How to Clean Aluminum For Welding

Aluminum requires a very careful approach – this is extremely important to know for beginners welders. Unlike steel and other metals, this material requires special treatment before welding. There are different ways to clean it, and in this article, we will look at how to clean aluminum for welding.

Stainless Steel Wire Brush

Often a tool for cleaning aluminum such as stainless steel brushes is used. There are manual and electric brushes: it is not unimportant that they perform the cleaning process and that they are used specifically for storing aluminum.

Improper cleaning process methods for welds can lead to imperfections in aluminum products. There are several guidelines for the cleaning of aluminum welds. Each step of the process is to be thorough.

A solvent should be used to cleaning aluminum. This will prevent contaminants and carbon deposits from appearing on the weld joint surface. You should also use a wire brush.

Dos And Don’ts Of Cleaning Aluminum Welds

The process of deburring welds is very thorough. Improper deburring of welds can cause a defect in the aluminum product. When deburring aluminum welds, some rules should be followed.

How to prepare aluminum for TIG, and MIG welding: you need to perform certain procedures. And for this, you need to know how to clean aluminum for welding.

The first thing to do is to remove contaminants from the metal before starting MIG welding.

Each cleaning step must be carefully performed. The following are methods of cleaning aluminum welds, incorporating the application of a wire brush:

• Do not attempt to use drafting techniques for cleaning aluminum that may harm it. For example, band saw cuts can contaminate the surface. Avoid using high-speed circular saws to cut aluminum. If necessary, you should use a sander with a coarse grinding wheel. In this case, the cut should be clean, fast, and without wear.
• When preheating, it is advisable to refrain from performing gas-oxygen cutting, plasma arc cutting, or using an oxygen flame for preheating. The heat-affected areas are damaged in this way and promote the growth and hydration of an oxide removal solutions.
• The oil or grease is supplied in an aluminum casing from the factory. The connection must be cleaned before assembly.
• Please do not use household shop rags to pre-weld cleaning joints. Oil and dirt can get on the shop rags.
• Use a wire brush to pre-clean the weld with solvent, or else hydrocarbons and other contamination will end up on the weld puddle.
• You should definitely never blow out a weld with compressed air. It is often contaminated with moisture and oil.

For aluminum, the safe ones are acetone and lacquer thinner. These are used to remove oil and grease from surfaces.

How tо clean aluminum for welding?

This preparation step includes 2 basic steps:

1. The aluminum degreasing procedure also includes the drying and removal of dirt. This process will remove substances from the aluminum surface that can cause welding damage or voids.
2. Oxide removal solution or oxide removal spray can be used to remove oxide layers on aluminum. Structural weakness of the joint usually results from the formation of oxidation in the weld of an aluminum workpiece compared to a clean aluminum weld. The oxidation also raises the melt temperature of the aluminum.

While this procedure is relatively simple (which it usually is), there are many ways to ensure successful cleaning and a smooth subsequent welding process if these two steps are followed.

Using a tool to clean aluminum before welding

To qualitatively strip aluminum for welding, you will need the appropriate equipment. The following items should be prepared before aluminum:

• Various clean microfiber cloths (standard textile cloths are not recommended). Two cloths should be used – a wet one to wipe the aluminum and a second dry cloth to ensure that the aluminum is completely dry after the cleaning and deoxidization process.

• Stainless steel and soft bristle brush. After decreasing the aluminum part with vinegar or descaling solution, use a wire brush to carefully remove all oxidation residue from the aluminum surface.
• Cleaning solution or mild alkaline solutions to degrease aluminum surfaces: there are several ways, such as common dish soap, but acetone and nail polish remover are the most common options.
• Hot Water: to get the full effect, most alkaline aluminum treatment solutions need to be immersed in pre-warmed water. A hot water basin should be used to clean the aluminum weld and in some cases, a sprayer should be used to rinse the aluminum coating.
• Brown kraft paper: It is necessary to ensure vertical storage of aluminum products. This will help minimize the formation of condensation and the absorption of water impurities in the gaps between the layers. Wrap the aluminum in brown kraft paper. This will help prevent re-oxidation. Aluminum with brown kraft paper secures the packing tape in place.

• Oxide cleaning spray (or vinegar): Special solvents, which are available in the form of substances in bottles or in spray form, are designed to remove oxides, but plain white vinegar too might be used for removing oxidation on aluminum surfaces.

Packing Tape

The brown kraft paper in which the aluminum has been wrapped may be reinforced with a packing tape. Do not come in direct contact with the surface of the aluminum to avoid contamination. For cleaning and drying the joint, use cheesecloth or paper towel.

Necessary preparations for cleaning welding aluminum

When cleaning aluminum parts for welding, you should first prepare them a little bit. Tools should be prepared well in advance, then you won’t have a situation where you have to interrupt the project halfway through, going to look for something.

To reduce the risk of debris transfer to the prepared aluminum during the cleaning process, place clean wire brushes and other cutting tools on the aluminum. 

Solvents that work well are lacquer thinner, acetone, paint thinner, toluene, and methyl ethyl ketone.

