March 2014 | ManufacturingEngineeringMedia.com 81
Lasers for welding have proven their worth
in the last 35 years in select applications.
Despite their high capital cost, the precise,
intense heat source makes lasers the right
choice where there are tight tolerances,
close fit-ups, and thin materials. These
are applications where lasers produce less distortion,
with their smaller heat-affected zone (HAZ) around
the weld. That lack of distortion is critical in applica-
tions from medical devices to sheetmetal lap joints on
automobile body parts, according to Ed Hansen, global
product manager for ESAB (Florence, SC), the interna-
tional welding company.
Combining the best of both worlds, lasers and
gas metal arc-welding together are expanding
possibilities for large gap welding applications.
Laser Welding Applications ExpandSolid-state laser technology has matured, leading to development of new, cost-effective welding applications, such as hybrid welding
Bruce MoreyContributing Editor
Laser Welding
Photo courtesy ESAB
He said that the laser has become more popular
as solid-state lasers have come to dominate the field.
Because of their operating wavelength in the near infrared,
solid-state lasers deliver their beams along flexible fiber
optics instead of the optics and mirrors required with older
CO2 technology.
“Fiber-delivered lasers are now useful on larger and
higher-volume parts,” he said, noting that automated welding
applications that do not currently use lasers should consider
them given the advances. “Most of the things you need to do
for automated welding,” he said, “you will need to do to be
successful at using a laser.”
However, as an autogenous process with no filler material,
laser-only welding has been limited to those thin-walled and
tight-tolerance applications. Laser-only welding is currently
limited to applications where joint tolerances allow no more
than about 0.1 mm of gap variation. In a number of ways that
is changing. One way is with hybrid welding.
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82 ManufacturingEngineeringMedia.com | March 2014
Laser Welding
Scanner welding of an automotive car door using Trumpf’s
programmable focusing optics PFO 3D. The yellow fiber
optic cable connects to a solid-state TruDisk laser.
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Trum
pf
Companies like ESAB are using their expertise in gas metal
arc welding (GMAW)—think MIG—combined with fiber-de-
livered laser energy to create the best of both in these hybrid
systems. The addition of GMAW means using an arc to add-in
filler material from a wire. Welds in thicker materials benefit
from the precise, deep penetration heat source of lasers,
and the combined system is faster and more forgiving. “With
a filler metal added, this allows you to start applying laser
welding to joint fit-ups and joint designs that are not optimal,”
Hansen said. Modest gaps can be bridged. Certain amounts
of surface contamination are tolerable and weld chemistry and
mechanical properties can be manipulated. Designers can
also add fillets and bead reinforcements for greater strength
and to resist fatigue failures. “This means laser welding can
be applied in more conventional applications,” he said.
ESAB’s Hybrio is such a hybrid system, combining a
solid-state laser with GMAW. It welds at 3–10 times the speed
of conventional processes, with 80–90% less heat input, ac-
cording to the company. Its wider bead bridges gaps that are
four times wider than a conventional laser-only process. Just
as importantly, an adaptive control system monitors the weld
joint in real time, adjusting for joint gaps and mismatches
and further broadening the process window to handle gaps
up to 1.5 mm. New applications now opened to laser welding
84 ManufacturingEngineeringMedia.com | March 2014
Laser Welding
A high power direct-diode laser from Laserline welding
an aluminum deck lid. Aluminum is a particularly good
application for direct-diodes, according to Laserline.
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Lase
rline
include shipbuilding, construction, pipeline supplies (such as
oil-country tubular goods), heavy equipment/off-highway, and
railroad equipment.
In terms of hybrid welding, Jim Hurley, southeast regional
sales manager for Trumpf Inc. Laser
Technology Center (Plymouth, MI),
also pointed out that the laser not only
saves time, but material as well. Many
weld joints prepared for welding are V-
grooves, and a wide joint is needed for
traditional GMAW to get heat energy to
the bottom. With laser’s deep penetra-
tion, a smaller included angle is needed
and hence less filler material.
Solid-State Lasers—
Power and Multiplexing
Hansen from ESAB noted that while
solid-state and fiber lasers now run
up to many 10’s of kW in power, the
practical limit of what they would use in
hybrid welding is around 12 kW. Beam
quality in terms of beam parameter
product (BPP) need not be finer than
10–12 mm-mrads, in most welding
applications. In fact, for “high power”
welding applications, from hybrid to
remote scanning, 75% or more of most
applications require lasers that provide
power between 4–6 kW, according to
Hurley from Trumpf, with a BPP around
8 mm-mrad or better. For example, a
common laser for welding is the Trumpf
TruDisk 6002. It provides a near-IR
beam at 6 kW with a BPP of 8 mm-
mrad. Another plus is that some models
deliver their energy through up to six
individual fibers, enabling a single laser
to power a number of independent
workcells, reducing capital cost.
