MIG or TIG for aluminium vehicle chassis? 1

[benno]

I have designed a light electric vehicle and I'd like to construct the chassis out of 2.5 inch , cold drawn 6061 aluminum tube. I have had conflicting opinions on whether it wold be better to MIG or TIG weld the structure. I'm aware that it will need to be heat treated after welding. I am relatively experienced in MIG (but not aluminium at present) but have no experience in TIG. Are the welds in aluminium from TIG superior enough to warrant me learning TIG (and buying a rig) or could I get a good enough weld out of MIG for my purposes? Ben Roberts

Broadcast Engineer

Sentient being.

 

[pipewelder1999]

The processes each have advantages and disadvantages. Both processes have the ability to produce sound welds in various applications.

Here are my opinions regarding the different processes

GMAW- Advantages

*MUCH Faster deposition rate than GTAW.

*Less manual dexterity required in most applications since the filler metal is applied by the welding machine.

*More efficient use of ARC energy

* The gun can sometimes reach places not possible with a tig torch and filler wire since only one item is to be controlled. An example would be reaching into a cluster of tubes that come together at one point.

* It is MUCH easier to tack things together by yourself. If you have to work alone, I suggest GMAW.


GMAW Disadvantages
*Gun is Bulky compared to GTAW

*Wire feeders are sometimes difficult to maintain in good working order. (Usually due to poor maint or setup)

*Variations in material thicness require adjustment of Voltage and WIRE Feed to maintain a stable arc.

*Changing Filler metal requires removal of a spool, changing tip sizes and resetting of voltage. The equipment does not change over easily to another filler metal for a "small job". GTAW is very quick to change over. Usually nothing more than getting a differnt piece of wire if all you do is change size. If you ogo from aluminul to SS, you change current to DCSP, sharpen tungsten, and you are ready to go.

* Aluminum wire is more difficult to feed and sometimes requires the use of a push-pull wire feed suystem depending upon your application. Changing from aluminum to steel wire would usually require to change the liner in the gun.

* Because of the higher deposition rates and energy being used, changes in the joint desing or poor fitup can be a little harder to overcome. A GTAW setup with remote amperage control allows users to change setting "on the fly".

Hope this helps a little.
Gerald Austin
Iuka, Mississippi

http://www.weldinginspectionsvcs.com

 

[TVP]

In addition to the excellent summary provided by Gerald, there is a lot of good, free information available on the web. Lincoln Electric has a great site, with many informative technical articles. Use the first link to review the different categories, and the others for specific info on Al:

http://www.lincolnelectric.com/knowledge/articles/list.asp

http://www.lincolnelectric.com/knowledge/articles/content/alum.asp

http://www.lincolnelectric.com/knowledge/articles/content/alumapp.asp

http://www.lincolnelectric.com/knowledge/articles/content/comistakes.asp

Miller also has an excellent site, again, with many technical articles. Use the following link for more info:

http://www.millerwelds.com/main/education/technical_articles/

 

[benno]

Thanks for the replies Gerald and TVP I agree with you TVP, excellent summary from Gerald! Extremely useful links from you also TVP. It looks like I'll spec up the MIG machine with the aluminium stuff and get practising!

CHeers!

Ben Roberts. Ben Roberts

Broadcast Engineer

Sentient being.