Magnet products that use their own magnetic force to work are very common in our daily lives, such as refrigerator magnets and magnetic knife holders.Among all magnets,sintered neodymium magnets are undoubtedly the strongest.So,compared to its own weight,how much weight can it actually attract?
To answer this question,we first need to understand how the magnetic force of magnet is generated.When a magnet approaches a ferromagnetic object,the magnetic field of magnet will change the direction of the magnetic moment of the object.This cause the magnetic field direction of the object to align with the magnet,resulting in the object being attracted to the magnet.
Magnetic force refer to the weight of ferromagnetic materials that can be completely attracted by a magnet, and its level mainly depends on factors such as the performance, volume, shape, and air gap of the magnet.Although we cannot accurately calculate the magnetic force directly through a formula,we can indirectly measure it using a tension meter.
As the distance between the magnet and the ferromagnetic object increases, the air gap between the two also increases accordingly.The larger the air gap, the weaker the magnet’s attraction to the ferromagnetic object until it disappears.
Testing the magnetic force of neodymium magnets
We have selected three shapes of neodymium magnets products:circular disc,cylinder and square.These magnets only differ in size and shape ,they all have the same performance level N42,and they all magnetized in the height direction.In addition,their surfaces are plated with a nickel-copper-nickel layer.
In the experiment, we measured the magnetic attraction force of the N pole of each magnet and converted it into the maximum weight that can be lifted.
The following are the experimental measurement results:
①Circular Disc
| Circular Disc | Diameter(mm) | Height(mm) | Volume(cm3) | Weight(g) | Maximum lifting weight(kg) | Maximum lifting weight/own weight |
| （1） | 6 | 1 | 0.03 | 0.21 | 0.4 | 1887 |
| （2） | 6 | 2 | 0.06 | 0.42 | 0.8 | 1887 |
| （3） | 6 | 3 | 0.08 | 0.64 | 1.2 | 1887 |
| （4） | 6 | 4 | 0.11 | 0.85 | 1.5 | 1769 |
| （5） | 6 | 5 | 0.14 | 1.06 | 1.9 | 1793 |
| （6） | 6 | 6 | 0.17 | 1.27 | 2.1 | 1651 |
| (7) | 8 | 1 | 0.05 | 0.38 | 0.5 | 1327 |
| (8) | 8 | 2 | 0.10 | 0.75 | 1.0 | 1327 |
| (9) | 8 | 4 | 0.20 | 1.51 | 2.0 | 1327 |
| (10) | 8 | 5 | 0.25 | 1.88 | 2.5 | 1327 |
| (11) | 20 | 0.5 | 0.16 | 1.18 | 0.6 | 510 |
| (12) | 20 | 1 | 0.31 | 2.36 | 1.3 | 552 |
| (13) | 20 | 3 | 0.94 | 7.07 | 3.9 | 552 |
| (14) | 20 | 5 | 1.57 | 11.78 | 6.4 | 544 |
| (15) | 20 | 10 | 3.14 | 23.55 | 12.5 | 531 |
②Cylinder
| Cylinder | Diameter(mm) | Height(mm) | Volume(cm3) | Weight(g) | Maximum lifting weight(kg) | Maximum lifting weight/own weight |
| (1) | 8 | 20 | 1.00 | 7.54 | 10.1 | 1340 |
| (2) | 8 | 30 | 1.51 | 11.30 | 14.9 | 1318 |
| (3) | 10 | 10 | 0.79 | 5.89 | 6.2 | 1053 |
| (4) | 10 | 20 | 1.57 | 11.78 | 12.6 | 1070 |
| (5) | 10 | 30 | 2.36 | 17.66 | 18.8 | 1064 |
③Square
| Square | Length（mm） | Width (mm) | Height(mm) | Volume(cm3) | Weight(g) | Maximum lifting weight(kg) | Maximum lifting weight/own weight |
| （1） | 3 | 3 | 3 | 0.03 | 0.20 | 0.7 | 3457 |
| （2） | 3 | 3 | 8 | 0.07 | 0.54 | 1.5 | 2778 |
| （3） | 5 | 5 | 2 | 0.05 | 0.38 | 0.7 | 1867 |
| （4） | 5 | 10 | 2 | 0.10 | 0.75 | 1 | 1333 |
| （5） | 20 | 10 | 5 | 1.00 | 7.50 | 5.1 | 680 |
| （6） | 22 | 7 | 2 | 0.31 | 2.31 | 1.8 | 779 |
| (7) | 22 | 11 | 2 | 0.48 | 3.63 | 2.2 | 606 |
| (8) | 50 | 25 | 10 | 12.5 | 93.75 | 24.8 | 265 |
| (9) | 50 | 50 | 5 | 12.5 | 93.75 | 18.1 | 193 |
| (10) | 50 | 50 | 25 | 62.5 | 468.75 | 88.5 | 189 |
Some articles claim that neodymium magnets can lift objects weighting 600 or 1300 times their own weight.However,experimental date shows that this statement is not accurate.
Neodymium magnets of various shapes and sizes exhibit significant differences in maximum lifting weight to their own weight ratio.Some neodymium magnets have a maximum lifting weight of less than 200 times their own weight,while others can reach around 3400 times.
In addition,from these experiments,we also found some important factors that affect the magnetic force:
①In most cases,the larger the size of the neodymium magnet,the stronger the magnetic force,but the ratio of maximum lifting weight to its own weight also decrease.Smaller neodymium magnets,on the other hand,have a higher ratio.
②The magnet has the strongest magnetic force in its magnetization direction(height direction).
| Square | Length（mm） | Width (mm) | Height(mm) | Volume(cm3) | Weight(g) | Maximum lifting weight(kg) | Maximum lifting weight/own weight |
| （1） | 3 | 3 | 3 | 0.03 | 0.20 | 0.7 | 3457 |
| （3） | 5 | 5 | 2 | 0.05 | 0.38 | 0.7 | 1867 |
In the experiment, the length and width of the square magnet (3) are larger than those of (1), and its volume and weight are almost double that of (1).Despite this, the maximum lifting weight of (3) is the same as that of (1).The reason for this is that the size of (1) in the magnetization direction is slightly larger than that of (3).
| Diameter(mm) | Height(mm) | Volume(cm3) | Weight(g) | Maximum lifting weight(kg) | Maximum lifting weight/own weight | |
| Circular Disc | 20 | 5 | 1.57 | 11.78 | 6.4 | 544 |
| Cylinder | 10 | 20 | 1.57 | 11.78 | 12.6 | 1070 |
Similarly, the circular disc and cylinder have the same volume and weight, but the maximum lifting weight of the cylinder is almost double that of the circular disc, because the cylinder has a larger size in the magnetization direction (height direction) than the circular disc.
Therefore, if the goal is to enhance the magnetic force of the magnet, the best strategy is to increase the size in the direction of magnetization.At the same time, in order to maximize the utilization of the magnetic force of the magnet, we should use its magnetization direction for work.
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Learn more:How many times heavier can a neodymium magnet attract an object? – YouTube