MW 5x30 / N38 - cylindrical magnet

Strengths and weaknesses of neodymium magnets.

Besides their remarkable pulling force, neodymium magnets offer the following advantages:

• Their power remains stable, and after approximately ten years it decreases only by ~1% (according to research),
• They maintain their magnetic properties even under close interference source,
• A magnet with a shiny nickel surface looks better,
• Neodymium magnets create maximum magnetic induction on a small area, which increases force concentration,
• Thanks to resistance to high temperature, they can operate (depending on the shape) even at temperatures up to 230°C and higher...
• Thanks to flexibility in designing and the ability to adapt to complex applications,
• Huge importance in innovative solutions – they are used in HDD drives, electric drive systems, advanced medical instruments, and industrial machines.
• Thanks to their power density, small magnets offer high operating force, with minimal size,

Disadvantages of neodymium magnets:

• Brittleness is one of their disadvantages. Upon strong impact they can break. We recommend keeping them in a strong case, which not only secures them against impacts but also increases their durability
• We warn that neodymium magnets can lose their power at high temperatures. To prevent this, we recommend our specialized [AH] magnets, which work effectively even at 230°C.
• When exposed to humidity, magnets start to rust. For applications outside, it is recommended to use protective magnets, such as those in rubber or plastics, which secure oxidation as well as corrosion.
• We suggest cover - magnetic mechanism, due to difficulties in creating threads inside the magnet and complex forms.
• Potential hazard related to microscopic parts of magnets can be dangerous, when accidentally swallowed, which becomes key in the context of child health protection. Furthermore, tiny parts of these devices can complicate diagnosis medical when they are in the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Breakaway strength of the magnet in ideal conditions – what it depends on?

Breakaway force is the result of a measurement for optimal configuration, assuming:

• with the use of a yoke made of low-carbon steel, ensuring full magnetic saturation
• whose transverse dimension reaches at least 10 mm
• with an ground touching surface
• without the slightest air gap between the magnet and steel
• for force applied at a right angle (pull-off, not shear)
• at temperature approx. 20 degrees Celsius

Practical lifting capacity: influencing factors

In practice, the actual lifting capacity results from several key aspects, listed from crucial:

• Clearance – the presence of foreign body (rust, tape, air) interrupts the magnetic circuit, which lowers power steeply (even by 50% at 0.5 mm).
• Load vector – maximum parameter is obtained only during perpendicular pulling. The force required to slide of the magnet along the surface is usually several times lower (approx. 1/5 of the lifting capacity).
• Substrate thickness – to utilize 100% power, the steel must be sufficiently thick. Paper-thin metal restricts the lifting capacity (the magnet "punches through" it).
• Steel grade – the best choice is pure iron steel. Stainless steels may generate lower lifting capacity.
• Plate texture – smooth surfaces ensure maximum contact, which improves field saturation. Rough surfaces weaken the grip.
• Heat – NdFeB sinters have a negative temperature coefficient. At higher temperatures they are weaker, and at low temperatures they can be stronger (up to a certain limit).

* Lifting capacity was measured by applying a steel plate with a smooth surface of suitable thickness (min. 20 mm), under vertically applied force, however under attempts to slide the magnet the lifting capacity is smaller. In addition, even a minimal clearance {between} the magnet’s surface and the plate decreases the holding force.