UMGZ 20x15x7 [M4] GZ / N38 - magnetic holder external thread

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their notable holding force, neodymium magnets have these key benefits:

• Their strength remains stable, and after around 10 years, it drops only by ~1% (according to research),
• Their ability to resist magnetic interference from external fields is notable,
• Thanks to the glossy finish and gold coating, they have an elegant appearance,
• They have extremely strong magnetic induction on the surface of the magnet,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• The ability for custom shaping or customization to custom needs – neodymium magnets can be manufactured in many forms and dimensions, which amplifies their functionality across industries,
• Wide application in new technology industries – they are used in hard drives, electromechanical systems, healthcare devices along with other advanced devices,
• Thanks to their power density, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of rare earth magnets:

• They are fragile when subjected to a powerful impact. If the magnets are exposed to physical collisions, it is advisable to use in a metal holder. The steel housing, in the form of a holder, protects the magnet from fracture and strengthens its overall resistance,
• High temperatures may significantly reduce the holding force of neodymium magnets. Typically, above 80°C, they experience permanent weakening in performance (depending on height). 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,
• They rust in a humid environment, especially when used outside, we recommend using moisture-resistant magnets, such as those made of polymer,
• The use of a protective casing or external holder is recommended, since machining internal cuts in neodymium magnets is restricted,
• Health risk due to small fragments may arise, in case of ingestion, which is significant in the protection of children. Furthermore, minuscule fragments from these magnets might interfere with diagnostics if inside the body,
• Due to a complex production process, their cost is above average,

Detachment force of the magnet in optimal conditions – what contributes to it?

The given pulling force of the magnet represents the maximum force, assessed in the best circumstances, namely:

• 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 zero air gap
• in a perpendicular direction of force
• in normal thermal conditions

Determinants of lifting force in real conditions

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

• Air gap between the magnet and the plate, because 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 carried out on plates with a smooth surface of suitable thickness, under perpendicular forces, however under attempts to slide the magnet the load capacity is reduced by as much as 5 times. Additionally, even a small distance {between} the magnet’s surface and the plate reduces the holding force.