For welding complex joints with unsurpassed strength for a wide range of metals, TIG welding is unrivaled. However, when it comes to cutting metal with speed and agility, nothing produces clean, burr-free edges like a plasma cutter. So wouldn’t it be great if it were possible to TIG weld and plasma cut with the same machine?
It can be done, but how can you TIG weld with a plasma cutter? The answer lies in what is known as a multithreaded machine which has three built-in features:
- Tig welding machine
- Plasma cutter
- Stick the welding machine.
This machine is good for small shops and hobbyists. They permit the operator to plasma cut metal and smoothly switch to TIG welding of the same parts, eliminating the need and cost of having dedicated machines for each task.
You know the three states of matter: solids, liquids, and gases. But did you know that there is a fourth state of matter? It is called plasma and results from gases that have become ionized and are electrically conductive. Gases reach this state when subjected to large amounts of energy (usually heat).
WA plasma cutter forces the gas through a limited opening and energizes this pressurized gas with an electric arc to produce plasma. Since plasma is electrically conductive, when the plasma torch tip is placed close to another conductive material (such as the metal being cut), the arc is transferred to the work at high speed, and the gas (the “plasma jet “) passes through the material.
For most entry-level and conventional plasma cutting machines, the gas is simply compressed air fed through an air compressor. However, higher precision plasma cutters, such as those in complex manufacturing operations, would require pressurized gases such as oxygen, nitrogen, argon, or gas mixtures.
Plasma Cutting with a Multi-Process Machine
The main benefits of owning a multi-process machine are plasma cutting your metal parts and TIG welding a few minutes later. The typical multi-process machine can plasma cut 1/4″ thick metal at speeds between 15 and 20 inches per minute. For parts thicker than 3/8″ thick, the speed slows down but remains at a respectable 3- 4 inches per minute.
Plasma cutting equipment differs from TIG welding equipment, so it is important to become familiar with the connection of the various part.
Setting Up A Plasma Cutting Connections on the Machine
Since multithreaded machines support three to four operations from a single machine, many ports and connections are shared between the different processes.
Within the TIG welding and plasma cutting processes, the shared connections or ports are:
- Gas inlet (rear of the machine)
- Torch connection (negative port)
- Torch control and gas lines
- The work cable (positive port)
Connecting the Compressed Air
For multi-process machines, conventional (or compressed) shop air is sufficient for plasma cutting. However, most manufacturers require an air compressor to provide a minimum of 70-75 PSI (pounds per square inch) and at least 5 CFM (cubic feet per minute). To meet these requirements, an air compressor must be a minimum size of 25 gallons.
Just like connecting the argon gas cylinder for TIG welding, plasma cutting requires a regulator to regulate the flow and pressure of the compressed air that feeds the machine. This device is pre-installed on most multi-process machines and includes a siphon and dirt filter to supply clean air to the plasma torch.
Connecting the Plasma Torch
The connections for a plasma torch are similar to those for a TIG torch. A line is a serial connector that connects to the negative (-) port on the front of the multithreaded machine. The control line is connected to the control port, and the air hose is connected to the “gas outlet” port.
Connecting the Work Cable (Ground Clamp)
Like TIG welding, plasma cutting involves a high-voltage electrical arc created and maintained through DC voltage. Any material that conducts electricity can be cut with plasma. The plasma torch connects to the negative port of the machine, and the work cable (return cable) connects to the workpiece and to the multi-process machine’s positive (+) port.
Plasma torches contain built-in safety features, and one of the most important is to disable arc start if any of the internal components are missing or installed in the wrong sequence. For example, even experienced plasma cutters forgot to put the vortex ring on their flashlights.
To get the cleanest, sharpest edges without burr, it is important to get the right torch angle and cutting speed. As a general rule, starting plasma cuts at the edge of the part will result in better cuts and protect the torch components from rapid wear.
For thinner materials, start the torch in a vertical position and when the plasma jet penetrates through the metal, tilt the torch slightly so that the jet directs the cut (in other words, tilt the plasma jet in the direction of the cut and the end of the torch). Away from the cut). For thicker material, a more vertical torch position will give better results.