Resistance brazing is widely used for joining highly conductive materials such as copper and silver, where precise heat control is essential. The key challenges in industry are finding optimal process parameters for secure joints and the electrode life. In many production lines, maintaining low electrode temperature is important, both to prevent electrode sticking to the workpiece and to avoid thermal deformation of the brazed part.
This case study uses SORPAS® 3D.welding to compare different electrode material combinations, evaluate heat balance at the brazing interface, and analyze how electrode temperature affects process stability, energy consumption, and production reliability.
Part 1 – Electrode material & heat generation
In the first part of this study, four electrode material combinations were evaluated using the same parts and identical welding parameters:
- Welding parameters: Force = 1.2 kN, Weld time = 300 ms, Current = 16 kA
Heat generation and balance
SORPAS® 3D.welding simulations were used to analyze peak temperature distribution in the cross-section and at the brazing interface.
Key findings:
- Same material on both sides (Cu–Cu or W–W) tends to support better heat balance at the brazing interface.
- Tungsten electrodes generate more heat than copper electrodes under the same parameters.
- Dissimilar combinations (W–Cu, Cu–W) produce more heat on the tungsten side.
Temperature in the brazing alloy
The peak temperature distribution in the upper electrode, upper workpiece, and brazing alloy shows:
- W–W (Tungsten–Tungsten): The brazing alloy is fully melted—temperature exceeds the melting point.
- Cu–Cu, W–Cu, Cu–W: Peak temperatures remain below the melting point with the same parameters, so full melting is not achieved.
Dynamic temperature curves
Nodal temperature curves from SORPAS® 3D.welding reveal:
- Fastest heat development: W–W (case 3) reaches the brazing temperature range quickly.
- Intermediate behavior: W–Cu (case 2) and Cu–W (case 4) show moderate heat development.
Insufficient heating: Cu–Cu (case 1) does not generate enough heat to reach the required brazing range with the given parameters.
Part 2 – Energy consumption & production issues
Through SORPAS® simulation, we determined the current levels necessary to achieve complete melting of the brazing alloy for each combination of electrode materials. It needs the lowest current and energy with both tungsten electrodes, while the highest current and energy usage for both copper electrodes.
- Cu–Cu: 23.9 kA
- W–Cu: 18.4 kA
- W–W: 16.0 kA
- Cu–W: 18.8 kA
Using tungsten electrodes reduces the required current and total energy compared to copper electrodes. The W–W combination is the most energy-efficient for achieving full melting.
Electrode temperature
High temperature at the electrode–workpiece interface can cause:
- Overheating
- Solid-state bonding
- Sticking of the electrode to the workpiece
Observations
- Tungsten electrodes are highly effective for heat generation but can reach higher peak temperatures.
- Elevated electrode temperatures increase the risk of sticking and may shorten electrode life in mass production.
Discussions
This case study demonstrates how electrode material selection directly affects heat generation, energy consumption, and electrode temperature during resistance brazing. Tungsten electrodes provide higher resistive heating and require lower current to melt the brazing alloy. Still, they also reach higher peak temperatures — increasing the risk of sticking, surface damage, or part deformation if cooling is insufficient.
- In production environments, maintaining low and stable electrode temperatures is a critical priority. Mixed electrode combinations or optimized cooling strategies can help balance heat flow, ensuring full melting of the brazing alloy while protecting both the electrodes and the workpiece.
- By using SORPAS® 3D.welding, engineers can evaluate these trade‑offs virtually, optimize process parameters, and reduce trial‑and‑error on the shop floor — leading to more reliable brazing performance and longer electrode life.
