MW 15x4 / N38 - cylindrical magnet

Pros and cons of rare earth magnets.

Apart from their consistent magnetism, neodymium magnets have these key benefits:

• They retain magnetic properties for around 10 years – the loss is just ~1% (in theory),
• They are resistant to demagnetization induced by presence of other magnetic fields,
• By covering with a reflective coating of silver, the element has an nice look,
• Magnetic induction on the working part of the magnet remains impressive,
• 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...
• Possibility of precise forming as well as adjusting to individual needs,
• Wide application in innovative solutions – they are used in mass storage devices, brushless drives, diagnostic systems, as well as other advanced devices.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Drawbacks and weaknesses of neodymium magnets and ways of using them

• At very strong impacts they can break, therefore we recommend placing them in special holders. A metal housing provides additional protection against damage and increases the magnet's durability.
• Neodymium magnets lose force 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 extremely resistant to heat
• Magnets exposed to a humid environment can rust. Therefore when using outdoors, we advise using waterproof magnets made of rubber, plastic or other material protecting against moisture
• Due to limitations in creating threads and complex forms in magnets, we recommend using casing - magnetic holder.
• Health risk related to microscopic parts of magnets pose a threat, when accidentally swallowed, which is particularly important in the context of child health protection. Additionally, small components of these magnets are able to complicate diagnosis medical in case of swallowing.
• Due to neodymium price, their price exceeds standard values,

Magnetic strength at its maximum – what contributes to it?

The declared magnet strength represents the peak performance, measured under laboratory conditions, specifically:

• with the application of a yoke made of special test steel, ensuring maximum field concentration
• whose transverse dimension equals approx. 10 mm
• characterized by lack of roughness
• with zero gap (without coatings)
• during pulling in a direction perpendicular to the plane
• in stable room temperature

Practical aspects of lifting capacity – factors

Bear in mind that the magnet holding will differ influenced by the following factors, starting with the most relevant:

• Distance – the presence of any layer (rust, tape, gap) interrupts the magnetic circuit, which reduces capacity rapidly (even by 50% at 0.5 mm).
• Direction of force – maximum parameter is reached only during pulling at a 90° angle. The resistance to sliding of the magnet along the surface is typically many times smaller (approx. 1/5 of the lifting capacity).
• Plate thickness – insufficiently thick steel does not close the flux, causing part of the power to be lost to the other side.
• Metal type – different alloys reacts the same. High carbon content weaken the attraction effect.
• Smoothness – full contact is obtained only on polished steel. Any scratches and bumps reduce the real contact area, reducing force.
• Operating temperature – NdFeB sinters have a sensitivity to temperature. At higher temperatures they are weaker, and at low temperatures they can be stronger (up to a certain limit).

* Lifting capacity was measured with the use of a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular pulling force, however under parallel forces the load capacity is reduced by as much as 75%. In addition, even a slight gap {between} the magnet’s surface and the plate lowers the holding force.