Aluminum is the most abundant metallic element in Earth’s crust. It is the most widely used nonferrous metal and can be tricky to fix with other metals as it is a fairly soft metal and can’t cope with too much heat.
Since we use this metal from indoor to outdoor, we need the appropriate joining techniques. And we often ended up choosing either welding or brazing.
But which one is right between brazing vs welding aluminum?
This choice depends on your requirements. Brazing can offer various metal-to-aluminum joints whereas welding is suitable for big aluminum projects.
What Is Welding?
Welding is a fabrication process that joins materials by using high heat to melt the parts together and allowing them to cool, causing fusion.
By melting the base metal, a filler material is typically added to the joint to form a pool of molten material. It is called the weld pool that cools to form a joint that can be stronger than the base material (parent metal). You can use pressure in conjunction with heat or by itself to produce a weld.
A form of shield is required to protect the filler metals or melted metals from being contaminated or oxidized.
Many factors influence the strength of welds and the material around them, such as the welding method, the amount and concentration of energy input, the weldability of the base material, filler material, flux material, the design of the joint, and the interactions between all these factors.
Various types of welding are –
- Electric resistance welding
- Gas tungsten arc welding
- Gas metal arc welding
- Gas tungsten arc welding
- Shielded metal arc welding
- Flux-cored arc welding
- Electroslag welding
- Glass welding
- Plastic welding
- Oxy-fuel welding
- Submerged arc welding
What Is Brazing?
Brazing is a metal-joining process in which two or more metal items are joined together by melting and flowing a filler metal into the joint.
The filler metal should have a lower melting point than the adjoining metal. The filler metal flows into the gap between close-fitting parts by capillary action.
The filler metal is brought slightly above its melting temperature while protected by a suitable atmosphere, known as flux. It then flows over the base metal and is then cooled to join the workpieces together.
The atmospheres should include air, combusted fuel gas, ammonia, nitrogen, hydrogen, noble gases, inorganic vapors, and vacuum.
The heating sources are:
- induction coil.
Types of brazing include the following:
- Torch brazing
- Silver brazing
- Furnace brazing
- Braze welding
- Vacuum brazing
- Cast-iron welding
- Dip brazing
Which One Is Easy For Aluminum – Brazing or Welding?
Welding and brazing both provide a robust and permanent joint, and they have their applications. Check out the comparison chart and differences, which are mentioned below, before going for a process.
|Melting point||The filler metal has a lower melting point than the adjoining metal||Filler metal has a higher melting point, like soldering|
|Melting the base metal||Fabricators don’t melt the base metal||Fabricators melt the base metal and each workpiece together.|
|Joining process||Capillary action||Fusion.
|Joining multiple alloys with aluminum
Aluminum welding needs many additional supplies such as shielding gas, filler well, and electricity. The cost of these shielding gases like argon and helium, and other materials are not cheap. So, the welding process is a bit costly.
But these aren’t necessary for aluminum torch brazing, which makes it much less expensive than welding. Again, brazing needs less heat that translates to less energy, which also contributes to lessening the cost.
Both aluminum brazing and welding require high heat. But aluminum brazing with gas torch does not need working with high voltage and electricity like welding. Hence, it is a more comfortable and safer way for metalworkers.
Tip: Wear non-flammable clothing, gloves, and safety goggles before you begin the brazing process.
If the aluminum and the adjoining metal are thicker than 0.5 inches, both techniques will work well. But the high heat involved in welding is difficult to use in thin metals because it can burn through or warp the thin metal while brazing’s broader heating and lower temperature join the metals without distortion.
Joining dissimilar metals
Brazing holds a significant advantage when joining dissimilar metals. If the adjoining metal has a different melting point, brazing is the optimal metalwork choice you have to go for. It’s challenging to fuse two metals with different melting points. So brazing solves the problem here.
Joining Metal To Ceramic
It is nearly impossible to weld aluminum to ceramics, but such a combination can be brazed without much difficulty. As brazing involves relatively low heat, it can incorporate ceramics into metals without damaging the ceramic.
Moreover, intermediate layers of materials can be brazed between the metal and the ceramic to absorb any stresses resulting from different material expansion.
Works On Multiple Alloys
Aluminum brazing can work on any alloy of aluminum or cast aluminum, allowing you to use this technique for many different projects. This versatility makes it a better choice over the welding.
