Automation and Control in Welding

**Chapter 1**

**Abstract**

*Elina Mylen Montero Puñales*

other documents found on the theme.

**1. Introduction**

ensure the highest quality.

obtained.

**3**

*and Sadek Crisóstomo Absi Alfaro*

Stability on the GMAW Process

The gas metal arc welding (GMAW) process is highly used in industrial production; therefore great efforts are made to select the appropriate procedure to ensure the highest quality. An area of study directly correlated to the quality of GMAW and widely studied is the control of process stability. The objective of this chapter is to present a bibliographical review of the scientific literature related to qualitative and quantitative indexes to evaluate the stability of the GMAW process. The documents present a compilation of the factors that affect stability, stability indexes, and, finally, a synthesis of the study. With a review of the literature, it was concluded that the highest percentage of investigation was aimed at the study of metal transfer stability, specifically with the short-circuit transfer mode. It is also evident that the main processing techniques to develop the indexes were the mathematical formulation; the statistical analysis; image processing; and monitoring of acoustic signals. In this text, the discussion surrounds the papers, the thesis, and

**Keywords:** welding, GMAW, quality index, GMAW, process stability

GMAW as a welding process presents a high degree of production, reliability, and automation capacity. With the appropriate parameter configuration, it allows welding in almost all positions and with almost all existing metal alloys. One peculiarity of the GMAW process is that, depending on the intensity of the current and voltage, different types of metal transfer can be observed. The metal transfer mode characterizes the way molten metal is deposited. The three main modes of metal transfer are short circuit, globular, and spray. The most relevant parameters involved in the process can be mentioned: amperage, voltage, welding speed, and stick out. Another peculiarity is that the process can be defined as chaotic; involves the interaction of several nonlinear welding variables; and presents a stochastic behavior. Therefore, great efforts are made to select the appropriate procedure to

Quality can be defined as the union of a client's requirements with respect to a product. In the particular case of welding, the main objective is to get a weld bead as close as possible to the requirements. The welding quality can be monitored in two moments: online while the process is running and offline after the welding bead is

The offline evaluation considered geometric factors such as proper penetration, reinforcement, and the length of the pieces. Destructive tests can be carried out and
