Lincoln Electric Tandem MIG User Manual

APPLICATION

WAVEFORM CONTROL TECHNOLOGY

Tandem MIG

High-Speed and High-Deposition Welding

Low cost and profitability are key business objectives, whether the product offering is a wheel, a water tank, or a truck frame. It used to be thought that on the road to lower cost, quality had to be sacrificed. That’s no longer true with Tandem MIG welding.

The following factors affect pricing per welded part:

• Capital Equipment

• Overhead

• Labor cost

• Part production rates

Lincoln Tandem MIG welding systems are designed to produce quality welds at welding speeds well above accepted single wire processes. The unique engineered output control of the Tandem MIG dual wire process is designed to overcome the barriers limiting the travel speed capabilities of conventional single wire GMAW processes.

Increased deposition

on thicker materials

reduces welding time

and distortion.

Fast travel speeds on thin

lap welds increase the

number of parts per day.

advantages

INCREASED TRAVEL SPEEDS

• The combined contribution of two separate welding arcs in one weld pool provides the control to overcome the lack of follow tendencies of single arc processes.

INCREASED DEPOSITION

• Two small diameter Tandem MIG wire electrodes provide higher melt-off rates per current drawn when compared to a single larger diameter wire electrode at similar current draws.

IMPROVED THROUGHPUT

• Higher travel speeds and higher deposition rates reduce part welding time cycles.

The future of welding is here.

WAVEFORM CONTROL TECHNOLOGY

APPLICATION

Tandem MIG

High-Speed and High-Deposition Welding

What Is It?

Tandem MIG is a dual wire GMAW process that is used in automated welding applications to improve welding productivity and part throughput. The process utilizes two welding power sources and two wire feeders acting in tandem to deliver two wire electrodes through a single welding torch. The dual wire welding torch, capable of often doubling the welding output of a single wire torch, is used in hard automation and robotic arc welding cells in the same manner as a single wire welding torch would be. The two welding arcs that are generated in the Tandem MIG process are electrically isolated from one another and are

Tandem MIG Configuration

Two Wire Feeders

2/16

controlled independently. The welding arcs work together, generally separated by less than 0.50 inches, in the same weld pool. The independent control of the two welding arcs is used to control the thermal and fluid dynamics of the weld pool to further enhance welding performance. The added deposit rate achieved by the dual wire delivery and the added weld pool control is used to overcome single wire limitations to produce high travel speeds and electrode melt-off rates (weld metal deposition). Special power source welding software is used to allow the two welding arcs to operate in unison.

Two Separate

Welding Arcs

Shielding Gas

Two

Power Sources

One

Welding Torch

One Weld Pool

The future of welding is here.

WAVEFORM CONTROL TECHNOLOGY

APPLICATION

Tandem MIG

High-Speed and High-Deposition Welding

How Does It Work?

The two welding arcs common to the Tandem MIG process have distinct functions. The lead arc (the first arc in the direction of torch travel) is operated in a spray transfer mode. The mode may be either a special Tandem MIG pulse mode, an adaptive constant voltage mode or a Tandem MIG power mode. The lead arc’s primary function is to establish initial root penetration and develop a molten weld pool for the trail wire. While performing these functions the lead wire typically accounts for 60% or more of the total weld metal deposited. The trail arc or second arc

Lead and Trail arc functions for high speed welding

Trail arc is focused on the crest of the pool

created by the lead.

Gas Nozzle

3/16

is operated in a special Tandem MIG pulse mode. The trail arc’s function is to add filler metal to the weld pool and control the bead characteristics such as edge wetting, physical contour, side-wall penetration and weld pool follow speed. The trail arc should be kept directly in line with the lead arc and focused on the center of the weld pool. The trail wire melting rate typically represents approximately 40% of the process deposition rate. The Tandem MIG trail pulse waveforms are designed to operate at low voltages to limit arc interaction and minimize arc blow.

Lead and Trail arc functions for high deposition welding

The trail arc is focused on the middle of the weld pool

to create additional fill.

Gas Nozzle

Lead Arc Trail Arc

Lead Arc

Penetration

Lead

Arc

Partial

Fill

Penetration Past the Root

The Lead Arc generates the

majority of the penetration

and leaves joint requiring

additional fill.

Molten Weld

Pool

Travel Travel

Completes

Fill

downward and forward

pressure on the weld pool

for better pool follow and

Weld Bead

Penetration

Trail

Arc

Wets Edges

The Trail Arc places a

wetting along the

bead edges.

Lead Arc Trail Arc

Lead Arc

Penetration

The Lead Arc creates the initial root penetration and the majority of the joint fill.

