You can weld almost any thickness of aluminum, from under 1mm (using specialized TIG) up to very thick sections (with powerful machines, helium, and good technique), but practical limits depend on the process: MIG generally starts at 3mm (1/8") and up, while TIG offers more control for thinner (sub-3mm) or highly detailed work, with techniques like pulsed MIG bridging the gap, making skill and equipment crucial for extremes.
2mm thick base metal is about as thin as you can get with MIG; any thinner and you'll need to TIG it.
The thickness of aluminum in industrial welding applications typically ranges from 1/8 inch to 16 gauge, but you may be welding up to 3/8 or 1/2 inch in some cases. Gas and filler metal selection, as well as proper technique, may differ depending on the material thickness and the goals of the application.
Welding thin aluminum requires skill and practice.
Aluminum is highly prone to oxidation in the air and during welding. The resulting aluminum oxide (Al2O3) has a high melting point, is very stable, and difficult to remove. It hinders the melting and fusion of the base material, and its high density makes it challenging to float to the surface.
TIG welding with an AC/DC TIG welder is typically the best choice for anything under 1/8" thickness and is often the best overall choice up to around 1/2" thick aluminum.
Pushing the weld provides better shielding gas coverage, which is crucial for aluminum. Due to its thermal properties, you can quickly burn through the aluminum, so you want your heat directed away (pushed) and evenly distributed, not build up (pulled).
It is preferably an excellent option to choose AC welding if the requirement is to weld a thin aluminum workpiece in a single pass. For thicker aluminum, you can use DC welding to achieve a greater penetration depth in a single pass.
For cast aluminum, 4043 is generally preferred due to its silicon content, offering better fluidity, lower cracking risk, and good wetting into the porous casting, making it ideal for engine parts and general repair; while 5356 offers higher strength but is better for structural wrought aluminum and applications needing better color match after anodizing, though it can crack at higher temperatures. Choose 4043 for cast components like housings or manifolds and 5356 for structural parts or when anodizing is critical.
The salt is added during the melting process, and it floats over the molten aluminum due to a lower density, protecting it from further oxidation.
There is a Rule of Thumb for fillet weld sizes that you have probably heard… “Fillet welds should be ¾ of the thickness of the material being weld.”
Preheating the casting to 200 degrees makes it easier to weld them together. Within limits, preheating can be helpful, although it's usually not required.
The 2mm aluminium sheet metal is highly sought after for the construction of robust tool boxes and storage containers, as it offers a combination of durability and portability, making it an ideal material for this kind of application.
Aluminum acts like a big heat sink and rapidly transfers heat away from the weld area, which makes puddle control crucial to success. Hand and torch placement are key to puddle control, so it's important to master torch and hand positioning first. Skipping this step often results in wasting good aluminum.
Remove Oxide
Light-pressure manual or powered wire brushing with a clean stainless steel wire brush usually removes oxides. The brush should have relatively flexible bristles that are not knotted. Be sure to use this brush only on aluminum and only after removing oil and grease from the aluminum surface.
No. This will not work. First of all, MIG welding aluminum is tricky at best. You can get away with running aluminum wire through your gun sometimes if it's in a nice straight run and you have a slick liner, but generally speaking you need a spool gun .
Conclusion. MIG and TIG are two very different processes, but both can weld aluminum. While MIG can handle aluminum using a DC, the TIG process requires the use of AC. If you plan to weld aluminum often or want to achieve the highest quality joint, AC TIG is irreplaceable.
Swapping your traditional MIG gun for a spool gun when welding aluminum can help prevent issues like binding. This guide covers the necessary equipment and settings for successful aluminum welding and provides practical tips for achieving optimal welds.
What's the number one rule in welding? The number one thing (other than safety precautions) is always welding from the bottom up.
Weldability and Malleability
Carbon content in both materials makes it more difficult to weld; however, stainless steel contains nickel which improves weldability. Regarding malleability, mild steel is generally more malleable due to its ductility.
Cracking. A problem that can be easily encountered when aluminum welding is solidification cracking or the hot cracking problem. This form of cracking in aluminum is typically caused by a combination of metallurgical weaknesses of the weld metal as it solidifies with transverse stress applied across the weld.
You should use . 030" welding wire for thinner materials (up to about 1/8 inch) because it provides better control and less heat input, reducing burn-through. Use . 035" wire for thicker materials, as it offers higher deposition rates and better penetration.
The aluminum samples bonded with Infinity Bond MMA 420 were able to withstand a higher level of force than the samples bonded with JB Weld Kwikweld adhesive.