Common Methods to Cut Metals
The two most common methods to thermal cut metals are oxy-fuel cutting and plasma arc cutting.
Oxy-fuel cutting uses high-purity oxygen and fuel gas, such as acetylene, to cut metals. The mixture of oxygen and acetylene is used to preheat the metal before cutting. A jet of high-purity oxygen is directed at the preheated area to initiate the cutting process via a chemical reaction called oxidation. This jet blows away the cutting slag and pierces through the metal.
Plasma arc cutting uses an electrical arc to heat gas to high temperatures. The gas, either compressed air or nitrogen, is ionized to form a plasma. This plasma is forced out of the orifice of a torch nozzle at great speeds and hits the metal in a very focused plasma stream. As the heat of the plasma arc melts the metal, the high-speed plasma stream blows away the metal droplets, making a clean, precise cut.
Plasma Cutting Basics
The plasma arc power source provides the electrical power for the cutting circuit, creating the arc between the cutting torch and metal. A pressurized cylinder, or an air compressor, delivers the gas for plasma arc cutting. The work cable and clamp connect the metal to the power source, completing the electrical cutting circuit.
The cutting capacity and efficiency are generally dependent on the amperage set on the plasma arc power source. When a higher amperage is set, the plasma arc becomes hotter. This allows for faster travel speeds or the ability to cut thicker metal.
When compared to oxy-fuel cutting, plasma cutting has the following advantages:
- Plasma cutting can be used to cut both ferrous and non-ferrous metals, such as carbon steel, cast iron, stainless steel, and aluminium.
- Eliminate the need for storing and managing explosive gases or working with an exposed flame.
- Great for cutting thinner or shaped metals quickly and precisely, with minimal distortion.
- Does not require preheating before cutting, improving productivity.
Miller® Spectrum® Plasma Cutters
Miller Electric manufactures plasma cutters under the popular Spectrum® trade name. There are three main products:
- Spectrum® 375 X-TREME™
- Spectrum® 625 X-TREME™
- Spectrum® 875 Auto-Line™
The Spectrum® 375 X-TREME™ and Spectrum® 625 X-TREME™ have a rated cutting capability of 9.5mm and 16mm respectively. These are light-weight, portable plasma cutters that allow the welder to easily move from location to location. The Spectrum® 875 Auto-Line™ is the largest plasma cutter amongst the three and has a rated cutting capability of 22.2mm. This product can be paired with automation accessories to upgrade from hand-held torch to machine torch applications.
If you would like to learn more about Miller® Spectrum® Plasma Cutters, reach out to us at SGOffice@MillerWelds.com