UMP 97x40 [M8+M10] GW F300 kg / N38 - search holder

Strengths and weaknesses of NdFeB magnets.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• They retain full power for around ten years – the drop is just ~1% (in theory),
• Neodymium magnets remain extremely resistant to magnetic field loss caused by external magnetic fields,
• The use of an shiny finish of noble metals (nickel, gold, silver) causes the element to present itself better,
• Magnetic induction on the top side of the magnet is extremely intense,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can work (depending on the shape) even at a temperature of 230°C or more...
• Thanks to freedom in designing and the ability to adapt to complex applications,
• Versatile presence in advanced technology sectors – they are commonly used in magnetic memories, electric motors, diagnostic systems, as well as industrial machines.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Characteristics of disadvantages of neodymium magnets and proposals for their use:

• Susceptibility to cracking is one of their disadvantages. Upon strong impact they can break. We advise keeping them in a strong case, which not only protects them against impacts but also increases their durability
• When exposed to high temperature, neodymium magnets suffer a drop in force. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size and shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• They rust in a humid environment. For use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• Limited ability of producing nuts in the magnet and complex forms - preferred is casing - magnet mounting.
• Potential hazard resulting from small fragments of magnets can be dangerous, in case of ingestion, which is particularly important in the aspect of protecting the youngest. Furthermore, tiny parts of these devices can complicate diagnosis medical when they are in the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Maximum lifting capacity of the magnet – what it depends on?

Holding force of 380 kg is a measurement result executed under standard conditions:

• using a sheet made of high-permeability steel, serving as a magnetic yoke
• whose thickness equals approx. 10 mm
• with an polished touching surface
• without any air gap between the magnet and steel
• under perpendicular force vector (90-degree angle)
• at ambient temperature room level

What influences lifting capacity in practice

Effective lifting capacity impacted by specific conditions, including (from most important):

• Distance – existence of any layer (rust, tape, air) interrupts the magnetic circuit, which lowers capacity rapidly (even by 50% at 0.5 mm).
• Pull-off angle – remember that the magnet holds strongest perpendicularly. Under shear forces, the holding force drops drastically, often to levels of 20-30% of the nominal value.
• Base massiveness – too thin steel does not accept the full field, causing part of the power to be lost into the air.
• Steel grade – ideal substrate is high-permeability steel. Cast iron may have worse magnetic properties.
• Surface quality – the more even the plate, the better the adhesion and higher the lifting capacity. Unevenness creates an air distance.
• Thermal conditions – neodymium magnets have a negative temperature coefficient. At higher temperatures they lose power, and at low temperatures they can be stronger (up to a certain limit).

* Lifting capacity testing was conducted on plates with a smooth surface of optimal thickness, under perpendicular forces, in contrast under attempts to slide the magnet the lifting capacity is smaller. In addition, even a minimal clearance {between} the magnet’s surface and the plate decreases the holding force.