NCM 20x13.5x5 / N38 - channel magnetic holder

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They retain their full power for almost ten years – the drop is just ~1% (in theory),
• They protect against demagnetization induced by ambient magnetic fields remarkably well,
• By applying a shiny layer of nickel, the element gains a modern look,
• They have very high magnetic induction on the surface of the magnet,
• Neodymium magnets are known for very high magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the geometry),
• Thanks to the flexibility in shaping and the capability to adapt to unique requirements, neodymium magnets can be created in diverse shapes and sizes, which expands their application range,
• Significant impact in cutting-edge sectors – they serve a purpose in HDDs, electric drives, healthcare devices or even high-tech tools,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in small dimensions, which allows for use in small systems

Disadvantages of NdFeB magnets:

• They may fracture when subjected to a heavy impact. If the magnets are exposed to shocks, it is advisable to use in a metal holder. The steel housing, in the form of a holder, protects the magnet from cracks and strengthens its overall strength,
• They lose power at high temperatures. Most neodymium magnets experience permanent degradation in strength when heated above 80°C (depending on the geometry and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• They rust in a wet environment. For outdoor use, we recommend using sealed magnets, such as those made of non-metallic materials,
• The use of a protective casing or external holder is recommended, since machining multi-axis shapes in neodymium magnets is not feasible,
• Possible threat related to magnet particles may arise, if ingested accidentally, which is important in the protection of children. Moreover, small elements from these devices can complicate medical imaging once in the system,
• Higher purchase price is one of the drawbacks compared to ceramic magnets, especially in budget-sensitive applications

Maximum lifting capacity of the magnet – what affects it?

The given lifting capacity of the magnet represents the maximum lifting force, assessed under optimal conditions, that is:

• with the use of low-carbon steel plate serving as a magnetic yoke
• of a thickness of at least 10 mm
• with a polished side
• in conditions of no clearance
• with vertical force applied
• under standard ambient temperature

Determinants of lifting force in real conditions

Practical lifting force is dependent on elements, by priority:

• Air gap between the magnet and the plate, since 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.

* Lifting capacity testing was performed on a smooth plate of suitable thickness, under perpendicular forces, in contrast under attempts to slide the magnet the load capacity is reduced by as much as fivefold. Additionally, even a slight gap {between} the magnet and the plate decreases the holding force.