When it comes to welding it can be difficult to know what welding is best for use on what type of metal. This is particularly difficult when it comes to metals like aluminium which can be prone to damage.
In this article, we will be exploring some of the most frequently asked questions regarding the use of MIG welders on aluminium, and what may need to be considered if you are welding this metal.
Can you use a MIG welder on aluminium?
You can certainly use a MIG welder on aluminium. However be prepared for it to be a little trickier to deal with than if you were welding stainless steel, for example. The reason for this is because of the higher heat needed to weld on metals such as aluminium.
You can typically expect voltages of around 21 to 24 volts to be needed for the welding of aluminium. This is not much different to the voltage needed for some other metals, but there are numerous other differences between the way you weld aluminium compared to stainless steel.
Nevertheless, it can still be done and you can expect to be able to weld thicknesses of around 14 to 18 gauge aluminium at a minimum. If you want to weld aluminium that is thinner than this then you will need a TIG welder. With a TIG welder, you can weld materials as thin as Coke and Pepsi cans!
In order to use your MIG welder for welding aluminium, you first need to ensure that the aluminium workpiece is at the correct level of thickness. You should ensure that you use your MIG welder slowly and steadily so that you avoid any mishap such as puddling. It is not uncommon to see weld puddles form due to the extreme heat needed. However, these puddles are quite different to those that can form with stainless steel.
The melting you may see on your aluminium workpiece is more akin to wet foil.
Moving the welding gun slowly will help to avoid this and ensure you penetrate the metal adequately to weld together with ease. You should also keep in mind that, when you use a MIG welder on aluminium, you will be using a spray transfer method.
This basically means that small particles of aluminium wire are sprayed onto your weld. To make this job easier you should ensure you use the correct voltage and also use the most suitable gas mixture to protect the weld.
If the MIG welding gun that you are going to be using is a wire feed welder model, then you also need to ensure that you have a spool gun. This will ensure that the extra soft aluminium wire does not ‘birds nest’ in your cable liner and can be applied much easier.
Lastly, don’t forget to use the correct gas! We recommend that you use pure argon gas rather than a MIG mix. This we’ll be preferable for the aluminium. If you have aluminium that is particularly thick then it may also be pertinent to choose a gas that also contains a small amount of helium.
This will help you to penetrate the aluminium workpiece far easier. An ideal ratio is 75% argon and 25% helium. Getting this aspect right will help you to achieve the spray transfer process needed.
What polarity is used for MIG welding aluminium?
The polarity needed for aluminium when you are using a MIG welder is DCEP. This means Direct Current Electrode Positive. The reason this is needed is to ensure that the electrons can travel through the machine and info the ground wire before going back through the gun.
You need to ensure you get this totally right to ensure that your welds come out correctly and you get a neat weld.
A good way to remember this in the future is to keep in mind that MIG welding always requires Direct Current Electrode Positive (DCEP), whether you are welding aluminium, stainless steel, or any other metal. This is in contrast with flux-cored process welding which requires Electrode Negative, regardless of what metal you are welding.
Can you weld aluminium with 75% argon 25% CO2?
We would recommend that you use pure argon or argon with helium. Carbon Dioxide is not really needed for aluminium and does nothing to improve it. Argon is a great choice, and helium is essential for helping to penetrate thicker aluminium workpieces.
Of course, if you only have an argon and carbon dioxide mix available to you then you should use that. However, it is preferable to use pure argon or argon with 25% helium on thick metal. As long as you use at least some sort of gas, especially if you plan to weld your aluminium outdoors or in a draught, then you will be fine.