MW 15x4 / N38 - cylindrical magnet

Pros and cons of neodymium magnets.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• Their power is maintained, and after around ten years it decreases only by ~1% (theoretically),
• They are resistant to demagnetization induced by external field influence,
• The use of an shiny finish of noble metals (nickel, gold, silver) causes the element to present itself better,
• Neodymium magnets create maximum magnetic induction on a small surface, which allows for strong attraction,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the shape) even at high temperatures reaching 230°C or more...
• In view of the ability of free forming and customization to unique solutions, NdFeB magnets can be modeled in a broad palette of shapes and sizes, which amplifies use scope,
• Fundamental importance in modern industrial fields – they find application in HDD drives, motor assemblies, medical equipment, also modern systems.
• Thanks to their power density, small magnets offer high operating force, occupying minimum space,

Drawbacks and weaknesses of neodymium magnets: weaknesses and usage proposals

• They are fragile upon too strong impacts. To avoid cracks, it is worth protecting magnets in a protective case. Such protection not only shields the magnet but also increases its resistance to damage
• We warn that neodymium magnets can lose their strength 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 producing nuts and complex forms in magnets, we propose using a housing - magnetic mechanism.
• Possible danger to health – tiny shards of magnets are risky, when accidentally swallowed, which is particularly important in the context of child health protection. It is also worth noting that small components of these magnets can be problematic in diagnostics medical in case of swallowing.
• With large orders the cost of neodymium magnets is a challenge,

Maximum lifting force for a neodymium magnet – what it depends on?

Information about lifting capacity was defined for ideal contact conditions, including:

• using a plate made of high-permeability steel, acting as a circuit closing element
• with a cross-section of at least 10 mm
• with an ideally smooth touching surface
• without any clearance between the magnet and steel
• for force acting at a right angle (pull-off, not shear)
• at ambient temperature approx. 20 degrees Celsius

Impact of factors on magnetic holding capacity in practice

Holding efficiency impacted by working environment parameters, such as (from most important):

• Space between magnet and steel – even a fraction of a millimeter of separation (caused e.g. by varnish or dirt) significantly weakens the pulling force, often by half at just 0.5 mm.
• Force direction – remember that the magnet holds strongest perpendicularly. Under sliding down, the holding force drops significantly, often to levels of 20-30% of the nominal value.
• Metal thickness – the thinner the sheet, the weaker the hold. Magnetic flux passes through the material instead of generating force.
• Material type – ideal substrate is high-permeability steel. Stainless steels may have worse magnetic properties.
• Surface structure – the more even the plate, the better the adhesion and higher the lifting capacity. Unevenness acts like micro-gaps.
• Temperature – temperature increase results in weakening of induction. It is worth remembering the maximum operating temperature for a given model.

* Lifting capacity was assessed with the use of a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular pulling force, however under attempts to slide the magnet the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet’s surface and the plate reduces the lifting capacity.