Molten Weld

Pool

Lead

Arc

Completed

Fill

Root

The Trail Arc is focused in

the weld pool providing additional joint side-wall penetration and joint fill.

Weld

Bead

Penetration

Trail

Arc

Sidewall

Penetration

The future of welding is here.

WAVEFORM CONTROL TECHNOLOGY

APPLICATION

Tandem MIG

High-Speed and High-Deposition Welding

Using Tandem MIG

For High-Speed Applications

Flat and Horizontal Lap Welds

1.5 mm - 5 mm

Automotive, Tank Fabrication

Flat and horizontal lap welds common to automotive components like control arms, stub or full chassis frames, cross members, shock absorbers, struts, stabilizer arms and flex axles are performed at welding travel speeds ranging from 70 - 130 ipm. On thinner components with metal thickness ranging from

1.5 - 3 mm, flat and horizontal lap welds are made with (2) .035” diameter electrodes at travel speeds ranging from 100 - 130 ipm. Thicker components with metal thickness from 3 - 5 mm are performed with (2) .045” diameter electrodes at travel speeds ranging from 70 - 100 ipm.

4/16

This thin gauge lap weld was made at a

travel speed of 100 ipm

Flat and Horizontal Fillet Welds 3 mm - 6 mm

General Light Gauge Steel Fabrication, Shipbuilding, Railroad

Light gauge steel fabrication of 3 - 4 mm fillet welds used to weld structural trusses, farm implements, residential and commercial storage systems, trash-hauling containers and similar components are welded with (2) .035” diameter electrodes to produce welds at travel speeds ranging from 80 - 100 ipm. Larger 4 - 6 mm fillet welds common to structural beams, light earth moving equipment, ship stiffeners, rail cars and similar components are welded with (2) .045” electrodes at travel speeds ranging from 50 - 80 ipm.

Joggle Joints 1.5 mm - 4 mm

Tanks and General Fabrication

Joggle joints require a careful balance of joint fill and controlled penetration. Tandem MIG provides the independent control of both, providing needed joint fill without excessive penetration. Joggle welds between

1.5 and 3 mm, common to the light tank, truck bodies, trash-hauling containers and similar components are welded at travel speeds ranging from 80 - 120 ipm using (2) .035” diameter electrodes. Larger 3 - 4 mm joggle joints used in larger tanks and thicker containers are performed at welding speeds ranging from 40 - 80 ipm using (2) .045” diameter electrodes.

3/16” (4.8 mm) Horizontal Lap Weld

6mm Horizontal Fillet

Joggle Weld

The future of welding is here.

WAVEFORM CONTROL TECHNOLOGY

APPLICATION

Tandem MIG

High-Speed and High-Deposition Welding

Using Tandem MIG

For High-Deposition Applications

Flat and Horizontal Fillet Welds 6 mm and Larger

Railroad, Structural, Industrial Equipment, Ship Building, Off Road Wheel Manufacturing

Flat and horizontal fillets common to structural building components, offshore platforms, railcar haulers, machine bases, large vehicle wheels, undercarriages/truck suspensions and other fabricated components of metal thickness of 6 mm and greater are performed at deposition rates ranging from 21 - 35 lbs./hr.

Single pass 5/16” flat fillets are commonly welded at 24 - 30 ipm with (2) .045” diameter electrodes.

5/16

1/2” Flat Fillet at 20 ipm

Single pass 5/16” flat fillets are commonly welded at 27 - 40 ipm with (2) .052” diameter electrodes.

Bevel and “V” Groove Joints

Heavy Plate Fabrication, Structural Members and Industrial Equipment

Single and multi-pass beveled butt welds used in industries fabricating ship hulls, earth moving equipment, structural platforms, pressure vessels, beams and similar heavy plate weldments are performed at deposition rates ranging from 22 - 35 lbs./hr. Welds are commonly performed using like electrode diameters, either .045 or .052 inch diameter. The lead electrode provides root penetration, the trail electrode adds to sidewall penetration.

“J” and “U” Groove Butt Welds

Earth Moving Equipment and Heavy Plate Fabrication

Single and multi pass “J” and “U” groove joints common to undercarriages, rollover protection equipment, sticks, booms, fifth wheels, frames, hydraulic cylinders, pant legs and similar earth moving equipment components are welded at deposition rates ranging from 22 - 35 lbs./hr. Welds are performed at a 30 - 50% reduction in heat input when compared to larger diameter single electrode processes. Lower heat input can substantially reduce post weld straightening activity caused by distortion.

8 mm Horizontal Fillet

Multi-pass Butt Weld

2 Pass “J” Groove

The future of welding is here.

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