SM 18x275 [2xM5] / N42 - magnetic separator

Strengths and weaknesses of NdFeB magnets.

Besides their immense strength, neodymium magnets offer the following advantages:

• They do not lose strength, even during nearly 10 years – the reduction in lifting capacity is only ~1% (theoretically),
• They do not lose their magnetic properties even under strong external field,
• By covering with a smooth coating of nickel, the element acquires an nice look,
• Magnetic induction on the surface of the magnet remains very high,
• 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 detailed forming and modifying to precise conditions,
• Versatile presence in future technologies – they are utilized in HDD drives, drive modules, medical devices, also modern systems.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Drawbacks and weaknesses of neodymium magnets and proposals for their use:

• At strong impacts they can crack, therefore we recommend placing them in strong housings. A metal housing provides additional protection against damage and increases the magnet's durability.
• Neodymium magnets lose power when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of power (a factor is the shape and dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are extremely resistant to heat
• They rust in a humid environment. For use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• We suggest a housing - magnetic mount, due to difficulties in producing threads inside the magnet and complex forms.
• Possible danger to health – tiny shards of magnets pose a threat, if swallowed, which becomes key in the aspect of protecting the youngest. Furthermore, small components of these magnets are able to disrupt the diagnostic process medical when they are in the body.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Magnetic strength at its maximum – what affects it?

Breakaway force is the result of a measurement for ideal contact conditions, including:

• using a base made of high-permeability steel, functioning as a circuit closing element
• possessing a thickness of minimum 10 mm to ensure full flux closure
• with an polished contact surface
• without the slightest clearance between the magnet and steel
• during detachment in a direction vertical to the mounting surface
• in neutral thermal conditions

What influences lifting capacity in practice

During everyday use, the real power depends on several key aspects, ranked from most significant:

• Distance – existence of foreign body (paint, tape, gap) interrupts the magnetic circuit, which lowers capacity steeply (even by 50% at 0.5 mm).
• Load vector – maximum parameter is obtained only during pulling at a 90° angle. The force required to slide of the magnet along the surface is standardly several times smaller (approx. 1/5 of the lifting capacity).
• Base massiveness – too thin steel does not accept the full field, causing part of the power to be escaped into the air.
• Metal type – not every steel reacts the same. High carbon content worsen the attraction effect.
• Base smoothness – the smoother and more polished the plate, the better the adhesion and stronger the hold. Unevenness acts like micro-gaps.
• Thermal factor – hot environment reduces magnetic field. Too high temperature can permanently demagnetize the magnet.

* Lifting capacity was measured by applying a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular detachment force, in contrast under attempts to slide the magnet the holding force is lower. Moreover, even a slight gap {between} the magnet’s surface and the plate decreases the holding force.