss is only ~1% (according to literature),
• Magnets effectively defend themselves against demagnetization caused by external fields,
• A magnet with a metallic silver surface looks better,
• They feature high magnetic induction at the operating surface, which improves attraction properties,
• 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...
• Possibility of precise machining as well as adjusting to defined requirements,
• Key role in high-tech industry – they find application in HDD drives, electric drive systems, advanced medical instruments, and technologically advanced constructions.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Disadvantages of neodymium magnets:

• To avoid cracks upon strong impacts, we recommend using special steel holders. Such a solution protects the magnet and simultaneously increases its durability.
• NdFeB magnets lose power when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of power (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 very resistant to heat
• When exposed to humidity, magnets usually rust. For applications outside, it is recommended to use protective magnets, such as those in rubber or plastics, which prevent oxidation and corrosion.
• We suggest cover - magnetic holder, due to difficulties in realizing threads inside the magnet and complex forms.
• Possible danger 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 small elements of these devices can be problematic in diagnostics medical in case of swallowing.
• Due to expensive raw materials, their price is relatively high,

Maximum magnetic pulling force – what affects it?

The specified lifting capacity concerns the maximum value, measured under optimal environment, namely:

• with the use of a yoke made of low-carbon steel, guaranteeing maximum field concentration
• whose transverse dimension is min. 10 mm
• with an polished touching surface
• without the slightest clearance between the magnet and steel
• for force applied at a right angle (pull-off, not shear)
• at conditions approx. 20°C

What influences lifting capacity in practice

In practice, the real power results from several key aspects, presented from crucial:

• Clearance – existence of foreign body (rust, dirt, gap) interrupts the magnetic circuit, which lowers power rapidly (even by 50% at 0.5 mm).
• Force direction – catalog parameter refers to detachment vertically. When applying parallel force, the magnet exhibits significantly lower power (often approx. 20-30% of maximum force).
• Substrate thickness – to utilize 100% power, the steel must be sufficiently thick. Thin sheet limits the lifting capacity (the magnet "punches through" it).
• Material composition – not every steel reacts the same. 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 acts like micro-gaps.
• Thermal factor – hot environment reduces pulling force. Exceeding the limit temperature can permanently damage the magnet.

* Lifting capacity was measured with the use of a polished steel plate of optimal thickness (min. 20 mm), under vertically applied force, however under attempts to slide the magnet the load capacity is reduced by as much as fivefold. Additionally, even a small distance {between} the magnet and the plate decreases the holding force.