SM 25x350 [2xM8] / N52 - magnetic separator

Strengths as well as weaknesses of rare earth magnets.

Besides their stability, neodymium magnets are valued for these benefits:

• They virtually do not lose strength, because even after ten years the decline in efficiency is only ~1% (according to literature),
• Magnets effectively protect themselves against demagnetization caused by foreign field sources,
• A magnet with a metallic nickel surface has an effective appearance,
• Magnets are characterized by extremely high magnetic induction on the surface,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and are able to act (depending on the form) even at a temperature of 230°C or more...
• Thanks to versatility in designing and the ability to modify to client solutions,
• Wide application in advanced technology sectors – they are commonly used in HDD drives, electromotive mechanisms, diagnostic systems, and complex engineering applications.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in tiny dimensions, which makes them useful in miniature devices

Drawbacks and weaknesses of neodymium magnets and ways of using them

• Susceptibility to cracking is one of their disadvantages. Upon strong impact they can break. We advise keeping them in a special holder, which not only secures them against impacts but also raises their durability
• When exposed to high temperature, neodymium magnets experience a drop in force. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size, as well as shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• They oxidize in a humid environment - during use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• Due to limitations in producing nuts and complex forms in magnets, we recommend using casing - magnetic mechanism.
• Health risk related to microscopic parts of magnets pose a threat, when accidentally swallowed, which is particularly important in the context of child safety. It is also worth noting that small elements of these magnets can 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

Best holding force of the magnet in ideal parameters – what it depends on?

Information about lifting capacity is the result of a measurement for the most favorable conditions, taking into account:

• using a plate made of mild steel, acting as a magnetic yoke
• possessing a thickness of minimum 10 mm to ensure full flux closure
• with an ground contact surface
• with zero gap (no paint)
• during detachment in a direction perpendicular to the mounting surface
• in neutral thermal conditions

Determinants of practical lifting force of a magnet

Please note that the working load will differ subject to elements below, starting with the most relevant:

• Clearance – the presence of foreign body (paint, dirt, gap) acts as an insulator, which lowers capacity steeply (even by 50% at 0.5 mm).
• Angle of force application – maximum parameter is obtained only during perpendicular pulling. The force required to slide of the magnet along the plate is typically many times lower (approx. 1/5 of the lifting capacity).
• Base massiveness – too thin plate does not accept the full field, causing part of the flux to be lost into the air.
• Plate material – mild steel gives the best results. Higher carbon content decrease magnetic permeability and holding force.
• Base smoothness – the smoother and more polished the plate, the larger the contact zone and stronger the hold. Roughness acts like micro-gaps.
• Operating temperature – NdFeB sinters have a sensitivity to temperature. When it is hot they lose power, and at low temperatures they can be stronger (up to a certain limit).

* Lifting capacity was measured by applying a steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular detachment force, in contrast under shearing force the lifting capacity is smaller. Additionally, even a slight gap {between} the magnet’s surface and the plate lowers the lifting capacity.