HH 25x7.7 [M5] / N38 - through hole magnetic holder

Pros as well as cons of rare earth magnets.

Besides their high retention, neodymium magnets are valued for these benefits:

• They have stable power, and over more than 10 years their attraction force decreases symbolically – ~1% (according to theory),
• They have excellent resistance to weakening of magnetic properties as a result of opposing magnetic fields,
• In other words, due to the aesthetic finish of nickel, the element is aesthetically pleasing,
• The surface of neodymium magnets generates a intense magnetic field – this is one of their assets,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their form) at temperatures up to 230°C and above...
• Thanks to flexibility in forming and the capacity to adapt to specific needs,
• Key role in high-tech industry – they serve a role in computer drives, brushless drives, medical equipment, as well as modern systems.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Disadvantages of neodymium magnets:

• 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 lose their strength at high temperatures. To prevent this, we suggest our specialized [AH] magnets, which work effectively even at 230°C.
• When exposed to humidity, magnets start to rust. For applications outside, it is recommended to use protective magnets, such as those in rubber or plastics, which prevent oxidation as well as corrosion.
• We recommend cover - magnetic holder, due to difficulties in creating threads inside the magnet and complex forms.
• Possible danger related to microscopic parts of magnets pose a threat, in case of ingestion, which becomes key in the context of child safety. Additionally, tiny parts of these magnets are able to be problematic in diagnostics medical in case of swallowing.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Magnetic strength at its maximum – what contributes to it?

Information about lifting capacity is the result of a measurement for the most favorable conditions, assuming:

• using a plate made of low-carbon steel, acting as a magnetic yoke
• possessing a massiveness of at least 10 mm to ensure full flux closure
• with a plane free of scratches
• under conditions of gap-free contact (metal-to-metal)
• for force applied at a right angle (pull-off, not shear)
• at temperature room level

Lifting capacity in practice – influencing factors

During everyday use, the actual holding force results from many variables, ranked from the most important:

• Gap (betwixt the magnet and the plate), since even a microscopic clearance (e.g. 0.5 mm) leads to a drastic drop in force by up to 50% (this also applies to paint, rust or debris).
• Force direction – 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.
• Substrate thickness – for full efficiency, the steel must be adequately massive. Paper-thin metal limits the attraction force (the magnet "punches through" it).
• Material composition – different alloys attracts identically. High carbon content worsen the interaction with the magnet.
• Surface structure – the more even the surface, the better the adhesion and higher the lifting capacity. Roughness creates an air distance.
• Heat – neodymium magnets have a negative temperature coefficient. At higher temperatures they are weaker, and at low temperatures they can be stronger (up to a certain limit).

* Lifting capacity was measured by applying 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. Moreover, even a minimal clearance {between} the magnet and the plate reduces the load capacity.