UMH 20x7x35 [M4] / N38 - magnetic holder with hook

Pros and cons of neodymium magnets.

Besides their stability, neodymium magnets are valued for these benefits:

• They retain attractive force for around 10 years – the loss is just ~1% (according to analyses),
• Magnets perfectly defend themselves against demagnetization caused by foreign field sources,
• In other words, due to the metallic surface of gold, the element looks attractive,
• Magnets possess impressive magnetic induction on the working surface,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their form) at temperatures up to 230°C and above...
• Thanks to freedom in designing and the capacity to adapt to individual projects,
• Wide application in modern technologies – they serve a role in computer drives, electric motors, medical devices, and industrial machines.
• Thanks to their power density, small magnets offer high operating force, in miniature format,

Disadvantages of NdFeB magnets:

• To avoid cracks under impact, we suggest using special steel holders. Such a solution secures the magnet and simultaneously improves its durability.
• We warn that neodymium magnets can lose their power at high temperatures. To prevent this, we recommend our specialized [AH] magnets, which work effectively even at 230°C.
• When exposed to humidity, magnets start to rust. To use them in conditions outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which secure oxidation and corrosion.
• Limited possibility of making nuts in the magnet and complicated forms - preferred is cover - magnet mounting.
• Potential hazard to health – tiny shards of magnets are risky, if swallowed, which becomes key in the context of child safety. It is also worth noting that tiny parts of these devices are able to complicate diagnosis medical when they are in the body.
• With budget limitations the cost of neodymium magnets is a challenge,

Best holding force of the magnet in ideal parameters – what affects it?

The load parameter shown represents the maximum value, measured under ideal test conditions, namely:

• with the use of a yoke made of special test steel, guaranteeing full magnetic saturation
• whose transverse dimension is min. 10 mm
• with a surface perfectly flat
• with zero gap (without paint)
• for force applied at a right angle (in the magnet axis)
• in stable room temperature

Lifting capacity in real conditions – factors

In practice, the actual lifting capacity results from several key aspects, ranked from the most important:

• Gap (betwixt the magnet and the plate), because even a microscopic clearance (e.g. 0.5 mm) leads to a decrease in force by up to 50% (this also applies to varnish, rust or dirt).
• Force direction – catalog parameter refers to pulling vertically. When applying parallel force, the magnet holds significantly lower power (often approx. 20-30% of maximum force).
• Steel thickness – too thin plate causes magnetic saturation, causing part of the power to be lost to the other side.
• Material composition – not every steel reacts the same. Alloy additives weaken the attraction effect.
• Base smoothness – the more even the plate, the better the adhesion and higher the lifting capacity. Unevenness creates an air distance.
• Temperature – heating the magnet causes a temporary drop of force. Check the thermal limit for a given model.

* Holding force was checked on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, in contrast under shearing force the holding force is lower. Moreover, even a slight gap {between} the magnet and the plate decreases the holding force.