Induction Heating System with double sensor technique

Increased heating quality of metallic work pieces with a central opening and round closed form.

bearing picture dual sensor 


This article describes a newly developed method for induction heating devices.  The developed by TM Induction Heating, increases the quality of heating metallic workpieces that form a closed round shape with a central opening (bearing, gears, etc.).  Throughout the entire warming process, temperature of the inner, as well as outer regions, are continuously monitored and control power is adapted to insure an optimum temperature differential, negating work piece damage due to residual stress.


Classic induction heaters control the heating process by only monitoring temperature of the inner region (bearing inner ring).  Temperature of the outer ring is neglected.  This runs the risk that the two rings will not expand evenly (see figure 1).  If the inner ring heats too rapidly in relation to the outer ring, large mechanical stresses between rings and roller elements will occur.  Damage related to cracks, fractures, or pitting may go unnoticed, reducing the life of the product.  One possible method to control this is, is heating in a controlled ramp mode.  Experience and careful attention are required to make sure the process differential is within allowable specifications.  Differences in work pieces make this method difficult and inappropriate in most situations.

Grafik 1

Figure 1

In view of increasing quality demands on the world market, TM Induction Heating has developed Dual Sensor Control to solve this problem.  Not only the inner region, but also the outter region temperatures are monitored with a corresponding power adjustment to maintain the optimal expansion ratio.  The new SURETHERM heaters provide the operator with a digital readout and graph representation of the heating process through the entire cycle. (see chart 2) This has proven to lead to increased operating life and allows for documented process quality control, ensuring the optimal ratio of heating time and power consumption.

Grafik 2

Figure 2

The new SURETHERM models will arrive in the US market this summer.  Be sure to contact your local representative or call us at 720-266-4403 for more information.









article translated and adapted from a publication by:

Dipl. Ing. Jaroslaw Mazankiewicz (FH)


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