HH 42x8.8 [M6] / N38 - through hole magnetic holder

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They have stable power, and over around ten years their attraction force decreases symbolically – ~1% (in testing),
• They are highly resistant to demagnetization caused by external magnetic fields,
• In other words, due to the metallic nickel coating, the magnet obtains an professional appearance,
• They have very high magnetic induction on the surface of the magnet,
• These magnets tolerate high temperatures, often exceeding 230°C, when properly designed (in relation to build),
• The ability for precise shaping or adjustment to custom needs – neodymium magnets can be manufactured in a wide range of shapes and sizes, which extends the scope of their use cases,
• Significant impact in advanced technical fields – they are used in data storage devices, electric drives, clinical machines or even sophisticated instruments,
• Compactness – despite their small size, they provide high effectiveness, making them ideal for precision applications

Disadvantages of magnetic elements:

• They are prone to breaking when subjected to a sudden impact. If the magnets are exposed to shocks, we recommend in a metal holder. The steel housing, in the form of a holder, protects the magnet from fracture and additionally reinforces its overall strength,
• High temperatures may significantly reduce the strength of neodymium magnets. Typically, above 80°C, they experience permanent loss in performance (depending on size). 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,
• Due to corrosion risk in humid conditions, it is wise to use sealed magnets made of plastic for outdoor use,
• The use of a protective casing or external holder is recommended, since machining fine details in neodymium magnets is not feasible,
• Potential hazard due to small fragments may arise, especially if swallowed, which is important in the context of child safety. Moreover, miniature parts from these products can interfere with diagnostics after being swallowed,
• In cases of large-volume purchasing, neodymium magnet cost may be a barrier,

Maximum magnetic pulling force – what it depends on?

The given lifting capacity of the magnet corresponds to the maximum lifting force, assessed in ideal conditions, specifically:

• with the use of low-carbon steel plate acting as a magnetic yoke
• having a thickness of no less than 10 millimeters
• with a polished side
• with no separation
• under perpendicular detachment force
• under standard ambient temperature

Lifting capacity in real conditions – factors

Practical lifting force is determined by elements, by priority:

• 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 was assessed by applying a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular pulling force, whereas under parallel forces the load capacity is reduced by as much as fivefold. Moreover, even a minimal clearance {between} the magnet’s surface and the plate reduces the holding force.