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Process: RapidArc - High Speed GMAW Welding PROCESS
W A V E F O R M C O N T R O L T E C H N O L O G Y
T M
RapidArc High Speed GMAW Welding
Faster travel speeds
Lower spatter levels
Out-of-position operation
Lower heat input
What if there was a way to make
welds up to 98 inches per minute
(2.5 meters per minute) on steel,
16 8 gauge (1.5 4 mm) in
thickness, without the risk of weld
skips, undercut, or high spatter
levels? Now there is, with
RapidArc pulse welding from
Lincoln Electric.
RapidArc is a pulsed GMAW
process solution designed to
increase productivity by reducing
cycle time in semi-automatic,
robotic, and hard automation
applications. Unlike traditional
pulse welding, RapidArc provides
excellent arc stability at lower arc
voltage (shorter arc length), with
reduced spatter and washed out
bead profile, allowing for significant
increase in torch travel speed.
The unique combination of pulse
and short arc metal transfer make
RapidArc suitable for high-speed,
low spatter carbon steel welding
applications, with both solid wire
and metal-cored electrodes.
FASTER TRAVEL SPEEDS
Arc stability at low voltage allows for a significant increase in travel speed.
LOWER SPATTER
Low spatter levels reduce post-weld cleanup time.
OUT-OF-POSITION OPERATION
The combination of short arc and pulse metal transfer enables all-position
welding and expands the range of applications.
LOWER HEAT INPUT
Low voltage operation results in lower heat input, reducing the risk
of burnthrough.
EXCELLENT BEAD PROFILE
Tight arc length control enables the puddle to follow the arc, avoiding
humpy (convex) bead shape and undercut.
EXCELLENT ARC STABILITY
Robust and adaptive waveform avoids stubbing at low voltage operation.
GOOD CHOICE FOR CARBON STEEL
WELDING APPLICATIONS
The combination of lower heat input, fast follow, and tight arc length control
makes RapidArc the ideal candidate for automated welding of steel
components 16 - 8 gauge (1.5 4 mm) thick.
RapidArc also has the capability to weld thicker materials, up to
1/2 in. (12.7 mm).
Patent pending for this process.
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NX-2.80 01/05
© Copyright 2005 The Lincoln Electric Company. All rights reserved.
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As these photos demonstrate,
RapidArc produces less
spatter than traditional pulse
welding. RapidArc
performs at a 30% faster
travel speed with similar
bead appearance results.
RapidArc Pulse Welding
Traditional Pulse Welding 24
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60
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No-Go
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verage V
oltage (V)
W A V E F O R M C O N T R O L T E C H N O L O G Y
T M
RapidArc High Speed GMAW Welding
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What
is RapidArc?
RapidArc is a refined pulse
process, designed specifically
for faster weld speeds than
traditional pulse waveforms.
RapidArc improves low voltage
welding at high speeds, as it
stabilizes the process for
shorter arc length. With
traditional waveforms, the arc
length is longer to avoid spatter,
limiting the travel speed. With
RapidArc, the arc length is kept
short and tight, and spatter is
avoided with precise control of
the short circuit cycle. RapidArc
stabilizes the shortened arc
length with controlled short
circuit cycles.
The short arc length and fast
travel speeds were developed
for robotic, hard automation,
and semi-automatic applications.
PROCESS
2/6
Traditional Pulse
RapidArc
RapidArc vs. Traditional Pulse
How
RapidArc Works
To produce the travel speeds that RapidArc
achieves, the arc length MUST be kept short.
In other pulse welding waveforms, a short arc
length results in stubbing and spatter. The RapidArc
waveforms promote short circuiting at low current,
which minimizes spatter. The RapidArc waveform
can be broken into four segments:
Pulse
A sudden increase in current increases
arc energy, and forms and squeezes a molten
droplet extending from the end of the electrode.
Puddle Rise
The ramp down of current relaxes
the plasma force, depressing the puddle, allowing
it to rise up towards the droplet.
Short
The arc collapses, and the droplet contacts the
weld puddle.
Puddle Repulsion
Immediately following a short break-
ing into an arc, a gentle plasma boost pushes
the puddle away and conditions the electrode tip.
