Magnets have a significant contribution in the world we live in and many modern gadgets and technologies make use of magnets. Magnets are a core component of a diverse range of modern technologies. From motors to headphones, toys, and machinery, magnets are responsible for a range of functions, from generating motion to the conduction of current. Magnets can be broadly classified into three types:
• Permanent: One of the most common and recognizable examples of a permanent magnet is the fridge magnet that is stuck to your refrigerator door. These magnets have a magnetic force that does not depend on electrical power or any external magnetic source.
• Temporary: These magnets become magnets only when a magnetic field surrounds them. Once they are out of the scope of the magnetic field they stop acting like a magnet. Annealed iron and steel are classified as temporary magnets. A general phenomena that explains temporary magnetism is when the paper clips stick to each other if they are in the range of a permanent magnet.
• Electromagnet: These magnets need an electrical source to have magnetic properties. Once the electric current passes through the material, it generates an electric field. Electromagnets are used in many electronic devices like earphones, generators, motors, etc. Their magnetic force is really powerful, but it can be switched on and off by cutting or supplying electricity.
Magnets are made through various processes since there are several types of magnets which are made from a range of magnetic materials. However, the most popular magnetic materials are Samarium Cobalt (SmCo) and neodymium-iron-boron (neo), which are metal alloys. Let us take a detailed look at the manufacturing process of these magnets.
The standard manufacturing procedure for making SmCo and neo magnets is through powdered metallurgy. The process involves the metal alloy being pulverized into a fine powder. After this it is compacted and subjected to a heating process to make it dense through a liquid phase sintering procedure.
The process begins with the melting of raw materials in vacuum conditions within an induction melting furnace. In some cases, an inert gas is used to provide a neutral environmental condition for the melting process. Once the alloy has melted, it is poured on a chill plate or a mold. It can also be poured in a strip caster to make magnetic strips. The metal pieces are than crushed into a powder with particles that have a size of 3 to 7 microns. This fine metal alloy powder can catch fire easily and is reactive to oxygen, so it should be stored carefully.
The next step is compaction of the powder. Compacting of powder can be achieved through multiple techniques. The basic principle of compacting is aligning particles so in the final result all particles have the magnetic field in a particular direction. One compaction technique is transverse pressing. In this method the powder is kept in an enclosed cavity and punches enter the cavity to compress the powder. Before compaction begins, the powder is subjected to an aligning field. Through compaction, the alignment of the particles is fixed. The pressing can be parallel (axial) or perpendicular (transverse). In axial pressing the aligning field is parallel to compaction direction. While in transverse pressing the field in perpendicular to compaction direction. Transverse pressing is the better method because the alignment is more precise as the particles increase in length in the same direction as the magnetic alignment direction, and the resulting magnets have a higher magnetic strength.
Another method for compacting is isostatic processing. This consists of filling a flexible container with powder. Then the container is sealed and subjected to an aligning force. The sealed container is placed in the isostatic press. The pressure to the sealed container is applied through means of a hydraulic fluid or water. The pressure is applied uniformly to all sides of the sealed container. This method of pressing is particularly suitable for making large sized magnets. The result is a powerful magnet since compaction pressure is applied uniformly.
The pressed parts are packed and transferred to the next stage of manufacturing, which is the sintering furnace. The temperature and presence of vacuum in the furnace are set according to the type of magnet that is being produced. The rare metal alloys are heated and then allowed to densify. SmCo is further treated after sintering as well. Once the alloys cool down, they are tempered with heat on a lower setting. In the sintering process, the magnet shrinks in length. After sintering, the magnets have a rough texture, and the dimensions are not exact.
Sintered magnets are passed through a machining process, grinding them until the surface becomes smooth. The magnet material has a high hardness and diamond tipped wheel are required to cut it. The cutting and grinding should be done carefully so that the magnet does not chip or crack. Cylindrical shaped magnets are finished using axial or core drilling processes. These cylindrical magnets can be further sliced by different industries into washer shaped magnets.
As far as shape of magnets is concerned, the manufacturing process is suited to produce simple shapes ad complicated shapes are seldom generated because tolerance level in compex shaped processing is hard to achieve.
Neo magnets can become corroded so they are coated with an anti-corrosion layer. The anti-corrosion layer consists of sprayed epoxy. Other layer types include electrolytic nickel and aluminum IVD.
Once the magnet is manufactured it also undergoes a charging process so that it can produce an external magnetic field. This is done by placing the magnet in a solenoid or through fixtures that give the magnet a unique magnetic pattern. The position and pattern of magnetic field depend on the application and should be discussed beforehand by the manufacturer.
Although the process of making magnets is lengthy and requires much precision and a advanced technology it is well worth it since magnets can perform some of the most amazing of tasks effortlessly and without their presence we would not have the latest technologies that make our life so easy.
