MW 8x1.5 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their consistent power, neodymium magnets have these key benefits:

• Their magnetic field remains stable, and after approximately ten years, it drops only by ~1% (according to research),
• They remain magnetized despite exposure to strong external fields,
• The use of a decorative nickel surface provides a refined finish,
• Magnetic induction on the surface of these magnets is impressively powerful,
• These magnets tolerate high temperatures, often exceeding 230°C, when properly designed (in relation to form),
• The ability for custom shaping or customization to custom needs – neodymium magnets can be manufactured in many forms and dimensions, which extends the scope of their use cases,
• Significant impact in advanced technical fields – they find application in data storage devices, electromechanical systems, clinical machines along with other advanced devices,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, with minimal size,

Disadvantages of magnetic elements:

• They are fragile when subjected to a strong impact. If the magnets are exposed to shocks, it is advisable to use in a steel housing. The steel housing, in the form of a holder, protects the magnet from cracks while also enhances its overall strength,
• Magnets lose pulling force when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible power drop (influenced by the magnet’s dimensions). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• They rust in a damp environment. If exposed to rain, we recommend using waterproof magnets, such as those made of polymer,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is not feasible,
• Possible threat related to magnet particles may arise, if ingested accidentally, which is crucial in the protection of children. It should also be noted that tiny components from these magnets have the potential to interfere with diagnostics when ingested,
• High unit cost – neodymium magnets are costlier than other types of magnets (e.g., ferrite), which may limit large-scale applications

Maximum lifting capacity of the magnet – what affects it?

The given strength of the magnet means the optimal strength, assessed under optimal conditions, that is:

• with the use of low-carbon steel plate acting as a magnetic yoke
• of a thickness of at least 10 mm
• with a refined outer layer
• with zero air gap
• in a perpendicular direction of force
• under standard ambient temperature

What influences lifting capacity in practice

In practice, the holding capacity of a magnet is affected by the following aspects, arranged from the most important to the least relevant:

• Air gap between the magnet and the plate, as even a very small distance (e.g. 0.5 mm) can cause a drop in lifting force of up to 50%.
• Direction of applied force, because the maximum lifting capacity is achieved under perpendicular application. The force required to slide the magnet along the plate is usually several times lower.
• Thickness of the plate, as a plate that is too thin causes part of the magnetic flux not to be used and to remain wasted in the air.
• Material of the plate, because higher carbon content lowers holding force, while higher iron content increases it. The best choice is steel with high magnetic permeability and high saturation induction.
• Surface of the plate, because the more smooth and polished it is, the better the contact and consequently the greater the magnetic saturation.
• Operating temperature, since all permanent magnets have a negative temperature coefficient. This means that at high temperatures they are weaker, while at sub-zero temperatures they become slightly stronger.

* Lifting capacity was determined by applying a polished steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, in contrast under attempts to slide the magnet the holding force is lower. Moreover, even a slight gap {between} the magnet’s surface and the plate decreases the load capacity.