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.