AM Haczyk M4 - magnetic accessories

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their tremendous strength, neodymium magnets offer the following advantages:

• They have stable power, and over more than ten years their attraction force decreases symbolically – ~1% (in testing),
• They are extremely resistant to demagnetization caused by external magnetic sources,
• By applying a reflective layer of nickel, the element gains a sleek look,
• They possess strong magnetic force measurable at the magnet’s surface,
• Neodymium magnets are known for exceptionally strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the magnetic form),
• The ability for custom shaping and adjustment to specific needs – neodymium magnets can be manufactured in many forms and dimensions, which enhances their versatility in applications,
• Significant impact in modern technologies – they find application in computer drives, rotating machines, healthcare devices and other advanced devices,
• Relatively small size with high magnetic force – neodymium magnets offer strong power in tiny dimensions, which makes them useful in compact constructions

Disadvantages of magnetic elements:

• They may fracture when subjected to a powerful impact. If the magnets are exposed to physical collisions, we recommend in a metal holder. The steel housing, in the form of a holder, protects the magnet from damage while also reinforces its overall resistance,
• Magnets lose field strength when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible magnetic decay (influenced by the magnet’s structure). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• They rust in a wet environment. For outdoor use, we recommend using waterproof magnets, such as those made of rubber,
• Using a cover – such as a magnetic holder – is advised due to the restrictions in manufacturing complex structures directly in the magnet,
• Possible threat due to small fragments may arise, especially if swallowed, which is crucial in the family environments. Furthermore, small elements from these products have the potential to disrupt scanning once in the system,
• Due to expensive raw materials, their cost is relatively high,

Highest magnetic holding force – what contributes to it?

The given pulling force of the magnet means the maximum force, measured in the best circumstances, that is:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• of a thickness of at least 10 mm
• with a polished side
• in conditions of no clearance
• under perpendicular detachment force
• under standard ambient temperature

Determinants of practical lifting force of a magnet

In practice, the holding capacity of a magnet is conditioned by the following aspects, from crucial to less important:

• 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 was assessed with the use of a steel plate with a smooth surface of suitable thickness (min. 20 mm), under vertically applied force, however under attempts to slide the magnet the lifting capacity is smaller. Moreover, even a small distance {between} the magnet’s surface and the plate reduces the holding force.