MP 62x42x25 / N38 - ring magnet

Advantages as well as disadvantages of NdFeB magnets.

Apart from their strong magnetic energy, neodymium magnets have these key benefits:

• Their strength is durable, and after approximately ten years it drops only by ~1% (theoretically),
• They feature excellent resistance to magnetism drop as a result of opposing magnetic fields,
• The use of an refined layer of noble metals (nickel, gold, silver) causes the element to look better,
• The surface of neodymium magnets generates a strong magnetic field – this is one of their assets,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their shape) at temperatures up to 230°C and above...
• Thanks to the ability of flexible forming and customization to specialized needs, magnetic components can be manufactured in a wide range of forms and dimensions, which expands the range of possible applications,
• Huge importance in electronics industry – they find application in HDD drives, electric drive systems, diagnostic systems, and technologically advanced constructions.
• Thanks to their power density, small magnets offer high operating force, in miniature format,

Characteristics of disadvantages of neodymium magnets: application proposals

• Susceptibility to cracking is one of their disadvantages. Upon intense impact they can break. We advise keeping them in a steel housing, which not only secures them against impacts but also increases their durability
• We warn that neodymium magnets can lose their strength at high temperatures. To prevent this, we recommend our specialized [AH] magnets, which work effectively even at 230°C.
• They oxidize in a humid environment. For use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• Due to limitations in creating nuts and complex forms in magnets, we recommend using casing - magnetic holder.
• Health risk resulting from small fragments of magnets can be dangerous, in case of ingestion, which becomes key in the context of child safety. It is also worth noting that tiny parts of these devices are able to 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

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

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

• using a base made of mild steel, acting as a circuit closing element
• whose transverse dimension equals approx. 10 mm
• with a plane cleaned and smooth
• without the slightest insulating layer between the magnet and steel
• for force applied at a right angle (pull-off, not shear)
• in temp. approx. 20°C

Practical lifting capacity: influencing factors

Bear in mind that the magnet holding may be lower depending on the following factors, starting with the most relevant:

• Space between surfaces – every millimeter of separation (caused e.g. by veneer or unevenness) significantly weakens the pulling force, often by half at just 0.5 mm.
• Force direction – note that the magnet has greatest strength perpendicularly. Under sliding down, the holding force drops drastically, often to levels of 20-30% of the maximum value.
• Substrate thickness – for full efficiency, the steel must be sufficiently thick. Paper-thin metal limits the lifting capacity (the magnet "punches through" it).
• Metal type – not every steel reacts the same. Alloy additives weaken the interaction with the magnet.
• Smoothness – ideal contact is possible only on polished steel. Any scratches and bumps reduce the real contact area, weakening the magnet.
• Thermal factor – high temperature weakens magnetic field. Too high temperature can permanently damage the magnet.

* Lifting capacity was assessed by applying a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular detachment force, however under shearing force the holding force is lower. Moreover, even a slight gap {between} the magnet and the plate lowers the lifting capacity.