SM 25x225 [2xM8] / N42 - magnetic separator

Pros and cons of NdFeB magnets.

Besides their tremendous magnetic power, neodymium magnets offer the following advantages:

• They have unchanged lifting capacity, and over more than ten years their performance decreases symbolically – ~1% (in testing),
• Magnets perfectly resist against loss of magnetization caused by foreign field sources,
• The use of an metallic layer of noble metals (nickel, gold, silver) causes the element to look better,
• Magnetic induction on the working part of the magnet turns out to be impressive,
• Neodymium magnets are characterized by very 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 the ability of flexible shaping and adaptation to specialized projects, neodymium magnets can be produced in a broad palette of geometric configurations, which expands the range of possible applications,
• Key role in modern technologies – they are commonly used in hard drives, electromotive mechanisms, medical devices, as well as multitasking production systems.
• Relatively small size with high pulling force – neodymium magnets offer high power in small dimensions, which allows their use in miniature devices

Problematic aspects of neodymium magnets: application proposals

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth securing magnets in special housings. Such protection not only shields the magnet but also increases its resistance to damage
• When exposed to high temperature, neodymium magnets experience a drop in power. 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
• Due to the susceptibility of magnets to corrosion in a humid environment, we recommend using waterproof magnets made of rubber, plastic or other material resistant to moisture, in case of application outdoors
• We suggest casing - magnetic mount, due to difficulties in realizing nuts inside the magnet and complicated forms.
• Health risk resulting from small fragments of magnets pose a threat, in case of ingestion, which gains importance in the aspect of protecting the youngest. Additionally, small components of these magnets are able to be problematic in diagnostics 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

Detachment force of the magnet in optimal conditions – what affects it?

Breakaway force was defined for optimal configuration, including:

• on a block made of mild steel, optimally conducting the magnetic field
• with a thickness minimum 10 mm
• characterized by even structure
• without any insulating layer between the magnet and steel
• under perpendicular force direction (90-degree angle)
• at room temperature

Practical aspects of lifting capacity – factors

In practice, the real power is determined by a number of factors, listed from most significant:

• Air gap (between the magnet and the plate), as even a very small distance (e.g. 0.5 mm) can cause a drastic drop in force by up to 50% (this also applies to paint, corrosion or debris).
• Loading method – catalog parameter refers to detachment vertically. When slipping, the magnet holds significantly lower power (often approx. 20-30% of nominal force).
• Metal thickness – the thinner the sheet, the weaker the hold. Magnetic flux passes through the material instead of converting into lifting capacity.
• Steel type – low-carbon steel attracts best. Alloy steels lower magnetic permeability and holding force.
• Surface finish – ideal contact is possible only on polished steel. Any scratches and bumps create air cushions, weakening the magnet.
• Temperature influence – high temperature weakens pulling force. Too high temperature can permanently demagnetize the magnet.

* Lifting capacity was assessed using a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular pulling force, in contrast under shearing force the lifting capacity is smaller. Additionally, even a small distance {between} the magnet’s surface and the plate decreases the load capacity.