The weld pool is the core of the welding process where complex welding phenomena originate. Skilled welders acquire their process feedback primarily from the weld pool. Observation and measurement of the three-dimensional weld pool surface thus play a fundamental role in understanding and future control of complex welding processes. To this end, a laser line is projected onto the weld pool surf...

The objective of this study was to characterize personal exposures to welding-related metals and gases for production welders and non-welders in a large manufacturing facility. Welding fume metals and irritant gases nitrogen dioxide (NO2) and ozone (O3) were sampled for thirty-eight workers. Personal exposure air samples for welding fume metals were collected on 37 mm open face cassettes and ni...

HUNDREDS OF THOUSANDS of people work in welding, cutting and brazing. It is estimated that welders compose 1 to 2% of the U.S. working population, including a significant segment of the aging workforce. According to OSHA’s Christine Petitti, the most commonly used welding processes are: 1) Flux-cored arc welding (FCAW). This process uses an arc between a continuous filler metal electrode and th...

METAL transfer describes the process of the molten metal movement from the electrode tip to the workpiece in gas metal arc welding (GMAW). A better understanding of the metal transfer process is important for improvements in the quality and productivity of welding. While several distinct modes of the metal transfer have been classified,[1] the globular and spray transfer modes have received att...

Laser-enhanced gas metal arc welding (GMAW) is an innovative process recently proposed and developed at the University of Kentucky (Refs. 1–3), shown in Fig. 1. It adds a relatively low-power laser to conventional GMAW, and the objective is to provide an auxiliary force to help detach the droplet at a desired diameter with a desired welding current. In laserenhanced GMAW, the droplet size is a ...

In this paper, stability and internal dynamics for a gas metal arc welding (GMAW) process will be studied. GMAW process is considered as a nonlinear MIMO system and input-output feedback linearization method will be applied for control purposes. Internal dynamics is the unobservable part of the system dynamics; its stability analysis is a vital step in the investigation of the system stability ...

Arc sensors have been used in seam tracking and widely studied since the 80s and commercial arc sensing products for T and V shaped grooves have been developed. However, it is difficult to use these arc sensors in narrow gap welding because the arc stability and sensing accuracy are not satisfactory. Pulse gas melting arc welding (P-GMAW) has been successfully applied in narrow gap welding and ...

Controlled metal transfer in gas metal arc welding (GMAW) implies controllable weld quality. To understand, analyse and control the metal transfer process, the droplet should be monitored and tracked. To process the metal transfer images in double-electrode GMAW (DE-GMAW), a novel modification of GMAW, a brightness-based algorithm is proposed to locate the droplet and compute the droplet size a...

Welding fume contains elements that, in their pure forms, can be hazardous to worker health if inhaled or ingested. Therefore, the chemical composition of welding fume must be examined when considering fume toxicity. Various chemical analysis techniques are presented and their applicability to airborne particles is described. Knowledge of particle size is important because a given characterizat...

Aluminum alloy welding suffers from problems such as solidification cracking and hydrogen-induced porosity, which are sufficiently severe to limit its potential applications. Because mitigated porosity incidence and solidification cracking are observed in aluminum welds using double pulsed gas metal arc welding (DP-GMAW), a comprehensive review of the mechanism is necessary, but absent from the...