Mistakes That Cause Defects in Aluminium Welds
Some inexperienced facilities managers often blame aluminium suppliers when they see lots of defects in the aluminium products that they fabricate. However, many of the defects in aluminium can be traced to mistakes that are made during the fabrication process. This article discusses some of those mistakes that may be causing those defects in your components.
Shielding Gas Defects
Many fabricators know that one of the best shielding gas blends to use when welding aluminium contains helium and argon. However, those fabricators may not have a system to prepare the blend just before it is needed at the tip of the welding torch. Such fabricators may have a blend stored in a cylinder. Those two gases may separate and stratify if the blend is stored for long. Consequently, your weld seams will crack because the arc used to weld them was not as hot as was required since the shielding gas wasn't flowing as a uniform mixture.
Incorrect Power Source
Welders can use direct current (DC) or alternating current (AC) when welding metals. The option selected depends on the specific attributes of the metal that needs to be welded. For instance, aluminium usually has an oxide layer on its surface. That oxide layer melts at a higher temperature than the metal beneath it. Consequently, it will be harder to weld aluminium if the welding power isn't strong enough to cut through that oxide layer. Alternating current is the best type of power to use because it produces a stronger current than direct current. Weld defects can therefore result if you use DC to weld aluminium.
Power Quality Torches
Some of the energy that is generated by a welding torch usually returns to the torch. This causes fabricators to place the torch down periodically during the welding process in order to let it cool. Welding defects often manifest in aluminium if a poor-quality torch is used in the welding process. This is because the torch quickly heats, so the welder has to pause often to cool it. High-quality torches, such as those cooled by water, heat up at a slower rate than poor-quality torches. The better torch therefore enables the welder to work for longer before having to lower the torch. Fewer interruptions result in fewer weld defects.
As you can see, many of the causes of welding defects in aluminium can be traced to shortcomings in the welding parameters and equipment. You can avoid these defects by working closely with your aluminium supplier so that he or she can give you detailed data sheets and suggestions that can guide you on how exactly to avoid the problems that you are having.
