HH 25x7.7 [M5] / N38 - through hole magnetic holder

Pros as well as cons of NdFeB magnets.

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

• They have constant strength, and over more than 10 years their performance decreases symbolically – ~1% (in testing),
• Neodymium magnets are characterized by extremely resistant to demagnetization caused by external field sources,
• A magnet with a metallic silver surface has better aesthetics,
• They show high magnetic induction at the operating surface, which increases their power,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their shape) at temperatures up to 230°C and above...
• Thanks to versatility in forming and the ability to adapt to specific needs,
• Versatile presence in modern industrial fields – they find application in data components, drive modules, diagnostic systems, as well as modern systems.
• Thanks to efficiency per cm³, small magnets offer high operating force, in miniature format,

Disadvantages of NdFeB magnets:

• At strong impacts they can break, therefore we advise 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 strength under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. Therefore, we recommend our special magnets marked [AH], which maintain durability even at temperatures up to 230°C
• They rust in a humid environment. For use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• Limited possibility of producing nuts in the magnet and complicated forms - recommended is casing - magnetic holder.
• Possible danger to health – tiny shards of magnets pose a threat, if swallowed, which is particularly important in the aspect of protecting the youngest. Additionally, small elements of these magnets can be problematic in diagnostics medical when they are in the body.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Best holding force of the magnet in ideal parameters – what contributes to it?

Breakaway force was determined for the most favorable conditions, assuming:

• with the use of a yoke made of special test steel, guaranteeing maximum field concentration
• whose thickness is min. 10 mm
• with an ideally smooth contact surface
• without any insulating layer between the magnet and steel
• for force applied at a right angle (in the magnet axis)
• at ambient temperature approx. 20 degrees Celsius

Lifting capacity in practice – influencing factors

During everyday use, the actual lifting capacity is determined by a number of factors, presented from the most important:

• Clearance – the presence of foreign body (rust, dirt, air) interrupts the magnetic circuit, which reduces capacity rapidly (even by 50% at 0.5 mm).
• Load vector – highest force is obtained only during pulling at a 90° angle. The resistance to sliding of the magnet along the plate is typically several times smaller (approx. 1/5 of the lifting capacity).
• Base massiveness – too thin steel causes magnetic saturation, causing part of the flux to be wasted to the other side.
• Metal type – different alloys reacts the same. High carbon content worsen the attraction effect.
• Plate texture – ground elements guarantee perfect abutment, which improves field saturation. Rough surfaces weaken the grip.
• Temperature influence – high temperature weakens pulling force. Too high temperature can permanently damage the magnet.

* Holding force was measured on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, whereas under shearing force the holding force is lower. In addition, even a small distance {between} the magnet and the plate decreases the lifting capacity.