MW 15x4 / N38 - cylindrical magnet

Pros as well as cons of rare earth magnets.

Apart from their consistent magnetism, neodymium magnets have these key benefits:

• They have stable power, and over nearly ten years their attraction force decreases symbolically – ~1% (in testing),
• They do not lose their magnetic properties even under strong external field,
• By using a shiny coating of gold, the element gains an elegant look,
• They show high magnetic induction at the operating surface, which increases their power,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their shape) at temperatures up to 230°C and above...
• Thanks to versatility in shaping and the ability to modify to complex applications,
• Huge importance in high-tech industry – they are commonly used in mass storage devices, electromotive mechanisms, diagnostic systems, also industrial machines.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They are fragile upon too strong impacts. To avoid cracks, it is worth protecting magnets in a protective case. 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 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
• Magnets exposed to a humid environment can rust. Therefore while using outdoors, we advise using waterproof magnets made of rubber, plastic or other material resistant to moisture
• Limited possibility of producing nuts in the magnet and complicated shapes - preferred is a housing - mounting mechanism.
• Health risk to health – tiny shards of magnets can be dangerous, if swallowed, which is particularly important in the aspect of protecting the youngest. Furthermore, tiny parts of these magnets can complicate diagnosis medical after entering the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

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

The declared magnet strength represents the maximum value, measured under laboratory conditions, meaning:

• on a plate made of structural steel, perfectly concentrating the magnetic field
• possessing a massiveness of min. 10 mm to ensure full flux closure
• with a plane free of scratches
• with total lack of distance (without paint)
• for force acting at a right angle (in the magnet axis)
• at room temperature

Key elements affecting lifting force

In real-world applications, the actual lifting capacity is determined by several key aspects, listed from the most important:

• Air gap (between the magnet and the metal), since even a tiny distance (e.g. 0.5 mm) leads to a decrease in lifting capacity by up to 50% (this also applies to varnish, rust or debris).
• Load vector – maximum parameter is obtained only during perpendicular pulling. The resistance to sliding of the magnet along the surface is typically several times smaller (approx. 1/5 of the lifting capacity).
• Plate thickness – insufficiently thick plate causes magnetic saturation, causing part of the flux to be escaped to the other side.
• Metal type – not every steel attracts identically. High carbon content worsen the interaction with the magnet.
• Surface condition – ground elements ensure maximum contact, which improves field saturation. Rough surfaces weaken the grip.
• Temperature influence – high temperature weakens magnetic field. Too high temperature can permanently demagnetize the magnet.

* Lifting capacity was determined by applying a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, however under parallel forces the lifting capacity is smaller. Additionally, even a minimal clearance {between} the magnet and the plate lowers the lifting capacity.