Magnets have a significant contribution in the world we live in and many modern gadgets and technologies make use of magnets. Magnets are a core component of a diverse range of modern technologies. From motors to headphones, toys, and machinery, magnets are responsible for a range of functions, from generating motion to the conduction of current. Magnets can be broadly classified into three types: • Permanent: One of the most common and recognizable examples of a permanent magnet is the fridge magnet that is stuck to your refrigerator door. These magnets have a magnetic force that does not depend on electrical power or any external magnetic source. • Temporary: These magnets become magnets only when a magnetic field surrounds them. Once they are out of the scope of the magnetic field they stop acting like a magnet. Annealed iron and steel are classified as temporary magnets. A general phenomena that explains temporary magnetism is when the paper clips stick to each other if they are in the range of a permanent magnet. • Electromagnet: These magnets need an electrical source to have magnetic properties. Once the electric current passes through the material, it generates an electric field. Electromagnets are used in many electronic devices like earphones, generators, motors, etc. Their magnetic force is really powerful, but it can be switched on and off by cutting or supplying electricity. Magnets are made through various processes since there are several types of magnets which are made from a range of magnetic materials. However, the most popular magnetic materials are Samarium Cobalt (SmCo) and neodymium-iron-boron (neo), which are metal alloys. Let us take a detailed look at the manufacturing process of these magnets. How Are Magnets Manufactured? The standard manufacturing procedure for making SmCo and neo magnets is through powdered metallurgy. The process involves the metal alloy being pulverized into a fine powder. After this it is compacted and subjected to a heating process to make it dense through a liquid phase sintering procedure. Melting The process begins with the melting of raw materials in vacuum conditions within an induction melting furnace. In some cases, an inert gas is used to provide a neutral environmental condition for the melting process. Once the alloy has melted, it is poured on a chill plate or a mold. It can also be poured in a strip caster to make magnetic strips. The metal pieces are than crushed into a powder with particles that have a size of 3 to 7 microns. This fine metal alloy powder can catch fire easily and is reactive to oxygen, so it should be stored carefully. Compaction The next step is compaction of the powder. Compacting of powder can be achieved through multiple techniques. The basic principle of compacting is aligning particles so in the final result all particles have the magnetic field in a particular direction. One compaction technique is transverse pressing. In this method the powder is kept in an enclosed cavity and punches enter the cavity to compress the powder. Before compaction begins, the powder is subjected to an aligning field. Through compaction, the alignment of the particles is fixed. The pressing can be parallel (axial) or perpendicular (transverse). In axial pressing the aligning field is parallel to compaction direction. While in transverse pressing the field in perpendicular to compaction direction. Transverse pressing is the better method because the alignment is more precise as the particles increase in length in the same direction as the magnetic alignment direction, and the resulting magnets have a higher magnetic strength. Another method for compacting is isostatic processing. This consists of filling a flexible container with powder. Then the container is sealed and subjected to an aligning force. The sealed container is placed in the isostatic press. The pressure to the sealed container is applied through means of a hydraulic fluid or water. The pressure is applied uniformly to all sides of the sealed container. This method of pressing is particularly suitable for making large sized magnets. The result is a powerful magnet since compaction pressure is applied uniformly. Sintering The pressed parts are packed and transferred to the next stage of manufacturing, which is the sintering furnace. The temperature and presence of vacuum in the furnace are set according to the type of magnet that is being produced. The rare metal alloys are heated and then allowed to densify. SmCo is further treated after sintering as well. Once the alloys cool down, they are tempered with heat on a lower setting. In the sintering process, the magnet shrinks in length. After sintering, the magnets have a rough texture, and the dimensions are not exact. Finishing Sintered magnets are passed through a machining process, grinding them until the surface becomes smooth. The magnet material has a high hardness and diamond tipped wheel are required to cut it. The cutting and grinding should be done carefully so that the magnet does not chip or crack. Cylindrical shaped magnets are finished using axial or core drilling processes. These cylindrical magnets can be further sliced by different industries into washer shaped magnets. As far as shape of magnets is concerned, the manufacturing process is suited to produce simple shapes ad complicated shapes are seldom generated because tolerance level in compex shaped processing is hard to achieve. Neo magnets can become corroded so they are coated with an anti-corrosion layer. The anti-corrosion layer consists of sprayed epoxy. Other layer types include electrolytic nickel and aluminum IVD. Magnetizing Once the magnet is manufactured it also undergoes a charging process so that it can produce an external magnetic field. This is done by placing the magnet in a solenoid or through fixtures that give the magnet a unique magnetic pattern. The position and pattern of magnetic field depend on the application and should be discussed beforehand by the manufacturer. Conclusion Although the process of making magnets is lengthy and requires much precision and a advanced technology it is well worth it since magnets can perform some of the most amazing of tasks effortlessly and without their presence we would not have the latest technologies that make our life so easy.
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