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There are three main types of magnets:
permanent magnets;
Temporary magnets;.
Electromagnets.
permanent magnets.
Permanent magnets are the most commonly used type of magnets. They are permanent in the sense that once magnetized, these magnets retain some level of remanence.
. Different types permanent magnets have various characteristics or properties relating to how easily they demagnetize, how strong they are, how their strength changes with temperature, etc.
Four main classes of materials are used to produce permanent magnets:
Neodymium - iron - boron (Nd - Fe - B, Ndfeb, NIB);
Samarium - cobalt (Smco);
Alnico (Alnico);.
Ceramic (ferrites.
temporary magnets.
Temporary magnets are magnets that act like permanent magnets only when they are in a strong magnetic field and lose their magnetism when the magnetic field disappears. Examples include paper clips and nails, as well as other "soft" iron products.
Electromagnets.
An electromagnet is a tightly wound coil of wire, usually with an iron core, that acts as permanent magnet only when current flows through the wire. Strength and polarity magnetic field, created by an electromagnet, are due to a change in the magnitude and direction of the electric current flowing through the wire.
What substances are attracted to a magnet?
Cast iron, steel, iron, and much weaker nickel and cobalt.
Souvenir No. 1, brought from a trip abroad, from another city, is a magnet with a beautiful picture. Most often this is a photo with views of the city, images of cute animals and more. The miniature size and aesthetic appeal make it possible to use magnets to decorate refrigerators. Many people even collect such products. However, not everyone knows how magnets affect work. household appliances and household health.
The debate about whether magnets are harmful to human health and the functioning of the refrigerator has been going on for several years. This is because magnets made of an alloy of boron, iron and neodymium are distinguished by a strong magnetic field. Therefore, it can be argued that such decorative elements and collectibles can have an impact on a person. But not on appliances in the house!
Why are magnets dangerous?
Neodymium-based magnets are often several times smaller in size than iron ones. Actually, only a small piece of metal is used to attach souvenirs, and the product itself is made of plastic and wood. Therefore, such magnets cannot have a significant impact on the health of the refrigerator. It is also worth considering the fact that magnets are a screen for external magnetic fields, but not for internal elements of working household appliances enclosed inside the case.
To distinguish neodymium magnets from iron ones, you need to pay attention to the color of the products. Ordinary iron products have a dull gray color, while neodymium is shiny.
A weak magnetic field, despite the assurances of physicists, can still affect environment. Household magnets are dangerous for people with pacemakers. Neodymium magnets can destabilize the operation of an electronic device.
Myths about the dangers of fridge magnets
Magnets attached to the surface of the refrigerator can only harm the coating of the refrigerator. If you often rearrange the elements, there may be traces on the paint - scratches. And if you do not take care of the refrigerator, do not remove dust under the magnets, rust may form on the surface of the equipment. Souvenir magnets can also leave dark spots on the paint. It's not easy to clean them up. Therefore, pay attention to the quality of products, check the places of their fastening. And do not buy frankly cheap magnets, items that have a strong chemical smell.
The use of magnets is also possible for medical purposes, magnetotherapy helps to improve blood circulation, speed up metabolism and eliminate congestion.
To protect relatives and guests from possible negative phenomena, purchase fridge magnets in trusted stores, and not in street stalls. It should be noted that neodymium-based magnets are often used for the production of toys, speakers and other products.
Magnets are necessary for the production of devices. Without them, it is impossible to manufacture, for example, HDD computer or speaker systems. There are few natural magnets, so artificially created magnets can fully satisfy the needs of mankind.
You will need
- Screwdriver, oil paper, fuse, switch, copper wire.
Instruction
It is possible to make a magnet in the simplest way just by passing several times in one direction over a magnetized object with a strong permanent magnet. But such a magnet will quickly lose its properties, will have a weak magnetic field and can be used for simple actions, for example, get a needle from a gap in the floor, or pull bolts.
Magnetization with a battery. An electromagnet will impart magnetic properties to a metal object. Let's take a screwdriver as an example. On a screwdriver wrapped in insulator, wind 200-300 turns of wire used to make transformers and connect it to a 5-12 volt battery or accumulator. The electromagnetic field will magnetize the screwdriver.
