Magnet pull force describes magnetic attraction strength.
This complete guide explains the basics of magnet pull force.
Learn how factors like flux density and air gaps impact force.
Discover how to calculate and optimize magnet pull force.
If you want to understand this key metric, read on.
Let’s kick started.
Magnetism Basics
Magnetism is a fundamental force in nature that causes certain materials to attract or repel each other.
This force is generated by the movement of charged particles, mainly electrons, within the atoms of a material.
Understanding Pull Force
Now that we have a basic understanding of magnetism, let’s explore the concept of pull force.
What is Pull Force?
The pull force of a neodymium magnet refers to how strongly it attracts and sticks to other magnetic materials like iron or steel.
- It is measured in units like pounds or kilograms of force.
A higher pull force means the magnet has a stronger adhesive force and an easier time lifting or attaching larger objects.
- The higher the pull force, the greater the strength of the magnet.
- Stronger neodymium magnets with higher grades like N52 have greater pull forces.
For buyers, pull force determines how much holding power you need for an application.
- A high pull force magnet can securely fasten heavier components or resist stronger external forces trying to separate the magnet.
For users, knowing the pull force helps ensure you select a magnet that can reliably do the job.
- Too weak a magnet may detach too easily.
- But too strong a magnet makes items harder to remove when needed, or dangerous for the user.
- Any neodymium magnet with a pull force over 7 pounds has the ability to pinch fingers, so you should use it carefully.
In summary, the pull force rating indicates the tenacity and strength of a neodymium magnet’s attraction.
Considering this specification helps match magnets to the required holding and lifting capacities.
Factors Affecting Pull Force
Material
Some magnetic materials have a higher maximum energy product, which results in a stronger magnetic field and greater pull force.
1. Type and Grade of Magnet: The type (shape) and grade of a magnet play a significant role in determining its pull force. Different types of magnets, such as neodymium, ferrite, or alnico, exhibit varying levels of magnetic strength. The grade of a magnet, denoted by designations like N35 or N52 for neodymium magnets, indicates the maximum magnetic energy product (BH)max. Higher-grade magnets generally have stronger pull forces.
2. Magnetic Pole Area: The size of the magnetic pole area on the magnet’s surface also affects its pull force. A larger pole area typically results in a stronger pull force.
3. Operating Temperature Range: The magnet’s operating temperature range is crucial. Magnetic properties can change with temperature, and magnets may lose some of their strength when exposed to elevated temperatures. Therefore, selecting a magnet with a suitable temperature resistance rating is essential for maintaining pull force.
4. Air Gap: The distance or air gap between the magnet and the object it’s attracting has a significant impact on pull force. As per finite element analysis, even a small air gap can substantially reduce the magnet’s pull force. The closer the magnet is to the object, the stronger the pull force.
5. Test Steel Plate: When measuring a magnet’s pull force, the type of test steel plate used is vital. It should be made of mild steel with high permeability and sufficient thickness to prevent magnetic saturation. Additionally, the flatness and surface roughness of the test plate can introduce variations in the air gap and should not be overlooked.
How to Maximize
Use larger and thicker magnets.
- The pull force of a magnet is proportional to its volume and cross-sectional area.
- Larger and thicker magnets have more magnetic material and can generate a stronger magnetic field.
Use higher grade magnets.
- The grade of a magnet indicates its maximum energy product, which is a measure of how much magnetic energy it can store.
- Higher grade magnets have higher energy products and can produce stronger magnetic fields.
Reduce the distance between the magnets and the objects they are attracted to.
- The pull force of a magnet decreases rapidly as the distance increases.
- The pull force is inversely proportional to the square of the distance, which means that doubling the distance will reduce the pull force by four times.
Align the magnets and the objects along their magnetic axes.
- The magnetic axis of a magnet is the direction along which it produces the strongest magnetic field.
- The magnetic axis of an object is the direction along which it is most easily magnetized by an external field.
- The pull force between a magnet and an object is maximized when they are aligned along their magnetic axes.
Use ferromagnetic materials for the objects that are attracted by the magnets.
- Ferromagnetic materials are materials that can be strongly magnetized by an external field, such as iron, steel, nickel, cobalt, etc.
- The pull force between a magnet and an object depends on how easily the object can be magnetized by the magnet’s field.
- Ferromagnetic materials have high magnetic permeability, which means that they can enhance the magnetic field inside them and increase the pull force.
Measuring the Pull Force
Ready to determine the pull force of a magnet? Here’s how you can do it.
Equipment Needed
A digital scale or force gauge
A flat, smooth ferromagnetic surface (such as a thick steel plate)
The magnet you want to measure
Measuring Pull Force
Set up the digital scale or force gauge on a stable surface.
Place the flat ferromagnetic surface on the scale or attach it to the force gauge.
Slowly bring the magnet towards the ferromagnetic surface until they are in full contact.
Pull the magnet straight away from the surface until it detaches.
Record the force reading on the scale or force gauge. This value represents the pull force of the magnet.
The pull strength of a magnet is another measurement of strength.
A magnet’s pull strength is the force that that you need to pull that magnet away vertically from a steel plate.
- The strength of a magnet can be measured in Gauss or Tesla.
- Higher numbers indicating stronger magnets.
Magnetic pull force and magnetic pull strength are the same thing.
- They both refer to the force that a magnet can exert on an object made of ferromagnetic material, such as iron, nickel, or cobalt.
The pull force of a magnet is determined by the strength of its magnetic field and the size and shape of the magnet.
It is usually measured in pounds or kilograms, and is the force required to pull that magnet straight free from a thick steel plate.
The pull force also tells you the limit of that magnet’s holding power.
- Generally, any magnet with a pull force above 7 pounds (3 kg) can pinch your fingers.
- Stronger magnets can be even more dangerous and should only be handled by experienced individuals.
Stacking Magnets
Stacking two magnets can increase their pull force, but not in a simple way.
- As a rule of thumb, the stacked magnet will work as one bigger magnet.
- It will offer bigger pull force.
- The best practice is to avoid the total thickness exceeds their width or diameter after stacking.
However, it doesn’t mean the pull force will double or triple after stacking.
- Meanwhile, stacking 3, 4 or even more magnets does not continue increasing the pull force dramatically.
- Limit the numbers of magnets to 2 pieces for stacking, which is the most cost-effective.
When you stack two magnets with opposite poles facing each other, they attract each other.
- The attracting force is almost twice as strong as the pull force of one magnet when they are touching.
However, as you increase the distance between them and the object they are attracting, the attracting force decreases faster than the pull force of one magnet.
When you stack two magnets with their poles aligned side by side, they behave as one larger magnet.
- The pull force of the stacked magnets is greater than the pull force of one magnet, but not twice as much.
This is because the area of contact and the volume of magnetic material increase with the thickness of the stack, but not linearly.
These are some possible methods to estimate how stacking two magnets impacts their pull force.
However, these methods are not very accurate or reliable.
And they may vary depending on the type, grade, temperature, and surface condition of the magnets and the object they are attracting.
- If you want to get more precise and consistent results, you should use a pull force tester.
- It is a device that measures the actual force required to pull a magnet away from a steel plate.
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Conclusion
This guide covered everything you need to know about the pull force of magnets.
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