As discussed in several articles in this blog the electrodes weld face grows during spot welding. Eventually the electrode must be replaced or the face dressed (machined) back to near original face contour. Depending upon the dressing method the weld current may need to be adjusted.
If a stepper program was being used the current would be reset to the start point and the stepper begins again. If a single current level was used with no stepper, at a restart little adjustment would be expected.
How the electrode was dressed will determine the restart. It is preferred that the electrode face is not refaced during dressing or at least lightly touched. This is meant to reduce the time it takes to reach equilibrium at restart upon the face of the electrode.
HAND DRESSER DESIGNED TO NOT TOUCH THE FACE
While the oxide layers build up on the weld face and becomes consistent weld face sticking, expulsion and weld nugget variation can be present and erratic. On new electrodes this may take as many as 15-25 welds. On redressed electrodes with untouched faces welding can settle out in fewer welds.
This is referenced in:
How Do I Dress a Resistance Welding Electrode Face
Yes, stepper programs can help increase the life of an electrode. The method used to program controls for stepping vary by control. That needs to be addressed with a control manual or supplier. It cannot be addressed in this blog.
References: RWMA – RWMA Resistance Welding Manual 4th Edition