MPL 5x5x1.5 / N38 - lamellar magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They do not lose their magnetism, even after nearly 10 years – the reduction of lifting capacity is only ~1% (based on measurements),
• They are extremely resistant to demagnetization caused by external magnetic sources,
• In other words, due to the glossy silver coating, the magnet obtains an professional appearance,
• The outer field strength of the magnet shows remarkable magnetic properties,
• Thanks to their enhanced temperature resistance, they can operate (depending on the form) even at temperatures up to 230°C or more,
• Thanks to the freedom in shaping and the capability to adapt to individual requirements, neodymium magnets can be created in various configurations, which increases their usage potential,
• Wide application in cutting-edge sectors – they are utilized in data storage devices, electric motors, diagnostic apparatus along with other advanced devices,
• Thanks to their power density, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of NdFeB magnets:

• They can break when subjected to a powerful impact. If the magnets are exposed to shocks, it is advisable to use in a steel housing. The steel housing, in the form of a holder, protects the magnet from breakage , and at the same time increases its overall resistance,
• Magnets lose power when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible magnetic decay (influenced by the magnet’s profile). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• Magnets exposed to wet conditions can degrade. Therefore, for outdoor applications, we advise waterproof types made of non-metallic composites,
• The use of a protective casing or external holder is recommended, since machining fine details in neodymium magnets is restricted,
• Safety concern from tiny pieces may arise, especially if swallowed, which is crucial in the health of young users. Additionally, minuscule fragments from these magnets may interfere with diagnostics after being swallowed,
• Higher purchase price is one of the drawbacks compared to ceramic magnets, especially in budget-sensitive applications

Detachment force of the magnet in optimal conditions – what it depends on?

The given lifting capacity of the magnet corresponds to the maximum lifting force, measured in a perfect environment, specifically:

• with mild steel, serving as a magnetic flux conductor
• having a thickness of no less than 10 millimeters
• with a polished side
• with no separation
• with vertical force applied
• in normal thermal conditions

Impact of factors on magnetic holding capacity in practice

The lifting capacity of a magnet is influenced by in practice key elements, 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.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, in contrast under attempts to slide the magnet the holding force is lower. In addition, even a small distance {between} the magnet’s surface and the plate reduces the holding force.