Sensing of the weld penetration at the beginning of pulsed gas metal arc welding

To guarantee good penetration status at the beginning of pulsed gas metal arc welding (GMAW-P), a sensing method based on arc voltage was proposed to sense the weld penetration. A stationary arc was applied to the workpiece for two seconds to mimic the beginning process of welding. The change in arc voltage at peak current period (detU) was used to characterize the penetration status. It declined when the arc started until it reached a relatively stable value when the weld pool stabilized. The critical penetration could be achieved when detU equals to 4.10 V herein. A penetration control strategy, by seeking the inflection point and comparing the detected detU with the set point, could control weld penetration at the beginning of pulsed gas metal arc welding.