UMP 97x40 [M8+M10] GW F300 kg / N38 - search holder

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They retain their full power for almost ten years – the loss is just ~1% (according to analyses),
• They protect against demagnetization induced by ambient electromagnetic environments remarkably well,
• In other words, due to the metallic silver coating, the magnet obtains an stylish appearance,
• They have extremely strong magnetic induction on the surface of the magnet,
• These magnets tolerate extreme temperatures, often exceeding 230°C, when properly designed (in relation to form),
• The ability for accurate shaping as well as adaptation to individual needs – neodymium magnets can be manufactured in many forms and dimensions, which extends the scope of their use cases,
• Significant impact in modern technologies – they serve a purpose in HDDs, rotating machines, diagnostic apparatus and other advanced devices,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in compact dimensions, which makes them ideal in small systems

Disadvantages of rare earth magnets:

• They can break when subjected to a powerful impact. If the magnets are exposed to mechanical hits, they should be placed in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from damage , and at the same time strengthens its overall robustness,
• They lose strength at elevated temperatures. Most neodymium magnets experience permanent loss in strength when heated above 80°C (depending on the dimensions and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• They rust in a damp environment – during outdoor use, we recommend using moisture-resistant magnets, such as those made of non-metallic materials,
• Using a cover – such as a magnetic holder – is advised due to the restrictions in manufacturing fine shapes directly in the magnet,
• Potential hazard related to magnet particles may arise, when consumed by mistake, which is crucial in the context of child safety. Furthermore, tiny components from these products might hinder health screening if inside the body,
• Higher purchase price is an important factor to consider compared to ceramic magnets, especially in budget-sensitive applications

Best holding force of the magnet in ideal parameters – what it depends on?

The given holding capacity of the magnet corresponds to the highest holding force, assessed in ideal conditions, namely:

• with mild steel, serving as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a refined outer layer
• with zero air gap
• in a perpendicular direction of force
• under standard ambient temperature

Lifting capacity in real conditions – factors

In practice, the holding capacity of a magnet is affected by the following aspects, arranged from the most important to the least relevant:

• Air gap between the magnet and the plate, as even a very small distance (e.g. 0.5 mm) causes a drop in lifting force of up to 50%.
• Direction of applied force, because the maximum lifting capacity is achieved under perpendicular application. The force required to slide the magnet along the plate is usually several times lower.
• Thickness of the plate, as a plate that is too thin causes part of the magnetic flux not to be used and to remain wasted in the air.
• Material of the plate, because higher carbon content lowers holding force, while higher iron content increases it. The best choice is steel with high magnetic permeability and high saturation induction.
• Surface of the plate, because the more smooth and polished it is, the better the contact and consequently the greater the magnetic saturation.
• Operating temperature, since all permanent magnets have a negative temperature coefficient. This means that at high temperatures they are weaker, while at sub-zero temperatures they become slightly stronger.

* Lifting capacity testing was performed on plates with a smooth surface of optimal thickness, under perpendicular forces, whereas under attempts to slide the magnet the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet’s surface and the plate lowers the holding force.