MPL 50x20x20 / N38 - lamellar magnet

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their strong magnetic energy, neodymium magnets have these key benefits:

• They retain their attractive force for nearly ten years – the loss is just ~1% (in theory),
• They protect against demagnetization induced by external electromagnetic environments very well,
• In other words, due to the shiny nickel coating, the magnet obtains an professional appearance,
• Magnetic induction on the surface of these magnets is notably high,
• These magnets tolerate high temperatures, often exceeding 230°C, when properly designed (in relation to build),
• The ability for accurate shaping as well as adaptation to custom needs – neodymium magnets can be manufactured in many forms and dimensions, which enhances their versatility in applications,
• Important function in advanced technical fields – they serve a purpose in data storage devices, electric motors, medical equipment or even technologically developed systems,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in small dimensions, which allows for use in miniature devices

Disadvantages of NdFeB magnets:

• They are fragile when subjected to a heavy impact. If the magnets are exposed to shocks, it is suggested to place them in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from breakage and strengthens its overall robustness,
• They lose power at increased temperatures. Most neodymium magnets experience permanent reduction in strength when heated above 80°C (depending on the dimensions and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Due to corrosion risk in humid conditions, it is common to use sealed magnets made of protective material for outdoor use,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is restricted,
• Health risk from tiny pieces may arise, if ingested accidentally, which is crucial in the health of young users. It should also be noted that minuscule fragments from these assemblies may interfere with diagnostics after being swallowed,
• Due to expensive raw materials, their cost is relatively high,

Maximum lifting capacity of the magnet – what contributes to it?

The given pulling force of the magnet corresponds to the maximum force, determined in the best circumstances, specifically:

• 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 smooth surface
• in conditions of no clearance
• under perpendicular detachment force
• in normal thermal conditions

Determinants of practical lifting force of a magnet

Practical lifting force is dependent on elements, by priority:

• Air gap between the magnet and the plate, since 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 measured with the use of a polished steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, however under attempts to slide the magnet the load capacity is reduced by as much as 75%. In addition, even a small distance {between} the magnet’s surface and the plate decreases the load capacity.