Repeatable Induction Brazing

Objective
Successfully demonstrate that repeatable brazing can be achieved without the need for skilled labor.  Achieved by simply setting up the sample in the coil and applying induction heating for a pre-set timed heating cycle.

Equipment
SM5/200 Power Supply
HS-4W Heat Station
Ultraflex custom coil

Key Parameters
Power: 5 kW
Temperature: Approximately 1200°F (650°C)
Time: 120 sec

Materials

• Brass base:
  Weight: 1.2lbs (0.54kg)
  Major diameter: 1.740” x 1.44” (44mm x 36mm) high
  Minor diameter: .91” x .68” (23mm x 17mm)
• Invar tube: 0.54” OD / 0.36” ID (14mm OD/ 9.1mm ID)
• Overall length: 8.94” (22.7cm)
• Alloy Safety Silv 56 wire formed as rings. Alloy wire diameter 0.062” (1.6mm)
• White brazing flux

Process:

1. Parts were pre-fluxed with White brazing flux and assembled with four pre-formed alloy rings placed at the interface entry area of the tube to the base. (see photos)
2. Heat time required to fully flow the alloy was 120-125 sec.
3. An additional 3 minutes were allowed following the braze cycle to permit the molten alloy to solidify.
4. Once the alloy was solidified, the assembly was removed and water-cooled.

Results/Benefits:

The test demonstrates that the assembly can be repeatedly used for brazing without the need for skilled labor. Pre-assembly of flux and alloy rings allows the brazing to take place by simply placing the sample in the coil and heating with a pre-set cycle. While one assembly is being heated, another one can be prepared.

Video