This ensures reliable separation of the wire tip and
the puddle resulting in a stable rhythm of the cycle.
A study was performed resulting in the following data:
The green areas represent usable voltages and travel speeds, which produce
acceptable arc stability and spatter level without stubbing, arc flare, or arc
outage at a given wire-speed-to-travel-speed ratio.
A
verage V
oltage (V)
Travel Speed (in./min)
Travel Speed (in./min)
Pulse
Short
Puddle
Repulsion
Puddle
Rise
Obtain faster travel speeds at lower voltage W A V E F O R M C O N T R O L T E C H N O L O G Y
T M
RapidArc High Speed GMAW Welding
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PROCESS
3/6
Air compressor end cap hard automation 1 mm to 1.5 mm
(0.04 in. to 0.06 in.) lap weld at 80 ipm (2.03 mpm)
Automotive engine cradle welding 2 mm to 2 mm
(0.08 in. to 0.08 in.) lap weld and 3 mm to 4 mm
(0.12 in. to 0.16 in.) lap weld at 70 ipm (1.78 mpm)
Using RapidArc
for Steel Welding Applications
RapidArc was specifically designed to address the
need for faster, all-position pulse welding of carbon
steel, while maintaining superior bead appearance
and acceptable spatter levels. It is a hybrid mode
that combines the pulsed spray transfer and short
circuiting transfer, which results in:
Rhythmic puddle oscillation that avoids excessive
current to clear the short circuit between the electrode
and the weld puddle, so spatter is drastically reduced.
An adaptive waveform that helps avoid stubbing at
low voltages.
Using RapidArc with Solid Wire
for Faster Travel Speeds
One aspect of the RapidArc procedure is the ability to
optimize the process to achieve maximum possible
travel speeds.
RapidArc welds consistently produce flat, bead profiles,
which indicate a smooth transition between the weld toe
and the base metal.
Arc length control can produce a shorter arc length that
results in faster follow, and better bead profile at higher
speeds. This helps eliminate the humpy, convex welds,
weld skips, or inconsistent bead profile typically produced
at higher travel speeds.
Using RapidArc with Metal-Cored Wire
For the optimal RapidArc experience, pair the
RapidArc waveform with Lincoln Electrics metal-cored
electrode, Metalshield
®
MC-6. This combination
delivers minimal spatter. Lower voltage metal-cored
welding increases the operating range of Metalshield
MC-6. RapidArc with MC-6 provides the
following advantages:
The ability to weld materials 1/2 in. (12.7 mm) to 16 gauge
(1.5 mm) in thickness.
Enhanced bead profile on materials with mill scale.
Higher deposition rate at same current as solid wire.
Tolerant of poor fit-up joints.
Reduced occurrence of undercut.
The ability to advance one wire diameter size.
Usable for semi-automatic, hard automation, and
robotic applications.
Power Source
Waveform
Mode
Wire
Diameter
Waveform
13
0.035
GMAW RapidArc Solid Wire
18
0.045
GMAW RapidArc Solid Wire
27
0.052
GMAW RapidArc Solid Wire
87
0.045
GMAW-C RapidArc Metal-Cored
88
0.052
GMAW-C RapidArc Metal-Cored
89
1/16 in.
GMAW-C RapidArc Metal-Cored
Table 1
Choose solid wire or metal-cored wire weld modes from the
list in Table 1. Select the mode number for your application
in the Power Wave
®
355M, 455M, 455M/STT, or F355i.
Customer targeted examples of applications: W A V E F O R M C O N T R O L T E C H N O L O G Y
T M
RapidArc High Speed GMAW Welding
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PROCESS
4/6
Using RapidArc
for Steel Welding Applications (cont.)
Controlling the Waveform
RapidArc is a member of the Waveform Control
Technology family, which allows for advanced
control over the power supply output.
Wire Feed Speed
Select the wire feed speed to produce a weld size
suitable for the joint fit-up and the base metal gauge.
Trim
Adjustments made to the trim value control the arc
length. Shorter arc lengths increase puddle follow and
travel speeds, but at a cost of increasing spatter.
Wave Control
Increased waveform control (available as a function of
the user interface or te