UMT 12x20 orange / N38 - board holder

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They do not lose their magnetism, even after around 10 years – the decrease of lifting capacity is only ~1% (theoretically),
• They protect against demagnetization induced by external magnetic fields remarkably well,
• By applying a shiny layer of nickel, the element gains a modern look,
• They possess strong magnetic force measurable at the magnet’s surface,
• Thanks to their high temperature resistance, they can operate (depending on the form) even at temperatures up to 230°C or more,
• With the option for fine forming and personalized design, these magnets can be produced in multiple shapes and sizes, greatly improving engineering flexibility,
• Significant impact in new technology industries – they find application in data storage devices, electric drives, healthcare devices along with sophisticated instruments,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in tiny dimensions, which makes them ideal in compact constructions

Disadvantages of magnetic elements:

• They may fracture when subjected to a heavy impact. If the magnets are exposed to shocks, they should be placed in a protective case. The steel housing, in the form of a holder, protects the magnet from cracks while also strengthens its overall durability,
• They lose power at increased temperatures. Most neodymium magnets experience permanent reduction in strength when heated above 80°C (depending on the geometry 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 wise to use sealed magnets made of plastic for outdoor use,
• Using a cover – such as a magnetic holder – is advised due to the limitations in manufacturing threads directly in the magnet,
• Potential hazard linked to microscopic shards may arise, if ingested accidentally, which is significant in the protection of children. Moreover, minuscule fragments from these devices may interfere with diagnostics if inside the body,
• Due to the price of neodymium, their cost is above average,

Magnetic strength at its maximum – what it depends on?

The given strength of the magnet means the optimal strength, assessed under optimal conditions, that is:

• with the use of low-carbon steel plate acting as a magnetic yoke
• with a thickness of minimum 10 mm
• with a refined outer layer
• with zero air gap
• with vertical force applied
• under standard ambient temperature

Practical aspects of lifting capacity – factors

The lifting capacity of a magnet depends on 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 testing was conducted on a smooth plate of optimal thickness, under perpendicular forces, however under shearing force the load capacity is reduced by as much as 75%. Additionally, even a minimal clearance {between} the magnet and the plate lowers the load capacity.