**Acknowledgements**

transfer. A low power laser helps to obtain greater strength in the detachment of the

Very correlated with the study of acoustic monitoring is the analysis of the arc light emission. It is used to control the metallic transfer. A low power laser helps to obtain greater strength in the detachment of the drop. Weglowski [47] demonstrate that light emission has a linear correlation with the current. By another hand, Shao et al. [48] affirm that the light signal indicates the arc radiation intensity and the arc radiation is proportional to the power released which has been a relevant indicator

To a lesser extent and with little representation in the scientific literature, there are works related to the quantification of the emission of fumes*.* Yamamoto et al*.* [49] conclude that a relation between heat content, fume emission rate, and molten metal transfer mode exists; consequently the fume emission rate per unit weight of

But Meneses et al. [50] proved that there is no correlation between the amount of spattering generated and fume generation rate, because the regularity of the transfer did not show influence on the morphology, size or composition of the fumes. Then the generation of fumes is not correlated with the stability of the

Finally, other techniques that can be developed are 3D computational modeling,

• The chapter shows reliable and precise methods to measure the stability in the

• The greatest amount of effort in the area has been directed towards the study

• The transfer mode for which most indexes have been created is the short circuit.

• The indexes have been developed through the analysis of process signals as

• Techniques such as mathematical formulation, statistical analysis, image processing, and monitoring of acoustic signals and light spectrum are

• The methods of artificial intelligence and machine learning have been little

used leaving an interesting path to be traveled in future research.

simulation, spectroscopy, spectral analysis, and X-ray observation system.

drop. It was also determined as a newly developed arc welding method and ultrasonic-wave-assisted arc welding. This new technique uses power ultrasound energy to radiate the arc and weld pool, modifying the speed with which the plasma heats and cools. According to Fan et al. [46], it allows increasing the stability of the

process.

*Welding - Modern Topics*

process.

**22**

**4. Conclusions**

GMAW welding process.

current, voltage, sound, and light.

mentioned among the most useful.

of metallic transfer.

**3.3 Areas where further study is required**

of the energy supplied into the weld.

consumed wire increases with the increase in heat content.

This work has been supported by the Brasilia University (UnB), the government research CAPES foundation and CNPQ.
