Page 34 - MetalForming June 2011

FAQs Address Welding
of Thin Materials
Here are ten frequently asked questions, and their answers, regarding gas-tungsten- arc-welding power-supply selection, fitup tolerances and recommended procedures for thin-gauge sheetmetal welding.
BY BRENT WILLIAMS
The gas-tungsten-arc-welding (GTAW) process has long been touted for its ability to weld a variety of materials, as well as its capacity to create clean, high-quality welds with no sparks, spatter or slag. It also gains favor for appli- cations using thin materials—sheetmetal 1⁄4 in. or thinner.
GTAW produces a narrow, focused arc with good direc- tional control and real-time amperage control, thereby reducing the likelihood of problems typically associated with welding thin materials, such as burnthrough or warp- ing. The process, when completed properly, also can reduce instances of cracking and porosity—the entrapment of gas in a weldment. These same benefits hold true whether welding aluminum, mild steel or stainless steel.
Following are answers to 10 frequently asked questions that can help metalformers increase their level of success when welding thin-gauge materials.
1]What is the best power source for welding thin stainless steel?
Standard DC power sources, as well as inverter-based machines, will provide good results, but an inverter power source offers the benefit of reliable low-amperage high-fre- quency arc starts and a narrow, focused arc to avoid burn- through. Set either type of machine to straight polarity—
Brent Williams is a marketing manager at Miller Electric Mfg. Co., TIG Welding Division, and a technical contributor to Weldcraft, a supplier of gas-tungsten-arc-welding apparatus: 920/882-6800; www.weldcraft.com.
Gas-tungsten-arc welding provides excellent control and a focused arc to reduce problems commonly associated with welding thin materials, such as burnthrough or warping.
direct current electrode negative (DCEN). Also, consider a power source with pulsing capabilities for stainless steel— these machines can switch the current between high peak amperage and lower background amperage at regular inter- vals. Pulsing effectively lowers the average amperage level, to help reduce distortion while improving control of the weld- penetration profile.
2]Can the same power source
be used for welding thin aluminum?
Aluminum welding requires a power source with AC capa- bilities. An AC/DC inverter provides the best high-frequency arc starts and directional arc control, as well as the ability (via
32 MetalForming/June 2011
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