MW 15x4 / N38 - cylindrical magnet

Advantages and disadvantages of rare earth magnets.

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

• They virtually do not lose strength, because even after ten years the decline in efficiency is only ~1% (based on calculations),
• Magnets effectively resist against loss of magnetization caused by ambient magnetic noise,
• Thanks to the elegant finish, the coating of nickel, gold-plated, or silver gives an visually attractive appearance,
• Magnets are distinguished by excellent magnetic induction on the surface,
• Thanks to resistance to high temperature, they are capable of working (depending on the form) even at temperatures up to 230°C and higher...
• Due to the option of accurate molding and adaptation to custom solutions, neodymium magnets can be manufactured in a variety of shapes and sizes, which amplifies use scope,
• Significant place in modern industrial fields – they are used in computer drives, electromotive mechanisms, medical devices, also complex engineering applications.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Drawbacks and weaknesses of neodymium magnets: tips and applications.

• Susceptibility to cracking is one of their disadvantages. Upon intense impact they can break. We advise keeping them in a strong case, which not only protects them against impacts but also increases their durability
• We warn that neodymium magnets can reduce their power at high temperatures. To prevent this, we recommend our specialized [AH] magnets, which work effectively even at 230°C.
• They oxidize in a humid environment. For use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• We suggest a housing - magnetic mechanism, due to difficulties in producing threads inside the magnet and complicated forms.
• Potential hazard to health – tiny shards of magnets pose a threat, when accidentally swallowed, which is particularly important in the context of child safety. Furthermore, small elements of these products can complicate diagnosis medical when they are in the body.
• Due to neodymium price, their price is relatively high,

Maximum lifting capacity of the magnet – what contributes to it?

The specified lifting capacity refers to the peak performance, recorded under ideal test conditions, meaning:

• using a sheet made of mild steel, acting as a circuit closing element
• whose transverse dimension is min. 10 mm
• with a plane perfectly flat
• without the slightest air gap between the magnet and steel
• under vertical force vector (90-degree angle)
• at temperature approx. 20 degrees Celsius

Practical aspects of lifting capacity – factors

Bear in mind that the magnet holding will differ depending on elements below, starting with the most relevant:

• Gap between magnet and steel – every millimeter of separation (caused e.g. by varnish or unevenness) diminishes the pulling force, often by half at just 0.5 mm.
• Direction of force – highest force is obtained only during pulling at a 90° angle. The shear force of the magnet along the surface is usually several times lower (approx. 1/5 of the lifting capacity).
• Steel thickness – insufficiently thick plate does not close the flux, causing part of the flux to be escaped to the other side.
• Steel grade – ideal substrate is high-permeability steel. Stainless steels may have worse magnetic properties.
• Surface condition – smooth surfaces guarantee perfect abutment, which increases field saturation. Uneven metal reduce efficiency.
• Heat – NdFeB sinters have a negative temperature coefficient. At higher temperatures they are weaker, and in frost gain strength (up to a certain limit).

* Lifting capacity testing was carried out on a smooth plate of optimal thickness, under perpendicular forces, in contrast under attempts to slide the magnet the lifting capacity is smaller. Moreover, even a small distance {between} the magnet and the plate reduces the load capacity.