What is a single-sided magnet?
Magnets have two poles, but in certain applications, a magnet with a single pole is required. To achieve this, one side of the magnet is covered with a metal plate to shield the magnetism on that side. The magnetism is then reflected through the plate to the other side, enhancing the magnetic force there. Such magnets are collectively referred to as single-sided magnets. There is no such thing as a true single-sided magnet.
The materials used for single-sided magnets are generally curved iron plates and high-strength neodymium-iron-boron magnets, with the latter typically taking the form of circular discs.
What are the uses of single-sided magnets?
(1) They are widely used in the printing industry and can be found in products such as gift boxes, cell phone packaging, tobacco and alcohol packaging, MP3 player packaging, and mooncake packaging.
(2) They are widely used in the leather goods industry and can be found in items such as luggage, briefcases, travel bags, cell phone cases, and wallets.
(3) They are widely used in the stationery industry, found in notebooks, whiteboard clips, file folders, magnetic nameplates, and other items.
What precautions should be taken when transporting magnets?
Pay attention to indoor humidity, which must be kept at a dry level. Temperature should not exceed room temperature; products in the form of black blocks or blanks may be lightly oiled during storage (ordinary machine oil is sufficient); plated products should be stored in vacuum-sealed containers or in an airtight environment to ensure the corrosion resistance of the plating; magnetized products should be stored in boxes while attached to each other to prevent them from attracting other metal objects; magnetized products should be stored away from magnetic disks, magnetic cards, magnetic tapes, computer monitors, watches, and other objects sensitive to magnetic fields. Magnetized products must be shielded during transport, especially when shipped by air, where thorough shielding is essential.
Which ferrite materials are conductive?
Soft magnetic ferrites are magnetic conductive materials characterized by high magnetic permeability and high resistivity. They are typically used at high frequencies and are primarily applied in electronic communications. They are found in everyday devices such as computers and televisions. Common types of soft magnetic ferrites include manganese-zinc and nickel-zinc ferrites, with manganese-zinc ferrites having a higher magnetic permeability than nickel-zinc ferrites.
What is the Curie temperature of permanent magnet ferrites?
It is reported that the Curie temperature of ferrites is around 450°C, typically greater than or equal to 450°C. The hardness is around 480–580. The Curie temperature of neodymium-iron-boron magnets generally falls between 350 and 370°C. However, neodymium-iron-boron magnets are rarely used at temperatures reaching their Curie temperature; at temperatures exceeding 180–200°C, their magnetic properties have already deteriorated significantly, magnetic loss is substantial, and they have lost their practical value. The Curie point (Curie temperature, Tc), also known as the magnetic transition point, refers to the temperature at which the spontaneous magnetization of a magnetic material drops to zero. It is the critical point at which ferromagnetic or antiferromagnetic substances transition to paramagnetic substances. Below the Curie point, the material behaves as a ferromagnet, and the material-specific magnetic field is difficult to alter. When the temperature exceeds the Curie point, the material becomes a paramagnet, and its magnetic field easily changes in response to variations in the surrounding magnetic field. At this point, the magnetic susceptibility is approximately 10⁻⁶. The Curie point is determined by the material’s chemical composition and crystal structure.
What are the typical effective parameters of a magnetic core?
Magnetic cores, particularly those made of ferrite materials, come in a wide variety of geometric dimensions. To meet various design requirements, the dimensions of the magnetic core are calculated to achieve optimal performance. These existing magnetic core parameters include physical parameters such as magnetic path, effective area, and effective volume.
Why is the corner radius so important for winding?
The corner radius is important because if the edges of the core are too sharp, they may damage the wire insulation during precise and tight winding. Care must be taken to ensure the core’s edges are smooth. Molds used to manufacture ferrite cores have a specified standard radius of curvature, and these cores are ground and deburred to reduce edge sharpness. In addition, most cores are painted or coated not only to round off their corners but also to ensure a smooth winding surface. Powder cores feature a pressure-formed radius on one side and a deburred semicircle on the other. For ferrite materials, an additional edge coating is provided.
