Carbon Arc Gouging
Air arc gouging tips
When the end goal is to get to clean metal on a work piece, carbon arc gouging is a frequently used process across many welding applications in the shop and in the field.
Carbon arc gouging, commonly referred to as air arc gouging, is often chosen for material removal because it’s a portable process that can quickly remove a lot of material. Sometimes gouging is necessary to complete a specific type of weld for the weld joint design.
Following some gouging best practices can help improve the efficiency of the process and the results you see.
Get answers to frequently asked questions about gouging.
Q1: When is gouging used?
A: Gouging is necessary for many tasks related to welding when the operator is trying 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.
The process is often a required step in the weld procedure for many full-penetration welds, which are frequently used for joints that will be subjected to high stress, such as those in structural construction. A procedure may require a gouge process to remove steel backing, burn off weld tabs or back gouge.
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.
Q2: Can I gouge in CV mode?
A: You can gouge in constant voltage (CV) mode, but it will result in a shallower penetration profile that is wider and flatter than gouging in 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.
Q3: How do I know what size of electrode to use for gouging?
A: 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.
Electrode size should be about 1/8 inch smaller than the desired groove width. 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.
Q4: What are the advantages of using electrodes of different geometries for gouging?
A: Typical cylindrical electrodes, also known as pointed electrodes, are best for all-purpose gouging. Flat electrodes are good for achieving a flush surface, as in removing weld reinforcement or creating rectangular grooves. Jointed electrodes allow the ends to connect — eliminating stub loss — and hollow electrodes allow for increased travel speed.
Q5: What should I do if it feels like I’m jabbing the electrode into the work piece?
A: If you are making forceful contact into the work piece, 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.
Q6: Why should I use a machine with a dedicated gouging process?
A:Gouging is a process just like stick or MIG welding. Just as with those welding processes, technology inMiller engine-driven welder/generators and plug-in welding power sources that include a gouging mode has resulted in optimized gouging performance. Reference the owner’s manual for your power source to find the gouging setup, if applicable.
A dedicated gouge mode enables operators to keep the arc lit more consistently and makes it easier to manipulate the arc. Otherwise, the arc going out can cause the operator to struggle.
Choosing a machine with a dedicated gouging process can help ensure you are best equipped to meet all the needs and unexpected repairs of the job.
Q7: Are inverter-based welding power sources bad for gouging?
A: 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.