-5 to 20 percent cooler, less spatter and operator-friendly

APPLETON, Wis., March 5, 2004-Miller Electric Mfg. Co. has introduced cool new wire welding technology-literally. RMD™, or Regulated Metal Deposition, is a unique, patented advanced software application for modified short circuit transfer GMAW (MIG welding) that precisely controls the electrode current during all phases of the short (see Fig. 1). RMD lowers heat input by 5 to 20 percent compared to standard short circuit transfer and it minimizes spatter.

"Lower heat input and less spatter improve weld quality and cosmetic appearance, which in turn reduce costs associated with rework and clean-up," says Randy Broadwater, product manager for Miller Electric. "Applications for RMD include filling gaps, open-root piping for transmission and process piping, welding thin gauge metal, welding stainless steel and other heat-sensitive alloys, and fabrication in the dairy, hospital, food industries."

RMD software is designed to operate with flexible primary power conversion "hardware" featured in the new *Axcess™ system platform. *Axcess is Miller's next generation of multi-MIG process capable, inverter-based welding systems that are now available in North America. The RMD process application software is optional and available as a factory upgrade or installed in the field with a Palm™ handheld. For more information on RMD or Axcess, visit MillerWelds.com.

Friendly and Flexible

Though RMD is a software-driven welding process, Broadwater emphasizes that it is very user-friendly. "In fact, RMD improves the performance of less experienced welders because it is very tolerant of gaps," he says. "It puts less heat into the work, which minimizes the chance of burn-through or warping, and it compensates for changes in contact tip to work distance." RMD maintains optimum arc characteristics because the electrode current is closely monitored and controlled during each phase of the welding process.

Using RMD requires only familiarity with everyday welding terms. In fact, operators simply enter the wire type, wire diameter, gas combination and the desired wire feed speed on the *Axcess welding system's simple interface. The RMD software then automatically maintains optimum arc conditions regardless of wire feed speed and contact tip to work distance.

Unlike specialty welding systems from other manufacturers that offer limited process options, the multi-MIG inverter-based welding system (*Axcess) for RMD provides unparalleled flexibility. In fact, *Axcess can create any GMAW output type imaginable. This allows users to combine RMD with other software generated processes or arc transfer modes (see Fig. 2). This allows selection of the best process for the application at hand. For example, RMD could be used for the root pass in pipe and Miller's new Accupulse™ pulsed GMAW process used for the hot and cover passes with out changing machines or secondary leads. In automated applications, RMD could be used to weld thin sections or fill gaps and then switched using remote program select to Accupulse for higher travel speeds.

With headquarters in Appleton, Wis., Miller is a leading worldwide manufacturer of Miller and Hobart brand arc welding equipment and related systems for metalworking, construction, maintenance and other applications. Miller Electric Mfg. Co. is a wholly owned subsidiary of Illinois Tool Works Inc. (ITW), Glenview; Ill. ITW is a diversified multinational manufacturer of highly engineered components, assemblies and systems.

Fig. 1-RMD transfer stages lower heat input and prevent excess puddle agitation. Stage descriptions are

Wet: Let the ball on the end of the wire wet-out to the puddle.

Pinch: Increase the current to a level high enough to initiate a pinch effect.

Clear: Maintain and slightly increase the pinch current to clear the short circuit while simultaneously watching for pinch detection.

Blink: Upon pinch detection, rapidly decrease the current. Pinch detection occurs before the short clears. The inverter "shuts off" and current decays to a low level before the short circuit breaks.

Ball: Increase current to form a ball for the next short circuit.

Background: Drop the current to a low enough level to allow a short circuit to occur.

Pre-short: If the background current exists for a relatively long time, the pre-short period drops current to an even lower level to make sure arc force does not push the puddle back (e.g., prevents excess agitation).

*Miller recently replaced Access with Pipe Pro 450 RFC for pipe welding applications.

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