SM 25x325 [2xM8] / N52 - magnetic separator

Strengths and weaknesses of NdFeB magnets.

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

• They do not lose power, even after around 10 years – the decrease in lifting capacity is only ~1% (based on measurements),
• They retain their magnetic properties even under external field action,
• A magnet with a smooth silver surface is more attractive,
• Neodymium magnets deliver maximum magnetic induction on a their surface, which ensures high operational effectiveness,
• Through (appropriate) combination of ingredients, they can achieve high thermal resistance, enabling functioning at temperatures approaching 230°C and above...
• Possibility of accurate shaping and modifying to precise needs,
• Versatile presence in high-tech industry – they find application in HDD drives, electric motors, advanced medical instruments, and industrial machines.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in small dimensions, which enables their usage in miniature devices

Cons of neodymium magnets: weaknesses and usage proposals

• Susceptibility to cracking is one of their disadvantages. Upon intense impact they can break. We recommend keeping them in a steel housing, which not only secures them against impacts but also increases their durability
• When exposed to high temperature, neodymium magnets experience a drop in force. Often, when the temperature exceeds 80°C, their power 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 rust in a humid environment. For use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• We suggest casing - magnetic mechanism, due to difficulties in producing nuts inside the magnet and complex shapes.
• Potential hazard related to microscopic parts of magnets pose a threat, when accidentally swallowed, which becomes key in the aspect of protecting the youngest. Furthermore, tiny parts of these devices can be problematic in diagnostics medical in case of swallowing.
• Due to expensive raw materials, their price is higher than average,

Optimal lifting capacity of a neodymium magnet – what affects it?

The declared magnet strength refers to the peak performance, measured under ideal test conditions, namely:

• on a plate made of structural steel, perfectly concentrating the magnetic flux
• possessing a massiveness of at least 10 mm to avoid saturation
• with a surface free of scratches
• under conditions of ideal adhesion (surface-to-surface)
• during pulling in a direction perpendicular to the mounting surface
• at ambient temperature approx. 20 degrees Celsius

Determinants of practical lifting force of a magnet

It is worth knowing that the magnet holding will differ influenced by the following factors, in order of importance:

• Distance (between the magnet and the metal), because even a very small clearance (e.g. 0.5 mm) can cause a reduction in force by up to 50% (this also applies to paint, rust or debris).
• Loading method – catalog parameter refers to pulling vertically. When applying parallel force, the magnet exhibits much less (often approx. 20-30% of maximum force).
• Element thickness – to utilize 100% power, the steel must be adequately massive. Thin sheet limits the lifting capacity (the magnet "punches through" it).
• Metal type – different alloys reacts the same. Alloy additives worsen the attraction effect.
• Surface quality – the smoother and more polished the surface, the larger the contact zone and higher the lifting capacity. Roughness acts like micro-gaps.
• Thermal factor – high temperature reduces pulling force. Exceeding the limit temperature can permanently demagnetize the magnet.

* Lifting capacity was measured by applying a polished steel plate of optimal thickness (min. 20 mm), under perpendicular pulling force, in contrast under shearing force the holding force is lower. Additionally, even a small distance {between} the magnet’s surface and the plate decreases the load capacity.