UMH 20x7x35 [M4] / N38 - magnetic holder with hook

Pros as well as cons of NdFeB magnets.

Besides their remarkable strength, neodymium magnets offer the following advantages:

• They do not lose magnetism, even during nearly 10 years – the decrease in power is only ~1% (according to tests),
• Neodymium magnets prove to be exceptionally resistant to demagnetization caused by external interference,
• In other words, due to the shiny layer of nickel, the element becomes visually attractive,
• They feature high magnetic induction at the operating surface, which improves attraction properties,
• Thanks to resistance to high temperature, they can operate (depending on the form) even at temperatures up to 230°C and higher...
• Possibility of precise creating and adjusting to concrete applications,
• Universal use in innovative solutions – they find application in HDD drives, drive modules, medical devices, as well as technologically advanced constructions.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Cons of neodymium magnets and ways of using them

• Brittleness is one of their disadvantages. Upon intense impact they can fracture. We recommend keeping them in a special holder, which not only protects them against impacts but also raises their 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 suggest using waterproof magnets made of rubber, plastic or other material stable to moisture, when using outdoors
• Due to limitations in producing threads and complex forms in magnets, we recommend using cover - magnetic mount.
• Health risk resulting from small fragments of magnets are risky, if swallowed, which is particularly important in the context of child safety. Additionally, tiny parts of these magnets are able to be problematic in diagnostics medical when they are in the body.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which hinders application in large quantities

Detachment force of the magnet in optimal conditions – what affects it?

Magnet power is the result of a measurement for the most favorable conditions, assuming:

• on a plate made of structural steel, perfectly concentrating the magnetic flux
• possessing a massiveness of at least 10 mm to ensure full flux closure
• characterized by lack of roughness
• without the slightest insulating layer between the magnet and steel
• under vertical application of breakaway force (90-degree angle)
• in neutral thermal conditions

Impact of factors on magnetic holding capacity in practice

Real force is affected by specific conditions, mainly (from priority):

• Clearance – the presence of foreign body (rust, dirt, air) interrupts the magnetic circuit, which reduces capacity steeply (even by 50% at 0.5 mm).
• Force direction – declared lifting capacity refers to detachment vertically. When slipping, the magnet holds significantly lower power (typically approx. 20-30% of nominal force).
• Wall thickness – thin material does not allow full use of the magnet. Part of the magnetic field penetrates through instead of generating force.
• Plate material – low-carbon steel attracts best. Alloy steels decrease magnetic properties and lifting capacity.
• Surface structure – the smoother and more polished the plate, the larger the contact zone and higher the lifting capacity. Roughness acts like micro-gaps.
• Temperature – heating the magnet results in weakening of force. It is worth remembering the thermal limit for a given model.

* Holding force was checked on the plate surface of 20 mm thickness, when a perpendicular force was applied, whereas under attempts to slide the magnet the lifting capacity is smaller. In addition, even a slight gap {between} the magnet and the plate lowers the load capacity.