MPL 13x10x5 / N35H - lamellar magnet

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their tremendous magnetic power, neodymium magnets offer the following advantages:

• They have constant strength, and over around ten years their attraction force decreases symbolically – ~1% (in testing),
• They protect against demagnetization induced by ambient electromagnetic environments effectively,
• In other words, due to the metallic silver coating, the magnet obtains an stylish appearance,
• They possess significant magnetic force measurable at the magnet’s surface,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• The ability for custom shaping or adaptation to custom needs – neodymium magnets can be manufactured in multiple variants of geometries, which extends the scope of their use cases,
• Wide application in advanced technical fields – they find application in computer drives, electric motors, clinical machines or even technologically developed systems,
• Compactness – despite their small size, they provide high effectiveness, making them ideal for precision applications

Disadvantages of magnetic elements:

• They are fragile when subjected to a strong impact. If the magnets are exposed to shocks, we recommend in a steel housing. The steel housing, in the form of a holder, protects the magnet from cracks and additionally enhances its overall strength,
• Magnets lose pulling force when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible magnetic decay (influenced by the magnet’s form). 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 recommended to use sealed magnets made of protective material for outdoor use,
• The use of a protective casing or external holder is recommended, since machining internal cuts in neodymium magnets is risky,
• Safety concern linked to microscopic shards may arise, if ingested accidentally, which is crucial in the health of young users. Additionally, small elements from these products may complicate medical imaging after being swallowed,
• Higher purchase price is one of the drawbacks compared to ceramic magnets, especially in budget-sensitive applications

Magnetic strength at its maximum – what it depends on?

The given strength of the magnet means the optimal strength, determined under optimal conditions, specifically:

• with mild steel, used as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a refined outer layer
• in conditions of no clearance
• under perpendicular detachment force
• under standard ambient temperature

Determinants of practical lifting force of a magnet

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

• Air gap between the magnet and the plate, because 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 a perpendicular pulling force, whereas under parallel forces the lifting capacity is smaller. Moreover, even a slight gap {between} the magnet’s surface and the plate lowers the holding force.