What Is Pull Force?

Pull force, also known as magnetic pull, is a measure of the magnetic field strength of a magnet. How much weight can a magnet can exert on objects made of ferromagnetic materials (such as iron, nickel or cobalt). The pull force of a magnet is determined by its magnetic field strength and the dimension and shape of the magnet.

Usually measured in pounds or kilograms,Generally speaking, any magnet with a pull of more than 7 pounds (3 kilograms) will pinch your finger. Stronger magnets may be more dangerous and can only be operated by experienced persons. We always recommend hand and eye protection for large magnets

Magnets are best able to attach to ferromagnetic surfaces rather than chrome, brass, aluminum, silver, gold, wood, plastic or ceramic tiles. It is best to fix magnet by a countersunk or self-adhesive on these surfaces.

What Effects Pull Force?

The magnet pull force is significantly dependent on following factors:

1. Magnet type and grade.

2. Polar field of the magnet.

3. Air gap.

The magnet air gap is the distance between a magnet and the ferromagnetic material that it is attracting or repelling. The air gap is an important factor to consider because it can dramatically affect the strength of the magnetic field and the performance of the magnet. Even small air gap will have a dramatic effect on the pull force in the theoretical calculations.

4. Test conditions:

• The composition, size and thickness of the steel can also affect the performance of a magnet. Different types of steel have different magnetic properties, and some types of steel are more magnetic than others. For example, low-carbon steel is generally more magnetic than high-carbon steel, and stainless steel is generally less magnetic than other types of steel.

• The thickness of the test plate.The test plate should be thick enough to carry all flux.

• Flatness and roughness. The flatness and roughness of the test plate have a powerful effect on the pull force of the magnet, and this variable has been neglected for a long time.

5. Operating temperature.

If you any questions or comments regard pull force of magnet, please feel free to contact with NINGBO BESTWAY MAGNET team.

How to test magnetic pull force?

In our daily or industrial design, we need to choose suitable size magnet according to it’s pull force, we often do not know how large a magnet should be used to meet the demand. Is there any way to calculate the attraction of a magnet of known size?

Usually, the magnet seller will give some related data, which contain magnetic pull force, or some online magnetic calculator can be used to determine the pull data. These data are generally summarized by professional manufacturers after thousands of tests. We usually test the magnetic attraction under different load conditions. If you use different methods, you should refer to different pull force results. First of all, let's see how we test it and what applications it is closely related to.

First Type:

This is a common situation. A magnet is stick on the thick and strong low-carbon steel plate. The surface is almost completely smooth after machining. The size is larger than the measured magnet touch surface. The pull force tester measures the maximum force required to pull the magnet from the low-carbon steel plate. If you draw the magnet from the bottom onto the low carbon steel plate fixed on the top, the magnetic force is the same when we send it down and place it on the iron plate after testing.

Second Type:

A typical use of this type is magnetic refrigerator stickers. How much weight can it bear if stick it on the refrigerator door? Like the first case of magnetic attraction, when the magnet is vertically attracted to the low-carbon steel plate, it will not produce any lateral force. The magnetic force of the magnet acts directly on the steel plate. But in the non-vertical state, when gravity tries to pull the magnet down, there will be friction between the magnet and the door to prevent the sliding. Rely on friction to prevent the magnet from sliding down the surface of the refrigerator door.

In this case, the magnetic force is very difficult to calculate. Because the friction coefficient varies greatly with different materials and possible lubricants. The paint friction coefficient on the refrigerator is different. Any small difference will make a big difference. Friction coefficient is an empirical measurement value, which must be measured by actual test, and is difficult to calculate.

Third Type:

This is also a common magnet application. The magnet is placed between two low-carbon steel plates, and then pull apart one of them . For very thin magnets, this will have a great amplification effect on the pull force. The thinner the magnet, the more obvious the effect. The magnetic force difference caused by the difference of the thickness of low carbon steel is not very obvious for magnets with a thickness of more than 20 mm.

We focus on the research of magnets and magnetic applications. If you have any questions about the magnet application in your life or production, you can contact us at any time. Our professional team will be happy to learn with you.

Choosing the Right Magnet

Due to there are many factors affect the magnetic pull force. It’s difficult to choose the best suitable magnet for your specific application. Testing magnets in your application is the best way to know if they will work as needed. If you have any questions or need help selecting the right magnet, you can contact NINGBO BESTWAY MAGNET at any time. We will be happy to help you choose the best magnet according to your request.