You can make a stronger permanent magnet in the following way - using an induction coil. The blank for the magnet must be of such a size that it fits completely inside the coil. Follow the steps above, but make about twice as many turns.
If you will use mains current, do not forget to install a fuse. Then connect the fuse coil in series. When plugged into the network, the fuse may burn out, but a strong electromagnetic field will have time to charge the metal inside the coil.
note
If you decide to make a permanent magnet at home, then do not forget about safety rules. You need to be extremely careful and remember that you are working with high voltage, and it is life-threatening. It may also cause a fire due to short circuit. Be very careful!
Useful advice
The magnet may lose its properties when heated above 50 degrees Celsius, as well as in the event of a blow or fall.
The use of permanent magnets is suitable not only for childish fun or engineering work, but also for everyday use. V Everyday life There are many uses for magnets. 
clamps
If to glue two surfaces you need to press them tightly against each other, then place these parts, like in a vise, between two magnets.
By placing one permanent magnet under the stack of paper and another on top, you can be sure that the sheets will not fly apart from the draft.
To remove green deposits, place with inside glass is a permanent magnet with a sponge glued to it, and from the outside - another powerful magnet. They will be attracted to each other and press the sponge against the glass. Move the magnet along the outer wall of the aquarium, and the sponge will clean the glass from the inside.
Health
It has been proven that beads, bracelets, earrings, rings made of small magnets, belts, bandages and insoles with sewn-in magnets normalize arterial pressure, accelerate metabolism, strengthen immunity, cardiovascular system, relieve pain in rheumatism, arthrosis and arthritis.
The use of permanent magnets sewn into the cap improves hair growth, prevents baldness, relieves headaches and insomnia.
Magnetized water is drunk for diseases of the gastrointestinal tract, genitourinary system, spleen, pancreas, to remove toxins from the body. To make such water at home, tie a watering can on a magnet on both sides of the spout. The water pouring out of this spout will already be slightly magnetized.
The use of permanent magnets - contraindications. Remember that it is not recommended to be treated with magnets for people whose heart activity is supported by a pacemaker, as well as for cancer patients, suffering from mental illness, hypotension, tuberculosis, patients with elevated temperature, pregnant women.
Why does a magnet attract to itself?
In fact, the interaction of a magnet with substances has many more options than just “attracts” or “does not attract”. Iron, nickel, some alloys are metals that, due to their specific structure, are very strongly attracted by a magnet.
Hard drives record data on thin magnetic coatings.
- Magnetic media: VHS cassettes contain reels of magnetic tape. Video and audio information is encoded on the magnetic coating on the tape. Also in computer diskettes and hard drives data is recorded on a thin magnetic coating. However, storage media are not strictly magnets, as they do not attract objects. Magnets in hard drives are used in the drive and positioning motors.
- Credit, debit and ATM cards - all these cards have a magnetic stripe on one side. This band encodes the information needed to connect to financial institution and links to their accounts.
- Conventional TVs and computer monitors: TVs and computer monitors containing a cathode ray tube use an electromagnet to control the electron beam and form an image on the screen. Plasma panels and LCD displays use other technologies.
- Loudspeakers and microphones: Most loudspeakers use a permanent magnet and a current coil to convert electrical energy (signal) into mechanical energy(movement that creates sound). The winding is wound on a coil, attached to the diffuser, and an alternating current flows through it, which interacts with the field of a permanent magnet.
- Another example of the use of permanent magnets in sound engineering is in the pickup head of an electrophone and in the simplest tape recorders as an economical erasing head.
Even in ancient times, people discovered unique properties certain stones - the attraction of metal. In our time, we often encounter objects that have these qualities. What is a magnet? What is his strength? We will talk about this in this article.
