Page 26 - MetalForming June 2017

New arc-welding wire feeders place the brains inside the welding system, allowing manufacturers to better manage weld quality, improve consistency, and reduce setup and cycle time.
BY GREG STAUFFER
Advanced
Functions of
Arc-Welding
Wire Feeders
and Controls
The simplest wire feeders for arc welding control wire-feed speed (WFS), voltage, wire inch (to feed the wire forward while it remains electrically cold) and gas purge (to remove atmosphere from the gas-metal-arc-welding (GMAW ) gun before welding). There’s a time and place for the simplest feeders— usually for operations with highly experienced welders.
Coupled with the need for continuous cost reduction and quality improvements, most fabricators can benefit from newer wire feeders and controls that offer advanced functions. Here we describe some of those functions, and how to best use them in the shop.
Creep Start/Run-in Speed Control
Creep start, when enabled, reduces WFS to some percentage of the value set on the control. Some feeders have an on/off function for creep start, where others are adjustable. After the control senses an arc, it ramps up WFS to the set value to produce a smooth, positive arc start.
Creep start especially benefits welding with smaller-diameter wires and when using the short-circuit GMAW process, performed with relatively low voltage. If the cold wire drives into a cold plate at high speed, the arc may stumble and pop during arc initiation. Not only does this produce spatter or “cat whiskers” of unmelted wire that need manual removal, it could lead to incomplete fusion at the start of the weld. Creep start avoids this, and also benefits GMAW of alu- minum—because it gives the arc time to burn through the layer of aluminum
Greg Stauffer is industrial projects coordinator, ESAB Welding and Cutting Products; www.esabna.com.
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MetalForming/June 2017
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