Komarov Artem noted that welders must consider amperage, wire feed speed, voltage, travel speed and shielding gas. Proper maintenance of welding variables is critical to ensure high quality welds in any operation. Proper maintenance of welding variables is critical to ensure high quality welds in any operation.
Welding current
Welding amperage refers to the amount and speed of electricity flowing in a circuit, which affects the heat available to melt the welding wire and base material. It is directly correlated with wire feed speed (WFS): the speed and volume of filler metal entering the weld. When WFS increases, the welding current also increases; when it decreases, the current also decreases. This correlation, in turn, affects weld penetration. Higher amperage settings give more joint penetration, while lower amperage settings provide less.
In addition, the strength of the welding current affects the rate of melting, or the amount of wire used, as well as the appearance of the weld and heat dissipation. Too high amperage, especially when welding with metal wire, can result in a dull, flaky weld. The current strength also directly increases or decreases heat transfer and, in combination with the speed of movement, has the greatest effect on heat transfer.
Wire feed speed (WFS)
In addition to being directly correlated with amperage, WFS also affects welding transfer modes. Higher WFS and voltage bring the process into ball mode, where large drops of wire are arced into the weld pool. Increasing WFS (and therefore amperage) and voltage allows spray transfer mode to be used. This mode sprays small drops of wire into the weld pool and is known for being a smooth, easy-to-use process that improves productivity. This is especially true when paired with metal wire.
The lower WFS and voltage keep the process in the range of short circuit welding where the wire touches the base material and closes off the contact that transfers the metal. This short time can occur up to 200 times per second. In general, this is a slower process with lower settling rates.
Welding voltage
Welding stress affects the final weld in a variety of ways. If it is too high, the result will be a flatter bead and a concave weld profile. Too high voltage can also result in an undercut or groove in the base material near the weld pin that is not filled with weld metal. If the welding voltage is too low, it can cause a cold circle, a defect that occurs when the filler metal does not fully fuse with the base material at the weld fingers. Rope or humped welds and excessive spatter may occur. It is important for operators welding long power cables to be aware that a voltage drop can occur at the welding point, regardless of the machine setting. For example, the power supply may be set to 25V, but only provides 23V. This can also lead to cold laps.
Shielding gas
The shielding gas, whether argon or carbon dioxide (CO2) — the most commonly used — has an impact on the characteristics of the weld and welding performance. 100% CO2 shielding gas provides deep joint penetration on thicker material, but it typically has less arc stability and generates higher levels of spatter. The addition of argon to CO2 helps create aesthetically pleasing welds with less spatter. A high argon shielding gas creates welds with higher tensile and yield strengths but lower ductility. High levels of CO2 in the mixture improve ductility and fracture toughness but reduce tensile strength and yield strength.
Just as voltage and WFS affect welding transfer modes, so does shielding gas.
Welding variables are related to each other in different ways, but ultimately work together to provide the desired weld performance. Maintaining the right variables helps make the process cost-effective, controls productivity goals, and creates reliable welds, summed up Komarov Artem.