How to Bond Aluminum without Welding

Last Updated: July 21, 2021

using-old-fashioned-welding-to-solder_Jacktamrong_shutterstock

Aluminum is by far one of the most utilized metals on earth, explaining why 75% of aluminum is still in use across the world—it can be recycled many times. The metal is preferred by many due to its flexibility, and you can bond it in many ways.

While welding is one of the most efficient ways to bond two aluminum pieces, it’s not the only way. For example, you have an option to glue them together using aluminum adhesive.

Other great ways to bond aluminum include:
  • Aluminum Epoxy
  • Brazing
  • Riveting

All these are alternative options that help you join aluminum but won’t require any welding to complete the process. To better understand them, it’s crucial to understand each step-by-step process and note what you need.

Additionally, when working with aluminum, you know the importance of preparing the surface before the process can commence.

Below are the different ways to bond aluminum without welding.

How to Bond Aluminum using Aluminum Epoxy

Ever heard of aluminum epoxy?

Aluminum epoxy is a bonding agent made specifically for this metal. Aluminum is a diversely used metal that many people enjoy working with for numerous reasons. Not only is it long-lasting, but it doesn’t rust.

Two points stand out when you opt to use aluminum epoxy as your bonding agent. One is the possibility of metal oxidation. Oxygen reacts with aluminum to form aluminum oxide. Unlike the pure metal, the oxidized version isn’t ideal for bonding with aluminum epoxy.

It’s impossible to form a tight bond using aluminum epoxy once the metal’s surface has a layer of aluminum oxide. The best way to prevent this is by using a clear coating to cover the metal surface.

Apart from oxidation, another concern is galvanized corrosion that can affect aluminum pieces or sheets. It happens even though aluminum is non-corrosive on its own.

Once the corrosion occurs, having a lasting bond isn’t possible, which is why it’s crucial to electroplate the aluminum first. The best option is to use gold or nickel, which are corrosion-resistant even under electrical contact.

After you take care of these two situations, you can now prepare the surface for bonding.

Surface Preparation for Aluminum Bonding using Epoxy

Aluminum epoxy is one of the best adhesives to use when you want to bond aluminum successfully. But, before you start using it, you must take the time to prepare the surface properly. Dust, dirt, and other particles on the metal surface will interfere with the metal’s general bond. Also, the adhesive isn’t capable of by-passing this top layer.

To clean aluminum properly and ensure the surface is ready for bonding, you must use trichloroethylene. It’s the best product to conduct what is known as degreasing, which means cleaning the aluminum surface.

Want to know more about degreasing? The process is necessary to get aluminum ready for bonding and must be done despite the surface appearing clean.

Other ways to degrease aluminum surface is by using:
  • Hot distilled water to rinse the surface
  • Soak in a 20% water solution, 10% sulfuric acid (96%), and 3% sodium dichromate.
Once you clean the surface, the next part of preparation is as follows:

1. Use Sandpaper

Using sandpaper on the aluminum surface is a crucial preparation step that helps to rough it up. The abrasion process ensures the glue can grip once you apply. Follow this using the same wiping agents to clean the surface again.

2. Use Deionized Water

Rinse the surface with deionized water after completing the surface cleaning. Now the surface is ready for proper bonding without wielding.

Joining Clean Aluminum Surfaces

Once you clean the surfaces, the next step is applying the glue. Follow the instructions to the letter for the best results.

Check to see if there’s a recommended epoxy hardener to mix it with, then use the proposed tool to apply it. You can now proceed to join the two parts together, ensuring you don’t leave any gaps in-between.

Leave them out for some time for the boding to form. You can clamp the two parts together to give the aluminum proxy ample time to cure and form a lasting bond. Clamping is one way to ensure a tight bond.


Step-by-Step Guide for Brazing Aluminum

Brazing involves joining two or more aluminum pieces using a filler metal. The filler metal must be molten and free-flowing for the process to work.

Once you have the metal pieces in position, you let the filler metal flow through the small openings without any assistance. Once the filler metal wets the aluminum joints, it’s cooled to form a lasting bond.

What makes brazing a good option for bonding aluminum? When aluminum undergoes brazing using a filler metal, it becomes stronger. Not only that, but you increase its ability to resist corrosion.  

One point to note is while the filler metal is molten, the aluminum must remain stable throughout the brazing process. It’s necessary to ensure the filler metal can cool once it fills the gaps between the aluminum pieces.

Nonetheless, to properly braze aluminum, you need the following tools and materials:
  • Aluminum
  • Superalloy 1
  • Blow torch
  • All-purpose flux

Preparation

Before you commence preparing the aluminum surface, followed by brazing, you must wear protective clothing.