Definition
What is a magnet? This is a material that has a certain degree of magnetization. This ability arises due to the fact that the molecules of a magnet have their own field and do not move randomly, as in many other substances, but strictly in two directions. This mutual opposition has the properties of attraction and repulsion of metallic objects. If you try to connect magnets with the same poles, you can feel rejection. opposite sides, in turn, attract each other. This is due to the direction in which the waves of magnetic fields move. It is worth noting that no single piece of a magnet can be unipolar. When it breaks, the molecules in each piece again form the north and south poles.
Types of magnets
What are magnets and how do they differ? The operation of many electrical appliances, sensors, home appliances depends on the type of magnets that are present in them. Each has its own characteristics. They perform certain functions, depending on the scope of use. The main types include electromagnets, permanent and temporary magnets. It is worth considering in more detail each type.
What is a permanent magnet? This is a material capable of retaining magnetization for a long time. Its molecules move in a constant direction and form a magnetic field in the absence of an electric current. It is also called a natural magnet.
An example of a temporary magnet is paper clips, buttons, nails, a knife and other household items made of iron. Their strength is that they are attracted to a permanent magnet, and when the magnetic field disappears, they lose their property.
The field of an electromagnet can be controlled by an electric current. How does this happen? A wire wound in turns on an iron core, when the current is applied and changed, changes the strength of the magnetic field and its polarity.
Types of permanent magnets
Ferrite magnets are the most famous and actively used in everyday life. This black material can be used as fasteners for various items, such as posters, wall boards used in the office or school. They do not lose their properties of attraction at a temperature not lower than 250°C.
Alnico is a magnet made from an alloy of aluminum, nickel and cobalt. This gave him such a name. It is very resistant to high temperatures and can be used at 550 ° C. The material is lightweight, but completely loses its properties when exposed to a stronger magnetic field. Used mainly in the scientific industry.
Samarium magnetic alloys are high performance material. The reliability of its properties allows the material to be used in military developments. It is resistant to aggressive environment, high temperature, oxidation and corrosion.
What is a neodymium magnet? It is the most popular alloy of iron, boron and neodymium. It is also called a supermagnet, as it has a powerful magnetic field with a high coercive force. Observing certain conditions during operation, a neodymium magnet is able to maintain its properties for 100 years.
Use of neodymium magnets
It is worth considering in detail what is a neodymium magnet? This is a material that is able to record the consumption of water, electricity and gas in meters, and not only. This kind of magnet belongs to permanent and rare earth materials. It is resistant to the strength of the magnetic fields of other alloys and is not subject to demagnetization.
Neodymium products are used in medical and industrial sectors. also in living conditions they are used for fastening curtains, decor elements, souvenirs. They are used in search instruments and in electronics.
To prolong the service life, magnets of this type are coated with zinc or nickel. In the first case, the coating is more reliable, as it is resistant to aggressive agents and withstands temperatures above 100°C. The strength of a magnet depends on its shape, size, and the amount of neodymium included in the alloy.
Application of ferrite magnets
Ferrites are considered the most popular magnets among permanent species. Due to the strontium contained in the composition, the material does not corrode. So what is a ferrite magnet? Where is it applied? This alloy is quite brittle. Therefore, it is also called ceramic. The ferrite magnet is applied in automotive industry and the industry. Used in various techniques and electrical appliances, and domestic installations, generators, acoustic systems. In the manufacture of automobiles, magnets are used in cooling systems, power windows and fans.
The purpose of the ferrite is to protect equipment from external interference and prevent damage to the signal received via the cable. Due to this property, magnets are used in the manufacture of navigators, monitors, printers and other equipment where it is important to obtain a clear signal or image.
Magnetotherapy
Physiotherapy with a magnet is often used. What it is? This procedure is called magnetotherapy and is carried out in medicinal purposes. The effect of this method is to influence the patient's body with the help of magnetic fields under low-frequency alternating or direct current. This method of treatment helps to get rid of many diseases, relieve pain, strengthen the immune system, improve blood flow.
It is believed that diseases are generated by a violation of the human magnetic field. Thanks to physiotherapy, the body returns to normal and the general condition improves.
From this article, you learned what a magnet is, and also studied its properties and applications.
