MW 12x4 / N52 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• Their magnetic field is durable, and after around 10 years, it drops only by ~1% (theoretically),
• They protect against demagnetization induced by ambient magnetic influence effectively,
• The use of a decorative gold surface provides a eye-catching finish,
• They exhibit superior levels of magnetic induction near the outer area of the magnet,
• These magnets tolerate high temperatures, often exceeding 230°C, when properly designed (in relation to form),
• With the option for tailored forming and targeted design, these magnets can be produced in multiple shapes and sizes, greatly improving engineering flexibility,
• Significant impact in advanced technical fields – they are utilized in computer drives, electric drives, diagnostic apparatus or even high-tech tools,
• Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They are fragile when subjected to a sudden impact. If the magnets are exposed to external force, it is advisable to use in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from fracture , and at the same time increases its overall robustness,
• High temperatures may significantly reduce the field efficiency of neodymium magnets. Typically, above 80°C, they experience permanent loss in performance (depending on size). To prevent this, we offer heat-resistant magnets marked [AH], capable of working up to 230°C, which makes them perfect for high-temperature use,
• Due to corrosion risk in humid conditions, it is advisable to use sealed magnets made of synthetic coating for outdoor use,
• Limited ability to create complex details in the magnet – the use of a mechanical support is recommended,
• Possible threat from tiny pieces may arise, especially if swallowed, which is notable in the health of young users. It should also be noted that miniature parts from these assemblies may hinder health screening when ingested,
• Due to expensive raw materials, their cost is considerably higher,

Breakaway strength of the magnet in ideal conditions – what affects it?

The given holding capacity of the magnet represents the highest holding force, measured under optimal conditions, specifically:

• with mild steel, serving as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a polished side
• with no separation
• under perpendicular detachment force
• under standard ambient temperature

Determinants of practical lifting force of a magnet

Practical lifting force is dependent on factors, by priority:

• 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 a smooth plate of suitable thickness, under perpendicular forces, however under shearing force the holding force is lower. Moreover, even a slight gap {between} the magnet and the plate decreases the holding force.