UMP 97x40 [M8+M10] GW F300 Lina / N38 - search holder

Advantages and disadvantages of rare earth magnets.

In addition to their magnetic efficiency, neodymium magnets provide the following advantages:

• They retain attractive force for around ten years – the drop is just ~1% (according to analyses),
• They retain their magnetic properties even under close interference source,
• Thanks to the shiny finish, the layer of nickel, gold-plated, or silver gives an modern appearance,
• 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 shape) even at a temperature of 230°C or more...
• Thanks to the ability of precise shaping and adaptation to specialized requirements, NdFeB magnets can be created in a broad palette of forms and dimensions, which makes them more universal,
• Huge importance in innovative solutions – they are used in HDD drives, electric motors, advanced medical instruments, as well as complex engineering applications.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in compact dimensions, which makes them useful in small systems

Problematic aspects of neodymium magnets and proposals for their use:

• They are fragile upon heavy impacts. To avoid cracks, it is worth securing magnets in special housings. Such protection not only protects the magnet but also improves its resistance to damage
• When exposed to high temperature, neodymium magnets suffer 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 corrode. Therefore during using outdoors, we suggest using waterproof magnets made of rubber, plastic or other material protecting against moisture
• Limited ability of creating nuts in the magnet and complex shapes - preferred is cover - magnetic holder.
• Possible danger resulting from small fragments of magnets can be dangerous, if swallowed, which becomes key in the context of child safety. Additionally, small components of these magnets are able to complicate diagnosis 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 contributes to it?

Breakaway force is the result of a measurement for optimal configuration, assuming:

• on a plate made of structural steel, optimally conducting the magnetic flux
• with a thickness minimum 10 mm
• with an ideally smooth contact surface
• with zero gap (no paint)
• for force applied at a right angle (pull-off, not shear)
• at conditions approx. 20°C

Lifting capacity in practice – influencing factors

In practice, the actual holding force results from a number of factors, listed from most significant:

• Gap between magnet and steel – every millimeter of distance (caused e.g. by veneer or dirt) significantly weakens the magnet efficiency, often by half at just 0.5 mm.
• Direction of force – highest force is obtained only during perpendicular pulling. The force required to slide of the magnet along the plate is standardly many times lower (approx. 1/5 of the lifting capacity).
• Base massiveness – too thin sheet does not accept the full field, causing part of the power to be lost to the other side.
• Steel type – mild steel gives the best results. Higher carbon content reduce magnetic properties and lifting capacity.
• Surface condition – smooth surfaces ensure maximum contact, which increases force. Rough surfaces reduce efficiency.
• Temperature – heating the magnet results in weakening of force. It is worth remembering the thermal limit for a given model.

* Holding force was measured on the plate surface of 20 mm thickness, when a perpendicular force was applied, however under shearing force the holding force is lower. Additionally, even a minimal clearance {between} the magnet and the plate lowers the lifting capacity.