UMH 75x18x68 [M8] / N38 - magnetic holder with hook

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their tremendous field intensity, neodymium magnets offer the following advantages:

• Their magnetic field is durable, and after around ten years, it drops only by ~1% (according to research),
• Their ability to resist magnetic interference from external fields is notable,
• By applying a bright layer of nickel, the element gains a clean look,
• They possess significant magnetic force measurable at the magnet’s surface,
• Thanks to their enhanced temperature resistance, they can operate (depending on the shape) even at temperatures up to 230°C or more,
• The ability for custom shaping or customization to specific needs – neodymium magnets can be manufactured in many forms and dimensions, which enhances their versatility in applications,
• Wide application in advanced technical fields – they find application in computer drives, rotating machines, medical equipment and high-tech tools,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, with minimal size,

Disadvantages of NdFeB magnets:

• They can break when subjected to a strong impact. If the magnets are exposed to external force, it is advisable to use in a steel housing. The steel housing, in the form of a holder, protects the magnet from damage , and at the same time strengthens its overall resistance,
• They lose strength at increased temperatures. Most neodymium magnets experience permanent loss in strength when heated above 80°C (depending on the geometry and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• They rust in a humid environment – during outdoor use, we recommend using sealed magnets, such as those made of polymer,
• Limited ability to create precision features in the magnet – the use of a magnetic holder is recommended,
• Possible threat from tiny pieces may arise, if ingested accidentally, which is notable in the context of child safety. It should also be noted that small elements from these devices have the potential to complicate medical imaging after being swallowed,
• Due to the price of neodymium, their cost is relatively high,

Breakaway strength of the magnet in ideal conditions – what affects it?

The given strength of the magnet means the optimal strength, measured in the best circumstances, namely:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• having a thickness of no less than 10 millimeters
• with a smooth surface
• with zero air gap
• with vertical force applied
• under standard ambient temperature

Practical lifting capacity: influencing factors

Practical lifting force is determined by factors, listed from the most critical to the less significant:

• Air gap between the magnet and the plate, because even a very small distance (e.g. 0.5 mm) can cause a drop in lifting force of up to 50%.
• Direction of applied force, because the maximum lifting capacity is achieved under perpendicular application. The force required to slide the magnet along the plate is usually several times lower.
• Thickness of the plate, as a plate that is too thin causes part of the magnetic flux not to be used and to remain wasted in the air.
• Material of the plate, because higher carbon content lowers holding force, while higher iron content increases it. The best choice is steel with high magnetic permeability and high saturation induction.
• Surface of the plate, because the more smooth and polished it is, the better the contact and consequently the greater the magnetic saturation.
• Operating temperature, since all permanent magnets have a negative temperature coefficient. This means that at high temperatures they are weaker, while at sub-zero temperatures they become slightly stronger.

* Holding force was tested on the plate surface of 20 mm thickness, when the force acted perpendicularly, however under parallel forces the holding force is lower. In addition, even a small distance {between} the magnet and the plate lowers the lifting capacity.