Weld quality assurance
4.2.13 Introduction There are four types of observations of weld quality: visual examination, destructive analysis, non-destructive examination and in-situ observations. These are discussed separately below. Which types of weld inspection …
Laser parameters: their measurement and control
4.2.4 Laser power and power density Continuously operating or CW lasers are invariably rated by their power output, measured in watts or kilowatts. This rating refers to the power generated …
Energy efficiency
4.2.1 Energy conversion A laser is an energy conversion device. The industrial laser converts electrical energy to light energy, but it does not do this very efficiently. A carbon dioxide …
Laser beam welding
V. MERCHANT, Consultant, Canada 4.1 Introduction: process principles 4.1.1 Brief history of lasers and laser beam welding The first operating laser, built by Thomas Maiman in 1960, was a pulsed …
Future trends
There are a number of misconceptions and genuine limitations relating to GTAW and these must be addressed if the process is to retain its relevance in the future. The ‘basic’ …
Formation of a root bead
The stability of the root bead can also be attributed to surface tension. For example, it is noted that the radius of curvature across the root bead (rw) must be …
Conventional view of keyholes in welding
Keyhole welding is usually identified with laser and electron beam processes. These two processes are known for their deep narrow keyholes, often with aspect ratios exceeding 10:1. Such keyhole cavities …
The keyhole GTAW process
3.4.1 Introduction Normally GTA welding of plates of more than a few millimetres in thickness calls for careful edge preparations and multiple passes. One route to achieving deeper penetration has …
Review of process mechanism
Most researchers believe that arc constriction increases the current density and heat intensity at the anode root, enabling a substantial increase in penetration depth to be achieved (Howse and Lucas, …
The A-TIG process
3.3.1 Introduction The tungsten inert gas (TIG or GTAW) welding process is suited to welding operations requiring considerable precision and high joint quality. However, these advantages are offset by the …
Weld pool behaviour
To complete a model of the GTAW process it is necessary to consider the behaviour of the liquid weld metal. The weld pool can be a very active part of …
Gas tungsten arc welding
B. L. JARVIS, CSIRO Manufacturing & Infrastructure Technology, Australia and M. TANAKA, Osaka University, Japan 3.1 Introduction Gas tungsten arc welding (GTAW) first made its appearance in the USA in …
Advantages and disadvantages
Welding processes are sometimes classified according to their power density. Those described in this book cover a wide range, with tubular wire welding somewhere in the middle. At the lower …
Optimising productivity
Most of the guidelines that apply to increasing productivity for other welding processes apply equally when the consumable is a tubular wire - fillets are more effective than butt welds, …
Materials used in tubular cored wire welding
Early flux-cored wires were developed by covered electrode developers who simply took formulations from MMA consumables and turned the product inside out. However, they failed to capitalise on the great …
Tubular cored wire welding
2.1 Introduction: process principles Tubular cored wire welding was foreseen in the 1911 patent application1 in which Oscar Kjellberg introduced the world to the concept of the coated welding electrode: …
Future trends
The following trends can be anticipated in GMA welding within the next five years. The following areas are important: (1) process simulation and modelling, (2) sensing and control, (3) cost …
GMAW hybrid processes and other developments
This section reviews miscellaneous GMAW-related improved processes such as hybrid laser/GMAW, tandem GMAW welding, narrow groove welding and digital power source networking. 1.5.1 Hybrid welding processes: GMAW/LBW This combination of …
GMAW process measurement and control
This section includes a review of recent advances in GMAW process analysis. Topics include process sensing/monitoring, control, modelling, automation and robotics, simulations, arc physics/droplet transfer modes and fume and spatter …
Advances in GMAW technologies
1.2.1 Power sources Traditional power sources for GMAW welding are the analogue constant voltage (CV) type, with the welding current setting controlled by the wire electrode feeding rate (Nadzam, 2003). …
