SM 32x200 [2xM8] / N52 - magnetic separator

Strengths and weaknesses of rare earth magnets.

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

• They do not lose magnetism, even after nearly 10 years – the reduction in lifting capacity is only ~1% (based on measurements),
• They do not lose their magnetic properties even under strong external field,
• Thanks to the metallic finish, the surface of Ni-Cu-Ni, gold-plated, or silver-plated gives an professional appearance,
• Neodymium magnets ensure maximum magnetic induction on a contact point, which ensures high operational effectiveness,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Thanks to flexibility in forming and the ability to modify to individual projects,
• Significant place in electronics industry – they serve a role in mass storage devices, brushless drives, medical devices, also technologically advanced constructions.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• At very strong impacts they can crack, therefore we advise placing them in strong housings. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
• Neodymium magnets decrease their power under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. Therefore, we recommend our special magnets marked [AH], which maintain durability even at temperatures up to 230°C
• Magnets exposed to a humid environment can corrode. Therefore while using outdoors, we suggest using waterproof magnets made of rubber, plastic or other material protecting against moisture
• Due to limitations in creating threads and complex forms in magnets, we recommend using a housing - magnetic mount.
• Potential hazard resulting from small fragments of magnets are risky, when accidentally swallowed, which becomes key in the context of child safety. Additionally, small elements of these products can be problematic in diagnostics medical when they are in the body.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which can limit application in large quantities

Magnetic strength at its maximum – what it depends on?

Magnet power was defined for ideal contact conditions, assuming:

• using a sheet made of high-permeability steel, serving as a ideal flux conductor
• whose thickness equals approx. 10 mm
• characterized by even structure
• under conditions of no distance (metal-to-metal)
• under vertical force direction (90-degree angle)
• at ambient temperature approx. 20 degrees Celsius

Determinants of practical lifting force of a magnet

It is worth knowing that the working load will differ depending on elements below, in order of importance:

• Clearance – existence of foreign body (rust, dirt, air) interrupts the magnetic circuit, which lowers power steeply (even by 50% at 0.5 mm).
• Force direction – note that the magnet holds strongest perpendicularly. Under sliding down, the holding force drops significantly, often to levels of 20-30% of the nominal value.
• Wall thickness – the thinner the sheet, the weaker the hold. Part of the magnetic field penetrates through instead of converting into lifting capacity.
• Material composition – different alloys reacts the same. High carbon content worsen the attraction effect.
• Plate texture – ground elements ensure maximum contact, which improves field saturation. Rough surfaces reduce efficiency.
• Thermal factor – high temperature reduces pulling force. Exceeding the limit temperature can permanently damage the magnet.

* Lifting capacity was assessed with the use of a polished steel plate of suitable thickness (min. 20 mm), under vertically applied force, in contrast under parallel forces the lifting capacity is smaller. In addition, even a minimal clearance {between} the magnet’s surface and the plate decreases the lifting capacity.