HH 16x5.3 [M3] / N38 - through hole magnetic holder

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They have constant strength, and over around ten years their performance decreases symbolically – ~1% (in testing),
• They are extremely resistant to demagnetization caused by external magnetic sources,
• In other words, due to the shiny silver coating, the magnet obtains an aesthetic appearance,
• The outer field strength of the magnet shows advanced magnetic properties,
• These magnets tolerate elevated temperatures, often exceeding 230°C, when properly designed (in relation to profile),
• With the option for fine forming and targeted design, these magnets can be produced in various shapes and sizes, greatly improving design adaptation,
• Wide application in modern technologies – they are used in hard drives, electromechanical systems, medical equipment along with high-tech tools,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, with minimal size,

Disadvantages of NdFeB magnets:

• They are prone to breaking when subjected to a sudden impact. If the magnets are exposed to mechanical hits, it is suggested to place them in a metal holder. The steel housing, in the form of a holder, protects the magnet from fracture and additionally increases its overall durability,
• They lose field intensity at elevated temperatures. Most neodymium magnets experience permanent decline in strength when heated above 80°C (depending on the shape and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• They rust in a wet environment – during outdoor use, we recommend using sealed magnets, such as those made of polymer,
• Using a cover – such as a magnetic holder – is advised due to the restrictions in manufacturing threads directly in the magnet,
• Health risk due to small fragments may arise, if ingested accidentally, which is crucial in the health of young users. It should also be noted that minuscule fragments from these magnets have the potential to disrupt scanning once in the system,
• High unit cost – neodymium magnets are more expensive than other types of magnets (e.g., ferrite), which can restrict large-scale applications

Maximum lifting capacity of the magnet – what affects it?

The given pulling force of the magnet represents the maximum force, calculated in ideal conditions, that is:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• having a thickness of no less than 10 millimeters
• with a polished side
• in conditions of no clearance
• in a perpendicular direction of force
• at room temperature

Determinants of lifting force in real conditions

In practice, the holding capacity of a magnet is conditioned by these factors, from crucial to less important:

• 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.

* Lifting capacity was determined by applying a steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular pulling force, in contrast under shearing force the holding force is lower. In addition, even a small distance {between} the magnet and the plate decreases the holding force.