MP 20x8x5 / N38 - ring magnet

Strengths and weaknesses of rare earth magnets.

Apart from their superior holding force, neodymium magnets have these key benefits:

• They have stable power, and over nearly ten years their performance decreases symbolically – ~1% (in testing),
• They are resistant to demagnetization induced by external field influence,
• By covering with a shiny coating of silver, the element acquires an aesthetic look,
• Neodymium magnets ensure maximum magnetic induction on a their surface, which allows for strong attraction,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and can work (depending on the shape) even at a temperature of 230°C or more...
• Thanks to versatility in forming and the ability to modify to client solutions,
• Universal use in future technologies – they are utilized in data components, drive modules, medical equipment, also other advanced devices.
• Thanks to efficiency per cm³, small magnets offer high operating force, in miniature format,

Drawbacks and weaknesses of neodymium magnets: weaknesses and usage proposals

• Brittleness is one of their disadvantages. Upon strong impact they can fracture. We advise keeping them in a strong case, which not only protects them against impacts but also increases their durability
• When exposed to high temperature, neodymium magnets experience 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
• They oxidize in a humid environment. For use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• Due to limitations in producing threads and complex forms in magnets, we recommend using cover - magnetic mount.
• Potential hazard related to microscopic parts of magnets are risky, if swallowed, which gains importance in the context of child safety. Furthermore, tiny parts of these products can be problematic in diagnostics medical when they are in the body.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

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

The declared magnet strength refers to the maximum value, recorded under optimal environment, meaning:

• using a plate made of high-permeability steel, acting as a circuit closing element
• possessing a thickness of min. 10 mm to avoid saturation
• with a surface cleaned and smooth
• with total lack of distance (no paint)
• for force acting at a right angle (in the magnet axis)
• at ambient temperature room level

Determinants of lifting force in real conditions

Holding efficiency is affected by working environment parameters, mainly (from priority):

• Distance (betwixt the magnet and the plate), since even a very small distance (e.g. 0.5 mm) results in a reduction in force by up to 50% (this also applies to varnish, corrosion or dirt).
• Angle of force application – highest force is available only during pulling at a 90° angle. The resistance to sliding of the magnet along the surface is typically several times lower (approx. 1/5 of the lifting capacity).
• Plate thickness – insufficiently thick plate does not accept the full field, causing part of the power to be wasted into the air.
• Plate material – low-carbon steel gives the best results. Alloy steels decrease magnetic permeability and holding force.
• Plate texture – ground elements ensure maximum contact, which improves force. Rough surfaces weaken the grip.
• Thermal factor – hot environment reduces magnetic field. Too high temperature can permanently damage the magnet.

* Lifting capacity testing was conducted on a smooth plate of optimal thickness, under perpendicular forces, however under shearing force the holding force is lower. Additionally, even a minimal clearance {between} the magnet’s surface and the plate decreases the holding force.