Feedability in GMAW Welding of Aluminium

Feedability is probably the most common problem experienced when moving from GMAW welding of steel to GMAW welding of aluminium. Welders mostly experience equipment problems such as fusion of the aluminium welding wire to the contact tip. This requires the breakdown of the feeding system and replacement of the contact tip. These problems are time-consuming and costly. This article covers the various issues associated with feedability in GMAW welding of aluminium and how to overcome them.

What is Feedability?

Feedability, in this instance, can be described as the ability to consistently feed the spooled welding wire when GMAW welding, without interruption, during the welding process.

Feedability in Steel vs Aluminium

Feedability is a far more significant issue with aluminium than steel. This is primarily due to the difference in the materials' mechanical properties. Steel welding wire is rigid, can be fed more easily over a greater distance, and can withstand far more mechanical stress compared to aluminium.

Aluminium is softer and more susceptible to being deformed or shaved during the feeding operation. It therefore requires far more attention when selecting and setting up a feeding system for GMAW welding. Feedability problems are increased when using smaller diameter wires and softer aluminium alloys — such as OK Autrod 4043 — compared to harder alloys such as OK Autrod 5356.

Understanding the Feeding System

Feedability problems often express themselves as irregular wire feed or as burn-backs — the fusion of the welding wire to the inside of the contact tip. To prevent excessive problems of this nature, it is important to understand the entire feeding system and its effect on aluminium welding wire.

Spool — Starting at the spool end of the feeding system, brake setting tension must be backed off to a minimum. Only sufficient brake pressure to prevent the spool from free-wheeling when welding stops is required. Any pressure over and above this increases the potential for feeding problems and burn-backs. Electronic braking systems and electronic/mechanical combinations have been developed to provide greater sensitivity within the braking system and are particularly useful for the improved feeding of aluminium wire.

Inlet and outlet guides and liners — Inlet and outlet guides, as well as liners, which are typically made from metallic material for steel welding, must be made from a non-metallic material — such as Teflon or nylon — to prevent abrasion and shaving of the aluminium wire.

Drive rolls — Drive rolls designed specifically for feeding aluminium should be used. These typically have U-type contours with chamfered, not sharp, edges. They should be smooth, correctly aligned, and set to the correct drive roll pressure. Sharp-edged drive rolls can shave soft aluminium wire, and the shavings that collect within the feeding system can cause burn-backs from blockages in the liner. Excessive drive roll pressure or misalignment can deform the aluminium wire and increase friction drag through the liner and contact tip.

Contact tip — Contact tip bore diameter and quality are critically important. Only contact tips made specifically for aluminium wire welding should be used. The tip must have smooth internal bores and no sharp burrs on the inlet or outlet ends, which can easily shave softer aluminium alloys. Contact tip bore diameter should be approximately 10–15% larger than the electrode diameter.

Significance of Welding Wire Quality in Feedability

The quality of the welding wire used for GMAW welding directly influences feedability. Surface smoothness, diameter consistency, and the final treatment of the wire during spooling all affect how easily the wire is delivered through the feeding system. ESAB's aluminium wire range — including OK Autrod 4043 and OK Autrod 5356 — is manufactured with a proprietary surface treatment for consistent, tangle-free feeding and optimised weld appearance.

Aluminium Wire Feeding Systems

There are four recognised feeding systems used for aluminium wire:

• Push feeders
• Pull feeders
• Push-pull feeders
• Spool-on-gun feeding systems

Push feeders and pull feeders

For aluminium welding, both push and pull feeders have recognised limitations depending on application and feeding distance. These systems are generally limited to a practical length of approximately 3.5 metres (12 feet). With push feeders, the distance limit results from the flexibility of the aluminium wire and its tendency to buckle and bend in the liner. With pull feeders, the limitation comes from a rapid increase in friction drag in the liner, particularly where there are bends in the conduit.

Push-pull feeders

Push-pull feeders were developed to overcome the wire feeding problems encountered by push-only and pull-only systems, and are the most reliable method of feeding aluminium welding wire. By maintaining constant wire tension between two sets of drive rolls — one in the feeder and one in the torch — push-pull systems eliminate common feeding problems including wire slippage, erratic arc performance, burn-back to the contact tip, cold lap, and bird-nesting at the feeder rolls.

Push-pull systems are often essential for critical and specialised operations such as robotic and automated welding, where consistent feedability is non-negotiable.

For aluminium welding applications requiring maximum feeding reliability and operator comfort, ESAB recommends the PP 350W Inline Push-Pull — the latest generation of ESAB push-pull torch technology.

Key features:

• Inline ergonomic design — distributes the weight of the push-pull mechanism along the torch body rather than concentrating it at the handle, significantly reducing wrist and hand strain during long welding sessions
• 360° rotatable neck — combined with a compact handle, gives easy access to difficult-to-reach areas without repositioning
• Smooth wire feeding at long distances — engineered specifically for soft wires and long cable runs, making it the optimal solution for aluminium welding where consistent feeding performance over distance is critical
• Automatic plug-and-play synchronisation with the ESAB Warrior Edge system — no manual configuration required, delivering market-leading feeding performance straight out of the box
• Built-in remote control — full parameter adjustment directly from the torch handle, so the welder never needs to walk back to the power source

Spool-on-gun feeding systems

The spool-on-gun system mounts a small spool of wire (typically 0.5 kg) directly in the gun, eliminating the liner distance problem entirely. These guns are generally air-cooled and limited to smaller wire diameters and lighter duty service. Because of their relatively low current rating, they are not well suited to heavy-duty continuous production welding, but are often effective for tack welding and other light-duty applications where the operator needs maximum mobility.

The choice of feeding system for any application depends on factors including the type of welding (light or heavy duty), the electrode diameter and alloy, the need for a long flexible conduit, and cost considerations — larger diameter wire is generally lower priced than smaller diameter.

ESAB Aluminium Welding Wires

The correct wire choice for your application will affect both feedability and weld quality. ESAB's aluminium MIG wire range includes:

• OK Autrod 4043 — general purpose AlSi filler, good fluidity, lower crack sensitivity, suitable for elevated temperature service. Softer wire — feedability requires more careful setup
• OK Autrod 5356 — most widely used aluminium welding alloy, higher shear strength, more rigid wire with better natural feedability than 4043
• OK Autrod 4047 — higher silicon content than 4043, exceptional fluidity for thin section and leak-critical work
• OK Autrod 5183 — developed specifically for welding 5083 and other high-magnesium alloys where 5356 will not meet tensile requirements

For full guidance on choosing between these alloys, see our Aluminium Filler Alloy Selection Guide.

The Bottom Line

The demands of welding applications vary considerably, and so does the cost of each feeding system. The cost of downtime from feeding problems and replacement parts can be significant. Choose the feeding system that is best suited to your application, set it up correctly, and use wire manufactured to consistent quality standards — these three factors together will deliver reliable, interruption-free aluminium welding.