MPL 3x3x2 / N38 - lamellar magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

Besides their durability, neodymium magnets are valued for these benefits:

• They virtually do not lose strength, because even after ten years, the decline in efficiency is only ~1% (based on calculations),
• They protect against demagnetization induced by ambient electromagnetic environments remarkably well,
• The use of a polished gold surface provides a smooth finish,
• They possess strong magnetic force measurable at the magnet’s surface,
• Thanks to their high temperature resistance, they can operate (depending on the geometry) even at temperatures up to 230°C or more,
• With the option for customized forming and targeted design, these magnets can be produced in numerous shapes and sizes, greatly improving application potential,
• Important function in new technology industries – they are used in HDDs, electric motors, medical equipment as well as high-tech tools,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of neodymium magnets:

• They are fragile when subjected to a strong impact. If the magnets are exposed to physical collisions, it is suggested to place them in a steel housing. The steel housing, in the form of a holder, protects the magnet from fracture and additionally increases its overall strength,
• Magnets lose magnetic efficiency 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,
• Due to corrosion risk in humid conditions, it is advisable to use sealed magnets made of plastic for outdoor use,
• Limited ability to create internal holes in the magnet – the use of a external casing is recommended,
• Possible threat related to magnet particles may arise, especially if swallowed, which is notable in the family environments. Furthermore, small elements from these devices can hinder health screening once in the system,
• High unit cost – neodymium magnets are costlier than other types of magnets (e.g., ferrite), which may limit large-scale applications

Maximum holding power of the magnet – what affects it?

The given lifting capacity of the magnet represents the maximum lifting force, measured under optimal conditions, specifically:

• with the use of low-carbon steel plate acting as a magnetic yoke
• having a thickness of no less than 10 millimeters
• with a polished side
• with no separation
• with vertical force applied
• at room temperature

Magnet lifting force in use – key factors

The lifting capacity of a magnet is determined by in practice key elements, from primary to secondary:

• Air gap between the magnet and the plate, because 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 measured on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under parallel forces the load capacity is reduced by as much as 75%. Additionally, even a minimal clearance {between} the magnet’s surface and the plate lowers the lifting capacity.