There are three primary methods of connecting metals in manufacturing. These are welding, brazing, and soldering. If you are unfamiliar with these processes, it can be challenging to determine which method will be the best for your project in question. For example, you may wonder how strong is aluminum brazing in comparison to other joining methods and whether or not it will create a strong enough bond for your needs.
This article will elaborate further on the brazing method for joining aluminum, but before we do so, let’s briefly review each of these methods. Welding is a process of joining two (or more) pieces of metal using high heat, pressure, or a mix of the two. Brazing, on the other hand, is a process of joining metals that relies on heat (less than welding) and filler metal. Soldering, like brazing, also relies on a lower heat (just enough to melt low-melting-point metal alloys) and filler metal to join pieces of metal. Now, let’s explore the brazing method in more detail.
What Is Aluminum Brazing?
As mentioned above, aluminum brazing is a type of metal joining process that connects two pieces of a metal (in this case, aluminum) using a filler metal — typically copper-based alloys, brass, bronze, or silver. This method works because the filler material has a slightly lower melting point than aluminum, so it becomes liquid and bonds the two pieces of aluminum together as it cools. Brazing can also be used to easily join two dissimilar metals because, unlike welding, you are not melting the metals themselves, only the filler metal.
This process tends to be more effective with aluminum than other metals (for example, steel) because aluminum itself has a relatively low melting point. This means that when aluminum comes into contact with the melted liquid filler metal, it becomes slightly more malleable and forms a very strong bond. Aluminum brazing also produces much less heat than welding and, therefore, can be advantageous when joining small or delicate parts without deformation.
Aluminum Brazing Methods
There are many aluminum brazing methods, but many metal fabricators will use one of the four following methods.
Dip brazing is a way to achieve a strong, leak-proof, and conductive joint between your pieces of metal. Like other brazing methods, it relies on melting a filler metal between the two metals you are aiming to join, and it is versatile because it can join metals with different melting points. The molten filler metal in dip brazing is drawn into the joint by capillary action.
Torch brazing is a method of brazing that uses heat from a gas-fueled torch to heat the aluminum until it is hot enough to melt the filler metal. This molten metal is then used to join the two aluminum pieces. This process is typically used for small parts as it is quick and easy and does not require special skills or tools.
This brazing method is often used for larger projects and is a suitable method for connecting larger or more difficult-to-reach joints. This brazing method requires a special furnace that can reach a high enough temperature to melt the filler metal.
Induction brazing is the final most common method of brazing aluminum. This method relies on induction heating to melt the solder, so it does not use an open flame. This can result in less solder waste, improved joint quality, and faster heating times.
Again, it is essential to note that brazing is one of three primary methods of joining pieces of metal together. Brazing or welding will typically be the best option if you are looking for a strong connection, as soldering is less sturdy. Brazing can be a good solution because it does not melt the base metals you are connecting, which means it does not compromise their integrity.
Factors that Affect the Strength of Aluminum Brazing
There are several factors that can affect the final strength of your finished joint. However, the most influential of these factors are the following.
- The design of your joint
- The quality of the joint upon completion
- The temperature at which you conducted the brazing
- How much clearance you left between the two pieces of metal you joined together
- The type of alloy used and composition of your base metals
- How well you cleaned and prepared the metals
Methods to Improve Aluminum Brazing Strength
To ensure that you have a solid joint when brazing, there are some things that you should focus on. Luckily, these practices can all be achieved with a bit of extra attention and do not require fancy equipment or tools other than those required to perform the brazing you are doing.
If you want a good connection, you should:
- Prepare and clean your metals before joining them. Imperfections and debris can interfere with the connection between your metals and lead to a faulty or weak joint.
- Perform the brazing process carefully and accurately. Make sure you know what you are attaching before you begin the process, and ensure that you use the proper temperatures and techniques.
- Ensure that your metals are high quality. Unfortunately, you will want to ensure this before you begin performing any machining because it cannot be changed during the brazing process. But, higher quality metals will result in better overall joints and improved strength.
- Contact a professional brazing service if you do not feel confident brazing in-house. If you do not have the necessary tools and experience to braze your joints on your work floor, it is typically best to commission this process. This can save you from wasting valuable resources with no-good joints and ensure that the products you end with are high quality and robust.
Applications of Aluminum Brazing
Aluminum brazing has numerous applications — from soda cans to kitchen utensils to aerospace craft parts. Essentially, any time you want to create a strong joint with a smooth surface finish, brazing your metals together will be a good option. Additionally, suppose you are looking for a strong connection that still offers conductivity. In that case, brazing can be better than welding, which can interfere with the conductivity of the metals joined.
Now that you have a better understanding of aluminum brazing and how strong it can be when performed correctly, you’re ready for your next project! If you do not have the necessary tools or experience to create solid joints that are strong enough for your project’s needs, New Age Metal Fabricating (NAMF) has you covered.
NAMF offers professional, top-of-the-line aluminum dip brazing services to ensure you have the durable and high-quality products you need for your projects. So, if you are working on a project that could use some aluminum brazing, contact us today.