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You should upgrade or use an alternative browser. Thread starter malcolm Start date Aug 25, Messages 9, Location Bedford UK. It doesn't seem unreasonable that it should be possible to weld aluminium on DC - after all that's how it's done with MIG. Hitch Moderator Staff member. Messages 12, Location England. For most jobs AC will produce a much cleaner and tidyer weld.
I would say that unless your into heavy alu fabrications AC is the optimum choice. You have to adjust your work style to meet the needs of the metal, filler, and setup that you are using. DC welding aluminum is no different. Some tips that will help you use direct current to TIG weld aluminum are:. Join my weekly newsletter and receive helpful tips, tools, and theories about welding and joining.
Please confirm the subscription Email in your inbox. The link is only valid for 60 minutes. If your workpiece is extremely dirty or oxidized, DC might not be the best choice.
If you are working on engine parts that have a coating of carbon, or old parts that are heavily oxidized, AC welds might be a better choice. DC welding is also a poor choice for joining pieces of cast aluminum.
The casting process produces more surface oxidation than other manufacturing processes like machining. The surface oxide makes it hard to get a good weld, so direct current is a poor choice for welding cast pieces. You should also avoid DC welding aluminum if the appearance of the weld is important. It is harder to get the traditional stack of dimes appearance with DC welding, so stick to AC if the look of the final weld is essential.
For some projects, using both AC and DC can be a winner. For very thick stock, you might need to combine techniques to get the best result. To get the best weld in thick material, use the following steps:. Alternating current is the standard for TIG welding aluminum with good reason.
It handles the properties of aluminum well and makes nice looking welds. However, AC welding has its limitations. When you need deep penetration into thick aluminum, direct current penetrates better and delivers a better weld. Also check out my article about MIG welding Aluminium. If you liked this article, have a look at my other articles I wrote about the topic! To address some of the questions I frequently got asked or was wondering myself during my job, I started this blog. It has become a bit of a pet project, as I want to learn more about the details about welding.
I sincerely hope it will help you to improve your welding results as much as it did improve mine. Countless questions have reached me about Aluminium welding.
However, getting an extra machine or learning an additional process Finding a MIG welder that is appropriate for use with aluminum can be a bit of a chore, as there is undoubtedly a need to pay close attention to the specifications and capabilities of the This site also participates in affiliate programs with other sites. Skip to content. The preferred method is AC because people do not know what they are doing when it comes to aluminum DC plain and simple. If you brush the material with a stainless brush, clean with acetone, machine settings, torch angle, etc the weld will be just as pretty as AC and have deep penetration as well.
The sooty layer will be present in the weld but very minimal, just lightly brush it off and you are good to go. Sat Oct 06, pm bryce39 wrote: Sorry, I had to register to comment on this. If everything is correct, people cannot tell the difference between DC and AC aluminum.
I will take a picture of the weld before I brush it off so you know that I am not bullshitting you. Sat Oct 06, pm Bryce, Don't be "sorry" that you had to register. All input is welcome here. I have no doubt on the DC Al. Though I've never had to do it myself, the logic is sound. The pre-clean is the key, as you don't have the electrode-positive phase to do that work for you. I look forward to seeing the pictures, and since I love to learn new things, I may have a question or two for you and RedIron.
I have a great deal of autonomy at work, so I can experiment with this there. There is an application that comes to mind where the penetration is more important than the appearance as I assume, like most things, I won't master it in the first go Steve S. Sun Oct 07, pm That's just a figure of speech, I am glad I stumbled upon this site as there are all kinds of tips and tricks to learn in this trade. I will do my best to upload some pictures as soon as my company lets me get back to welding what I was hired for.
I had the luxury of working with some pretty sharp NDT guys over the years in the space program and experimented with a lot of aluminum finding that DC is the way to go for thick to thin transitions. Mon Oct 08, am Aerospace background explains a lot. I've known a couple of people who worked at the Micoud facility in New Orleans East, at the fuel tank assembly plant. I absorbed anything I could from them. Steve S. When welding in AC mode the current supplied by the welding inverter operates with either positive and negative elements or half cycles.
This means current flows one way and then the other at different times so the term alternating current is used. The combination of one positive element and one negative element is termed one cycle. The number of times a cycle is completed within one second is referred to as the frequency.
In the UK the frequency of alternating current supplied by the mains network is 50 cycles per second and is denoted as 50 Hertz Hz. This would mean that the current changes times each second.
The number of cycles per second frequency in a standard machine is dictated by the mains frequency which in the UK is 50Hz. It is worth noting that as frequency increases magnetic effects increase and items such as transformers become increasingly more efficient. Also increasing the frequency of the welding current stiffens the arc, improves arc stability and leads to a more controllable welding condition. However, this is theoretical as when welding in the TIG mode there are other influences on the arc.
The AC sine wave can be affected by the oxide coating of some materials which acts as a rectifier restricting the electron flow. This is known as arc rectification and its effect causes the positive half cycle to be clipped off or distorted. The effect for the weld zone is erratic arc conditions, lack of cleaning action and possible tungsten damage. The sinusoidal wave consists of the positive element building up to its maximum from zero before falling back to zero often referred to as the hill.
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