Air arc gouging tips
When the end goal is to get to clean metal on a workpiece, 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.