UMS 20x8.6x4.5x7 / N38 - conical magnetic holder

Advantages as well as disadvantages of rare earth magnets.

Besides their remarkable field intensity, neodymium magnets offer the following advantages:

• They retain attractive force for almost ten years – the drop is just ~1% (based on simulations),
• They possess excellent resistance to magnetic field loss when exposed to external magnetic sources,
• A magnet with a shiny silver surface has better aesthetics,
• Magnetic induction on the top side of the magnet turns out to be maximum,
• Thanks to resistance to high temperature, they can operate (depending on the form) even at temperatures up to 230°C and higher...
• Due to the option of accurate forming and adaptation to unique requirements, magnetic components can be manufactured in a wide range of geometric configurations, which amplifies use scope,
• Universal use in advanced technology sectors – they serve a role in magnetic memories, electromotive mechanisms, precision medical tools, as well as technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in tiny dimensions, which enables their usage in miniature devices

Disadvantages of neodymium magnets:

• Brittleness is one of their disadvantages. Upon strong impact they can break. We recommend keeping them in a strong case, which not only protects them against impacts but also raises their durability
• We warn that neodymium magnets can reduce 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 advise using waterproof magnets made of rubber, plastic or other material resistant to moisture, in case of application outdoors
• Due to limitations in realizing threads and complex forms in magnets, we propose using casing - magnetic holder.
• Potential hazard related to microscopic parts of magnets pose a threat, when accidentally swallowed, which is particularly important in the context of child safety. Furthermore, small components of these magnets can be problematic in diagnostics medical when they are in the body.
• With large orders the cost of neodymium magnets can be a barrier,

Maximum lifting capacity of the magnet – what affects it?

Breakaway force was determined for ideal contact conditions, assuming:

• on a block made of mild steel, perfectly concentrating the magnetic field
• with a cross-section no less than 10 mm
• with an ground contact surface
• with direct contact (without paint)
• under perpendicular force vector (90-degree angle)
• at conditions approx. 20°C

Lifting capacity in practice – influencing factors

Bear in mind that the magnet holding may be lower influenced by the following factors, in order of importance:

• Air gap (betwixt the magnet and the metal), since even a microscopic distance (e.g. 0.5 mm) leads to a decrease in lifting capacity by up to 50% (this also applies to paint, rust or dirt).
• Loading method – catalog parameter refers to pulling vertically. When applying parallel force, the magnet exhibits significantly lower power (typically approx. 20-30% of maximum force).
• Element thickness – for full efficiency, the steel must be sufficiently thick. Thin sheet restricts the attraction force (the magnet "punches through" it).
• Metal type – different alloys attracts identically. Alloy additives weaken the interaction with the magnet.
• Surface structure – the smoother and more polished the plate, the larger the contact zone and stronger the hold. Roughness 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 determined using a steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular pulling force, whereas under shearing force the lifting capacity is smaller. Additionally, even a small distance {between} the magnet’s surface and the plate reduces the load capacity.