How to Spot Weld Copper – Tricks No One Will Tell You (except me)

We rarely see a bus bar spot weld fail but recently a client brought in a PEBB (Power Electronic Building Block) which had an internal explosion causing the thick copper bus bars to separate with enormous speed. The damage was significant, which meant we needed to make three new copper bus bars before we attempted to repair the control circuitry.

As this is quite rare, we don’t actually own a spot welder but our neighbour which is an engineering fabrication firm, loaned us their portable unit. After cutting and bending the copper strips, we failed on numerous attempts to spot weld the copper bars. We scratched our heads, rubbed a rabbit’s foot and even performed a short war dance, but the copper strips would not spot weld. So, to the internet we went to learn Spot Welding for Beginners.

Our error was obvious, a standard spot welder normally uses copper electrodes so welding copper strips with copper electrodes was not a good idea. The current just passed through like a short circuit. This is where we realized we needed tungsten tips for our spot welder, and a very special flux spread between the copper bars being welded to provide the resistance heat to melt the copper.

The error of our ways was now corrected, and we successfully spot welded 25mm wide and 3mm thick copper strips, and repaired the PEBB’s control circuitry. As a new PEBB was not available from the manufacturer for many weeks, our client was desperate so you can imagine how happy they were when the refurbished unit was finally installed and functioning.

If you wish to talk to us further about how we can assist in your project, either telephone us on 1300 766 287 or click on to message us for more information.