Tandem Welding Systems - Midwest Engineered Systems

Midwest Engineered Systems can design and manufacture automated tandem welding systems with multiple welding technologies. With the variety of welding processes available today, each has its own relative strengths and weaknesses depending on the welding application needs. At MWES, we use a variety of industry-leading technology, equipment and techniques to integrate into systems to bring out the best of those processes.

AWS's Robotic Arc Welding ConferenceThe tandem welding process consists of two electronically isolated wires, two separate power sources and two feed units. This means that the wires can operate independently, allowing for respectively different current levels, i.e., pulsed or continuous operating modes or different wire diameters. Usually, the weld occurs with the two wires along the joint line, but the torch can be rotated around the joint.

Automated tandem welding is capable of depositing much more metal at a much faster pace than what is possible for traditional single-wire welding, even when it is automated. The increased productivity and other benefits from this automated welding process have led to several different reasons to adopt the technology, including:

  • Increasing the overall profitability of already-installed automation systems.
  • Decrease the payback periods that are linked to newer automated welding solutions.
  • Justifying the costs of adopting, using and maintaining automated equipment.

Materials Used for Tandem Welding

Automated welding robots must work with a weave pattern to properly read each side of the weld joint. Joints and materials that are similar to sheet metal cannot realistically be put through the tandem welding process successfully. For those materials, it’s better to consider laser tracking or an alternative automated process.

Some materials that work well in this welding process include:

  • Steel
  • Aluminum (including alloys)
  • Coated plates
  • Chrome-Nickel materials
  • High-strength steel
  • Weld overlays

Tandem Welding Operating Fundamentals

Standard Tandem Welding Process
In its standard operating mode, the Tandem MIG DC positive CV (constant voltage) mode is programmed for the lead arc, while the Tandem MIG DC positive pulse mode is programmed for the trailing wire. The CV lead arc helps to optimize travel speed and penetration. The pulsed trail arc has a reduced heat input, which prevents EM arc interference between the two arcs. This trail arc is pulsed to assist the overall process of controlling and cooling the resulting molten weld puddle that is created in the process. This standard configuration has many operating ranges, and the CV and pulse modes can be independently changed to create penetration and fill balance.

Alternative Tandem Welding Process
A second mode involves placing both the lead and trail welding wires in the Tandem MIG pulse mode. Synchronization of frequency (or integer multiples of each other) is a requirement for this mode, and the feed speeds of both must be varied simultaneously to limit the amount of independence between fill and penetration.

Industries that Benefit

The industries that gain the most from this welding process include:

  • Shipbuilding manufacturing process
  • Offshore drilling fabrication process
  • Railway vehicle and component construction
  • Boiler pressure vessel construction
  • Automotive production

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