As important as the advent of hybrid
welding is, Hurley also noted that remote
laser welding remains important. Re-
mote welding uses the unique standoff
capability of lasers and scanning optics.
Remote welding systems rapidly direct a laser beam over large
parts like automotive doors and closures. They weld a num-
ber of spots and short seams separated by distance, saving
time over traditional spot-welding methods. In many cases, it
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produces a better weld, according to Hurley. Remote welding
started with far-IR beams from CO2 lasers delivered in flying op-
tics. Today, he noted that solid-state lasers are now the choice.
This means that laser heads mounted on common six-axis
articulated arm robots provide unprecedented mobility, combin-
ing motion of the head with directed motion of the beam.
With advancements like solid-state remote welding and hy-
brid welding, Hurley believes there is plenty of room for growth
for laser welding, especially in North America. “The Europeans
are leaders in developing and deploying it,” he said. They are
more comfortable with the technology, according to Hurley.
“They are seeing the benefits,” he said. Those benefits will
grow on manufacturers in North America, he believes.
The Foundation Elements for Growth
“Laser cutting is like a divorce, but laser welding is like
a marriage,” said Paul Denney, senior laser applications
engineer of Lincoln Electric (Cleveland, OH). “For a cut getting
separation cleanly and quickly is what you worry about. How-
ever, for a successful weld you do not only worry about getting
things to ‘stick’ together but also what has to be done so that
‘union’ will last in the long term. For laser welds you have to
be concerned about the chemistry of the base and weld met-
al, the resulting microstructure of the weld and the HAZ, and
the size.” He sees laser-welding growing, from remote welding
to creating tailor-welded blanks. Lincoln Electric supplies
laser-welding systems, hybrid laser systems that combine
laser and GMAW, and hot wire cladding laser systems.
The key, as Denney sees it, is to think of laser welding as
a revolutionary, not an evolutionary, process, especially for the
newer hybrid approaches. “You do not want to try and replace
a resistance or arc-welding process one-for-one. For example,
lasers want to give you a high aspect, deep penetration weld,
but if you look at the drawings from most companies they
might specify an edge-lap joint or fillet-type joint,” he ex-
plained. Simply using a laser to weld the fillet they specify, you
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86 ManufacturingEngineeringMedia.com | March 2014
Laser Welding
cannot get high enough deposition rates to justify the laser.
“What you want to do is use a joint that works to the strength
of the laser like a butt joint,” he said.
Anecdotes like these speak to the need to introduce laser
welding early in the design process, with design engineers
involved as well as the manufacturing engineers on the factory
floor. At that point, it is vital to explain the process in terms of
economics. “You almost need to talk to the finance guys,” he
said, explaining that with a rapid process like lasers, if the part
is designed to the laser process, you can actually reduce the
cost per part.
At the same time, manufacturers are necessarily cautious
about adopting novel approaches to mainline products. “You
need to ease into some novel areas and then, once it has
proven itself, [manufacturers] can trust it and use it more
broadly,” he said. “That has happened in transmissions and
in car seats. Eight years ago, no one was really using laser
remote welding for car seats and now almost all suppliers are
doing it. Why? Because they trust it,” he said.
“For laser welds you have to be concerned about the chemistry of the base and weld metal, the resulting microstructure of the
weld and the HAZ, and the size.”
He also pointed out that for select industries and ap-
plications, laser welding has reached a certain maturity, like
tailor-welded blanks, drive train, and medical components.
Costs for lasers have decreased, but he sees that cost-curve
flattening in the last couple of years. Nevertheless, he predicts
both hybrid and remote welding applications will expand, re-
placing other welding methods. “Sweeping a laser beam from
spot to spot is much faster than moving a resistance weld
gun between spots even as the welds themselves take about
the same,” he said. Therefore, for the same number of spot
welds, that means faster cycle times and higher throughput.
Machine Tool Approach to Laser Systems
“Welding once was background noise compared to laser
cutting, which is where the majority of systems were sold,”
said Mark Barry, vice president sales & marketing of Prima
Power Laserdyne (Champlin, MN). “But about five years ago,
we began to see an expansion in laser welding applications.”
