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

Pros as well as cons of neodymium magnets.

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

• They have unchanged lifting capacity, and over more than 10 years their attraction force decreases symbolically – ~1% (according to theory),
• Neodymium magnets prove to be exceptionally resistant to demagnetization caused by magnetic disturbances,
• The use of an shiny coating of noble metals (nickel, gold, silver) causes the element to look better,
• Neodymium magnets deliver maximum magnetic induction on a small surface, which ensures high operational effectiveness,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and are able to act (depending on the shape) even at a temperature of 230°C or more...
• Possibility of precise modeling as well as adjusting to defined requirements,
• Huge importance in modern industrial fields – they are utilized in mass storage devices, electromotive mechanisms, medical devices, and complex engineering applications.
• Relatively small size with high pulling force – neodymium magnets offer high power in tiny dimensions, which enables their usage in small systems

Cons of neodymium magnets: application proposals

• At strong impacts they can crack, therefore we recommend placing them in strong housings. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
• When exposed to high temperature, neodymium magnets suffer a drop in force. Often, when the temperature exceeds 80°C, their power 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
• When exposed to humidity, magnets usually rust. To use them in conditions outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which prevent oxidation as well as corrosion.
• Limited possibility of creating nuts in the magnet and complex shapes - preferred is cover - magnet mounting.
• Potential hazard to health – tiny shards of magnets are risky, when accidentally swallowed, which becomes key in the context of child safety. It is also worth noting that small components of these devices are able to disrupt the diagnostic process medical in case of swallowing.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Magnetic strength at its maximum – what it depends on?

The load parameter shown concerns the maximum value, measured under ideal test conditions, specifically:

• using a sheet made of mild steel, acting as a ideal flux conductor
• whose transverse dimension reaches at least 10 mm
• with an polished touching surface
• under conditions of no distance (surface-to-surface)
• under vertical application of breakaway force (90-degree angle)
• in temp. approx. 20°C

Key elements affecting lifting force

Effective lifting capacity is affected by working environment parameters, such as (from most important):

• Distance – existence of any layer (rust, dirt, air) interrupts the magnetic circuit, which reduces power steeply (even by 50% at 0.5 mm).
• Load vector – highest force is available only during perpendicular pulling. The shear force of the magnet along the plate is usually many times lower (approx. 1/5 of the lifting capacity).
• Metal thickness – the thinner the sheet, the weaker the hold. Part of the magnetic field passes through the material instead of converting into lifting capacity.
• Material type – ideal substrate is pure iron steel. Cast iron may generate lower lifting capacity.
• Surface finish – ideal contact is obtained only on polished steel. Any scratches and bumps reduce the real contact area, weakening the magnet.
• Thermal factor – high temperature reduces magnetic field. Too high temperature can permanently demagnetize the magnet.

* Lifting capacity was assessed with the use of a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular detachment force, whereas under parallel forces the load capacity is reduced by as much as fivefold. Additionally, even a minimal clearance {between} the magnet’s surface and the plate decreases the load capacity.