MPL 25x12.5x5 / N38 - lamellar magnet

Pros and cons of rare earth magnets.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They do not lose strength, even during around ten years – the decrease in strength is only ~1% (theoretically),
• They are noted for resistance to demagnetization induced by external magnetic fields,
• The use of an elegant coating of noble metals (nickel, gold, silver) causes the element to have aesthetics,
• Neodymium magnets achieve maximum magnetic induction on a contact point, which ensures high operational effectiveness,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can function (depending on the shape) even at a temperature of 230°C or more...
• Possibility of exact forming as well as modifying to complex conditions,
• Versatile presence in high-tech industry – they are commonly used in hard drives, electric motors, diagnostic systems, and technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in small dimensions, which makes them useful in small systems

Disadvantages of neodymium magnets:

• At strong impacts they can crack, therefore we recommend placing them in strong housings. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
• Neodymium magnets decrease their strength under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
• They rust in a humid environment - during use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• We suggest a housing - magnetic mount, due to difficulties in creating nuts inside the magnet and complex forms.
• Potential hazard related to microscopic parts of magnets are risky, if swallowed, which is particularly important in the context of child safety. It is also worth noting that small components of these magnets can be problematic in diagnostics medical in case of swallowing.
• With budget limitations the cost of neodymium magnets is economically unviable,

Magnetic strength at its maximum – what it depends on?

Magnet power was defined for the most favorable conditions, assuming:

• using a sheet made of high-permeability steel, acting as a ideal flux conductor
• whose thickness equals approx. 10 mm
• characterized by lack of roughness
• under conditions of ideal adhesion (surface-to-surface)
• for force acting at a right angle (pull-off, not shear)
• in neutral thermal conditions

What influences lifting capacity in practice

Please note that the application force may be lower depending on elements below, in order of importance:

• Air gap (betwixt the magnet and the plate), because even a microscopic distance (e.g. 0.5 mm) results in a reduction in lifting capacity by up to 50% (this also applies to paint, rust or debris).
• Force direction – note that the magnet holds strongest perpendicularly. Under sliding down, the capacity drops drastically, often to levels of 20-30% of the maximum value.
• Plate thickness – too thin steel does not accept the full field, causing part of the flux to be lost to the other side.
• Material type – ideal substrate is pure iron steel. Hardened steels may attract less.
• Surface condition – ground elements guarantee perfect abutment, which increases force. Rough surfaces weaken the grip.
• Temperature influence – high temperature weakens magnetic field. Too high temperature can permanently damage the magnet.

* Holding force was checked on the plate surface of 20 mm thickness, when a perpendicular force was applied, however under shearing force the load capacity is reduced by as much as 5 times. In addition, even a minimal clearance {between} the magnet’s surface and the plate reduces the load capacity.