Robotic welding aluminium
Robotic welding aluminium
(OP)
Hello and thank You in advance! I have been charged with setting up and programming an old GE P-50 welding robot to Mig weld .060" and .080" aluminium. I am using .035 aluminium wire and a Miller deltaweld 450 welder. I have done a fair amount of laser welding in the past but am not very experienced with mig welding. I was hoping that someone could give me some advice on where to start as far as speed, amperage, voltage, wire feed rate, etc. Weld quality is more important than speed for this application. Any tips tricks or info would be greatly appreciated!
Thanks, Fingerz
Thanks, Fingerz





RE: Robotic welding aluminium
Al has great heat conductibility.
The equipment manufacturers such as Miller, Esab and Fronius have synergic database for welding. They have for aluminium too. If quality is most important, it depends on the legths of the weld. The longer you weld, the more heat you introduce the space between the Al plates will get wider and wider. Thus you should be very carefull with the heat you introduce. To controll this, the welding current comes lower and lower according to a certain current slope, that manufacturers programmed in the memory unit of the source. If your source is not synergic, that's also not that big problem (I hope), ask your Miller dealer to give you this database and you programme it into your robot.
The synergic sources have inside database, you only introduce parameters as type and thikness of parent material, gas type, type and diameter of wire, and it gives you the wirefeed, volts and you can only fine-tune them, depending on your specific task, several percent + or -. This way you can not miss too big with the parameters.
Other problem would be Al2O3 from the surface of the plates, it is 4 times heavier then Al, so when welding, it goes to the root of the weld, or remains inside the weld, anyway, you have a fair chance for craks. Clean material is essential. The ionised Ar gas brakes that oxid while welding, if there is not too much.
If you weld tubes, you might want to protect the root from inside with forming gas (I would use Ar, but you have to check the pressure inside the tubes, it can blow upwards the weld), and outside you weld it.
RE: Robotic welding aluminium
Even if you get all the parameters, I guarentee you will still have problems.
Wire feed consistency is the key. You need a push/pull wire feed unit. Keep the length of your welding torch short if possible without too big an angle in it. Use a shorter hose package.
Your contact tips must be the aluminium rated type i.e they are slightly bigger inner diameter due to the aluminium wire expanding with heat. Get a rep to supply you with alu rated..!
Try and use only 15kg welding spools of wire if possible.
Gas flow is critical, pre gas flow is critical as well. Make sure you program a pre gas flow before you ignite the arc.
You may find you welds are very cold and porous at the start, try starting your weld lenghts 5mm or so down the seam, then quickly drive the robot back to the start with the arc on, then weld over the top.
Failing this for total removal of porous weld, you can try a lighter gas i.e Helium, it's expensive but its fantastic for alu welding.
If you want anymore help let us know....
RE: Robotic welding aluminium
I wouldn't use He. That is used for stainless steel. At the aluminium welding process you use Ar, because they are heavy molecules, with a much higher ionizing potential, so at welding you phisically bombard and destroy the Al2O3 from the surface of the Alu plates. You have to do this because the melting point of the Al is at about 723 Celsius while Al2O3 from the surface has roughly 2500 Celsius melting point. Helium is not heavy enough for this purpose.
You could use some Ar75%He25% gas. That would help. Also you could use pulsed welding current, it has the same effect as a.c. current at WIG welding.
Also 28021973 is right about the contact tips and push/pull unit.
RE: Robotic welding aluminium
You would end up with tooling costing you 10x the price by adding this to all weld seams, if it was at all possible.
Then there would be additional costs for clamping and unclamping sequences in the process, plc programming, cross communications between plc and robot. Access for the torch, what about a tandem wire feed torch, its a lot larger than a standard mig torch.
We had porosity in a job using aluminium and the Welding Institute recommended using Helium, the lighter molecules in Helium allow the gas to escape in the early part of the weld before the weld pool cools. Because the weld pool is cold at the beginning due to good conductivity of ALU, this traps the ARGON underneath the surface of the weld causing porosity. Hence, no need for welding plates..!
www.twi.co.uk
ionization properties = 24.587 Helium
ionization properties = 39.948 Argon
Correct on this assumption.
Attilion - Your theory is 100% correct I cannot disagree with you, but in Practise, and I have over 10yrs ALU robot mig welding experience, it doesnt work.
Until im prooved otherwise, I will live and die by my own methods.
RE: Robotic welding aluminium
Also that's why I like welding. It can work in many ways, and then people wouldn't try something else if they already found a way. And they are right about it.
I also have some experience with many kinds of aplications, beeing welding engineer for eight years. I'm also sure that with the "begin somewhere and come back" starting method you can never garantee that underneath the start you wouldn't left some pores, but if you dont't have other choise, that would be the best shot you've got.
Regarding shield gases, ionization properties and arc stability (Ar, He and Ar-He) for Aluminium MIG you can check this link: ht
Now the materials welded by Fingerz are thin, so keeping this in mind I'd do as follows: first I'd try pure argon, if it wouldn't be ok, then I'd try Ar+He, and only if that wouldn't give the required quality only then I'd shift to pure He.
RE: Robotic welding aluminium