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March 2014 | ManufacturingEngineeringMedia.com 89
Laser Welding
From a negligible slice of their business, he has seen weld-
ing grow to about 25%. Laserdyne specializes in delivering
turnkey class 1 laser installations that provide all of the stable
movement and control of an accurate machine tool. Cus-
tomers include turbine, high-precision medical device, and
electronics device manufacturers. He attributes two reasons
for the growth of laser welding: the nature of the parts and
the availability of efficient and economical fiber lasers. “The
parts we deal with today are more often near-net shape. We
are joining finished parts together,” he said. These highly ma-
chined, high-value parts already have the tight fit-up needed
for an autogenous process. They also need a process that
minimizes distortion—ideal for laser welding.
The fiber lasers Laserdyne incorporates into its machines are
providing an ideal and convenient laser source to meet the needs
for precision welding. The fiber delivery means an output beam
source that is evenly distributed as a top-hat (as opposed to a
peak Gaussian distribution), with the advantage of low divergence.
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90 ManufacturingEngineeringMedia.com | March 2014
Laser Welding
Hybrid welding, combining GMAW with high-power lasers,
is also suitable for automation, as shown here.
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ESA
B
Even with the advent of fiber lasers, laser welding capital
expense costs can be relatively high but are offset by many
advantages. As Barry found out from an extensive review with
existing customers, capital cost was not the most important
buying factor. The factors that matter
include good process control; high-quality
welds; robust operation with high uptime;
and ease of use by operators not expert
in lasers.
“Fiber lasers when employed cor-
rectly are easy to use and easy to teach
people to use,” he said. “They provide
a large window of acceptable param-
eters.” Some customers prefer a lower
average power with many pulses; others
prefer high power with few pulses.
Customers can obtain a variety of re-
sults from the same basic system. “The
simple processes actually mean we can
do more interesting welding,” he added.
Laser Developments
Another key development Barry is
seeing is a single laser system tasked to
do multiple operations, such as cutting,
drilling, and welding. He attributes this
to the newer quasi-continuous wave
(QCW) fiber laser. “Before, manufactur-
ers would cluster lasers in the same
area, now they are distributing them into
work cells because they can perform
multiple operations and they do not
need specialized operators who are
experts with lasers,” he explained.
The next big jump in development
may very well be high-brightness direct
diode lasers, according to Hansen.
Attributes he likes include lower cost,
higher electrical efficiency and the small
footprint or form factor. In fact, they are
similar in size to current welding power.
What are direct-diode lasers? Many
solid-state lasers use diodes to excite a
lasing material. Therefore, disk-lasers or
fiber-lasers use diode lasers as an inter-
mediate power source. The direct diode laser skips the interme-
diate process. The trade-off is poorer beam quality but higher
efficiency. Laserline (Santa Clara, CA) is a supplier of high-power
direct diodes used to create the laser beam used in welding, cut-
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ting, or brazing. “The wall plug efficiency of a direct-diode system
is between 40–48%,” said Wolfgang Todt of Laserline.
Laserline’s LDF series direct-diode lasers range from
3-20 kW power, though beam quality decreases as power
increases. For example, the Laserline’s
LDF 3-kW version is 20 mm-mrad, the
6-kW version is only 40 mm-mrads, with
standoff distances of 150 mm.
These are better than they used
to be and today there are a number
of applications where this is sufficient
beam quality, especially in aluminum
welding, Todt said. Welding with direct
diode lasers is not always autogenous.
Audi uses LDF diodes to weld aluminum
with aluminum-silicon wire filler, using
2–6kW LDF lasers.
In other applications requiring
higher quality, Laserline introduced
a beam converter device for its LDF
line of laser diodes. “For up to 4 kW,
the beam converter provides 8 mm-
mrads of beam quality with a standoff
distance of 500–650 mm,” Todt said.
There are trade-offs for the enhanced
quality. Wall-plug efficiency is reduced and the beam
converter adds capital expense. Said Todt: “It is our answer
to fiber lasers in applications requiring higher-quality fiber-
optic delivery of a beam.” ME
March 2014 | ManufacturingEngineeringMedia.com 93
Laser Welding
ESAB Welding & Cutting ProductsWeb site: www.esabna.com/
Hybrid Laser Microsite: www.esab.com/hlaw
Ph: 843-669-4411 / 800-ESAB123
LaserdynePh: 763-433-3700
Web site: http://tinyurl.com/ laserdynesme
LaserlinePh: 408-834-4660
Web site: www.laserline.de/t
Lincoln ElectricPh: 888-935-3876
Web site: www.lincolnelectric.com/en-us/
Trumpf Inc.Ph: 860-255-6000
Web site: www.us.trumpf.com/en
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