MW 5x30 / N38 - cylindrical magnet

Strengths as well as weaknesses of rare earth magnets.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They do not lose power, even during around ten years – the reduction in strength is only ~1% (according to tests),
• Neodymium magnets are remarkably resistant to demagnetization caused by external magnetic fields,
• By applying a shiny layer of silver, the element has an aesthetic look,
• The surface of neodymium magnets generates a maximum magnetic field – this is a key feature,
• 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...
• Due to the possibility of flexible molding and customization to custom requirements, magnetic components can be manufactured in a wide range of geometric configurations, which makes them more universal,
• Fundamental importance in high-tech industry – they find application in HDD drives, brushless drives, diagnostic systems, and technologically advanced constructions.
• Thanks to their power density, small magnets offer high operating force, occupying minimum space,

Cons of neodymium magnets: weaknesses and usage proposals

• Susceptibility to cracking is one of their disadvantages. Upon strong impact they can break. We recommend keeping them in a steel housing, which not only protects them against impacts but also raises their durability
• Neodymium magnets lose their strength under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 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 stable to moisture, when using outdoors
• Limited ability of making nuts in the magnet and complicated shapes - preferred is a housing - mounting mechanism.
• Possible danger related to microscopic parts of magnets are risky, if swallowed, which becomes key in the context of child health protection. Additionally, tiny parts of these products are able to be problematic in diagnostics medical when they are in the body.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Optimal lifting capacity of a neodymium magnet – what contributes to it?

The specified lifting capacity represents the limit force, obtained under optimal environment, meaning:

• using a sheet made of low-carbon steel, functioning as a magnetic yoke
• possessing a thickness of minimum 10 mm to avoid saturation
• characterized by even structure
• under conditions of gap-free contact (metal-to-metal)
• under vertical force vector (90-degree angle)
• at conditions approx. 20°C

Lifting capacity in real conditions – factors

Effective lifting capacity is influenced by working environment parameters, mainly (from most important):

• Distance – the presence of any layer (paint, dirt, air) interrupts the magnetic circuit, which reduces capacity steeply (even by 50% at 0.5 mm).
• Force direction – remember that the magnet has greatest strength perpendicularly. Under shear forces, the capacity drops significantly, often to levels of 20-30% of the nominal value.
• Base massiveness – insufficiently thick steel does not accept the full field, causing part of the flux to be escaped to the other side.
• Metal type – different alloys reacts the same. High carbon content weaken the attraction effect.
• Surface structure – the smoother and more polished the surface, the better the adhesion and stronger the hold. Unevenness creates an air distance.
• Temperature – temperature increase causes a temporary drop of induction. It is worth remembering the thermal limit for a given model.

* Lifting capacity was measured with the use of a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular detachment force, 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.