UMH 20x7x35 [M4] / N38 - magnetic holder with hook

Pros as well as cons of rare earth magnets.

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

• Their magnetic field remains stable, and after around 10 years it drops only by ~1% (theoretically),
• They retain their magnetic properties even under strong external field,
• The use of an elegant finish of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• Neodymium magnets achieve maximum magnetic induction on a small surface, which allows for strong attraction,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their form) at temperatures up to 230°C and above...
• Possibility of detailed shaping as well as adjusting to defined requirements,
• Wide application in modern technologies – they are commonly used in hard drives, drive modules, medical devices, as well as multitasking production systems.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in small dimensions, which makes them useful in small systems

Disadvantages of NdFeB magnets:

• Brittleness is one of their disadvantages. Upon strong impact they can fracture. We recommend keeping them in a strong case, which not only secures them against impacts but also raises their durability
• When exposed to high temperature, neodymium magnets suffer a drop in force. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size and shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• When exposed to humidity, magnets start to rust. To use them in conditions outside, it is recommended to use protective magnets, such as those in rubber or plastics, which secure oxidation and corrosion.
• Limited possibility of producing threads in the magnet and complex forms - preferred is cover - mounting mechanism.
• Potential hazard related to microscopic parts of magnets can be dangerous, when accidentally swallowed, which becomes key in the context of child safety. Additionally, tiny parts of these magnets are able to disrupt the diagnostic process medical in case of swallowing.
• Due to expensive raw materials, their price is relatively high,

Optimal lifting capacity of a neodymium magnet – what affects it?

Information about lifting capacity is the result of a measurement for ideal contact conditions, including:

• with the use of a sheet made of low-carbon steel, ensuring maximum field concentration
• whose transverse dimension equals approx. 10 mm
• characterized by lack of roughness
• with zero gap (no paint)
• under axial force vector (90-degree angle)
• at room temperature

Lifting capacity in practice – influencing factors

Effective lifting capacity is affected by working environment parameters, mainly (from most important):

• Distance – the presence of foreign body (paint, tape, gap) interrupts the magnetic circuit, which reduces capacity rapidly (even by 50% at 0.5 mm).
• Force direction – remember that the magnet holds strongest perpendicularly. Under sliding down, the capacity drops drastically, often to levels of 20-30% of the nominal value.
• Element thickness – to utilize 100% power, the steel must be sufficiently thick. Thin sheet restricts the attraction force (the magnet "punches through" it).
• Steel type – mild steel gives the best results. Alloy steels decrease magnetic permeability and holding force.
• Smoothness – full contact is obtained only on smooth steel. Rough texture create air cushions, weakening the magnet.
• Temperature – temperature increase causes a temporary drop of induction. It is worth remembering the thermal limit for a given model.

* Lifting capacity was assessed by applying a polished steel plate of suitable thickness (min. 20 mm), under perpendicular pulling force, in contrast under parallel forces the lifting capacity is smaller. Additionally, even a slight gap {between} the magnet and the plate reduces the lifting capacity.