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Un-braze and re-braze copper angle brackets to a copper strip with induction

Home/Induction Heating Applications/Induction Brazing/Un-braze and re-braze copper angle brackets to a copper strip with induction
Un-braze and re-braze copper angle brackets to a copper strip with induction 2017-04-20T16:13:55+00:00

Induction brazing sterling silver to copper bars

Objective
Evaluate several coil designs for un-brazing and re-brazing copper angle brackets to copper strips. Achieve the desired un-brazing and re-brazing in under 1 minute.

Equipment
UltraHeat L 50/50 Power Supply
HS -35LF
Pancake earmuff coil
Rectangular Coil

Test 1

Materials
Copper right angle bracket, 4.3mm (0.170”) thick
Copper strips, 1.3mm (0.05”) thick

Key Parameters
Power: 25 kW
Temperature: Approximately 1400° F (760° C)
Frequency: 48 kHz
Time: 60 sec to un-braze and re-flow existing braze

Test 2

Materials
Three 2.5mm (0.1″) thick copper plates
Two 1.6mm (0.06″) thick copper plates

Key Parameters
Power: 25 kW
Temperature: Approximately 1400° F (760° C)
Frequency: 48 kHz
Time: 60 sec to un-braze and re-flow existing braze

Process 1:

  • Power was limited to 25kW to represent the use of a 25 kW power supply.
  • The assembly was positioned in between the two coils (see photo and video).
  • Induction heat was applied until the existing brazed bond was re-flowed.

Process 2:

  • The larger braze sample was positioned below the coil with the coil ID centered above and around the bracket.
  • A non-conductive solid was used to counteract electromagnetic forces and keep the coil in place above the bracket.
  • A heat cycle of 60 seconds was sufficient to re-flow the existing braze in this area.

Results/Benefits:

  • The split earmuff coil, where applicable, will provide a more efficient heat source as the RF field is directed to both surfaces of the braze area.
  • Where this coil design is not usable, a coil similar to the modified coil used for test 2 will provide the required heat for the process.
  • These coils require a fixture to counter the electromagnetic forces that act on the coil and move it upward away from the surfaces to be heated.

Video