Copper is a very conductive material and therefore can require different procedures. It can be resistance welded to similar materials. Factors that will be present are:
• Currents will be high to generate heat.
• Projections may be a good design idea to concentrate heat in a small area.
• Resistance brazing may be a method to simplify the attachment.
There is not a lot of published data available for the highly conductive coppers brasses and bronzes. AWS C1.1 has one table which offers one set of forces, currents and weld times for about a dozen of these conductive materials. The values range as shown:
Weld times 4-6 cycles
Forces approx. 400 lbs
Currents 21,000 amps
For the complete listing and complete details on resistance welding and testing obtain a copy of AWS C1.1.
With this high amperage RWMA Class 1 electrodes would be used. In some resistance brazing applications when the heat is high and times are long Class 11 refractory facings are employed.
The electrical industry resistance welds and brazes coppers and brasses every day by the thousands. Circuit breakers and switches of all sizes and configurations are assembled by these methods. Brute power, projections and brazes are the norm. Often the conductor is plated with a less conductive weld friendly coating such as brass or nickel. These coatings add resistance to the joint and may act as a brazing agent.
LOW INERTIA HOLDER USED FOR RESISTANCE BRAZING
For more information on Resistance Brazing of Copper in this blog see:
"WHAT IS RESISTANCE BRAZING?"
"CAN COPPER BE RESISTANCE WELDED TO STEEL?"
"HOW DO RESISTANCE BRAZING SCHEDULES VARY FROM SPOT WELDS?"
References: AWS C1.1 Recommended Practices for Resistance Welding
CMW Resistance Welding Product Catalog
RWMA Resistance Welding Manual 4th Edition