ALUMINUM AND THE

THE PANASONIC BLUES

 

This company welds 6xxx series, extruded aluminum, thin gage parts. They had purchased a “Panasonic VR OOGAL 11” robot, with a 350 amp Panastar, RA 350, pulsed power source. They weld with a 1.2 mm, 4043 wire. The MIG wire spool is mounted on top of the robot, and they used a regular four-drive roll feeder with a standard water-cooled gun.

 

The problem robot welds were 5/8 to ¾ long. The robot welds are made on aluminum square tubes 0.070 thick. The tubes are welded to a thicker alum part 3/16 thick. Since they purchased the robot the completed welds never look consistent over their length. All the thin tube welds were made with the same weld data, yet some welds look fluid while other welds look cold. Most of the welds end up with a black and dirty appearance yet we use a push gun angle and the weld voltage is correct. These welds caused so many issues the company was ready to give up the robot and go back to manual GTAW.

The reason the company purchased this robot, is the owner of the company took some sample alum parts to the AWS weld show. At the show a Panasonic rep impressed the owner by producing some “manual” weld samples. On these samples the welds were four inches or longer. In the 12 months since this company purchased the robot, they have never produced a part with welds that look as good as the weld show samples. Panasonic experts and and the robot integrator personnel spent many weeks at this company and they did not resolved the welding issues.

THE CUSTOMER ASKED ME TO REVIEW THE APPLICATION.

After evaluating the equipment, process and application, the primary problem was found in the power source and its response time.A factor few power source manufacturers give consideration to, is called “time”. It takes time for a welding arc to stabilize. It takes time for a robot interface to communicate to a MIG power source.The robot interface has to inform the power source of the required,

[a] weld start data which then needs “time” to change to
[b] the weld data, which then needs time to figure out
[c] the pulsed data which needs time to change to
[d] the weld end data.

It takes some pulsed welding equipment more “time” than other equipment to perform it's electronic pulsed diagnostic check. It takes “time” with an aluminum weld for the plasma arc to break the aluminum surface oxides and provide an oxide free area for the weld. It takes a specific amount of time for each weld depending on the heat in the part for the aluminum to become fluid so the weld can proceed.

The pulsed aluminum weld issues were generated simply because the weld cycle time was lower than the time required for this specific robot / interface power source to respond. Having the long weld lengths produced manually at the weld show simply did not address the short weld length / time issues.

I believe Panasonic may have addressed the time issue with it's new "Artificial Intelligence" (AI) power source. Please note. This specific application was really unique in it's very short cycle welding requirements. The Panasonic power source used was not up to the challenge. Their was equipment out there better suited. The new Panasonic AI equipment will be justified if it resolves the issue, otherwise stay away from intelligent power sources and instead make intelligent weld process and equipment decisions.

Weld process note:
When welding with a robot. Never use a small spool of aluminum wire when you can use a large reel with larger cast and less helix issues. The Alco Tec de-reeler is the most practical method of feeding wire to a robot, its also one of the best aluminum wires you can purchase. For many applications the dee-reeler and >0.046 can be used without a push pull gun.