UMS 16x6.5x3.5x5 / N38 - conical magnetic holder

Strengths and weaknesses of NdFeB magnets.

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

• Their power is durable, and after around ten years it decreases only by ~1% (according to research),
• They retain their magnetic properties even under close interference source,
• Thanks to the elegant finish, the coating of nickel, gold-plated, or silver-plated gives an elegant appearance,
• The surface of neodymium magnets generates a concentrated magnetic field – this is one of their assets,
• Thanks to resistance to high temperature, they are capable of working (depending on the form) even at temperatures up to 230°C and higher...
• Thanks to freedom in shaping and the ability to modify to individual projects,
• Significant place in advanced technology sectors – they are utilized in mass storage devices, brushless drives, diagnostic systems, also modern systems.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• At strong impacts they can break, therefore we advise placing them in strong housings. A metal housing provides additional protection against damage and increases the magnet's durability.
• When exposed to high temperature, neodymium magnets experience a drop in power. 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
• Due to the susceptibility of magnets to corrosion in a humid environment, we suggest using waterproof magnets made of rubber, plastic or other material immune to moisture, in case of application outdoors
• Due to limitations in producing nuts and complex shapes in magnets, we propose using a housing - magnetic holder.
• Possible danger related to microscopic parts of magnets pose a threat, if swallowed, which gains importance in the context of child safety. Additionally, small components of these devices are able to be problematic in diagnostics medical after entering the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Breakaway strength of the magnet in ideal conditions – what it depends on?

Holding force of 5 kg is a result of laboratory testing executed under standard conditions:

• with the use of a yoke made of low-carbon steel, ensuring maximum field concentration
• whose transverse dimension reaches at least 10 mm
• characterized by even structure
• without the slightest insulating layer between the magnet and steel
• for force acting at a right angle (in the magnet axis)
• at ambient temperature room level

Determinants of lifting force in real conditions

Effective lifting capacity is affected by specific conditions, such as (from priority):

• Gap (between the magnet and the metal), because even a very small clearance (e.g. 0.5 mm) leads to a drastic drop in lifting capacity by up to 50% (this also applies to varnish, rust or dirt).
• Load vector – highest force is available only during pulling at a 90° angle. The force required to slide of the magnet along the surface is standardly many times lower (approx. 1/5 of the lifting capacity).
• Plate thickness – insufficiently thick plate does not accept the full field, causing part of the flux to be escaped into the air.
• Material composition – different alloys attracts identically. High carbon content worsen the interaction with the magnet.
• Smoothness – full contact is possible only on polished steel. Rough texture reduce the real contact area, reducing force.
• Operating temperature – NdFeB sinters have a negative temperature coefficient. When it is hot they are weaker, and in frost gain strength (up to a certain limit).

* Holding force was measured on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, in contrast under attempts to slide the magnet the holding force is lower. Additionally, even a minimal clearance {between} the magnet’s surface and the plate lowers the holding force.