Where are magnets used? Neodymium magnets - use in everyday life
Today, anyone can buy neodymium bars, discs or rings and use them in the household. Depending on the task, you can choose right size, weight and shape of the product, in accordance with your wallet. Below we give several options for using magnetic devices, although, in reality, the scope of use is almost limitless and is limited only by the imagination of the owner.
Video What is a magnet.
Permanent magnet. neodymium permanent magnets
They represent the latest and most significant development in this field over the past decades. Their discovery was first announced almost simultaneously in late 1983 by metalworkers from Sumitomo and General Motors. They are based on the NdFeB intermetallic compound: an alloy of neodymium, iron and boron. Of these, neodymium is a rare earth element extracted from the mineral monazite.
The great interest that these permanent magnets have aroused arises because for the first time a new magnetic material, which is not only stronger than the previous generation, but also more economical. It consists mainly of iron, which is much cheaper than cobalt, and neodymium, which is one of the most common rare earth materials and is more abundant on Earth than lead. The main rare earth minerals monazite and bastanesite contain five to ten times more neodymium than samarium.
How magnets are made. Method three
Making a magnet can seem like a daunting task. Since the above methods do not guarantee that the properties will be preserved for a long time. A stronger magnet can be created with an inductor coil. The metal blank should be small, as it will need to be placed inside the coil. After that, you should follow exactly the same procedure as indicated in the previous method. The only difference is that the turns of wire need to be made twice as many, that is, 600. Only in this case can a good magnet be obtained.
The unique properties of certain substances have always surprised people with their unusualness. Special attention I was attracted by the ability of some metals and stones to repel or attract each other. Throughout all epochs, this aroused the interest of the sages and the great surprise of ordinary people.
Starting from the 12th - 13th centuries, it began to be actively used in the production of compasses and other innovative inventions. Today you can see the prevalence and diversity of magnets in all areas of our lives. Every time we see another magnet product, we often ask ourselves the question: “So how are magnets made?”
Types of magnets
There are several types of magnets:
- Constant;
- Temporary;
- Electromagnet;
The difference between the first two magnets lies in their degree of magnetization and the time the field is held inside. Depending on the composition, the magnetic field will be weaker or stronger and more resistant to external fields. An electromagnet is not a real magnet, it's just the effect of electricity that creates a magnetic field around a metal core.
: for the first time, research on this substance was carried out by our domestic scientist Peter Peregrin. In 1269, he published The Book of the Magnet, which described the unique properties of matter and its interaction with the outside world.
What are magnets made of?
For the production of permanent and temporary magnets, iron, neodymium, boron, cobalt, samarium, alnico and ferrites are used. They are crushed in several stages and melted together, baked or pressed together until a permanent or temporary magnetic field is obtained. Depending on the type of magnets and the required characteristics, the composition and proportions of the components change.
Related materials:
Why does a magnet attract - all about magnetic fields
This production allows you to get three types of magnets:
- Pressed;
- cast;
- sintered;
Making magnets
Electromagnets are made by winding wire around a metal core. By changing the size of the core and the length of the wire, the field power, the amount of electricity used and the size of the device change.
Component Selection
Permanent and temporary magnets are produced with different field strengths and resistance to environmental influences. Before starting production, the customer determines the composition and shape of future products, depending on the place of application and the high cost of production. Accurate to the gram, all components are selected and sent to the first stage of production.
Smelting
The operator loads all the components of the future magnet into the electric vacuum furnace. After checking the equipment and matching the amount of material, the furnace is closed. With the help of a pump, all the air is pumped out of the chamber and the melting process is started. Air is removed from the chamber in order to prevent oxidation of the iron and possible loss of field power. The molten mixture is poured into the mold on its own, and the operator waits for it to cool completely. The result is a briquette that already has magnetic properties.
Magnets are divided into several types: permanent, electrical and temporary. They differ from each other in characteristics, durability and features of operation.
permanent magnets
The most popular are permanent magnets - that's what we mean when we talk about magnets in general. Their main feature is that they retain their magnetic charge for a long time. How long and with what strength this element will last depends on what the magnet is made of.The most powerful magnets are neodymium
They are made from different metal alloys:
- neodymium, boron and iron. Such elements are called supermagnetsbecause they retain for a long time performance characteristics and demagnetize at a rate of 1-2% per 100 years. It is almost impossible to demagnetize neodymium.
