AM ucho [M12] - magnetic accessories

Strengths as well as weaknesses of NdFeB magnets.

Apart from their consistent power, neodymium magnets have these key benefits:

• They virtually do not lose power, because even after ten years the decline in efficiency is only ~1% (according to literature),
• Magnets perfectly resist against loss of magnetization caused by external fields,
• Thanks to the smooth finish, the coating of Ni-Cu-Ni, gold, or silver-plated gives an visually attractive appearance,
• Magnetic induction on the top side of the magnet remains very high,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their form) at temperatures up to 230°C and above...
• Thanks to freedom in constructing and the capacity to adapt to unusual requirements,
• Universal use in future technologies – they find application in data components, electric motors, precision medical tools, and modern systems.
• Thanks to concentrated force, small magnets offer high operating force, in miniature format,

Disadvantages of neodymium magnets:

• At very strong impacts they can crack, therefore we recommend placing them in strong housings. A metal housing provides additional protection against damage and increases the magnet's durability.
• We warn that neodymium magnets can reduce their power at high temperatures. To prevent this, we advise our specialized [AH] magnets, which work effectively even at 230°C.
• Due to the susceptibility of magnets to corrosion in a humid environment, we recommend using waterproof magnets made of rubber, plastic or other material resistant to moisture, in case of application outdoors
• Due to limitations in realizing nuts and complicated shapes in magnets, we recommend using a housing - magnetic mount.
• Potential hazard resulting from small fragments of magnets can be dangerous, if swallowed, which becomes key in the aspect of protecting the youngest. It is also worth noting that tiny parts of these magnets are able to be problematic in diagnostics medical in case of swallowing.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Optimal lifting capacity of a neodymium magnet – what it depends on?

Breakaway force was determined for optimal configuration, taking into account:

• using a base made of low-carbon steel, acting as a ideal flux conductor
• with a cross-section minimum 10 mm
• with a plane free of scratches
• without the slightest insulating layer between the magnet and steel
• under axial force direction (90-degree angle)
• at conditions approx. 20°C

Impact of factors on magnetic holding capacity in practice

Bear in mind that the working load may be lower influenced by the following factors, starting with the most relevant:

• Clearance – existence of foreign body (paint, dirt, air) interrupts the magnetic circuit, which lowers capacity steeply (even by 50% at 0.5 mm).
• Pull-off angle – note that the magnet has greatest strength perpendicularly. Under sliding down, the holding force drops significantly, often to levels of 20-30% of the maximum value.
• Steel thickness – insufficiently thick steel does not accept the full field, causing part of the power to be escaped to the other side.
• Steel type – mild steel gives the best results. Alloy admixtures reduce magnetic permeability and holding force.
• Surface finish – ideal contact is possible only on polished steel. Rough texture create air cushions, weakening the magnet.
• Heat – neodymium magnets have a sensitivity to temperature. When it is hot they lose power, and at low temperatures gain strength (up to a certain limit).

* Lifting capacity was measured by applying a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, in contrast under shearing force the lifting capacity is smaller. Additionally, even a minimal clearance {between} the magnet and the plate decreases the lifting capacity.