HH 16x5.3 [M3] / N38 - through hole magnetic holder

Advantages as well as disadvantages of neodymium magnets NdFeB.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• They retain their attractive force for nearly ten years – the loss is just ~1% (based on simulations),
• They remain magnetized despite exposure to magnetic surroundings,
• By applying a bright layer of nickel, the element gains a clean look,
• They possess strong magnetic force measurable at the magnet’s surface,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• With the option for tailored forming and targeted design, these magnets can be produced in multiple shapes and sizes, greatly improving engineering flexibility,
• Important function in new technology industries – they find application in hard drives, electric drives, diagnostic apparatus or even other advanced devices,
• Thanks to their power density, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of magnetic elements:

• They may fracture when subjected to a heavy impact. If the magnets are exposed to external force, it is suggested to place them in a protective case. The steel housing, in the form of a holder, protects the magnet from breakage and additionally strengthens its overall resistance,
• High temperatures may significantly reduce the field efficiency of neodymium magnets. Typically, above 80°C, they experience permanent loss in performance (depending on shape). To prevent this, we offer heat-resistant magnets marked [AH], capable of working up to 230°C, which makes them perfect for high-temperature use,
• Magnets exposed to humidity can oxidize. Therefore, for outdoor applications, we advise waterproof types made of non-metallic composites,
• Using a cover – such as a magnetic holder – is advised due to the restrictions in manufacturing threads directly in the magnet,
• Safety concern linked to microscopic shards may arise, when consumed by mistake, which is notable in the health of young users. Moreover, small elements from these magnets can complicate medical imaging once in the system,
• Due to expensive raw materials, their cost is relatively high,

Magnetic strength at its maximum – what affects it?

The given strength of the magnet represents the optimal strength, calculated under optimal conditions, that is:

• with the use of low-carbon steel plate serving as a magnetic yoke
• with a thickness of minimum 10 mm
• with a polished side
• with no separation
• in a perpendicular direction of force
• at room temperature

Lifting capacity in practice – influencing factors

Practical lifting force is determined by elements, listed from the most critical to the less significant:

• Air gap between the magnet and the plate, as even a very small distance (e.g. 0.5 mm) causes 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 carried out on plates with a smooth surface of suitable thickness, under perpendicular forces, whereas under attempts to slide the magnet the lifting capacity is smaller. Additionally, even a minimal clearance {between} the magnet and the plate lowers the lifting capacity.