SM 32x450 [2xM8] / N42 - magnetic separator

Strengths as well as weaknesses of NdFeB magnets.

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

• Their strength is maintained, and after approximately ten years it decreases only by ~1% (according to research),
• They are extremely resistant to demagnetization induced by external magnetic fields,
• In other words, due to the shiny layer of nickel, the element is aesthetically pleasing,
• Neodymium magnets deliver maximum magnetic induction on a their surface, which ensures high operational effectiveness,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Possibility of custom creating as well as adapting to defined conditions,
• Versatile presence in advanced technology sectors – they are utilized in mass storage devices, electric drive systems, diagnostic systems, also complex engineering applications.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Disadvantages of neodymium magnets:

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth protecting magnets in special housings. Such protection not only shields the magnet but also increases its resistance to damage
• Neodymium magnets lose 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 stability even at temperatures up to 230°C
• They rust in a humid environment. For use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• Limited possibility of making threads in the magnet and complicated forms - preferred is cover - magnet mounting.
• Potential hazard related to microscopic parts of magnets can be dangerous, in case of ingestion, which gains importance in the context of child safety. It is also worth noting that small elements of these devices are able to disrupt the diagnostic process medical in case of swallowing.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which hinders application in large quantities

Maximum lifting capacity of the magnet – what it depends on?

Information about lifting capacity was determined for the most favorable conditions, assuming:

• with the use of a yoke made of low-carbon steel, guaranteeing full magnetic saturation
• possessing a thickness of min. 10 mm to ensure full flux closure
• with a plane perfectly flat
• with direct contact (no coatings)
• under axial force direction (90-degree angle)
• at standard ambient temperature

Practical lifting capacity: influencing factors

Real force is affected by working environment parameters, including (from priority):

• Gap (betwixt the magnet and the metal), since even a very small distance (e.g. 0.5 mm) leads to a reduction in lifting capacity by up to 50% (this also applies to varnish, rust or dirt).
• Force direction – declared lifting capacity refers to pulling vertically. When applying parallel force, the magnet holds significantly lower power (typically approx. 20-30% of nominal force).
• Wall thickness – the thinner the sheet, the weaker the hold. Magnetic flux passes through the material instead of converting into lifting capacity.
• Steel grade – ideal substrate is pure iron steel. Hardened steels may attract less.
• Smoothness – full contact is obtained only on polished steel. Any scratches and bumps reduce the real contact area, weakening the magnet.
• Temperature – temperature increase results in weakening of force. Check the thermal limit for a given model.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under attempts to slide the magnet the holding force is lower. Additionally, even a minimal clearance {between} the magnet’s surface and the plate lowers the lifting capacity.