Vibration and radiated sound during CO2 arc welding have been measured in order to analyze the behavior of the molten pool. The results indicate that the welding vibration such as the low frequency motion of the molten pool can be measured with accuracy by a piezo-electric accelerometer of sensitivity of 100 mV/G class, and that the welding vibration has a good competence as the information singal to exhibit the behavior of the molten pool.
