If you're seeking to purchase magnets, whether for industrial use, production of consumer appliances, automotive motors, MRI, and other similar uses, you are likely curious about the strength of the magnet you will be purchasing. If you are wondering, 'What determines the strength of a magnet? You're not alone.
Several factors, including its size, shape, manufacturing process, temperature, and other environmental interactions, determine a magnet's strength.
If you want to know how magnetic fields operate and how to understand and identify the strength of a magnet, read on for all the details you need.
What Does it Mean for a Magnet to be Strong?
When you describe a magnet as 'strong', you mean that it can induce magnetism in objects around it and can exert a certain level of force on magnetic materials.
Here are some things that can help understand a magnet's strength.
Magnetic Field Strength
Magnetic field strength shows the ease or difficulty of creating a magnetic field. The standard of measurement is Amperes/meter.
Magnetic Flux Density
Magnetic Flux Density shows how much magnetic flux passes through an area at a given time, as well as the strength of the magnetic field.
Coercivity
Coercivity shows a magnet's resistance to demagnetization. A magnet with high coercivity can maintain its strength under tough conditions.
Remanence
Remanence measures the remaining magnetic strength after the external field has been removed. This measurement shows whether a magnet will be attracted to other objects after it has become a permanent magnet.
With these parameters cleared up, you can better understand a magnet's strength and the factors affecting it as we go further.
What Factors Can Affect the Strength of a Magnet?
In simple terms, the strength of a magnet refers to its magnetic force or magnetic field strength. The strength depends on the ability of the magnet's material to sustain magnetism and the force of the magnetic field generated by the magnet.
Factors that can impact the strength of a magnet include the following:
Material composition
The composition will affect its magnetic properties. A typical example is that neodymium magnets made of neodymium iron boron alloy have high remanence and high coercivity, so they are stronger than aluminum nickel cobalt and ceramics. However, neodymium magnets are prone to corrosion and need to be protected by coatings (such as nickel and zinc).
Size and shape
A magnet's size and shape affect its strength. In most cases, the magnetic force is increased in magnets with a larger surface area. Meanwhile, some shapes of magnets, such as disc or cylindrical magnets, often have higher concentration.
Manufacturing Process
The manufacturing process of a magnet has a major impact on the magnet's strength. For example, the use of aligned magnetic fields in manufacturing boosts magnetism, which results in a magnet with maximum strength.
How is Magnetism Affected by Temperature?
Another factor you will find that massively affects magnetism is the temperature of the magnet.
When temperatures increase, atoms undergo thermal agitation, which may cause the magnetic domains within the material to misalign. This misalignment reduces the magnetic force.
Curie Temperature
Curie temperature refers to the temperature at which a magnet loses its magnetism. The Curie temperature of ceramic magnets exceeds 450°C, while the Curie temperature of neodymium magnets is between 80°C and 230°C. Ordinary grades such as N35 are about 80°C, while high-temperature grades with dysprosium added can reach over 200°C.
Thermal Demagnetization
Thermal Demagnetization occurs following the exposure of magnets to high temperatures over time, which disrupts the magnetic domain alignment and reduces magnetism.
Residual Flux Density
Residual Flux Density refers to the remaining strength of the field after the demagnetizing force is withdrawn. When temperatures are high, the residual flux density reduces along with the magnet's effectiveness.
Maximum Energy Product
Maximum Energy Product refers to the power of a magnet compared to its size. When temperatures rise, the maximum energy product reduces, which indicates a reduction in magnetic energy.
How Magnetic Field Interaction Affects Magnet Strength
In simple terms, magnetic field strength measures the strength of the electrical current that flows through a material to form a magnetic field. The strength of this force will determine the amount of magnetization that can be induced into the material.
Magnetic field strength helps to understand the different behaviors that are exhibited by magnets, which form various parts of an engineering unit. For instance, relays, generators, and motors.
External magnetic fields largely affect the behavior and strength of a magnet. Hence, it is important to consider several parameters when subjecting a magnetic material to an external magnetic field.
Hysteresis Loop
Hysteresis Loop describes the time that passes before the occurrence of applied and actual magnetization. It also indicates the loss of energy across the material, which impacts its efficiency in application.
