SM 32x450 [2xM8] / N42 - magnetic separator

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They do not lose their strength approximately 10 years – the reduction of strength is only ~1% (according to tests),
• They protect against demagnetization induced by external electromagnetic environments effectively,
• The use of a polished silver surface provides a smooth finish,
• They exhibit superior levels of magnetic induction near the outer area of the magnet,
• These magnets tolerate high temperatures, often exceeding 230°C, when properly designed (in relation to form),
• With the option for customized forming and targeted design, these magnets can be produced in numerous shapes and sizes, greatly improving application potential,
• Significant impact in advanced technical fields – they find application in data storage devices, electric motors, medical equipment as well as high-tech tools,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of NdFeB magnets:

• They are fragile when subjected to a heavy impact. If the magnets are exposed to physical collisions, it is suggested to place them in a steel housing. The steel housing, in the form of a holder, protects the magnet from damage , and at the same time increases its overall resistance,
• They lose strength at increased temperatures. Most neodymium magnets experience permanent decline in strength when heated above 80°C (depending on the form and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to damp air can oxidize. Therefore, for outdoor applications, we advise waterproof types made of coated materials,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is risky,
• Possible threat linked to microscopic shards may arise, especially if swallowed, which is notable in the family environments. It should also be noted that small elements from these products can interfere with diagnostics when ingested,
• High unit cost – neodymium magnets are costlier than other types of magnets (e.g., ferrite), which can restrict large-scale applications

Highest magnetic holding force – what contributes to it?

The given strength of the magnet corresponds to the optimal strength, calculated in ideal conditions, specifically:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• having a thickness of no less than 10 millimeters
• with a smooth surface
• with no separation
• with vertical force applied
• at room temperature

What influences lifting capacity in practice

The lifting capacity of a magnet is influenced by in practice key elements, ordered from most important to least significant:

• Air gap between the magnet and the plate, as even a very small distance (e.g. 0.5 mm) can cause a drop in lifting force of up to 50%.
• Direction of applied force, because the maximum lifting capacity is achieved under perpendicular application. The force required to slide the magnet along the plate is usually several times lower.
• Thickness of the plate, as a plate that is too thin causes part of the magnetic flux not to be used and to remain wasted in the air.
• Material of the plate, because higher carbon content lowers holding force, while higher iron content increases it. The best choice is steel with high magnetic permeability and high saturation induction.
• Surface of the plate, because the more smooth and polished it is, the better the contact and consequently the greater the magnetic saturation.
• Operating temperature, since all permanent magnets have a negative temperature coefficient. This means that at high temperatures they are weaker, while at sub-zero temperatures they become slightly stronger.

* Holding force was checked on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, whereas under parallel forces the holding force is lower. Additionally, even a slight gap {between} the magnet and the plate decreases the load capacity.