### When selecting the frequency of induction heating equipment , is it necessary to calculate?

When selecting the frequency of induction heating equipment , is it necessary to calculate?

The choice of current frequency is mainly to select the frequency range, that is, to select the frequency band, not to accurately select the value of a certain frequency, it is meaningless. It should be said that 8kHz and 10kHz are basically the same; 25kHz and 3kHz can also be used in common; but 8kHz and 30kHz, 30kHz and 250kHz can not be used in common, because they are not in the same frequency band, there is an order of magnitude difference.

The frequencies of high-frequency and intermediate-frequency power supply equipment have rated frequencies in all countries. According to the requirements of the diameter of different parts and the depth of the hardened layer, the appropriate frequency can be selected according to Table 2-1 and Table 2.2.

Table 2-1 Hardened layer depth of standard frequency value

 Frequency /kHz 250 70 35 8 2. 5 1. 0 0.5 Hardened layer depth /mm The smallest 0. 3 0. 5 0. 7 1. 3 2.4 3.6 5. 5 maximum 1.0 1.9 2.6 5. 5 10 15 twenty two optimal 0. 5 1 1.3 2.7 5 8 11

① At 250kHz , due to the extremely fast heat conduction, the actual data can be larger than the value in the table.

Table 2-2 Selection of frequency during surface quenching of cylindrical parts

 frequency Allowable minimum diameter Recommended diameter frequency Allowable minimum diameter Recommended diameter /kHz / mm / mm /kHz /mm /mm 1.0 55 160 35.0 9 26 2.5 35 100 70.0 6 18 8.0 19 55 250.0 3.5 10

Table 2-3 is the current frequency selection chart during induction hardening of the parts of the John Deere Company in the United States. The diameter of the part and the depth of the hardened layer have been combined, and it can also be used as a reference chart for current frequency selection.

Table 2-3 Selection of current frequency of induction hardened parts

 Power supply Induction hardened parts category Generator solid state power High frequency generator Power /kW 7 ~ 2000 5 -600 Frequency /kHz 1 3 10 50 ~ 100 200 〜600 1000 Diameter /mm Hardened layer depth /mm W12 0.2 minimum 0.7 A A B 13 – 18 0. 7 Minimum 2 B B A A A
 Power supply Induction hardened parts Another class IJ Mechanical generator solid-state power supply High frequency generator Power /kW 7 – 2000 5 -600 Frequency /kHz 1 3 10 50 ~ 100 200 〜600 1000 19 ~59 2 minimum 4 A A B N60 3.5 minimum A B C

Note: 1. The depth of the hardened layer in the table is taken from hot-rolled medium carbon steel, and the depth of the hardened layer is measured to 45HRC .

2. The minimum hardened layer depth depends on the material properties of the short-time heating (pre-heat treatment state), and the maximum hardened layer depth depends on the hardenability of the material and the degree of surface overheating.

3. A represents the most suitable frequency; B represents the more suitable frequency; C represents the less suitable frequency.