MPL 40x10x4 / N38 - lamellar magnet

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They retain their magnetic properties for around ten years – the drop is just ~1% (according to analyses),
• Their ability to resist magnetic interference from external fields is notable,
• Because of the reflective layer of silver, the component looks high-end,
• Magnetic induction on the surface of these magnets is notably high,
• These magnets tolerate high temperatures, often exceeding 230°C, when properly designed (in relation to profile),
• Thanks to the flexibility in shaping and the capability to adapt to individual requirements, neodymium magnets can be created in different geometries, which broadens their application range,
• Key role in advanced technical fields – they find application in data storage devices, electromechanical systems, clinical machines and high-tech tools,
• Compactness – despite their small size, they provide high effectiveness, making them ideal for precision applications

Disadvantages of magnetic elements:

• They are prone to breaking when subjected to a strong impact. If the magnets are exposed to mechanical hits, it is advisable to use in a protective case. The steel housing, in the form of a holder, protects the magnet from cracks , and at the same time strengthens its overall strength,
• Magnets lose magnetic efficiency when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible field weakening (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 damp air can degrade. Therefore, for outdoor applications, it's best to use waterproof types made of rubber,
• The use of a protective casing or external holder is recommended, since machining internal cuts in neodymium magnets is not feasible,
• Potential hazard linked to microscopic shards may arise, in case of ingestion, which is important in the protection of children. It should also be noted that small elements from these magnets may hinder health screening when ingested,
• Due to expensive raw materials, their cost is considerably higher,

Maximum magnetic pulling force – what contributes to it?

The given pulling force of the magnet represents the maximum force, measured in the best circumstances, specifically:

• with the use of low-carbon steel plate serving as a magnetic yoke
• 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

Impact of factors on magnetic holding capacity in practice

In practice, the holding capacity of a magnet is conditioned 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 was assessed by applying a smooth steel plate of optimal thickness (min. 20 mm), under perpendicular pulling force, whereas under shearing force the holding force is lower. In addition, even a minimal clearance {between} the magnet and the plate decreases the load capacity.