Induction Brazing of Stainless-Steel Tubes to Fittings

Objective: A current induction user from the automotive industry is looking to replace existing induction heating equipment and needs to verify the results with a brazing application test.

The customer produced the low-carbon tubing and fittings assemblies. His main goal for this application is to automate the production process for high-volume parts.

The samples we received for this induction brazing application have dimensions of 0.78” (1.98 cm) OD x 0.07” (0.18 cm) wall for the tube and 0.78” (1.98 cm) ID for the fitting. The critical process requirements are to reach a heating cycle time between 20 and 30 seconds with a max temperature of 1400°F (760°C).

Industry: Automotive & Transportation

Equipment: SOLO 16kW Induction Heating System

Process: The objective is to show the different brazing methods with our induction heating system SOLO 16kW. We decided to do tests with two distinct induction coils.

For the first test, we used a helical inductor with two turns. The power supply was set up to 5kW power, 1600°F (~871°C) temperature, and reached a heat cycle time of 13 sec.

For the second one, we used a three turns C-shape induction coil. This time we set up the power to 13kW and temperature to 1600°F (~871°C) and reached the same heat cycle time.

We conclude that the helical coil will be more efficient and reliable since there is no need for movement during the brazing cycle.

The C-coil cannot be stationary during the cycle as it will overheat before conduction has enough time to get the heat over to the open side.

In the testing, a rotation shows promise. Since steel is so effectively heated in the rotation case, there is a part that will stay overheated. A faster rate of rotation could get rid of this.

Benefits: The advantages of implementing induction heating technology are:

1. Precision: Induction heating allows for precise and accurate control of the heating process, enabling consistent and uniform heating of the material.
2. Speed: Induction heating is a fast method of heating, which is particularly useful in production environments where quick turnaround times are essential.
3. Energy efficiency: Induction heating is an energy-efficient process that generates heat directly within the metal, reducing energy loss and wastage compared to other heating methods.
4. Safety: Induction heating is a safe and environmentally friendly method of heating, as it does not require open flames or hot surfaces, and it generates minimal emissions.
5. Repeatability: The consistent and controlled nature of induction heating means that heating processes can be repeated accurately, reducing the risk of errors and producing consistent results.

Reference Info: Application Note 3463-7299

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