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

Strengths and weaknesses of neodymium magnets.

In addition to their magnetic capacity, neodymium magnets provide the following advantages:

• They virtually do not lose power, because even after 10 years the decline in efficiency is only ~1% (according to literature),
• Neodymium magnets are distinguished by extremely resistant to loss of magnetic properties caused by magnetic disturbances,
• By applying a lustrous coating of silver, the element presents an elegant look,
• Magnets possess impressive magnetic induction on the outer layer,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the form) even at high temperatures reaching 230°C or more...
• Due to the option of accurate forming and adaptation to individualized solutions, neodymium magnets can be produced in a variety of forms and dimensions, which expands the range of possible applications,
• Significant place in future technologies – they are utilized in hard drives, electromotive mechanisms, precision medical tools, also multitasking production systems.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in tiny dimensions, which makes them useful in compact constructions

Disadvantages of NdFeB magnets:

• Susceptibility to cracking 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
• We warn that neodymium magnets can reduce their power at high temperatures. To prevent this, we suggest our specialized [AH] magnets, which work effectively even at 230°C.
• They rust in a humid environment. For use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• Due to limitations in realizing threads and complex shapes in magnets, we propose using cover - magnetic mechanism.
• Potential hazard related to microscopic parts of magnets pose a threat, if swallowed, which gains importance in the context of child safety. Additionally, tiny parts of these magnets are able to complicate diagnosis medical in case of swallowing.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Highest magnetic holding force – what it depends on?

The force parameter is a theoretical maximum value performed under standard conditions:

• using a base made of low-carbon steel, acting as a circuit closing element
• whose thickness is min. 10 mm
• with a surface perfectly flat
• under conditions of ideal adhesion (surface-to-surface)
• under axial force vector (90-degree angle)
• at conditions approx. 20°C

Determinants of lifting force in real conditions

Please note that the magnet holding will differ influenced by the following factors, in order of importance:

• Clearance – existence of any layer (paint, tape, air) interrupts the magnetic circuit, which reduces capacity steeply (even by 50% at 0.5 mm).
• Load vector – maximum parameter is available only during perpendicular pulling. The resistance to sliding of the magnet along the surface is standardly several times lower (approx. 1/5 of the lifting capacity).
• Steel thickness – too thin sheet does not accept the full field, causing part of the power to be wasted into the air.
• Chemical composition of the base – mild steel gives the best results. Alloy admixtures lower magnetic permeability and lifting capacity.
• Plate texture – smooth surfaces ensure maximum contact, which improves field saturation. Rough surfaces reduce efficiency.
• Temperature – temperature increase results in weakening of induction. Check the thermal limit for a given model.

* Holding force was measured on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under shearing force the holding force is lower. Additionally, even a slight gap {between} the magnet and the plate lowers the holding force.