The size of the assembly is an important consideration here. Welding is preferable for joining larger masses. Use brazing for smaller projects since heat reaches broader areas and tends to lose quite fast in this process.
Losing heat means losing energy that makes it difficult to reach the flow point for the filler metal. Welding’s intense localized heat overcomes this drawback.
Aluminum brazing is much faster than any welding. It makes brazing a better option for metalworking projects that have to be done fast.
Both welding and brazing can produce spot joints. If you are joining two metal strips at one point, the localized heat of welding offers the advantage of speed and low cost. But when it comes to linear joints, brazing is preferable to welding as it requires no manual tracing, unlike welding.
Subjective To Temperature And Surroundings
While aluminum brazing and welding both are equally strong, brazing is easy to regulate. Firstly, lower temperature allows the metals to retain the tensile strength of the base material without being affected by heat damage. Again, aluminum is less subject to oxidation, porosity issue, or other joint damage issues in lower temperatures.
Tip: Go for an all-purpose flux which covers a wide range of temperatures and is advantageous for general purpose brazing.
Ease Of Use
Brazing is a relatively uncomplicated process than welding. The operators can acquire brazing skills faster than welding. A linear welded joint has to be traced with precise synchronization of heat application and deposition of filler metal. In contrast, a brazing joint is more automated and does the job through capillary action.
Brazing wins here also. Brazing produces tiny neat strip joints that are more attractive than the irregular bead of a welded joint. Hence, brazed joints can be used without any additional finishing operation most times.
Maintaining Dimensions Of The Finished Product
The high heat in welding can often distort the dimensions of a finished assembly. But the base metal is never melted in brazing that provides a smooth finish minimizing dimensional distortion. If you need precision in your work, you should go for brazing.
Welding vs Brazing – Which One To Choose?
The choice depends on your preferences. Welding joins metals by applying concentrated heat at the joint to melt and fuse them, usually adding filler metal. Here the filler metal has a higher melting point, and the temperature must exceed the melting point of the metals and the filler.
On the other hand, brazing involves considerably lower temperatures and does not melt the base metal. It melts the filler metal and draws it into the joint using capillary action. It works by creating a metallurgical bond between the filler metal and part surfaces.
Brazing is quick, portable, and inexpensive option for repairing leaks, cracks, or holes in aluminum. This technique is often found in air-conditioning repairs. It does not require high amounts of voltage as well. And brazing acts like metallic glue.
In contrast, welding will always be stronger than brazing. Here, the base and filler material melt together and coalesce together. However, a proper AL weld is more difficult (no matter the process) than a AL braze.
Brazing differs from welding in that it does not involve melting the workpieces. A significant advantage of brazing is the ability to join the same or different metals with considerable strength.
Why Choose To Braze:
- Does not melt the base metal of the joint,
- Allows much tighter control over tolerances and
- Produces a clean joint without the need for secondary finishing.
- Dissimilar metals and non-metals (metalized ceramics) can be brazed.
- Produces less thermal distortion than welding due to the uniform heating of a brazed piece.
- Complex and multi-part assemblies can be brazed cost-effectively.
- can be coated or clad for protective purposes
- easily adapted to mass production
- easy to automate because the individual process parameters are less sensitive to variation
Why Choose Welding:
- Excellent joint strength.
- Suitable to join large sections
- Does not require a high degree of base-metal cleanliness when done in an industrial setting.
- Can’t be damaged under high service temperatures
- Does not require the use of adequate fluxing agents to control cleanliness.
- Keeps the joint color the same as the base metals
Do you need flux for aluminum brazing?
Yes, you will need flux for aluminum brazing to protect the joint.
Why is it hard to weld anodized aluminum?
It is hard to weld anodized aluminum for the thick coating. Since aluminum oxide melts at around 3,700 degrees F, the oxide doesn’t melt during welding.
Aluminum alloys are widely used in various projects because of their high strength to weight ratio, corrosion resistance, high thermal and electrical conductivity, and many other unique characteristics.
Though there are many techniques to join aluminum, the choices narrow down to either welding or brazing when it comes to strong and permanent joints.
So, did you find out your winner between brazing vs welding aluminum?
Let me know in the comment section!