Above: Plasma gouging requires a process-specific tip and shield cup but otherwise uses the same power source, torch, start cartridge and electrode. Gouging consumables expand plasma power source capabilities

Gouging consumables expand plasma power source capabilities

October 2019 - A plasma system is a tool that produces delicate razor cuts on thin metal yet has the power to sever steel up to 2-in. thick. There’s another process besides cutting that plasma can perform: gouging. The plasma gouging process can remove bad welds and torn metal, as well as scarf away rivet heads and frozen bolts and nuts. Plasma gouging can be more precise than carbon arc gouging, and it can prove more convenient for shops that already own plasma equipment.

Many users overlook plasma gouging, often because they’ve never been exposed to gouging consumables or don’t understand the difference between consumables for cutting and gouging. Plasma gouging requires a process-specific tip and shield cup but otherwise uses the same power source, torch, start cartridge and electrode.

Tips for plasma gouging feature a larger orifice than those used for cutting because a larger hole creates a broader arc, which improves metal removal rates. Recognizing that different applications require different gouge profiles, Thermal Dynamics offers four tip options for the 1Torch manual torch that comes with all Cutmaster power sources:

Tip A. Use up to 40 amps for shallow depth and narrow width.

Tip B. Use at 50 to 100 amps for a deep and narrow gouge.

Tip C. Use at 60 to 120 amps for moderate depth and width.

Tip D. Use at 60 to 120 amps for a shallow and wide gouge.

Gouging advice

There are five types of gouging techniques: straight, U-shaped, circle, wipe and back gouges. Before beginning, set the machine’s output to maximum, as more power removes metal faster. Next, select the correct mode. The Cutmaster 60i has a gouge-specific mode; most other systems at least have an expanded metal mode, which is a good choice. In these modes, the system automatically restarts the arc if users accidentally extinguish the arc by stretching it too far (compared to standard cutting mode, where the operator needs to re-trigger the torch to start the arc).

Speaking of arc stretch, which is how far you can move the torch away from the work before the arc breaks off, some plasma systems provide notably better arc stretch than others. Because plasma gouging mechanics involve quite a bit of torch manipulation, good arc stretch and fast restarts definitely improve the gouging experience.

Stay safe

Gouging sprays molten metal 10 ft. or more, so clear the work area from flammable materials or anything that could be damaged (such as already painted weldments). Always point the torch in a safe direction, and use safety curtains and blankets as appropriate. Use a face shield with at least a number 8 shade, or better yet, a helmet with an adjustable shade. In most cases, using a darker shade, even up to shade 12 or 13, helps to visualize features during the gouging that will allow the operator to be more precise.

Technique

To position the torch for gouging, hold it about 30 to 45 degrees from perpendicular. Flatter angles produce a shallower gouge, while steeper angles create a deeper gouge. Hold the tip about ¼-in. off the work surface (do not let the tip touch the work surface, as that will end tip life). Trigger the torch and immediately begin to manipulate the torch in one of the five techniques:

Straight: Move the torch forward in a straight line; move more slowly for a deeper gouge and faster for a shallower gouge.

U-shaped: Rock the torch in a U shape while moving forward.

Circle gouge: Move the torch in a circular pattern while moving forward; make smaller circles for a narrower gouge and bigger circles for a wider gouge.

Wipe: Rest the edge of the shield cap on the metal, use a flatter angle (10 to 30 degrees) and quickly wipe the arc from side to side across. This works great for removing rivet heads.

Back  gouge: Start sweeping the torch forward, then sweep it back across the area just gouged, move forward a bit and repeat, keeping all motion directed in a straight line (much like a clock pendulum).

With a bit of practice and the right consumables choice, plasma gouging can easily remove a bad weld on metal as thin as 1/8 in. without burning through the plate, can auger out a weld defect deep into a plate or burn off that frozen nut that prevents wheel removal. All in all, adding plasma gouging consumables to your torch kit gives you several more versatile tools in the toolbox. 

ESAB
Annapolis Junction, Maryland
800/ESAB-123