You've been successfully running the same resistance spot welding program for days - months - years when all of a sudden it stopped working. What do you do? Where should you start? When troubleshooting a problem with your resistance welding process, we've learned that it's best to start with the materials and move back toward the power supply. Troubleshoot using 7 simple steps, in this order:
- Check the materials that are being welded. See if your supplier is using the same base materials, plating, process, etc.. If a new lot of materials is causing problems, look for some parts from a previous lot to see if they will still weld normally.
- Check the electrodes. Make sure the material, size and shape of the electrodes has not changed. Also look at the electrode condition and resurfacing procedure.
- Check the tooling that holds the parts in position. Make sure it has not been modified or damaged and that it holds the parts in the proper position.
- Check the weld head. Inspect the electrode holders to make sure they are clamping the electrodes correctly. Check the weld head motion and look for friction that might cause problems with follow-up. Check all of the electrical connections from the electrode holders, flexures, power bars, and weld cables to the power supply output terminals. Check the mounting location of the Voltage Sense cables and make sure they are screwed down tight.
- Check the power supply. Make sure it is connected to the correct line voltage. Make sure all of the electrical connectors are secure. Make sure it is operating properly and not giving any alarms.
- Verify all of the process settings including the power supply schedule, menu settings and weld head force and speed settings.
- Check with the operators to see if they are doing anything differently including electrode maintenance, part handling, initiation procedure. If new operators are using the equipment, make sure they have been properly trained on footswitch operation, etc.
If you complete this troubleshooting list and are unable to identify the problem, you may want to conduct a process audit, in which case you'll find this Process Audit Worksheet helpful. It can be used to document your process and includes many details that you may not have considered as important, but could negatively affect your process if not controlled. If, after conducting a process audit you STILL can't identify the problem, feel free to contact us - our application engineers would be happy to assist.
For more information please read Optimizing the Welding Process.