Induction Machine, Case Depth: Use the Right Equipment

When determining the proper Induction Machine for your job, several things to consider including the case depth and surface area of the part to be hardened

First let’s talk about induction machines in general.  Each induction machine is characterized by its output power (kW) and its output frequency (kHz).  When choosing your equipment, these are the most important numbers you will need to know.  At Zion we have induction machines ranging in power from 5 – 300 kW and frequencies from 3 – 450 kHz.  Not every machine can operate at every power level and every frequency.  Typically the frequencies are fixed and the power outputs are stated as maximums.  A typical machine rating would be 100kw and 10kHz, where the power level is a maximum and the frequency is fixed.

Knowing what your case depth requirements are will help you choose the correct machine frequency (kHz).  The following table can be used as a guideline to determine the correct frequency for your required case depth.

Frequency (kHz)	Required Case Depth (inches)
1	.250 – .370
3	.130 – .250
10	.060 – .130
450	.015 – .060

Determining your power (kW) requirements takes slightly more math.  First you must determine the surface area (in^2) of the part to be hardened.  For a simple shaft with a diameter (D) of 1” and a hardened length (L) of 2”, the surface area is D x π x L or 6.28”.  Once you have determined your surface area, you simply multiply this by a power density factor of 10 kW/in^2.  For our example, this gives you a value of 62.8 kW required to effectively heat up this shaft.

So in a nutshell you can see that there is much to determining the right induction machine for the job.  Each induction machine can be different and can provide different results for your induction hardening requirements.  We would be happy to talk with you about any of your induction equipment questions.

Bob Puls Jr.
President
Zion Industries, Inc.