Induction Heating Consultant

Induction Heating

Stanley Zinn

Stanley Zinn

When Induction Brazing Saves on Energy, Labor and Alloys  View as PDF

Some typical applications are discussed here to illustrate haw to reduce

overall cost per joint while maintaining joint quality.

by STANLEY ZINN, Induction Heating Consultants • June 2011

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The three key factors most affecting factory brazing operations today are:

  1. Energy costs
  2. Labor costs
  3. Alloy costs

Along with maintaining joint quality, reducing overall cost per joint ranks with increased productivity as the biggest production problems. To realize how savings in these areas can be achieved with induction heating, let's discuss a typical application.

As with any brazing process, alloy will flow evenly into a properly designed joint via capillary action if both pans achieve equal temperature at the same time. Fig. 1 illustrates optimal temperature distribution between a carbide tip insert and steel shank on a basic single point cutting tool. Placement of the induction coil assures that both parts are brought simultaneously to the alloy flow temperature, assuring good flow through the joint. Once the coil/part relationship has been established, repeatable quality based on fixed time and fixed induction power is assured.

The key to proper coil placement is an effective balance between the relative mass of the two parts and the relative resistivity of the materials being joined. The relationship of coil to part must be arranged so that the larger mass and/or lower resistivity material is more closely coupled to the work coil. This is usually achieved by balancing the coupling distance between part and coil or by providing a larger number of coil turns to heat the larger part.

With respect to the single point tool shown, the open type construction couples more energy to the heavy tool shank than the carbide insert. The shape of the coil also tends to restrict the heat to the joint area.

With carbide tools, "puddling" or moving the tip during brazing operations is normally necessary to break down surface tension of the molten alloy. The use of open coil construction rather than a "basket" or fully encircling coil thus provides good operator accessibility.

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Stanley Zinn • Induction Consultants • Tel: 585-737-8824
15307 Strathearn Drive, Unit 11202, Delray Beach FL 33446 •
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