ALUMINUM PARTS WITH OILD ON THEM

By KEVIN-CARRIER Date 03-02-2001 21:37

I AM CURRENTLY WELDING ALUMINUM PARTS TOGETHER TO MAKE A LARGE FRAME FOR THE TRANSPORT REFERIGERATION INDUSTRY. PRIOR TO WELDING THESE PARTS I WASH THEM IN A MILD ALKALINE SOLUTION AND THE AIR DRY PRIOR TO USING THEM. THIS PROCESS PROVIDES A NICE CLEAN SURFACE FOR THE OPERATORS TO MAKE QUALITY WELDS. HOWEVER RECENTLY THERE HAS BEEN SOME DISCUSSION WITHIN THE COMPANY TO MOVE TO EVAPORATIVE LUBES WHICH CAN BE APPLIED TO THE SHEETS OF ALUMINUM PRIOR TO BEING PUNCHED AND BENT. THESE PARTS WOULD THEN COME TO ME AND POSSIBLY NOT GET WASHED. WHAT COULD I EXPECT IN TERMS OF A QUALITY WELD WOULD I GET FROM A "OILY" PROCESS? IS THERE ANY AMOUNT OF OIL I CAN HAVE ON THE ALUMINUM PARTS BEFORE IT STARTS CAUSING PROBLEMS? WHAT IS THE INDUSTRY STANDARD FOR "CLEAN" PARTS?

THANKS

By BP Maas (**)

Date 03-05-2001 15:16

Sounds suspect to me, but at any rate, do a series of tests covering all your different processes up stream. If the parts come to you with out
hydro-carbons, you will be in good shape. If not keep cleaning with caustic soda.

Best of luck, Brad M.

By sparx

Date 03-24-2001 17:00

I am not quite sure of an industry standard for 'clean', but in aluminum welding (either tig or mig) Cleanliness is next to Godliness. I have found that any contamination (especially hydrocarbon based) will have extremely detrimental effects on weld quality- the weld could be made to look nice for the most part, but a cross section will almost surely show defects in the weld. Aluminum is a funny animal to weld, and if the preweld prep is not done right, the best weld in the world will suffer.

By Ti double-G er (*)

Date 03-27-2001 01:38

Kevin

I work for a ship building company that specializes in aluminium hulls. I can honestly tell you that it is my experience that contamination is the single largest factor working against a quality aluminium weld. We have done in house ndt and excavate tests with both pristine clean plate which had been brush deoxided and plates that were intentionally contaminated with pencil lines, magic marker, edge handling with dirty hands, cutting lubricants and waxes, and even tig filler rod that had been handled by "average" shop hands. In every single instance NDT found porosity, inclusions or fusion problems. The only exeption to this seems to magic marker, but time will tell. As a result we do not use any cutting lubricants or waxes on our tools other than water, and no graphite pencils are allowed on the production floor.

Good luck
....Sean

By Darvin

Date 03-31-2001 09:12

I used to weld when the government maintained mil specs and we had the following requiremnts for MIG, TIG and spot welding aluminum:

Class A (failure could cause injury) - etch and deoxidize within 24 hours.

Class B (failure could cause equipment damage)-etch and deoxidize no specified time.

Class C (failure would not cause other damage) Use descretion.

I think they are good guidlines. A problem with aluminum is the surface oxide is very refractory. And new material normally has an oxide film on it. Un-etched oily parts? I don't know. I wouldn't want to put my stamp on it. But I guess it depends on the economics and if there are any safety concerns.

Remember, if the part fails, it's always the welders fault (LOL).