SM 32x325 [2xM8] / N52 - magnetic separator

Strengths and weaknesses of neodymium magnets.

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

• They do not lose power, even over around 10 years – the drop in lifting capacity is only ~1% (theoretically),
• They maintain their magnetic properties even under external field action,
• In other words, due to the aesthetic surface of nickel, the element looks attractive,
• Magnets possess huge magnetic induction on the outer layer,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their form) at temperatures up to 230°C and above...
• Possibility of custom shaping and optimizing to complex needs,
• Key role in high-tech industry – they are used in HDD drives, brushless drives, precision medical tools, and complex engineering applications.
• Thanks to efficiency per cm³, small magnets offer high operating force, occupying minimum space,

Problematic aspects of neodymium magnets and proposals for their use:

• They are fragile upon heavy impacts. To avoid cracks, it is worth securing magnets in special housings. Such protection not only shields the magnet but also improves its resistance to damage
• Neodymium magnets decrease their strength 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
• Due to the susceptibility of magnets to corrosion in a humid environment, we recommend using waterproof magnets made of rubber, plastic or other material stable to moisture, when using outdoors
• Due to limitations in creating threads and complex shapes in magnets, we recommend using a housing - magnetic mechanism.
• Potential hazard related to microscopic parts of magnets pose a threat, in case of ingestion, which gains importance in the context of child safety. Furthermore, small components of these devices are able to disrupt the diagnostic process medical when they are in the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Maximum lifting force for a neodymium magnet – what contributes to it?

Breakaway force is the result of a measurement for optimal configuration, assuming:

• using a sheet made of high-permeability steel, functioning as a ideal flux conductor
• possessing a massiveness of at least 10 mm to ensure full flux closure
• with an ground contact surface
• with total lack of distance (without paint)
• under perpendicular application of breakaway force (90-degree angle)
• in temp. approx. 20°C

What influences lifting capacity in practice

Real force is affected by working environment parameters, mainly (from most important):

• Gap between magnet and steel – every millimeter of separation (caused e.g. by varnish or dirt) drastically reduces the magnet efficiency, often by half at just 0.5 mm.
• Pull-off angle – remember that the magnet has greatest strength perpendicularly. Under sliding down, the holding force drops drastically, often to levels of 20-30% of the nominal value.
• Wall thickness – thin material does not allow full use of the magnet. Part of the magnetic field passes through the material instead of converting into lifting capacity.
• Material composition – different alloys reacts the same. High carbon content weaken the attraction effect.
• Plate texture – smooth surfaces guarantee perfect abutment, which improves field saturation. Uneven metal reduce efficiency.
• Thermal factor – high temperature weakens magnetic field. Exceeding the limit temperature can permanently demagnetize the magnet.

* Lifting capacity was measured by applying a polished steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, however under parallel forces the holding force is lower. Additionally, even a small distance {between} the magnet and the plate reduces the lifting capacity.