Welding Aluminum 2

[ukmet]

Dear All,

We are making a conveyor belt structure of aluminum. Its the first aluminum job in our workshop and repeatedly its welding got cracked or piece got over heated. I studied on it and came out with following points:

1. use a heat sink to avoid over heating
2. remove the oxide layer from aluminum with help of SS brush or amri paper.
3. preheat the piece before welding
4. use 4043 wire (right now we using 4047)

Are these points ok? If not can you guide me please? We have not implemented these points yet.

 

[berkshire]

You do not say what the grades of aluminum are that you are welding. 5000 series will weld quite well ( 5356 or 4043 rod). Some of the 6000 series alloys will give you a little difficulty, see how you do with 4043 rod.
B.E.

 

[ukmet]

Sir we are using 6061 and wire 4047. Guide please

 

[metengr]

Switch to the 4043 or 5356 for welding 6061. You are having solidification issues with using 4047. There should be no preheating required. Since this is your first experience with welding aluminum, look here;

http://www.lincolnelectric.com/en-us/support/welding-how-to/Pages/guide-aluminum-welding-detail.aspx

 

[ukmet]

thankyou metengr sir. Can you please guide on using GTAW for aluminum?

 

[kingnero]

GTAW is a good choice for this. I do not understand how overheating happened though. Can you post pictures?
You might want to consider ron-on and run-off tabs depending on your welding geometry.

Cleanliness is very important. As you said, thorough cleaning with SS wire brush and welding immediately after (not the next day).

 

[ukmet]

Pictures not available right now. Can you further elaborate on run on or run off tabs?

 

[metengr]

Can you please guide on using GTAW for aluminum?

http://www.maxal.com/files/QuickSiteImages/Maxal_Guide_for_Aluminum_Wldg_6-11_doc.pdf

 

[Metalfixer]

Depending on the thickness of the material, I've been using a spool gun.

http://www.millerwelds.com/products/wire_feeders/pistol_grip_-_spoolmatic_30a/

Spool guns are available in different sizes, and are sometimes easier to use
instead of GTAW for certain applications.

 

[kingnero]

cracking might happen because of % of certain elements (Si, Cu, Mg) are within a given range. the rods or wire you're using should be of such a chemical composition that these ranges are exceeded, and you get into the weldable range. When starting and stopping a weld, one typically doesn't add metal but just but keeps the weld pool molten (by lack of better description). Hence there you might fall back into the dangerous ranges. Using run-on/off tabs, you start outside your actual weld and hence the possible zones that are prone to cracking can be easily removed afterwards.