MW 10x5 / N38 - cylindrical magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They do not lose their strength approximately 10 years – the decrease of lifting capacity is only ~1% (according to tests),
• Their ability to resist magnetic interference from external fields is notable,
• Because of the lustrous layer of silver, the component looks aesthetically refined,
• The outer field strength of the magnet shows elevated magnetic properties,
• These magnets tolerate elevated temperatures, often exceeding 230°C, when properly designed (in relation to profile),
• The ability for custom shaping as well as adaptation to individual needs – neodymium magnets can be manufactured in many forms and dimensions, which amplifies their functionality across industries,
• Key role in new technology industries – they find application in HDDs, electric drives, healthcare devices along with other advanced devices,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in tiny dimensions, which makes them useful in compact constructions

Disadvantages of magnetic elements:

• They are prone to breaking when subjected to a strong impact. If the magnets are exposed to mechanical hits, they should be placed in a steel housing. The steel housing, in the form of a holder, protects the magnet from fracture and additionally enhances its overall durability,
• They lose strength at extreme temperatures. Most neodymium magnets experience permanent reduction in strength when heated above 80°C (depending on the shape 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, especially when used outside, we recommend using moisture-resistant magnets, such as those made of plastic,
• Using a cover – such as a magnetic holder – is advised due to the restrictions in manufacturing threads directly in the magnet,
• Safety concern linked to microscopic shards may arise, in case of ingestion, which is notable in the protection of children. Additionally, small elements from these devices might complicate medical imaging once in the system,
• In cases of mass production, neodymium magnet cost may not be economically viable,

Maximum holding power of the magnet – what contributes to it?

The given strength of the magnet represents the optimal strength, determined in the best circumstances, that is:

• with mild steel, used as a magnetic flux conductor
• having a thickness of no less than 10 millimeters
• with a refined outer layer
• in conditions of no clearance
• in a perpendicular direction of force
• under standard ambient temperature

Lifting capacity in practice – influencing factors

The lifting capacity of a magnet depends on in practice the following factors, from primary to secondary:

• Air gap between the magnet and the plate, since even a very small distance (e.g. 0.5 mm) can cause 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 conducted on a smooth plate of optimal thickness, under perpendicular forces, however under attempts to slide the magnet the holding force is lower. Moreover, even a minimal clearance {between} the magnet’s surface and the plate decreases the lifting capacity.