Since you’ll be using fire, it’s best to wear flame-resistant clothes, including shoes and any other accessories like gloves. Safety is crucial at all times when handling fire.

Preparing the Aluminum Surface

Brazing works to the bond aluminum surface like welding when performed on clean areas. The best way to start cleaning is to remove all dust from the surface, followed by applying a degreasing solvent.

The solvent removes what you can’t see with the naked eye, including all particles that can interfere with the bond.

Continue the process with sanding, grilling, or sandblasting the joints or the place that needs repair. Having a rough surface gives the brazing filler material the ability to form a stronger bond. Once you’re done, support the pieces by clamping them together.

Brazing the Aluminum

Pick your filler rod and dip it into all-purpose flux. The flux must be suitable for the aluminum and surrounding temperature. Proceed to also pour some in between the metal pieces joints or area that needs repair.

Take your torch and heat the joint area of the aluminum pieces or area needing repair until it’s clear. Though hot metal is bright orange, flux makes it clear. Simultaneously, melt the brazing metal in a metallic container and pour it into the joint or crack length.

In case it starts to cool, you can move the torch to keep it molten until it fills the whole area. Leave the filler to solidify, and then remove flux by dipping the joint in cold water. Once it cools, you can brush the area with an emery cloth then apply a coat of rust-resistant topping to prevent corrosion.


Riveting Aluminum

You can use rivets in any process that requires bonding aluminum; all you need is a riveting gun and rivets. Rivets have a long history that can be traced back post-WW1 and continue to be a bonding method of choice for many.

While the whole concept of using rivets isn’t new, the type of rivets used has evolved to what you get in hardware today. Now they serve a great purpose, especially when you have repairs to make on an aluminum surface.

Among the most popular rivets you can find are the blind rivets that are easy to use. Once you master how to operate the riveting gun, you can begin the bonding process.

A blind rivet has two parts:
  • The central wire that comes with a nub at the tip
  • Tubular rivet

All rivets are easy to use on aluminum and other metals since the whole structure comprises soft metal.

How Does Riveting Work?

Well, all you need is a pulling motion to use the rivet for bonding. Simply pull the central/inner wire between the tubular parts of the rivet out the other end. This end is the part underneath the two pieces of aluminum you’re bonding.

In the process, the rivet undergoes flaring, which is how the two aluminum sheets or pieces are bonded.

One advantage of this is that you can remove the rivets later on without damaging the surface.

Preparing an Aluminum Surface for Riveting

Cleaning is at the top of your to-do list as you get ready to use rivets on aluminum surfaces or sheets.

After cleaning, you can proceed to grind any sharp edges. At times you might need to cut the aluminum sheets to smaller sizes leaving behind sharp edges. Then you can use a polishing wheel to get everything nice and smooth.

Riveting Aluminum Surfaces/Sheets

How would you like the rivets to line up on your aluminum surfaces? Use a ruler and pencil to draw this out, which gives you an excellent and neat layout. You can also use a permanent marker to place dots where the rivets will go.

Once you have the marks in place, stabilize the surface using a clamp on. You’ll need to use force to drive the rivets in which you can quickly move loose surfaces. Also, it’s dangerous to work with a rivet on an unclamped surface.

While you clamp, ensure the rivet marks are visible. Follow this by placing a rivet on the riveting gun, and place it directly on the marked spot. (X marks the spot). Remember, the longer end of the rivet goes into the gun while the head and cap remain on the outer part.

Proceed to squeeze the handle while pressing the gun down to release the rivet and bond the two surfaces in place. Repeat the procedure on all marked spots until the whole area is secured.

In case any of the rivets aren’t on the right spot, you can use a drill to get it out and repeat the riveting process. However, you can’t reuse a rivet once you drill it out.

Conclusion

With these three ways to bond aluminum, you no longer have to rely on welding alone for the process. You can use adhesive, brazing, or riveting to get the job done. The bottom line is to know how all the processes work and what you need to make excellent aluminum bonds.

Check out some of our top-trending posts:


Featured image credit: Jacktamrong, Shutterstock

Cameron Dekker
 

Cameron grew up in Allentown, Pennsylvania, a once-proud steel town on the Lehigh River, where he got a taste of TIG welding in his high school shop class. He holds certificates for Certified WeldingEducator (CWE) and Certified Resistance Welding Technician (CRWT) from the American Welding Institute. His interests include scuba diving, sculpture, and kayaking.