MW 20x5 / N38 - cylindrical magnet

Advantages and disadvantages of rare earth magnets.

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

• They do not lose power, even over nearly ten years – the reduction in power is only ~1% (based on measurements),
• They show high resistance to demagnetization induced by external magnetic fields,
• A magnet with a smooth nickel surface looks better,
• Magnetic induction on the working part of the magnet remains strong,
• Thanks to resistance to high temperature, they are able to function (depending on the shape) even at temperatures up to 230°C and higher...
• Thanks to the potential of free molding and customization to individualized requirements, NdFeB magnets can be created in a broad palette of forms and dimensions, which increases their versatility,
• Universal use in future technologies – they are commonly used in magnetic memories, electromotive mechanisms, advanced medical instruments, and other advanced devices.
• Thanks to their power density, small magnets offer high operating force, with minimal size,

Characteristics of disadvantages of neodymium magnets: application proposals

• Brittleness is one of their disadvantages. Upon intense impact they can fracture. We recommend keeping them in a steel housing, which not only protects them against impacts but also increases their durability
• When exposed to high temperature, neodymium magnets suffer a drop in strength. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size and shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• Magnets exposed to a humid environment can corrode. Therefore during using outdoors, we recommend using waterproof magnets made of rubber, plastic or other material protecting against moisture
• Due to limitations in producing nuts and complicated forms in magnets, we recommend using a housing - magnetic mount.
• Health risk resulting from small fragments of magnets pose a threat, when accidentally swallowed, which becomes key in the context of child safety. It is also worth noting that small components of these magnets can be problematic in diagnostics medical after entering the body.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which can limit application in large quantities

Detachment force of the magnet in optimal conditions – what contributes to it?

The specified lifting capacity refers to the limit force, measured under ideal test conditions, meaning:

• using a plate made of high-permeability steel, functioning as a circuit closing element
• possessing a massiveness of at least 10 mm to avoid saturation
• with an ideally smooth contact surface
• under conditions of ideal adhesion (metal-to-metal)
• during detachment in a direction vertical to the mounting surface
• in temp. approx. 20°C

Determinants of practical lifting force of a magnet

In practice, the actual holding force depends on a number of factors, ranked from most significant:

• Gap (betwixt the magnet and the plate), because even a tiny clearance (e.g. 0.5 mm) leads to a decrease in lifting capacity by up to 50% (this also applies to paint, rust or dirt).
• Force direction – catalog parameter refers to pulling vertically. When attempting to slide, the magnet exhibits much less (often approx. 20-30% of nominal force).
• Base massiveness – too thin sheet causes magnetic saturation, causing part of the flux to be lost to the other side.
• Metal type – different alloys reacts the same. Alloy additives worsen the attraction effect.
• Surface finish – ideal contact is obtained only on polished steel. Any scratches and bumps reduce the real contact area, weakening the magnet.
• Temperature influence – hot environment weakens pulling force. Exceeding the limit temperature can permanently demagnetize the magnet.

* Lifting capacity testing was carried out on a smooth plate of suitable thickness, under perpendicular forces, whereas under attempts to slide the magnet the lifting capacity is smaller. Moreover, even a small distance {between} the magnet’s surface and the plate lowers the lifting capacity.