MW 25x6 / N38 - cylindrical magnet

Advantages as well as disadvantages of rare earth magnets.

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

• They retain full power for almost 10 years – the drop is just ~1% (according to analyses),
• They have excellent resistance to magnetism drop as a result of opposing magnetic fields,
• Thanks to the metallic finish, the coating of nickel, gold, or silver-plated gives an aesthetic appearance,
• Magnetic induction on the working layer of the magnet remains strong,
• Thanks to resistance to high temperature, they are capable of working (depending on the form) even at temperatures up to 230°C and higher...
• Thanks to modularity in shaping and the capacity to modify to unusual requirements,
• Fundamental importance in innovative solutions – they serve a role in data components, brushless drives, diagnostic systems, also technologically advanced constructions.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Drawbacks and weaknesses of neodymium magnets: application proposals

• Susceptibility to cracking is one of their disadvantages. Upon intense impact they can break. We advise keeping them in a steel housing, which not only secures them against impacts but also raises their durability
• When exposed to high temperature, neodymium magnets suffer a drop in power. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size, as well as shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• Magnets exposed to a humid environment can rust. Therefore while using outdoors, we suggest using waterproof magnets made of rubber, plastic or other material resistant to moisture
• Due to limitations in realizing nuts and complex shapes in magnets, we propose using casing - magnetic holder.
• Health risk to health – tiny shards of magnets can be dangerous, if swallowed, which is particularly important in the context of child health protection. Additionally, small components of these magnets can complicate diagnosis medical after entering the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Magnetic strength at its maximum – what affects it?

The load parameter shown refers to the peak performance, obtained under optimal environment, meaning:

• with the contact of a yoke made of special test steel, ensuring maximum field concentration
• possessing a massiveness of at least 10 mm to avoid saturation
• characterized by lack of roughness
• with total lack of distance (no impurities)
• during pulling in a direction vertical to the mounting surface
• at temperature room level

Practical aspects of lifting capacity – factors

Bear in mind that the working load may be lower depending on the following factors, in order of importance:

• Gap (between the magnet and the metal), because even a microscopic distance (e.g. 0.5 mm) results in a drastic drop in lifting capacity by up to 50% (this also applies to paint, corrosion or dirt).
• Pull-off angle – note that the magnet has greatest strength perpendicularly. Under shear forces, the holding force drops drastically, often to levels of 20-30% of the nominal value.
• Plate thickness – insufficiently thick plate does not close the flux, causing part of the flux to be wasted to the other side.
• Steel type – low-carbon steel attracts best. Alloy steels reduce magnetic permeability and holding force.
• Surface condition – ground elements ensure maximum contact, which improves field saturation. Rough surfaces reduce efficiency.
• Heat – NdFeB sinters have a negative temperature coefficient. At higher temperatures they are weaker, and at low temperatures gain strength (up to a certain limit).

* Lifting capacity testing was conducted on a smooth plate of suitable thickness, under perpendicular forces, however under attempts to slide the magnet the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet’s surface and the plate decreases the load capacity.