CANADA'S LEADING INFORMATION SOURCE FOR THE METALWORKING INDUSTRY

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CANADA'S LEADING INFORMATION SOURCE FOR THE METALWORKING INDUSTRY

CANADA'S LEADING INFORMATION SOURCE FOR THE METALWORKING INDUSTRY

TECH TIPS: What to know about feedability in GMAW aluminum welding

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This TECH TIPS is provided by the experts at ESAB University.

When moving from GMAW welding of steel to GMAW welding of aluminum, feedability can become a problem and lead to issues, like fusion of the aluminum welding wire to the contact tip. This requires a breakdown of the feeding system and replacement of the contact tip.

How can you avoid these time-consuming troubles when switching to GMAW welding of aluminum? Here’s what to know.

Feedability in Steel vs. Aluminum

Feedability is a bigger issue with aluminum than steel because it is so much softer. It’s more susceptible to deformities or shaving off during the feeding operation, as a result. This means it needs more attention when selecting and setting up a feeding system. Otherwise, you’ll wind up with problems, like an irregular wire feed or burn-backs (which is the fusion of the welding wire to the inside of the contact tip).

Understand the Feeding System

To avoid these kinds of issues, it’s important to understand the feeding system and properly set it up. It includes:

  • Spool:  Starting with the spool end, first consider the brake settings. Brake setting tension should be backed off to a minimum. Any pressure above this will trigger feeding problems and burn-backs.
  • Inter Inner and Outlet Guides and Liners: Inlet and outlet guides, as well as liners must be made from a non-metallic material such as Teflon or nylon to prevent abrasion and shaving of the aluminum wire.
  • Drive Rolls: Only use drive rolls designed specifically for feeding aluminum. These have U-type contours with edges that are chamfered and not sharp. They should be smooth, aligned, and provide correct drive roll pressure. Drive rolls that have sharp edges can shave the soft aluminum wire, then collect within the feeding system and cause blockages. Excessive drive roll pressure and/or drive roll misalignment can also cause deformities with the aluminum wire and increase friction drag through the liner and contact tip.
  • Contact Tip: Only use contact tips made specifically for aluminum wire welding. The contact tip should also have smooth internal bores and the absence of sharp burrs on the inlet and outlet ends of the tips. Contact tip bore diameter should be approximately 10% to 15% larger than the electrode diameter.
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