Welding Journal - April 2012 - (Page 48)

How Today’s Power Sources Aid Pulsed GMAW New power source technology makes it easier to perform AC Pulsed GMAW of aluminum as well as ferrous alloys BY LARRY BARLEY (lbarley@daihen-usa.com) is senior applications engineer, OTC Daihen, Inc., Tipp City, Ohio. Based on a paper presented at the What’s New in Power Sources conference held during FABTECH, November 16, 2011, Chicago, Ill. W hen I was in school, we learned about constant voltage (CV) and constant current (CC) arc welding machines from some of the people who helped invent and/or perfect these machines. These machines were based on motor generators, or transformers, inductors, and diodes. Then the power source designers started looking into silicon-controlled rectifiers (SCRs) for power and transistors for control. These were the mainstay of power source design for 50 years and are still in use today. The early 1990s ushered in the first usable insulated gate bipolar transistors (IGBTs), which operated in the 20-kHz range. Today’s IGBTs run in the 80–120 kHz range. As the evolution of welding power sources has progressed, we have been able to adjust the welding arcs to perform welding tasks that were thought to be impossible just a few years ago. In the 50/60 Hz world, there are limitations on what a power source designer can do with the arc welding system and its performance. With the high-speed switching and computing available today, the power source designer is capable of presenting a welder a machine that can predict and out react the physics of the arc. The advanced power sources of today can create and deliver power to the arc that is not based on the 50/60 Hz power that is supplied. These power sources are capable of delivering welding power in whatever form we deem useful. Not only can the power be delivered to the arc in most any form, the power source is capa- Fig. 1 — Basic AC/DC inverter diagram. 48 APRIL 2012

Table of Contents for the Digital Edition of Welding Journal - April 2012

April 2012 - TOC Listing
Unlocking Your Gas Metal Arc Welding Potential - A study sponsored by the National Shipbuilding Research Program investigated low-cost modifications to equipment or parameters that improved welding performance - P. A. Blomquist
Community College Welding Program Update - Many community colleges around the country are equipping future workers with the skills manufacturers need D. Postlethwaite
Modern Power Source Technology Drives Process Improvement - New technology in weld monitoring is making it easier to access the data by all the appropriate personnel and understand how it should be applied to benefit weld quality - T. McEllis
Building a Welding Career from the Ground Up - A thirty-two-year career welder shares her passion for the profession with others in hopes of inspiring them to expand their skills and knowledge
How Today’s Power Sources Aid Pulsed GMAW - The advanced welding machines of today can deliver power to the arc in almost any form and can react with split-second timing to avoid adverse arc phenomena - L. Barley
Fiber Lasers Perform Precision Cutting for Medical Devices - There are many methods to cut thin tubular structures often used in medical devices, but fiber lasers are emerging as the precision machines of choice
Arc Characteristics in Pulsed-GMA Welding with Acute - Groove Angles The characteristics of a joint tracking sensor were monitored under conditions of different groove angles and root openings - R-H. Kim et al.
Design of Experiment and Goal Programming Application for the GMAW Process - This study was conducted to determine critical gas metal arc welding variables and ways to optimize them - Y. T. Iç et al.
Predictive and Measurement Methods for Delta Ferrite Determination in Stainless Steels - The advantages and limitations of predictive measurement methods for δ ferrite are outlined - M. A. Valiente Bermejo
Susceptibility of IN740 to HAZ Liquation Cracking and Ductility-Dip Cracking - Conditions that lead to cracking susceptibility of nickel-based IN740 were simulated to determine an action for its prevention - J. E. Ramirez
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Welding Journal - April 2012