Find products best meet your needs. No more worries about the authenticity of suppliers.Find Suppliers
Posted on Jan 23, 2021
Due to its low resistance, a high level of current is required when welding aluminium, even more so than steel of equal thickness by at least two to three times higher. In addition, aluminium tends to degrade the surface of copper electrodes within a small number of welds, meaning that it is hard to achieve stable, high-quality welding for aluminium. For this reason, despite the growing prevalence of aluminium, the use of aluminium spot welding is still quite niched in industries, even though new technologies are emerging to stabilize the quality of aluminium spot welding.
When we hear the term "spot welding", popular and resistive metals like steel usually come to mind. But can you use a spot welder to weld aluminium? Of course, you can. As a matter of fact, aluminium spot welding has become more common as aluminium is starting to replace steel in many industrial applications where weight is more important, such as automobiles. This is where aluminium spot welders come in, an emerging welding machine that is dedicated to weld aluminium and its alloys.
Before we dive into aluminium welding, I’d like to take a little time to discuss what kind of materials you can weld with a spot welder. Steel remains to be the most prevalent welding material yet because of its low thermal conductivity and higher electrical resistance, making it relatively easy to weld compared to other metals. But that does mean they are always the preferred material option. For instance, steels with exceedingly high carbon content are susceptible to fracture or crack in the weld; galvanized steel (zinc-coated) requires a high welding current to ensure smooth workflow. This is when aluminium may be a better alternative as per the requirements of your projects.
Aluminium has a low melting point because of its high level of thermal conductivity and electrical resistance similar to that of copper, meaning that spot welding aluminium is indeed possible. However, there is a reason why steel remains predominantly popular. Due to its low resistance, a high level of current is required when welding aluminium, even more so than steel of equal thickness by at least two to three times higher. In addition, aluminium tends to degrade the surface of copper electrodes within a small number of welds, meaning that it is hard to achieve stable, high-quality welding for aluminium. For this reason, despite the growing prevalence of aluminium, the use of aluminium spot welding is still quite niched in industries, even though new technologies are emerging to stabilize the quality of aluminium spot welding.
With the above said, we can now move on to the main topic of the day: how to go about spot welding aluminium? To recap, spot welding is a process in which the weld area of two metals is joined to form a weld. Two electrodes clamp the workpieces simultaneously and convey the electrical current required to produce the weld. The current is delivered directly to one spot, which is how “spot welding” gets its name. Now let’s discuss how to spot weld aluminium:
1. The spot-weld of aluminium is a three-phase process. It provides electrical power large enough to make sure the weld is possible. Spot welding aluminium typically conveys current for 0.1 seconds or less, so the current output must be extremely high. An aluminium spot welder typically delivers at 150 amps per phase draw on a 440-volt system and usually costs between $60,000 and $85,000. And a rebuilt version is significantly cheaper.
2. The next thing you'll do is to acquire capacitor discharge welders. The purpose of the welders is to store the electrical energy and deliver it at an extremely high current as required to perform your welding task. The primary advantage of this type of spot welder is that only a minimal power draw is required, which allows smaller workshops to perform aluminium spot welding without having to upgrade the electrical supply. This also allows thicker aluminium pieces to be welded at assembly lines without the lights flickering.
3. Take the physical attributes of aluminium into consideration when performing your spot welds. As mentioned earlier, aluminium has high-level conductivity and warms up very easily, meaning that it has to be welded faster than steel in order to prevent the overheating of workpieces. Aluminum generally needs two to three times the electrical energy and one-quarter of the weld duration than steel does. The high current and weld time also entails that the electrodes have to be cooled with water.
Your welding approach may also differ depending on what kind of aluminium sheet you intend to weld. Mill-finished sheet, for instance, is generally weldable, but you may have to be mindful of aluminium oxide which forms naturally on the surface of aluminium. The oxide can become heavy thus leading to inconsistent welding. Next, when welding abraded sheets, you can remove the oxide prior to welding for better consistency, but it may result in very low surface resistance, meaning a much higher current is required. You can also consider a surface modification treatment, a kind of chemical surface treatment often applied by material suppliers, in which a medium to high surface resistance can be achieved for more consistency and weldability. Last but not least, you can consider anodized, heavy chromate treatments which provide very high consistency and sometimes completely insulated, unweldable surface layers.
IMTS gathered worldwide Spot Welder manufacturers into this online platform. Browse and search for your next supplier with us.
Should you run into any difficulties, please do not hesitate to contact us.