SM 25x200 [2xM8] / N52 - magnetic separator

Pros as well as cons of rare earth magnets.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• They do not lose power, even after nearly 10 years – the drop in strength is only ~1% (theoretically),
• They do not lose their magnetic properties even under strong external field,
• A magnet with a shiny silver surface is more attractive,
• Magnets possess exceptionally strong magnetic induction on the outer layer,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the form) even at high temperatures reaching 230°C or more...
• In view of the ability of flexible shaping and customization to custom requirements, NdFeB magnets can be modeled in a broad palette of shapes and sizes, which increases their versatility,
• Fundamental importance in future technologies – they are commonly used in mass storage devices, electric motors, diagnostic systems, as well as complex engineering applications.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in compact dimensions, which allows their use in compact constructions

Cons of neodymium magnets: application proposals

• To avoid cracks under impact, we recommend using special steel housings. Such a solution protects the magnet and simultaneously increases its durability.
• We warn that neodymium magnets can lose their power at high temperatures. To prevent this, we suggest our specialized [AH] magnets, which work effectively even at 230°C.
• They rust in a humid environment - during use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• Limited ability of creating threads in the magnet and complex forms - preferred is a housing - mounting mechanism.
• Health risk related to microscopic parts of magnets are risky, if swallowed, which is particularly important in the context of child safety. It is also worth noting that small components of these devices are able to complicate diagnosis medical when they are in the body.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which hinders application in large quantities

Maximum holding power of the magnet – what it depends on?

The declared magnet strength concerns the peak performance, measured under ideal test conditions, specifically:

• on a block made of mild steel, effectively closing the magnetic field
• with a cross-section no less than 10 mm
• with a surface cleaned and smooth
• with total lack of distance (without paint)
• during detachment in a direction perpendicular to the mounting surface
• at ambient temperature approx. 20 degrees Celsius

Practical lifting capacity: influencing factors

During everyday use, the real power is determined by several key aspects, presented from most significant:

• Gap (betwixt the magnet and the metal), because even a tiny clearance (e.g. 0.5 mm) leads to a reduction in force by up to 50% (this also applies to varnish, corrosion or dirt).
• Angle of force application – maximum parameter is obtained only during perpendicular pulling. The shear force of the magnet along the plate is typically many times smaller (approx. 1/5 of the lifting capacity).
• Steel thickness – too thin plate does not accept the full field, causing part of the flux to be lost to the other side.
• Steel grade – ideal substrate is high-permeability steel. Hardened steels may generate lower lifting capacity.
• Surface condition – ground elements ensure maximum contact, which improves field saturation. Uneven metal reduce efficiency.
• Temperature influence – high temperature reduces magnetic field. Too high temperature can permanently demagnetize the magnet.

* Lifting capacity was assessed with the use of a polished steel plate of optimal thickness (min. 20 mm), under vertically applied force, however under parallel forces the lifting capacity is smaller. In addition, even a slight gap {between} the magnet’s surface and the plate reduces the lifting capacity.