Plasma cutting use compressed air and electricity to create a focused jet of heat that melts the metal and blow the melted metal away in one motion. To achieve a clean cut from the metal, it is essential to use the correct settings for the plasma cutting machine, and the most important setting to decide before beginning the plasma cutting process are the amperage settings. The amperage settings for plasma cutting machines will range according to the thickness of the mild steel that the plasma cutting machine can cut.
For instance, a 20-amp plasma cutting machine are used for cutting light sheet metal. In contrast, a 45-amp plasma cutting machine is used for cutting structural steel plate. Furthermore, 80-amp and 100-amp plasma cutting machines is used for cutting heavier metals because they require more speed and more edge qualityly when cutting the metal.
Plasma Cutting Settings and Tips
A chart that displays the amperage settings of plasma cutting machines and the thickness of metals that they can cut will allow the operator to choose an apropiate plasma cutting machine for the metal thickness that will be cut. The metal that will be being cut will also affect the plasma cutting process requirements. Mild steel will react to the plasma cutting machines travel speed correctly, and the mild steel will release the dross cleanly if the travel speed is set to the correct speed.
However, stainless steel holds heat for longer then mild steel, so plasma cutting settings will need to be adjusted to use more amperage and reduce the speed at which the torch move across the metal to avoid discoloring the stainless steel. On the other hand, aluminum metal will conduct heat away from the cutting site very quickly. Hence, the plasma cutting settings will need to be adjusted to use higher amperage and move the torch more fast across the metal to prevent the metal from melting at the metals top edge.
The travel speed that the plasma cutting machines torch move across the metal will impact the quality of the cut. If the travel speed is too slow for the thickness of the metal, the plasma cutting torch will melt more metal than necessary, and the melted metal will harden at the bottom edge of the metal plate. However, if the travel speed is too fast for the metal thickness, the plasma arc will not be able to fully cut through the metal, and the cut will appear rough on the metals surface.
The operator should watch the plasma arc as it exits the bottom edge of the cut metal; the arc will indicate whether the travel speed for the plasma cutting machine is correct set. A nearly vertical stream of plasma with light drag lines is the goal for achieving the correct travel speed for the plasma cutter. Air supply is one of the variable to consider in the plasma cutting process.
Plasma cutting requires the use of clean, dry air at the appropriate volume and pressure. A small compressor may be able to provide the necessary air supply for a 20-amp plasma cutter. However, the same small compressor will struggle to provide enough air for cutting thicker metals or performing longer cutting operations.
Moisture in the air line can damage an electrode. Furthermore, the moisture can enlarge the orifice of the nozzle. An enlarged orifice will create a wider kerf in the metal.
This will destroy the edge quality of the plasma cut. Using the apropiate air supply based off the amperage of the plasma cutter will prevent the need to replace consumables of the plasma cutter. Consumables in a plasma cutter must be replaced according to the rules set for each consumable.
The rules state that the electrode and nozzle must be replaced at the same time. This is because using a worn electrode will result in a plasma arc that wander from side to side across the metal. This wandering plasma arc will damage a new nozzle.
Furthermore, cutting into the metal will reveal if the hafnium on the electrode has worn down to the prescribed depth. The roundness of the nozzle orifice can also be checked to prevent quality issue in the plasma cut. The plasma cutting technique will significantly affect the outcome of the plasma cutting process.
The operator must maintain the correct distance between the plasma torch and the metal being cut. Holding the torch too high will bevel the edges of the metal being cut. Dragging a non-drag torch will direct metal spatter into the nozzle.
Starting the pierce for the metal at an angle will direct molten metal toward the consumables in the torch. Using an amperage chart will remove guesswork from the plasma cutting process. By matching the plasma cutter with the metal being cut, the thickness of that metal, and the air supply to the plasma cutter, the plasma cutting process become automatic.
The operator must maintain the correct travel speed for the plasma cutting process and replace the consumables before they fails.
