Help, Please.

Date 06-17-2003 21:26

I recently posted "wobbly welds" on this forum. Since then I have borrowed an Miller Econotig ACDC to have a go at ally welding.

When I used the DC on mild steel and SS my runs where neater and they started to look more professional.Is this because the set is a transformer set or is it because my inverter is one of the cheaper models. I am really happy with the way I am performing using this machine(the miller). I feel I am progressing now( on SS and MS but not ally).

My first few attempts were OK whilst welding a run on top of a peice of ally. However I tried to do a lap weld and what a mess. I was either burning one back and the other did not heat or the bottom heated and went through before I could get the heat on to the top one. Then the puddle stayed a dull appearance with a slag on top and it would not move. Could anyone offer advice. I am on 1.6 rods and tungsten, pure argon using 1mm ally with a lap joint. I have now got multiple pieces with nearly one rod used on welds 15mm long. It looks awful.

One more thing, on mild steel if the weld has a dull grey appearance as if reheated, what causes this is it too low CFH.

By 49DegreesNorth (**)

Date 06-18-2003 00:27

Aluminum is hard! You need to keep practicing at it. You are using AC, right? It is very, very important to clean the aluminum thoroughly. Still, it is difficult, and the line between getting enough melt and blowing through is very fine.

I'll be interested to hear what other people say, as I suck at welding aluminum, too. I'm using an Invertec 205, and I know it is me not the machine as occasional welds have come out great.

Cheers,
Chris

By welder_guy2001 (***)

Date 06-18-2003 01:36

put it on AC current, and around 100 amps, and the gas on 20 CFH. use pure tungsten, not the thoriated tungsten that you're using on mild steel and SS. i don't know what size it is in mm, but a .040" or 1/16" tungsten should be good. sharpen the tip and if while you're welding you see the tip ball up, that's good. if the tip looks like it's forming a drop like it's melting and falling off, the tungsten is too small. keep the tungsten as close to the joint as possible so the heat doesn't spread out and heat up a bigger area than you need. sometimes it's easier to learn how to weld aluminum on 1/8" (around 2.5 mm i believe) scrap pieces because it's more forgiving when it comes to burnthrough.

By jwright650 (*****)

Date 06-18-2003 11:27

UKmxer,
Use the "search" function on this forum and type in "aluminum". Change the "max post age" to a larger number(the larger the number, the farther back in time it will go looking), and set the limits to 100(to get the most out of your search). You should get a wealth of info back concerning tips and difficulties that others have had welding aluminum.
Hope this helps,
John Wright

By MikeR

Date 06-23-2003 16:49

I don't know how thick 1mm is, but it sounds pretty thin. On thin aluminum lap joints, fit up is CRITICAL!! If there are any gaps, or ifthe top piece lifts up because of heat, you're done. Use plenty of tacks. Also, point the arc straight down on the joint, with your usual lead angle.

By welder_guy2001 (***)

Date 06-24-2003 01:13

very true...and in fact, it would be great to put a thick piece of copper, or at least steel, underneath the aluminum and clamp it down so it can absorb the heat. that would greatly help the situation.

By billvanderhoof (****)

Date 06-24-2003 04:10

1mm= 1/25.4 inch. More than a 32nd less than a 16th.
Bill