Aluminum is one of the most valuable commodities on Earth. It's one of the most common materials on the planet, but it's also the least known and most versatile. Nowadays, it's being used as the base metal to make things from the home to the office to industry to anything and everything.
In addition, it is a silver-colored, lustrous metal that is highly resistant to corrosion and has an excellent heat capacity and a high strength-to-weight ratio.
Aluminum is an increasingly popular building material for both commercial and residential applications. In addition, it has many industrial and consumer uses, including cooking utensils, beverage cans, and even alloys that transform the strength of steel.
As the amounts of aluminum use are growing, the need for soldering aluminum and brazing aluminum is increasing.
What is aluminum soldering?
Aluminum soldering is a process that joins aluminum to another material, usually steel, copper, or brass. The term "soldering" comes from the solder used to join metals.
Soldering is a process in which two or more workpieces are joined together by melting and putting a filler metal (solder) into the joint; the solder cools down and hardens. Then, it forms an alloy with the base metal.
Aluminum soldering, also called hard soldering, is a metalworking process that uses filler wire and power to join metal. An electric current heats the filler wire until it melts into the parent material, creating a strong bond between the parts.
As the use of aluminum objects in manufacturing has increased over the years, the need to create bond aluminum to aluminum is increasing. This process is often used in place of welding because it's easier and can create strong joints when done properly.
Aluminum soldering is an excellent skill in the current world. And, if you are someone who wants to do aluminum soldering, then you are at the right place. In this article, we are going to tell you every single detail about how to solder aluminum. So, follow all the steps mentioned below carefully and execute your aluminum soldering project flawlessly.
Preparation for soldering aluminum:
Before starting the soldering process, you need to do some preparation to execute the soldering flawlessly. You need to do the necessary preparation mentioned below.
- Safety equipment: Get a full-sleeve shirt, pant, boots, goggles, helmet, And gloves for hand. These things should be not-insulated, and you should wear them before starting the aluminum joining method as it can be dangerous some time.
- Classify the aluminum alloys: You can use pure aluminum or aluminum alloys for soldering. But pure aluminum pieces are not easy to work with, and mostly aluminum alloys are being used for soldering projects. Though the rules of soldering for all aluminum base alloys are the same, a few alloys are difficult to work with. So, try to identify the alloys. You can classify it by the number or letter marked in the alloy. However, if there aren't any, then it's almost impossible to classify them. But don't worry because joining an aluminum metal sheet with most other metals doesn't require any specific things. But, aluminum to steel joint requires special methods and an experienced welder.
- Get a low-temperature solder: For most soldering, people use general-purpose solder, but in the case of soldering aluminum, you can't use it because aluminum melts at 660ºC, which is relatively low. That's why you need specific low-temperature solder. While buying, check the label of the solder and make sure it has a lower melting point. Again, lead-free solder is a must to execute your welding smoothly.
- Select proper flux: You must choose the correct aluminum soldering flux for your project. The flux depends on the aluminum metal sheet or other metal combination you are going to use. Some metal requires special flux. So, get the flux and solder from the same source to help you get the correct one. Use brazing flux if the melting temperature of solder is more than 450ºC. But remember, brazing flux doesn't work well for thin aluminum wires and aluminum sheets.
- Pick a heat source: Heat is mandatory for soldering. You can use an electric soldering iron for aluminum wires. But for thinner or thicker aluminum component, use a propane torch. But your workplace doesn't go well with the torch, use a 150-watt electric soldering iron.
- Equipment and work area: Get all the equipment and try to arrange the optional equipment like clamp, specific solution for cleaning, acetone, etc. Do your work in a well-ventilated area. Arrange a fire extinguisher and place it nearby.
How to solder aluminum:
After making the necessary arrangements, start your soldering process. Read the steps mentioned below accurately and throughout and follow them properly to execute your soldering flawlessly.
- Cleanliness: Aluminum tends to react when it comes in contact with air, and as a result, an aluminum oxide layer gets created on the aluminum surface, which is not good for the strong aluminum joint. So, clean the surface of aluminum before soldering with the help of a stainless steel brush. Also, the old aluminum metal pieces tend to react more, and that's why you might need to clean it with the help of acetone and isopropyl alcohol.
- Clamp the base metal pieces together: If you are doing soldering to repair a particular object, there is no need to clamp. But if you are joining two aluminum pieces or metals, you should clamp them together tightly according to your need and keep a gap of 1mm or less between the pieces so that the solder can flow. You can lose the clamp to clean the oxidized layer or others and then re-clamp them tightly.
- Flux application: After cleaning and clamping, apply the flux immediately to the area you want to be joined. Immediate application of the flux will prevent oxidation. You can apply the flux using a soldering rod or any other small metal tool. But, if you are soldering wire, then instead of applying flux on them, dip them in the flux.
- Start the heating: Choose the heating methods for your soldering. Use soldering iron or torch accordingly and then, start heating the metal. Start the heating at the starting of the place you want to make joint. But, don't put the flame in one place for a long time as it can overheat the flux and solder. So, maintain a distance of 4 to 6.5 inches between the base metal and torch tip. Move the heat source slowly and constantly so that the heat can distribute evenly.
- Applying the solder: After the flux reaches the correct temperature, start applying the solder. Apply the solder while heating that area continuously from a distance. Drag the solder across the area where you want the joint to happen. The movement should be slow and constant if you want an even and smooth finishing. If you see that the solder is not bonding the metals, then clean the place as it can happen because of oxidization and then immediately apply the solder. To get a flawless finishing, you need to do more practice.
- Remove excess flux and oxide: After finishing the soldering, let the joint cool down. Then clean the extra flux and oxide. For water-based flux, just use water to rinse off. And, for resin-based flux, use acetone. After you finished removing the flux, clean the oxides using a pickling solution. After you have removed the oxide and flux, you have finally completed your soldering process.
By following all the steps mentioned above, you can do your soldering perfectly. All the steps are described in detail so that you can execute your soldering project flawlessly. But, of course, to be a pro and have smooth finishing, you might need more and more practice. Hence, read our article, prepare everything and enjoy a smooth soldering experience.