MW 20x5 / N38 - cylindrical magnet

Pros as well as cons of rare earth magnets.

In addition to their magnetic capacity, neodymium magnets provide the following advantages:

• Their power is durable, and after around ten years it decreases only by ~1% (theoretically),
• They are noted for resistance to demagnetization induced by external disturbances,
• The use of an elegant layer of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• They feature high magnetic induction at the operating surface, which improves attraction properties,
• Through (appropriate) combination of ingredients, they can achieve high thermal resistance, allowing for action at temperatures reaching 230°C and above...
• Possibility of detailed creating as well as adjusting to specific applications,
• Significant place in modern industrial fields – they are commonly used in HDD drives, electromotive mechanisms, advanced medical instruments, also other advanced devices.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in compact dimensions, which allows their use in miniature devices

Drawbacks and weaknesses of neodymium magnets: tips and applications.

• They are fragile upon too strong impacts. To avoid cracks, it is worth securing magnets in a protective case. Such protection not only shields the magnet but also improves its resistance to damage
• We warn that neodymium magnets can lose their power at high temperatures. To prevent this, we recommend 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 resistant to moisture, in case of application outdoors
• Limited ability of creating nuts in the magnet and complicated forms - recommended is a housing - magnet mounting.
• Potential hazard related to microscopic parts of magnets pose a threat, if swallowed, which is particularly important in the context of child health protection. Additionally, small components of these magnets are able to complicate diagnosis medical in case of swallowing.
• Due to neodymium price, their price is relatively high,

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

Magnet power is the result of a measurement for optimal configuration, assuming:

• using a base made of high-permeability steel, acting as a ideal flux conductor
• with a thickness minimum 10 mm
• with an polished contact surface
• with direct contact (without impurities)
• during pulling in a direction vertical to the plane
• in temp. approx. 20°C

Lifting capacity in practice – influencing factors

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

• Gap (between the magnet and the metal), as even a microscopic clearance (e.g. 0.5 mm) results in a decrease in force by up to 50% (this also applies to varnish, rust or debris).
• Angle of force application – highest force is available only during pulling at a 90° angle. The shear force of the magnet along the plate is usually several times lower (approx. 1/5 of the lifting capacity).
• Base massiveness – insufficiently thick steel causes magnetic saturation, causing part of the flux to be lost into the air.
• Steel type – low-carbon steel gives the best results. Alloy steels decrease magnetic permeability and lifting capacity.
• Smoothness – full contact is obtained only on smooth steel. Rough texture reduce the real contact area, weakening the magnet.
• Heat – NdFeB sinters have a negative temperature coefficient. At higher temperatures they are weaker, and in frost gain strength (up to a certain limit).

* Lifting capacity was determined using a smooth steel plate of suitable thickness (min. 20 mm), under vertically applied force, in contrast under shearing force the holding force is lower. Additionally, even a minimal clearance {between} the magnet’s surface and the plate reduces the lifting capacity.