- Samarium and cobalt - due to resistance to aggressive environments and high temperatures, it is actively used in the military industry. In terms of its operational features, it is similar to neodymium counterparts.
- Alnico is an alloy of aluminum, cobalt and nickel. Lightweight and heat-resistant material, but quickly demagnetized by a different magnetic field.
- Magnetoplastics - consist of polymers, magnetic powder and various additives. Unlike all other types, these magnets are easy to process, plastic and elastic. Thanks to this, products are created from them. complex shape and experiment with the arrangement of the poles. The power of such elements depends on the amount of magnetic powder in the composition of the magnetic mixture, which can reach 94% of the mass of the finished product.
- Ferrites are an alloy of iron with other metals. The most common type, as it is inexpensive to manufacture and has broad scope operation, however, when exposed to high temperatures, it quickly loses its properties.
Temporary magnets
Another interest Ask What is a temporary magnet made of? To do this, use any metal object. For example, a paper clip, scissors, a screwdriver, etc. If you briefly bring it to a source of a powerful magnetic field or another strong magnet, then this metal part will temporarily take on its magnetic properties. But leaving the action of this field, the properties are instantly lost. Such elements are actively used in electromechanics and automotive industry.electromagnets
Unlike permanent ones, they have a magnetic field only when electricity passes through them. Such magnets are made from a metal billet. Any sample of iron or its alloys that are well magnetized will do - it acts as a core. Check the iron piece for the ability to act as a source electromagnetic field simple - use a standard fridge magnet. If he is attracted to a piece of iron, then it is suitable for the role of the core. This bar is wrapped copper wire, having previously isolated one metal from another, and then a current source is connected. Electromagnets are easy to make yourself, following a simple instruction.
The simplest electromagnet is made in 5 minutes from a nail, wire and a battery
Unlike all other types, electromagnets change characteristics under the influence of electric current - the power of the device, the direction of the poles are regulated. It is used in electrical devices, in motors and generators, in industry when transporting metal goods. And craftsmen create many options for home-made designs.
Such a device is convenient in that its work is easy to control with the help of electric current - change the poles, the force of attraction. In some matters, it becomes truly indispensable, and is often used as a constructive element of various homemade products. It is not difficult to make a simple electromagnet with your own hands, especially since almost everything you need can be found in every home.
- Any suitable sample of iron (it is well magnetized). This will be the core of the electromagnet.
- The wire is copper, always insulated to prevent direct contact between the two metals. For a homemade electric / magnet, the recommended cross section is 0.5 (but not more than 1.0).
- A source direct current- battery, battery, power supply.
Additionally:
- Connecting wires for connecting an electromagnet.
- Soldering iron or electrical tape to fix the contacts.
This general recommendation, since the electromagnet is made for a specific purpose. Based on this, the components of the scheme are selected. And if it is done at home, then there can be no standard - everything that is at hand will do. For example, in relation to the first point, a nail, a lock shackle, a piece of an iron rod are often used as a core - the choice of options is huge.
Manufacturing procedure
Winding
The copper wire is neatly, coil by coil, wound onto the core. With such scrupulousness, the efficiency of the electromagnet will be as high as possible. After the first "pass" over the iron sample, the wire is laid in a second layer, sometimes a third. It depends on how much power the device needs. But the winding direction must be unchanged, otherwise the magnetic field will be “unbalanced”, and the electromagnet is unlikely to be able to attract something to itself.
To understand the meaning of the ongoing processes, it is enough to recall the lessons of physics from the course high school- moving electrons, the EMF created by them, the direction of its rotation.
After winding is completed, the wire is cut so that it is convenient to connect the leads to the power source. If it's a battery, then directly. When using a PSU, battery or other device, you will need connecting wires.
What to consider
There are certain difficulties with the number of layers.
