automated aluminum gmaw

Date 02-19-2002 12:58

I can offer some opinions based on my own experience.
1) For strength and conductivity, 5356 filler is correct for 6061-t6.
2) Helium is generally added for thicker sections of aluminum.
3) Using a push system for aluminum wire is a tough way to go and will often cause a lot of headaches with "birdnesting" as you described. I know of no filler metal that in itself will solve this problem. A teflon liner may help.
4) A dirty weld area can be caused by A) dirty work piece, improper or inadequate cleaning prior to welding. B) inadequate shielding gas. C) inproper electode angle or improper direction of travel.

Mike Sherman
Shermans Welding

By jhayes Date 02-19-2002 13:50

hey michael. using helium for higher heat input for faster travel speed, and currently using a teflon liner. torch to work angle looks good. would higher magnesium content 'stiffen' the wire, higher silicon keep the weld cleaner, and do you know of a commercially available wire meeting these requirements?
thanks, jh

By Michael Sherman (***)

Date 02-19-2002 21:58

I would be careful changing the composition of the filler metal, unless it just does not matter (your decision here). Larger diameter wire will by nature push better. Do you have any other choices in the process or the equipment that the welding is being done with? If not, I am afraid that I am out of suggestions at the moment.

Mike Sherman
Shermans Welding

By jhayes Date 02-20-2002 11:17

the weld composition is not critical. the only real welding concerns are surface appearance, and burn through. i'm just trying to reduce cycle time and eliminate (if possible) the need for our cleaning operation. i'm using .045 wire right now, but would be willing to try thicker diam. unfortunatley, i don't have a whole lot of options regarding process and equipment. it's a pretty basic shop i work for and i'm having enough trouble getting consistant parts for the assy'. thanks for the help mike.

By BP Maas (**)

Date 02-19-2002 13:22

This question asked raises numerous questions, best long term answer for yourself and your company is to attend AlcoTech's welding school in Traverse City, MI It is only three to four days.
Short Term Answer: Mount your drive rolls or feeder 4Ft away from the torch, don't know the robot name, but they all have methods for this.
If you are not anodizing after welding consider 4047 filler, you can get an almost "smut free" weld, have someone wipe the parts immediately after welding with a cotton cloth, the smut will come off easily. Use 100% Argon on thin sections with any filler for 6061.
Tune the drive system, drive roll pressure, alignment, liner, contact tip for aluminum wire, etc.

Regards, Brad

By jhayes Date 02-19-2002 13:54

hey brad. we're using a 4' long whip, teflon liner. drive roll pressure is minimal, alignment is good, contact tips are clean. will look into 4047.
thanks, jh.

By DGXL

Date 02-20-2002 01:59

JHAYS,
Had a client last year with an identical problems such as yours. While observing the production welding, I noticed the gun angle while the welder was welding. I had him change his work and travel angles, the clean-up problem was solved in a few seconds. All the soot had disappeared completely.

The above posts are good ones as far as feeding the filler metal. Make sure the tension or pressure on the drive rolls is not excessive. Too much pressure on the wire will cause it to deform or, flake and jam after it builds up within the liner and contact tip, or both.

Also agree with the idea of attending one of Alcotec's courses. I have attended one of their seminars and found it to be excellent. Very well informed speakers.

I also agree with sticking with the 5356. You'll spend more dough repairing welds than you will baking it.

By jhayes Date 02-20-2002 11:31

the part requires flat lap welds and vertical (down) fillet welds. my travel angle is about 15 degrees for both. for the lap welds i've had to go to 20 to 30 degrees from flat. the reason for this is to compensate for inconsistant joint fit up. the fillet weld angles are around 50 degrees with the wire toward the thicker of the two sections. wire stick out is 13/16" with a 5/8" diameter nozzle. considering changing to a 3/8" diam. nozzle for better joint access, and less stickout. what kind of angles do you reccomend?

By DGXL

Date 02-20-2002 17:22

JH,
The welder I was observing was welding lap and T joint fillet welds. This was a thick to thin application (sheet to extrusion). I ran a few beads and showed him how to hold the gun. He duplicated what he observed.

I basically had the welder point the gun directly into the joint (travel angle) now at approximately 90 degrees to the axis of the joint. This was used in lieu of his forehand technique. In other words, he was no longer using a forehand (push) or backhand (drag) angle.

The work angle was now at approximately 45 degrees (centered between the 90 degree parts) from the surface of the vertical and horizontal members of the T joint.

What had actually occurred was the welder now had the still molten weld material well within the shielding envelope. (The shielding gas was evenly distributed around the arc).

One more important item, I reduced the gas flow to about 45 cfh. He had about 60 - 70 cfh as noted on the flowmeter. This was reduced after we modified his technique and the welds magically became clean by themselves. There was concern there would not be enough shielding, but he was surprised to find out (so was the owner) how much gas he was wasting and the fact that he was probably drawing in atmosphere through the vortex created by the high gas flow. As we all know mixed gases are not cheap.

By jhayes Date 02-20-2002 19:59

well, my gas pressure is around 35 to 40 psi already, but i'll try changing the angles tomorrow. thanks.