MW 8x15 / N38 - cylindrical magnet

Advantages and disadvantages of NdFeB magnets.

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

• They retain full power for almost ten years – the loss is just ~1% (according to analyses),
• Magnets effectively resist against demagnetization caused by foreign field sources,
• Thanks to the elegant finish, the layer of nickel, gold-plated, or silver-plated gives an clean appearance,
• Neodymium magnets ensure maximum magnetic induction on a small area, which ensures high operational effectiveness,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can function (depending on the form) even at a temperature of 230°C or more...
• Thanks to the ability of free forming and adaptation to individualized needs, magnetic components can be produced in a wide range of forms and dimensions, which makes them more universal,
• Universal use in advanced technology sectors – they serve a role in mass storage devices, electric motors, medical equipment, also complex engineering applications.
• Thanks to efficiency per cm³, small magnets offer high operating force, with minimal size,

Disadvantages of neodymium magnets:

• Susceptibility to cracking is one of their disadvantages. Upon strong impact they can fracture. We advise keeping them in a special holder, which not only protects them against impacts but also raises their durability
• When exposed to high temperature, neodymium magnets suffer a drop in force. Often, when the temperature exceeds 80°C, their strength 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. For applications outside, it is recommended to use protective magnets, such as those in rubber or plastics, which secure oxidation as well as corrosion.
• We recommend cover - magnetic mechanism, due to difficulties in realizing threads inside the magnet and complicated forms.
• Potential hazard related to microscopic parts of magnets pose a threat, when accidentally swallowed, which becomes key in the context of child safety. It is also worth noting that tiny parts of these products are able to be problematic in diagnostics medical when they are in the body.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which hinders application in large quantities

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

The declared magnet strength represents the limit force, measured under ideal test conditions, meaning:

• with the application of a sheet made of special test steel, guaranteeing full magnetic saturation
• with a cross-section minimum 10 mm
• with an ideally smooth touching surface
• with zero gap (no impurities)
• under perpendicular application of breakaway force (90-degree angle)
• in stable room temperature

Practical aspects of lifting capacity – factors

In real-world applications, the real power depends on many variables, presented from the most important:

• Gap between magnet and steel – even a fraction of a millimeter of separation (caused e.g. by veneer or dirt) significantly weakens the pulling force, often by half at just 0.5 mm.
• Force direction – note that the magnet holds strongest perpendicularly. Under sliding down, the capacity drops drastically, often to levels of 20-30% of the nominal value.
• Wall thickness – thin material does not allow full use of the magnet. Magnetic flux passes through the material instead of generating force.
• Chemical composition of the base – mild steel gives the best results. Alloy steels decrease magnetic permeability and holding force.
• Smoothness – ideal contact is obtained only on smooth steel. Any scratches and bumps create air cushions, reducing force.
• Thermal environment – temperature increase results in weakening of force. It is worth remembering the thermal limit for a given model.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, in contrast under attempts to slide the magnet the lifting capacity is smaller. Additionally, even a slight gap {between} the magnet’s surface and the plate decreases the holding force.