Other recommendations for preparing aluminum

• Carbon arc cutting or gas-oxygen gouging are methods that are not used. This is because moisture appears when the oxygen is burned. Moisture is not allowed in the prepping aluminum machining process.
• Heating to temperatures above 1500F is not permitted, as it leads to oxidation processes.
• Compressed air is not recommended for cleaning the aluminum joint for welding.
• In some cases, it is quite difficult to know exactly what the rag is impregnated with. If it has been used directly to clean gasoline or other volatile substances, it can lead to a risk of ignition due to sparks.

The Disadvantages of Welding Contaminated Aluminum

Welders may be tempted to skip the prepping aluminum stripping procedure immediately before welding. There are certain risks associated directly with attempting to weld dirty aluminum, including the following:

• Erratic arc: Incorrect arc operation causes slag to spatter and move to the edges of the weld, where it will be difficult to remove. Incorrect arc operation results in an unsightly and unprofessional-looking weld. This makes it difficult to control the welding procedure itself.
• Added resistance: Due to the additional resistance, the amount of heat involved in the weld increases, and the surface of the weld may be too large.
• Sooting: There may be a defect at the welding spot due to fouling, rather than an even, silver-colored border. The combustion of a film of oxide and other particles on the aluminum surface results in the fouling.
• Lack of fusion: Problems with lack of fusion in aluminum welding can be caused by the presence of contaminants.
• Poor wire feeding: Poor wire feeding can result in increased filler material consumption, unhelpful downtime for welding decisions, and overall poor weld quality.

There are many disadvantages to trying to weld with contaminated aluminum; similarly, there are many advantages to making sure your aluminum is clean before you try to weld it. 

Advantages of a Clean Weld

• Consistency: The use of clean welding materials promotes a certain level of consistency in the production environment and allows aluminum to be used as an element of weld quality control.
• If something fails during the welding process and the aluminum is clean, this is further significant evidence that it is not the cause of the problem.
• High quality: cleaning aluminum before welding is necessary in order to do a quality job.
• Freedom from porosity: Porosity is a property of a metal that results from the residual contaminants impurities, such as hydrocarbons or oxidation, being introduced into the metal during welding operations.
• Metal porosity reduces the reliability of the joint, and if the metal at the point of welding is sufficiently porous, the welded joint may not be able to withstand the load at all.
• High strength: Because welds made of pure aluminum do not contain contaminants, they have a higher tensile strength than those made of contaminated aluminum or aluminum with aluminum oxides present. Stronger welds should be used to prevent unintentional damage to the structure.

The largest varieties of contaminants for aluminum

Several contaminants affect aluminum from the time it is manufactured for sale on a mass scale to the time it arrives at the welder’s shop. These contaminants can be broken down into three major categories.

Moisture

As aluminum oxidizes extremely quickly, it is necessary to insulate it from exposure to moisture as much as possible. As a result of oxidation, rust begins to form on aluminum, and it is difficult to stop the rusting process.

Moisture affects aluminum both in transit and in storage after it enters the house. This can be either direct exposure to moisture, such as leakage, or moisture in the air.

Aluminum can also be directly damaged by moisture from condensation. This can often occur in rooms where temperature and humidity are not regulated, as temperature fluctuations during storage cause condensation to form on the surface of the aluminum sheet.

Lubricants

Building materials are often coated with greases or other oils to improve their appearance (after all, who doesn’t like shiny things?) or to protect them from moisture.

These oils and greases, unfortunately, can cause combustion during the process, resulting in the release of chemicals that cause imperfections in the weld.

These materials can also cause an oxidation process by releasing hydrocarbons when left on aluminum for an extended period.

Due to the grease content of aluminum coatings, a grease, oxide removal agent is the first step in preparing the aluminum coating for welding.

Oxides

The oxide of aluminum is a substance formed when aluminum becomes exposed to moisture and is oxidized or rusted. This type of rust layer has a higher melting point than pure aluminum alloy and is ultimately much harder to weld.

The melting point of aluminum alloys is 12000F, unlike the aluminum oxide layer, which has a welding point of 37000F. As you can see, it is much more difficult to achieve aluminum alloy melting if it has had time to rust before use.

Oxidation significantly complicates the welding process and can lead to various defects, such as oxide inclusions in the weld, which affects the overall performance evaluation and increases the likelihood of structural damage.

Types of contaminants

Some of the major classes of contaminants that can cause aluminum surfaces to corrode are listed below, although other substances affecting the aluminum before it is even in use are also listed here:

• Oil;
• Ink;
• Grease;
• Dirt.

Several factors can cause a dirty and deoxidized aluminum welding surface, and such contaminants have a significant impact on the condition of the weld. For this reason, it is imperative to degrease and clean aluminum for welding.

FАQ related to how to clean aluminum for welding

1. What kind of brush do you use to clean Aluminium welding? We recommend using soft and thin bristles – this will help remove all traces of oxidation from the surface of the metal. It is important not to use power brushes with heavy, twisted bristled bristles; these bristles are not as effective at removing oxides as soft bristles. To avoid dirt, it is best to prevent the packing tape from coming into contact with the aluminum surface.

2. How do you remove oxidation from aluminum? Example of using a stainless steel wire brush with soft bristles: when you have degreased a piece of aluminum and immersed it in vinegar or a solution with a deoxidizing effect, you will need to use a wire brush to scrub the oxidation residue off the aluminum surface.

3. How do you clean porous aluminum? There are several options for this: dish soap, acetone, lacquer thinner, and oxidizing spray (or vinegar). Also, white vinegar and a metal brush are used.