Magnetic Saturation
When a material is exposed to external fields at high levels, the material reaches a certain point where its magnetization stops increasing. That is the highest magnetism point.
Demagnetizing Factor
As the demagnetization factor increases, it reduces the effective magnetization within the magnet, degrading performance and damaging its internal structure. External alternating magnetic fields, such as in motors, can cause magnets to gradually demagnetize.
Magnetic Anisotropy
An external magnetic field can change the properties of a material, making its overall strength increase or decrease, depending on the alignment of the field with the axes of anisotropy within the material.
How to Measure Magnetic Strength
Magnetic strength is measured in several standard units, including Gauss, Tesla, and Newtons.
Gauss (G)
Gauss is used to measure small magnetic fields, such as for MRI machines and in medicine to understand the influence of air gaps and temperatures. Ten thousand Gauss One Tesla
Tesla (T)
Tesla is referred to as the SI unit of magnetic flux density. It calculates and shows how much power will be produced by a magnet in its magnetic field.
Newtons (N)
Newton measures how strongly a magnet pulls an object towards itself. Pull forces measure how well a magnet attracts ferromagnetic objects.
Pull force refers to how much force you need to pull on a magnet to move it away from an object, such as another magnet or a steel surface. It can be expressed in kilograms or Newtons, or even in kilograms.
What are the Strongest Types of Magnets out there?
Here are the strongest types of magnets in order of their strength, as well as what they are largely used for:
NdFeB Magnet
A NdFeB magnet comprises three materials, which are boron, iron, and neodymium. It is a rare earth magnet that is most commonly used across several products, including mobile phones, earphones, hard drives, and other kinds of battery-powered equipment.
SmCo Magnet
A SmCo magnet is a rare-earth material created through the combination of samarium, cobalt, and other metals. The allow is crushed and pressed before it is sintered. This product has a high magnetic energy. It also has 350°C as its maximum operating temperature.
AlNiCo Magnet
AlNiCo magnet is made of several elements, including nickel, iron, cobalt, and aluminum. AlNiCo magnets can be made through several processes, including bonding and casting.
Ferrite Magnet
Ferrite magnets are also permanent magnets. They are low in magnetic energy. They primarily comprise BaO, Fe2O3, and SrO. An advantage to these magnets is that their production process is cheap and simple, and they don't easily get corroded or demagnetized.
Strong Magnets and Their Uses
Now that you know the most powerful magnets, here are some of the major uses of these magnets.
Automotive Applications
Strong magnets are used to produce different automotive applications, such as electric power steering systems, while considering thermal demagnetization resistance and maximum operating temperature.
Consumer Electronics
Consumer electronic applications such as speakers, earphones, and headphones use strong magnets for sound effects. The important factors considered are flux density and magnet size as they affect volume and sound quality.
Data Storage Devices
Strong magnets are also used for data storage such as is the case with hard disk drives. The factors considered for this usage are remanence and coercivity of the magnetic material, as it can affect the speed of writes and reads, as well as data retention.
Electric Motors
Electric motors like industrial machines and electric vehicles also need strong magnets for improved efficiency and reduced weight and dimensions and weight. Parameters measured are torque ratings and maximum operating temperature.
Home Appliances
Strong magnets are used to produce practically every home appliance, ranging from magnetic closure systems to refrigerator doors. The parameters considered are temperature fluctuation, durability, and adhesion force.
Magnetic Resonance Imaging (MRI)
Strong magnets are an important component of MRI machines as they rely on high magnetic fields to generate high-resolution images.
Sensors
Strong magnets are also used in robotics applications as they help to ensure accurate positioning of sensors. Also, feedback mechanisms for robotics need actuators with high temperature and sensitivity coefficients.
Wind Turbines
Strong magnets are used to improve wind turbine efficiency and reduce maintenance. The parameters measured for this purpose include temperature stability and energy output about the maximum energy product.
Conclusion
The strength of a magnet is determined by several factors, as we have discussed, including material, size and shape, manufacturing process, temperature, and magnetic field exposure. We have also concluded that the strongest magnet is the Neodymium (NdFeB) magnet, with other magnets available for industrial and home use.
Now that you understand how the strength of a magnet is measured, what magnet do you need for your production purposes? We have all the best rare magnets and can guide you through the process of securing the best magnet for whatever purpose necessary.