Let's take a look at the application and development of magnets used in medium frequency induction heating power supplies

In the past, it was customary to use silicon steel sheet laminations or pure iron sheet laminations as magnets on medium frequency induction heating power supplies. In order to reduce iron loss, the thickness of the silicon steel sheet is selected to become thinner as the frequency increases. Theoretically, the thickness of the silicon steel sheet should be smaller than its current penetration depth. For example, for medium frequency magnets, when f=8-10kHz, choose a thickness of 0.2-0.35mm. Due to the development of manufacturing technology, foreign cold-rolled steel sheets already have products with a thickness of 0.05mm, which can be used at 100kHz under strong cooling, but they are expensive.

1. High frequency magnet

Since the frequency is as high as 500kHz, high-frequency magnets can only be made from powder. The powder particles are fine and are pressed and sintered, but they will also generate heat under high-frequency current.

The former Soviet Union and my country had produced ferrite high-frequency magnets as early as the 1950s. The disadvantages of high-frequency magnets sintered into ceramics are that they are hard, brittle, and extremely difficult to process, which affects their use and promotion. Later, mud-like magnets were developed, but the magnetic permeability was low.

Ferrite high-frequency magnets are produced by many magnet factories in China. In addition, soft ferrite materials produced by radio equipment factories have higher Curie point temperatures (500°C) and operating frequencies (300 -700MHz).

2. Processable magnets

Processable magnets are supplied in cylinders, rectangular strips and plates, and can be machined into the required shape. Processable magnetic conductors are generally made of carbonyl iron, also known as magnetodielectrics, which are made of fine iron powder and adhesives that are molded and dried. Iron powder particles are insulated from each other. The higher the frequency of use of magnetic conductors, the finer the iron powder required; the higher the density of the processable magnetic conductors, the higher the magnetic permeability. Temperature resistance depends on the adhesive material.

The service life of the processable magnetic conductor is related to its service temperature. Like the silicon steel sheet magnet, the inductor of the medium frequency induction heating power supply must be designed so that the effective circle can well take away the heat from the magnet.

3. Performance comparison of magnetic conductors

Through multiple performance comparisons of various magnetic conductors, we have found that laminated sheets (silicon steel sheets or pure iron sheets) have high magnetic flux density under different magnetic field strengths, and can process magnetic conductors (magnetodielectric materials) under strong magnetic fields. There is a higher magnetic flux density, ferrite has a lower magnetic flux density.

In short, powerful sensors are efficient and energy-saving from concentrating energy to the required heating parts, which is the development direction of sensor technology. The development of magnetic conductors, especially processable magnetic conductors, has created necessary conditions for the development of powerful sensors. The development of computer simulation technology can more accurately assess the efficiency of powerful sensors.

The magnetic conductor seems to be a small part, but it is very important for the heat treatment of the workpiece. Some customers even require the purchase of magnetic conductors. Today we have a brief understanding of the application and development of magnets. Whether it is the medium frequency induction heating power supply itself or the heat treatment of the workpiece, it seems simple, but in fact it covers a lot of content, and you need to explore more details slowly.