NCM 30x13.5x5 / N38 - channel magnetic holder

Pros and cons of rare earth magnets.

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

• They virtually do not lose power, because even after 10 years the decline in efficiency is only ~1% (according to literature),
• Neodymium magnets are distinguished by exceptionally resistant to magnetic field loss caused by magnetic disturbances,
• A magnet with a shiny silver surface looks better,
• Neodymium magnets ensure maximum magnetic induction on a small surface, which allows for strong attraction,
• Through (appropriate) combination of ingredients, they can achieve high thermal resistance, allowing for action at temperatures approaching 230°C and above...
• Thanks to freedom in constructing and the ability to adapt to specific needs,
• Significant place in innovative solutions – they serve a role in hard drives, electric motors, medical devices, as well as multitasking production systems.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Disadvantages of neodymium magnets:

• Susceptibility to cracking is one of their disadvantages. Upon strong impact they can break. We advise keeping them in a steel housing, which not only secures them against impacts but also raises their durability
• When exposed to high temperature, neodymium magnets experience a drop in force. Often, when the temperature exceeds 80°C, their power decreases (depending on the size, as well as shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 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
• We recommend a housing - magnetic mount, due to difficulties in realizing threads inside the magnet and complicated shapes.
• Health risk to health – tiny shards of magnets pose a threat, in case of ingestion, which gains importance in the context of child health protection. Furthermore, tiny parts of these devices are able to be problematic in diagnostics medical after entering the body.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Magnetic strength at its maximum – what it depends on?

The load parameter shown refers to the peak performance, obtained under optimal environment, namely:

• using a base made of mild steel, acting as a magnetic yoke
• with a cross-section no less than 10 mm
• characterized by smoothness
• under conditions of gap-free contact (metal-to-metal)
• under axial application of breakaway force (90-degree angle)
• at conditions approx. 20°C

Key elements affecting lifting force

Real force impacted by specific conditions, including (from most important):

• Clearance – the presence of any layer (paint, tape, gap) interrupts the magnetic circuit, which lowers power steeply (even by 50% at 0.5 mm).
• Pull-off angle – remember that the magnet holds strongest perpendicularly. Under sliding down, the holding force drops significantly, often to levels of 20-30% of the maximum value.
• Substrate thickness – to utilize 100% power, the steel must be sufficiently thick. Thin sheet restricts the attraction force (the magnet "punches through" it).
• Chemical composition of the base – low-carbon steel attracts best. Alloy admixtures reduce magnetic permeability and lifting capacity.
• Surface quality – the more even the plate, the larger the contact zone and stronger the hold. Roughness creates an air distance.
• Operating temperature – NdFeB sinters have a negative temperature coefficient. When it is hot they are weaker, and at low temperatures gain strength (up to a certain limit).

* Holding force was measured on the plate surface of 20 mm thickness, when a perpendicular force was applied, however under shearing force the load capacity is reduced by as much as 5 times. Additionally, even a minimal clearance {between} the magnet and the plate lowers the lifting capacity.