Plasma gouging — removing metal using a plasma arc — is similar to plasma cutting. A plasma arc between the torch and the workpiece melts the metal, and a gas jet blows away the molten material. However, in gouging, specially designed consumables produce a somewhat wider arc, the torch is held at an angle, and only some of the material is blown away.
Plasma gouging works on any conductive metal, including mild steel, stainless steel, aluminum, and copper. With a bit of practice, it is possible to achieve smooth, clean, consistent gouges. Compared to other processes, such as carbon arc gouging, plasma gouging can reduce the amount of noise and pollutants in the work environment.
Gouging can be performed freehand or with a mechanical aid such as a track cutter. It can also be done on fully automated CNC cutting tables.
Trends in plasma gouging
- Need for faster operating speeds and less time spent on primary or secondary grinding work
- Regulatory requirements and work environment concerns requiring reduction in noise and fume levels
- Requirements for reduced contamination of the workpiece — i.e. no carbon contaminates
- Safety concerns when using incumbent methods such as oxy or carbon arc
- Desire to reduce operator training time and shorten the learning curve
- Spot weld removal on automotive body panels made of high strength steel
How plasma gouging works
The plasma gouging process removes any amount of material from a workpiece regardless of shape or rate, without actually severing or piercing the material. Just as in plasma cutting, a plasma arc is formed between a negatively charged electrode inside the torch and a positively charged workpiece. Heat from the transferred arc rapidly melts the metal, and a high-velocity gas jet blows the molten material away. In order to prevent cutting the metal when gouging with plasma, gouging specific shields and nozzles should be used.
In addition, many plasma systems have a dedicated operation mode for gouging that adjusts the amount of pressure traveling to the torch. You can still gouge with the system set to cutting mode, but it’s advisable to use gouging consumables to help keep the arc from piercing or severing the workpiece.
For Powermax® systems there are different gouging consumable options to choose from based on desired gouging results and operator preference.
Air plasma vs. other gases
A number of different plasma and shielding gases – including air, nitrogen, oxygen, an argon/hydrogen mix, and other combinations – can be used when gouging with plasma. However, it’s a good idea to check the operator manual first to make sure the gas you want to use is compatible with your particular plasma system. Here are some general rules when deciding on which gas to use:
- Air plasma provides the lowest cost of operation and acceptable quality on mild steel, stainless, and aluminum.
- An argon / hydrogen mix can produce a clean, bright, smooth gouge on aluminum and stainless.
- Nitrogen gas is good if you want to extend the life of your consumables.
Gouging with Powermax plasma systems
Learn about the different Powermax® gouging processes available.