Magnets — features, types, applications

By CrimeaNEWS On Июн 3, 2024

CrimeaPRESS reports:

For you, is a magnet solely the basis on which souvenirs brought from trips are attached? Then you don’t know anything about magnets. In fact, magnets have a wide range of applications both in everyday life and in production — https://www.magnitrade.ru/. Here are some basic examples of their use:

At home:

holders for knives and tools: Magnetic strips are often used in kitchens to conveniently store knives and other metal tools.
refrigerators: Magnets are used to hold notes, drawings and schedules on refrigerator doors.
closing doors and cabinets: Small magnets are built into cabinet and drawer doors to ensure a tight closure.
toys and puzzles: Many children’s toys and construction kits use magnets to connect parts.
magnetic chargers: used for conveniently connecting chargers to various gadgets, such as smartphones and tablets.

In production:

electric motors and generators: Magnets are key components in electric motors and generators, converting electrical energy into mechanical energy and vice versa.
transport systems: Magnetic levitation (maglev) is used in magnetic levitation trains to achieve high speeds with minimal friction.
metal sorting: Magnets are used to sort metal waste and separate ferromagnetic and non-magnetic materials.
magnetic flaw detection: Used in non-destructive testing to identify cracks and defects in metal structures.
medical equipment: Magnets are used in MRI (magnetic resonance imaging) to create detailed images of internal organs.
filtration: Magnets are used in filtration systems to remove metal particles from liquids.

Other uses:

audio and video equipment: Speakers, microphones, and hard drives use magnets to convert audio and digital signals.
computers and electronics: Magnets are used in hard drives and SSDs to store data.
laboratory research: Magnets are used in a variety of experimental settings, including physics and chemistry.
creating strong magnetic fields: Superconducting magnets are used in research facilities such as particle accelerators.
search magnets (magnetic traps): used to find and lift metal objects from water, soil or hard-to-reach places. They are powerful permanent magnets, usually neodymium, mounted in a durable housing with a fastening for a rope or cable.

Thus, magnets play an important role in many aspects of our lives, from simple everyday tasks to complex industrial processes.

Types of magnets

There are several main types of magnets, each with its own unique properties and applications. Here are the main types of magnets:

Permanent magnets

Ferrite magnets:

compound: oxides of iron and other metals (for example, barium or strontium).
characteristics: inexpensive, corrosion resistant, have a medium magnetic field strength.
application: speakers, magnetic holders, toys.

Neodymium magnets (NdFeB):

compound: neodymium, iron and boron.
characteristics: very strong magnets, compact, but susceptible to corrosion (often covered with a protective layer).
application: computer hard drives, headphones, medical devices, engines.

Samarium Cobalt Magnets (SmCo):

compound: samarium and cobalt.
characteristics: Very strong magnets, resistant to high temperatures and corrosion, but expensive.
application: aerospace technology, military technology, high-temperature sensors.

Alnico magnets:

compound: aluminum, nickel and cobalt.
characteristics: High temperature resistance, moderate magnetic field strength.
application: electric guitars (pickups), microphones, pickups.

Electromagnets:

compound: Copper wire wound around an iron core.
characteristics: create a magnetic field when an electric current passes, can be turned on and off.
application: electric motors, generators, relays, magnetic lifters, medical equipment (e.g. MRI).

Flexible (rubber) magnets:

compound: magnetic powder mixed with rubber or plastic.
characteristics: flexible, easy to cut, low magnetic field.
application: magnetic tapes, advertising materials, refrigerator magnets.

Special magnets

Hybrid magnets:

compound: combine the properties of two or more types of magnets to achieve unique characteristics.
application: specific industrial and scientific applications.

Rare earth magnets:

compound: Magnets made from rare earth elements such as neodymium and samarium.
application: High-tech devices that require powerful and compact magnets.

Each type of magnet has its own advantages and disadvantages, which determines its application in various fields.

Magnet quality criteria

There are various criteria by which the quality of magnets is assessed. These criteria depend on the intended use of the magnet and may include both physical and magnetic properties. Here are the main ones:

Magnetic properties

Residual induction (Br):

measures the intensity of the magnetic field of a magnet after magnetization to saturation.
high Br values indicate strong magnets.

Coercivity (Hc):

the ability of a magnet to resist demagnetization.
high Hc values are important for magnets used in environments with high temperatures and strong external magnetic fields.

Maximum product energy (BHmax):

The maximum density of magnetic energy that a magnet can store.
the higher the BHmax, the stronger and more efficient the magnet.

Temperature stability:

the ability of a magnet to maintain its magnetic properties when temperature changes.
important for applications where the magnet is subject to significant temperature fluctuations.

Physical properties

Material and composition:

The quality of the source material and the purity of the composition affect the durability and efficiency of the magnet.
for example, neodymium magnets (NdFeB) must have the correct ratio of components for optimal performance.

Hardness and strength:

magnets, especially used in mechanical applications, d Must be sufficiently durable and resistant to physical damage.

Corrosion resistance:

important for magnets used in harsh environments or outdoors.
Some magnets, such as neodymium, are often coated with a protective layer (such as nickel) to prevent corrosion.

Workmanship

Dimensional and shape accuracy:

important to ensure correct operation in specific applications, especially in cases where an exact match with other components is required.

Magnetic field uniformity:

The magnetic field must be uniform over the entire surface of the magnet, especially important for applications requiring high precision.

Stability during operation:

Magnets must retain their properties over a long period of time and under various operating conditions.

Testing and Standards

Certification and Compliance:

Magnets must comply with international standards and specifications such as ISO, IEC and others.
certification confirms that the magnet has passed all necessary tests and meets the declared characteristics.

Demagnetization test:

testing for resistance to demagnetization when exposed to external magnetic fields and high temperatures.

Examples of standards and specifications

ISO 9001: Quality management standard that confirms the reliability of the manufacturer.
RoHS: Restriction of hazardous substances directive, important for environmentally friendly products.

Thus, the quality of a magnet is determined by a complex of magnetic, physical and operational characteristics, as well as compliance with standards and requirements during the production process.

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