UMH 20x7x35 [M4] / N38 - magnetic holder with hook

Pros and cons of rare earth magnets.

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

• They do not lose magnetism, even during approximately ten years – the drop in strength is only ~1% (based on measurements),
• Neodymium magnets prove to be highly resistant to demagnetization caused by external magnetic fields,
• In other words, due to the glossy layer of silver, the element looks attractive,
• Magnetic induction on the top side of the magnet is impressive,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the form) even at high temperatures reaching 230°C or more...
• Thanks to flexibility in forming and the ability to adapt to client solutions,
• Significant place in electronics industry – they serve a role in computer drives, brushless drives, diagnostic systems, also multitasking production systems.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in tiny dimensions, which makes them useful in small systems

What to avoid - cons of neodymium magnets: tips and applications.

• At very strong impacts they can break, therefore we recommend placing them in steel cases. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
• Neodymium magnets decrease their power under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. 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 advise using waterproof magnets e.g. in rubber, plastic
• Due to limitations in producing nuts and complex forms in magnets, we propose using a housing - magnetic mechanism.
• Possible danger resulting from small fragments of magnets are risky, in case of ingestion, which is particularly important in the aspect of protecting the youngest. Furthermore, tiny parts 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

Highest magnetic holding force – what affects it?

The declared magnet strength concerns the maximum value, obtained under optimal environment, meaning:

• using a base made of low-carbon steel, functioning as a circuit closing element
• possessing a massiveness of min. 10 mm to ensure full flux closure
• with a surface free of scratches
• under conditions of ideal adhesion (metal-to-metal)
• during pulling in a direction vertical to the mounting surface
• at conditions approx. 20°C

Lifting capacity in real conditions – factors

Bear in mind that the application force may be lower subject to elements below, starting with the most relevant:

• Space between surfaces – even a fraction of a millimeter of separation (caused e.g. by varnish or unevenness) significantly weakens the pulling force, often by half at just 0.5 mm.
• Pull-off angle – remember that the magnet holds strongest perpendicularly. Under sliding down, the capacity drops drastically, often to levels of 20-30% of the maximum value.
• Base massiveness – insufficiently thick sheet causes magnetic saturation, causing part of the flux to be escaped to the other side.
• Material type – the best choice is high-permeability steel. Cast iron may generate lower lifting capacity.
• Plate texture – smooth surfaces ensure maximum contact, which increases field saturation. Uneven metal reduce efficiency.
• Thermal environment – heating the magnet causes a temporary drop of force. It is worth remembering the thermal limit for a given model.

* Lifting capacity testing was performed on plates with a smooth surface of optimal thickness, under perpendicular forces, however under attempts to slide the magnet the load capacity is reduced by as much as 75%. In addition, even a small distance {between} the magnet’s surface and the plate reduces the load capacity.