Process controls / parameters for TIG

By M.Lindsey Date 06-12-2002 15:37

I have been helping a supplier resolve some porosity problems that have occured when TIG welding small diameter (.375 OD) 6061-T6 aluminum tubing. We performed a design of experiment where we controlled certain factors in the process to see which affects the porosity the most. Some of the factors included cleaning method, nozzle diameter, filler rod supplier, current frequency, and shielding gas flow (argon). We were not able to produce any definite results pointing us to a direct cause. Does anyone have any input or thoughts on what type of controls that are needed to be establashed to reduce or eliminate porosity on aluminum welds? Thanks.

By HINZEAR Date 06-26-2002 22:14

We do not tig aluminum, but we do have pin hole problems on stainless. We have reduced our problems by eliminating tungston contamination. We grind stainless rod only on a grinder only for stainless. We were using mild, galv. and ss on the same grinders.

Side note, we have used lab-metal on our porosity holes, and powder coated with success.

Hope this helps.

By DGXL

Date 07-01-2002 00:10

Sounds like a SPC exercise. Does the cleaning include types of materials used (e.g., lint free rags), flow rates w/a specific nozzle size, dimensional properties of the joint including tolerances and variations, etc.? It appears what you want is to identify the cause or source of discontinuities and not key characteristics of the process.

Fine pores in Al are common, what does your AC require?
Is your client trying to completely remove all porosity?