What Is Arc Gouging? Get Answers to 7 Common Questions

How to air arc gouge

When the end goal is to get to clean metal on a workpiece, carbon arc gouging—often called air arc gouging—is a go-to method across shop and field welding applications. 

Carbon arc gouging is often chosen for material removal because it’s a portable process that can quickly remove a lot of material. Gouging may also be required to achieve specific weld joint design.  

By following best practices, welders can improve both the efficiency and quality of their gouging results, while addressing common challenges and questions along the way.

When is gouging in welding used?

Gouging is often a required step in the weld procedure for many full-penetration welds used in high-stress joints like those found in structural construction. It’s often required to remove steel backing, burn off weld tabs or back gouge. 

Welders use gouging to remove material to get to clean metal. The most obvious use of gouging is to remove large amounts of metal or welds that need to be repaired. In these cases, gouging is much faster than removing this material with a grinding wheel, which is typically used to remove surface defects or excess reinforcement. 

Casting work may also frequently require this process. If a casting has a defect or flaw, operators can gouge out the defect then fill it back up with weld metal.

Can I arc gouge in CV mode?

You can gouge in constant voltage (CV) mode but it comes with tradeoffs. CV gouging produces a wider and flatter groove with shallower penetration compared to constant current (CC) mode. Although a CV process can provide satisfactory performance, most industries prefer the arc characteristics of a CC process, which provides arc consistency and a deeper, cleaner trough. For this reason, many Miller® industrial power sources have a dedicated CC gouge process, which optimizes the arc for gouge applications.

How do I know what electrode sizes to use for gouging?

Gouging electrodes are available in a range of sizes, so understanding your machine’s capabilities is key to avoid using too large of an electrode. The spec sheet or owner’s manual for some machines will specify the electrode diameter ranges that can be run and list the maximum electrode size that can be used for carbon arc gouging. Or, as best practice, get the amperage ratings from the carbon electrode manufacturer. 

The electrode size should be about 1/8 inch smaller than the desired groove width. The depth of the groove will be dictated by travel speed and travel angle. Keep in mind that the capabilities of your power source typically limit your maximum electrode diameter, but you can also perform multiple passes to create larger grooves.

What are the advantages of using different types of welding electrode geometries for gouging?

What should I do if it feels like I’m jabbing the electrode into the workpiece?  

If you are making forceful contact into the workpiece, it means your amperage isn’t high enough. If you’re using a dedicated gouge mode (CC), increase the amperage. If you are gouging in CV mode, increase the voltage. 

Why should I use a machine with a dedicated gouging process?  

Gouging is a process--just like stick or MIG welding—and benefits from equipment designed specifically to support it. Many Miller engine-driven welders and plug-in welding power sources include a gouging mode which helps optimize arc gouging performance.  

Using a machine with a gouge-specific setting offers several advantages: 

• Improved arc stability: A dedicated gouge mode helps keep the arc lit more consistently, making it easier to control and manipulate.
• Reduced operator fatigue: Without a stable arc, operators may struggle to maintain performance, especially during long or demanding gouging jobs.
• Better job readiness: Machines with gouge modes are better equipped to handle a wide range of gouging needs, including unexpected repairs or field adjustments. 

To get started, check your power source’s owner’s manual for gouging setup instructions, if available. 

Are inverter-based welding power sources bad for gouging?  

While this used to pose a problem with older inverter machines, today’s inverter-based power sources from Miller have been engineered, designed and tested for the gouging process, providing exceptional reliability and operation. 

Understanding carbon arc gouging  

Carbon arc gouging is an important part of many welding applications — from structural steel construction to field repairs. Understanding the gouging process and how to choose the right equipment and electrodes for the job can help improve efficiency and optimize results with this process. To learn more about challenges and solutions in structural construction welding and fabrication, visit MillerWelds.com/construction.