UMGGZ 88x8.5 [M8] GZ / N38 - rubber magnetic holder external thread

Strengths and weaknesses of rare earth magnets.

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

• They have unchanged lifting capacity, and over nearly 10 years their attraction force decreases symbolically – ~1% (in testing),
• They have excellent resistance to magnetism drop due to external fields,
• Thanks to the shiny finish, the coating of nickel, gold-plated, or silver gives an professional appearance,
• Magnetic induction on the surface of the magnet is exceptional,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the form) even at high temperatures reaching 230°C or more...
• Thanks to flexibility in forming and the ability to customize to specific needs,
• Fundamental importance in high-tech industry – they are used in mass storage devices, electromotive mechanisms, diagnostic systems, and technologically advanced constructions.
• Thanks to efficiency per cm³, small magnets offer high operating force, with minimal size,

Disadvantages of neodymium magnets:

• To avoid cracks under impact, we suggest using special steel housings. Such a solution secures the magnet and simultaneously increases its durability.
• We warn that neodymium magnets can reduce their power at high temperatures. To prevent this, we recommend our specialized [AH] magnets, which work effectively even at 230°C.
• They rust in a humid environment. For use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• Due to limitations in realizing threads and complicated shapes in magnets, we propose using casing - magnetic mechanism.
• Potential hazard related to microscopic parts of magnets are risky, in case of ingestion, which is particularly important in the context of child safety. Furthermore, small components of these magnets can disrupt the diagnostic process medical when they are in the body.
• Due to neodymium price, their price is relatively high,

Maximum lifting capacity of the magnet – what affects it?

Holding force of 42.9 kg is a theoretical maximum value performed under the following configuration:

• with the application of a yoke made of special test steel, guaranteeing full magnetic saturation
• with a cross-section of at least 10 mm
• with an ideally smooth contact surface
• without the slightest clearance between the magnet and steel
• for force applied at a right angle (pull-off, not shear)
• at ambient temperature approx. 20 degrees Celsius

Lifting capacity in practice – influencing factors

During everyday use, the actual holding force results from many variables, listed from most significant:

• Clearance – the presence of any layer (rust, dirt, gap) interrupts the magnetic circuit, which lowers power rapidly (even by 50% at 0.5 mm).
• Pull-off angle – note that the magnet has greatest strength perpendicularly. Under shear forces, the capacity drops significantly, often to levels of 20-30% of the maximum value.
• Steel thickness – insufficiently thick plate does not accept the full field, causing part of the flux to be escaped to the other side.
• Steel type – low-carbon steel gives the best results. Alloy steels lower magnetic permeability and holding force.
• Surface finish – ideal contact is possible only on smooth steel. Any scratches and bumps create air cushions, reducing force.
• Temperature influence – hot environment weakens magnetic field. Exceeding the limit temperature can permanently damage the magnet.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under attempts to slide the magnet the lifting capacity is smaller. In addition, even a minimal clearance {between} the magnet and the plate lowers the holding force.