AM Haczyk M4 - magnetic accessories

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their tremendous pulling force, neodymium magnets offer the following advantages:

• They have unchanged lifting capacity, and over nearly 10 years their attraction force decreases symbolically – ~1% (in testing),
• They protect against demagnetization induced by external magnetic fields effectively,
• Because of the lustrous layer of gold, the component looks aesthetically refined,
• The outer field strength of the magnet shows advanced magnetic properties,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• Thanks to the possibility in shaping and the capability to adapt to individual requirements, neodymium magnets can be created in different geometries, which expands their usage potential,
• Key role in advanced technical fields – they are used in computer drives, rotating machines, medical equipment and sophisticated instruments,
• Compactness – despite their small size, they provide high effectiveness, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They may fracture when subjected to a strong impact. If the magnets are exposed to shocks, they should be placed in a steel housing. The steel housing, in the form of a holder, protects the magnet from breakage and additionally increases its overall robustness,
• They lose field intensity at elevated temperatures. Most neodymium magnets experience permanent decline in strength when heated above 80°C (depending on the form and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to moisture can rust. Therefore, for outdoor applications, we recommend waterproof types made of coated materials,
• Using a cover – such as a magnetic holder – is advised due to the limitations in manufacturing fine shapes directly in the magnet,
• Potential hazard due to small fragments may arise, if ingested accidentally, which is crucial in the health of young users. Additionally, minuscule fragments from these magnets might complicate medical imaging after being swallowed,
• Higher purchase price is an important factor to consider compared to ceramic magnets, especially in budget-sensitive applications

Best holding force of the magnet in ideal parameters – what contributes to it?

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

• with the use of low-carbon steel plate acting as a magnetic yoke
• with a thickness of minimum 10 mm
• with a polished side
• in conditions of no clearance
• under perpendicular detachment force
• at room temperature

Lifting capacity in practice – influencing factors

The lifting capacity of a magnet is determined by in practice the following factors, ordered from most important to least significant:

• Air gap between the magnet and the plate, since 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 measured with the use of a smooth steel plate of optimal thickness (min. 20 mm), under vertically applied force, in contrast under shearing force the lifting capacity is smaller. Additionally, even a minimal clearance {between} the magnet and the plate reduces the holding force.