Aluminum welders typically use a welding process called "pulsed gas metal arc welding" (GMAW) or "pulsed MIG welding" for welding aluminum. In this process, the welding machine alternates between a high peak current and a low background current during each welding cycle.
The power source used for pulsing is usually a pulse AC (alternating current) waveform. However, this pulse AC is not a pure sine wave like the AC power you get from the electrical grid. Instead, it is a modified square wave or a tailored waveform designed to suit the specific welding requirements.
The main advantage of using pulse AC in aluminum welding is to control the heat input better, reduce the risk of burn-through or distortion, and improve overall weld quality. The pulsing action allows the weld pool to cool slightly during the background current phase, which helps control the weld puddle size and prevents excessive heat buildup.
Pulse AC welding machines also provide better arc stability, reduce spatter, and offer a more controlled weld bead appearance compared to traditional constant current (CC) welding machines. This makes them a preferred choice for welding aluminum and other non-ferrous metals.
It's worth mentioning that there are various types of welding machines available in the market, and the specific features and waveforms may vary between different manufacturers and models. Always refer to the manufacturer's guidelines and recommendations to use the appropriate settings and techniques for welding aluminum with your specific welding machine.