A plasma cutter provides a quick, clean method for cutting metal while working on a welding project or fabricating materials in a welding shop. Welders can use a variety of methods to cut metal, including a saw, grinder, torch, or plasma cutter, but a plasma cutter provides an efficient way to make clean cuts, especially for thick metals.
However, using a plasma cutter effectively and safely requires a little bit of learning and practice. While it’s ideal to read the instructions for a plasma cutter before you begin using it, here are six tips to keep in mind in order to make the best cuts possible.
Take Precautions with a Plasma Cutter
While a plasma cutter offers the advantage of never using unstable cutting fuels such as acetylene, it’s not an entirely risk-free cutting process. Plasma cutters operate at a very high voltage and should never be handled without work gloves on. Beware touching your metal work piece without gloves, especially.
As with any process involving a lot of electricity, watch out for water or flammable materials in nearby drums or containers. Be fully aware of the hazards present in your workplace. Also be aware that the dross from your cutting will fall to the floor and could catch fire if there’s a lot of sawdust below your cutting set up.
Cut with the Tip Near the Metal
While a thin metal can sometimes be cut at a low amperage with the plasma torch right on the metal, be sure that’s a safe and viable option for your cutting project. One welder compared these cuts on thin metal to dragging a pencil along a piece of paper.
Typically, plasma cutters work best with a 1/8 inch distance from the metal you plan to cut. Take some time to practice some dry runs with your torch to get a feel for maintaining that distance for a sustained period of time. The arc for the plasma cutter should be directed straight down before you begin cutting.
Adjust Your Cutting Speed
A plasma cutter begins with a few seconds of pre-flow air before the pilot starts. Once the pilot engages, start moving your torch across the metal so that dross falls below, meaning that you’re cutting right through the metal cleanly without having to hold the torch in place for an extended period of time. You should be able to keep the torch moving slowly across the metal.
Too much amperage will distort the metal and leave a sloppy cut, but too little means you won’t be able to maintain a steady travel speed either.
Piercing with a Plasma Cutter
Move the plasma cutter toward the metal at a slight angle when piercing roughly 60 degrees should work. As you move the torch down, rotate it to a 90 degree angle. This keeps the metal moving away from the torch. Moving straight down on the metal at a 90 degree angle from the start runs the risk of blowing melted metal right up into the torch.
You can often pierce metal that is up to one half of your machine’s cutting capacity.
Gouging with a Plasma Cutter
For gouging metal, you never want to move the torch straight down at a 90 degree angle. Rather, you should begin at a 40-45 degree angle over the metal and keep the arc length at 1-1 ½ inches as you move it across the metal. Gouging is a far more gradual process compared to piercing, so adjust your torch and arc length as you go, but don’t be afraid of making multiple passes as you work. Gouging too deeply on your first pass could wreck your work piece.
Finishing Your Cut with a Plasma Cutter
By the time you reach the end of your cut, angle your torch slightly toward the final edge, taking care that you don’t burn yourself. Or pause briefly at the end so that it severs the metal without distorting it.
The metal and the torch will be hot when you’re done working, so be careful that you don’t touch the metal by the cut right away and that your torch has time to cool off. The post-flow air will pass through the torch for about 20 to 30 seconds after you let go of the trigger. Avoid pressing the trigger during this process in order to ensure that your torch has enough time to cool off.