Cleaning up aluminum before welding is essential to make sure that the end product is structurally strong. If you’ve done your research on how to best do it, you probably found the same information everywhere:
- Remove grease and oil using a liquid degreaser. This includes solvents or mild alkaline solutions like acetone and lacquer thinner.
- Dry the surface with a clean cloth.
- Remove the aluminum oxide layer with a stainless steel wire brush.
This manual method is good but time consuming. For many welders, finding an alternative method is crucial to spend less time on manual cleaning. One of these methods is laser cleaning.
How Does Laser Cleaning Work?
Laser cleaning, also known as laser oxide removal, removes all types of contaminants at once. When the laser beam hits the aluminum surface, grease, oil, dirt and aluminum oxides are all vaporized into dust and fumes. The laser sends the right amount of energy to remove those contaminants without introducing impurities in the aluminum.
The resulting weld quality is excellent. As shown in our report on laser cleaning for welding, laser cleaning significantly reduces the number and the size of porosities in the weld joints. You can see the results obtained with and without pre-weld cleaning.
A wide range of laser cleaning solutions exist. Some of them are handheld while others are fully or semi-automated. To give you an idea of the potential of laser cleaning in welding applications, you can watch the following video.
Is Laser Cleaning Always a Good Choice When Welding Aluminum?
Simply put, no. Laser cleaning is not always a good solution. The cleaning method needs to be chosen on a case-by-case basis. People who buy a laser to clean their welds usually do so because they get a high return on investment, save time, and obtain high-quality results. However, lasers require an initial investment that is only worth it if you process enough parts.
What Are the Other Pre-Weld Cleaning Methods?
Mechanically removing oxides using rotating brushes is usually a good alternative when lasers aren’t fast enough, which can be the case when cleaning thick oxide layers and large surfaces.
Electrochemical oxide removal is also widely used, although an increasing number of welders are moving away from chemicals, as they are expensive, hazardous and difficult to manage.
If you’re interested in learning more about these methods, read our post on removing oxide from aluminum.
Tips for Preparing Aluminum for Welding
Whether you’re doing TIG welding, MIG welding or any other type of welding, there are things you should always do, and others you should avoid. Miller, an important manufacturer of arc welding products, provides useful tips on how to create high-quality aluminum welds.
Trying to weld with dirty base and filler metals adds unnecessary difficulty and can lead to poor weld quality. You also have to deal with the natural oxidation that takes place with aluminum. Suitable preparation prior to welding is important.
In their article, they provide tips to help you protect the welds from contaminants that could mix with the weld puddle, even if you cleaned the surface properly. Some of these contaminants include hydrocarbons and moisture that can cause lack of fusion, lack of penetration, and porosity.
If you’re using laser cleaning, you can ignore Miller’s tips on how to clean aluminum before welding, as they use a manual method. We’ve summed up below the things you should and should not do if you are a laser user.
Things You Should Do
- Store your filler and base materials in a dry location where temperature is regulated
- Store your aluminum parts vertically
- Bring your filler and base metals in advance into the welding area to allow them to reach room temperature
- Keep your filler materials covered until the last minute
- Use plasma arc cutting or laser cutting to cut the parts to be welded
- If you’re working with aluminum alloys from the 2000, 6000 or 7000 series, remove 1/8 of an inch from the melted edges that result from cutting
Things You Should Not Do
- Do not cut aluminum parts to be welded using methods that leave a smeared or ground surface (for example, avoid grinders)
- Do not use lubricants when cutting aluminum parts to be welded
- Do not preheat the parts to be welded using oxyfuel or carbon
- Do not use compressed air to blow dust off the joints
- Do not wipe the parts to be welded using shop rags
What to Do After Welding
After the welding process is over and you’ve done everything right to prevent contaminating the welds, your job isn’t over. You still need to clean the oxide byproducts generated during welding. You may have done this before using a wire brush. However, you can also remove these oxides using laser cleaning.
If you’re interested in laser cleaning to remove oxides for welding applications, contact our experts to discuss your application.