- As the turns increase, the reactance increases. This means that the current strength will begin to decrease, and the attraction will become weaker.
- On the other hand, increasing the current rating will cause the winding to heat up.
That is why it is not worth focusing on third-party advice from “experienced and seen”. There is a specific core (with its own magnetic conductivity, dimensions, cross section), wire and power source. Therefore, you will have to experiment, achieving the optimal combination of parameters such as current, resistance and temperature.
The principle of operation of an electromagnet is described in detail in the following video:
Connection
- Cleaning the conclusions of the "copper". The wire is initially covered with several layers of varnish (depending on the brand), and, as you know, it is an insulator.
- Soldering copper and connecting wires. Although this is not fundamental - you can make a twist by isolating it or with adhesive tape.
- Fixing the second ends of the wires on the clamps. For example, like "crocodile". Such removable contacts will allow you to easily change the poles of the electromagnet, if necessary during its use.
- To make a powerful electromagnet, home craftsmen often use a coil from an MP (magnetic starter), relays, and contactors. They are available for both 220 and 380 V.
It is not difficult to pick up an iron core according to its internal section. For ease of control, a rheostat (variable resistance) must be included in the circuit. Accordingly, such an e / magnet is already connected to the outlet. The force of attraction is controlled by changing the R of the chain.
- It is possible to increase the power of an electromagnet by increasing the cross section of the core. But only up to certain limits. And here you have to experiment.
- Before making an electric / magnet, you need to make sure that the selected iron sample is suitable for this. The check is quite simple. Take an ordinary magnet; there are a lot of things in the house on such “suckers”. If it attracts the part selected for the core, it can be used. With a negative or “weak” result, it is better to look for another sample.
Making an electromagnet is quite simple. Everything else depends on the patience and ingenuity of the master. You may have to experiment to get what you need - with the supply voltage, wire size, and so on. Any homemade product requires not only a creative approach, but also time. If you do not feel sorry for him, then excellent result secured.
Sometimes people ask how to make a neodymium magnet with your own hands. Let's try to figure out, as far as possible, and what is the process of manufacturing such products in general.
So, the devices we sell consist of an alloy that is 70% iron and almost 30% boron. Only some fractions of a percent in its composition fall on the rare earth metal neodymium, the natural deposits of which are extremely rare in nature. Most of they are in China, they are still only in a few countries, including Russia.
Before making neodymium magnets, manufacturers create sand molds for them. Then the tray with the forms is doused with gas and subjected to heat treatment, due to which the sand hardens and retains the future outlines of the metal blank on its surface. Hot metal will later be placed into these molds, from which, in fact, the necessary products will be obtained.
Now let's take a closer look at how a neodymium magnet is made. Unlike ferromagnetic products, the metal here does not melt, but is sintered from a powder mixture placed in an inert or vacuum environment. Then the resulting magnetoplast is pressed with simultaneous exposure to an electromagnetic field of a certain intensity. As we see, even initial stage production, it is noticeable that the question of how to make neodymium magnets at home sounds out of place. The operations and the equipment used are too complicated. Creating such conditions at home is hardly possible.
After the blanks are removed from the molds, they are subjected to mechanical processing - they are carefully polished, then they are fired to improve the coercive force of the products.
Finally, we come to the last steps that will help to finally answer the question of how neodymium magnets are made. The sintered NdFeB alloy is refinished on the machine with a special tool. During operation, a cooling lubricant is used to prevent overheating or ignition of the powder.
applied to magnets protective covering. This is due, firstly, to the fact that sintered metals are quite brittle and need to be strengthened, and, secondly, the metal will be protected from corrosion processes and other effects. external environment. So manufacturers are worried in advance about how to make a neodymium magnet stronger and more durable. The coating can be copper, nickel, zinc. In the last phase of the production process, magnetization is applied by means of a strong magnetic field. Further - they are sent to the warehouse, and from there to the buyers.
So, after we examined the production process in more or less detail, it became clear that, probably, you should not seriously ask yourself the question "how to make a neodymium magnet at home." After all, this requires not only the presence of certain knowledge, but a lot of complex units.
