Although aluminum is quite a common and popular metal which is largely used in the manufacturing and fabrication industry. However, some of its properties make it a little difficult to work with.
It is lightweight, highly sensitive, non-corrosive, soft, and is covered by an oxidized layer. Since it has a great affinity for oxygen, it makes aluminum oxide which leads to oxide inclusions and fragile welds.
Before getting onto the methods of welding for aluminum, let us first briefly understand how aluminum welding is more challenging than that of steel. Some of the challenges are sited below:
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Factors Affecting Aluminum Welding
Aluminum’s affinity towards oxygen causes the formation of a layer of alumimum oxide. The melting point of this layer is about three times the melting of alumimum. So during its welding high heat input will be required which is possible with either TIG or MIG welding.
Aluminum comes in various thickness dimensions and most of the parameters changes as the thickness varies. Like if the metal is thin, you have to control the welding arc to avoid burning. Similarly, if aluminum is thick then you have to careful penetrate through it to make a firm and durable weld.
Impurities and Porousness
If you do not give adequate shielding to the welding arc, aluminum easily gets contaminated by water, air, etc. Moreover, when it reacts with oxygen, the ductility and strength reduce to a significant amount. This whole arrangement largely affects the quality and appearance of your welds.
Coming to porousness, while welding aluminum quickly absorbs the hydrogen as it reaches a certain temperature. However, once the metal gets solidified, the hydrogen separates from it but it leaves bubbles on the surface which makes your material weak.
Methods to Weld Aluminum
Broadly there are two welding ways namely TIG (Tungsten Inert Gas) and MIG (Metal Inert Gas) through which you can weld aluminum material. Other than this, there are solid-state joining methods as well which are not that relevant at this point of time.
Although both TIG and MIG are effective methods for aluminum welding, TIG is more preferred than MIG for obvious reasons. Let’s see how we can achieve our goal in these ways.
- Before starting your process, you may use a mild alkaline solution or acetone or even effective soap which can remove grease and other impurities from the surface.
- Also, a stainless steel hard wire brush can completely remove the oxides. You may rinse the aluminum carefully as it is prone to contamination through air, dust, water, etc and dry it thoroughly.
- Now make the arrangement and put the joints as you want to be welded. However, if you are not going to weld them immediately, it is better to cover them to avoid contamination.
- The last tip is to keep aluminum dry and store it at room temperature. The important thing in all this process is to keep the joint clean and free from dirt etc.
Aluminum Welding through TIG or GTAW
In TIG welding, we can use aluminum as the filler material and since it uses alternating current so it protects the aluminum from oxidized layers as you weld.
- Since we are doing aluminum welding, go for a pure tungsten electrode. Clean and preheat your aluminum material for the weld.
- Constrict the overflow of Argon at the welding torch to avoid irregular or discontinuous arc. You can use a heat sink, it will avert warping.
- Now when you start welding, take care of the angle of the aluminum filler electrode and melt it with the base material, it will create a constant welding puddle. Keep doing it and you will get a perfect joint.
Aluminum Welding through MIG or GMAW
As we use external aluminum filler in TIG, MIG uses a wire feeding technique in which a spool gun makes the wire feeding. Further, make sure both the filler rod and your base material are cleaned thoroughly. In MIG welding, you get a perfect shielding gas which protects your material surface from contamination.
- As you did before, clean the surface, scrap the oxides, and keep the joints in the arrangement, you want to weld.
- Note that you push the aluminum at an angle of 10 to 15 degrees rather than pulling it in between.
- To give your weld a finish and a professional look, you can utilize multiple pass straight beads. It will also help you in removing defects.
- Also, use a heat sink that will absorb the additional heat.
Summing it Up
As I explained how TIG and MIG welding can help you get you a perfect aluminum welding. Besides these methods, there are other several ways you weld aluminum.
Resistance welding, shield metal arc welding, electron beam and laser beam welding, to name a few. You can avoid the welding which utilizes any kind of flux as it increases porosity in aluminum. So I hope this brief guide has added valuable knowledge to your kitty. Try it and thank me later.