MW 20x5 / N38 - cylindrical magnet

Pros as well as cons of rare earth magnets.

In addition to their magnetic capacity, neodymium magnets provide the following advantages:

• They do not lose strength, even over nearly 10 years – the decrease in lifting capacity is only ~1% (according to tests),
• Magnets perfectly protect themselves against demagnetization caused by external fields,
• By using a decorative layer of gold, the element presents an professional look,
• Magnetic induction on the surface of the magnet remains very high,
• Thanks to resistance to high temperature, they are capable of working (depending on the shape) even at temperatures up to 230°C and higher...
• Considering the possibility of accurate forming and customization to individualized needs, neodymium magnets can be produced in a wide range of geometric configurations, which expands the range of possible applications,
• Significant place in advanced technology sectors – they are commonly used in hard drives, electric motors, precision medical tools, also industrial machines.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Disadvantages of neodymium magnets:

• To avoid cracks upon strong impacts, we suggest using special steel holders. Such a solution protects the magnet and simultaneously improves its durability.
• When exposed to high temperature, neodymium magnets experience a drop in strength. Often, when the temperature exceeds 80°C, their power decreases (depending on the size, as well as shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• When exposed to humidity, magnets usually rust. To use them in conditions outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which secure oxidation as well as corrosion.
• We suggest casing - magnetic mechanism, due to difficulties in producing threads inside the magnet and complex shapes.
• Potential hazard related to microscopic parts of magnets can be dangerous, when accidentally swallowed, which is particularly important in the context of child safety. Additionally, small components of these products are able to be problematic in diagnostics medical after entering the body.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Maximum holding power of the magnet – what it depends on?

The load parameter shown refers to the peak performance, obtained under optimal environment, meaning:

• on a base made of structural steel, effectively closing the magnetic flux
• whose thickness is min. 10 mm
• with an ideally smooth touching surface
• with zero gap (without impurities)
• during pulling in a direction perpendicular to the mounting surface
• at temperature approx. 20 degrees Celsius

Determinants of practical lifting force of a magnet

Effective lifting capacity is influenced by working environment parameters, such as (from most important):

• Gap (betwixt the magnet and the metal), because even a microscopic clearance (e.g. 0.5 mm) results in a decrease in lifting capacity by up to 50% (this also applies to varnish, rust or debris).
• Loading method – declared lifting capacity refers to pulling vertically. When attempting to slide, the magnet holds significantly lower power (typically approx. 20-30% of maximum force).
• Base massiveness – insufficiently thick steel does not accept the full field, causing part of the flux to be lost to the other side.
• Material composition – different alloys reacts the same. High carbon content weaken the interaction with the magnet.
• Surface condition – smooth surfaces guarantee perfect abutment, which improves field saturation. Uneven metal reduce efficiency.
• Temperature – heating the magnet causes a temporary drop of induction. It is worth remembering the thermal limit for a given model.

* Holding force was tested on the plate surface of 20 mm thickness, when the force acted perpendicularly, whereas under attempts to slide the magnet the load capacity is reduced by as much as 75%. Additionally, even a slight gap {between} the magnet and the plate reduces the lifting capacity.