Laser Technologies Offer a Growing Array of Choices L - …€¦ · Laser Technologies Offer a Growing Array of Choices Bruce Morey Contributing Editor When it comes to cutting, welding,

It is important to note that the power range most useful for material processing, such as cutting or welding is about 2–6 kW, as

shown in this Mazak Optonics OPTIPLEX 3015 equipped with a fiber laser for cutting. The company’s Intelligent Multi-Function

Torch and Nozzle technology controls fiber beam diameter and focus.

May 2015 | AdvancedManufacturing.org 105

AdvAncements in LAsers

Laser Technologies Offera Growing Array of Choices

Bruce MoreyContributing Editor

When it comes to cutting, welding,

drilling, and marking, lasers have proven

their worth. New improvements are

further driving down cost and expanding

the list of laser choices available

Lasers first started making a significant

impact for manufacturing in the early to mid

1970s. Since then, a number of advances,

both evolutionary and revolutionary, have

made lasers a common tool of choice for applica-

tions such as cutting, welding, drilling, brazing,

and cladding. They are often easier to automate

than many of their mechanical competitors. No

moving part contacts the metal, so no tool wears

out that needs replacement.

As the field has developed, there has been a

proliferation in the number of choices available,

from gas lasers to solid state to ultrashort pulse.

Photo courtesy Mazak Optonics Corp.

106 AdvancedManufacturing.org | May 2015

In the Beginning CO2 and Nd:YAG

CO2 and solid-state lasers are now considered a mature

technology, and they offer practical, cost-effective industrial

material processing. The CO2 is a gas laser, with the gas act-

ing as a lasing medium excited by electricity. For solid-state

lasers, what emerged as the most common for industrial

processing was a laser that dopes Neodymium in an yttrium-

aluminum-garnet medium, or Nd:YAG. The solid core rod is

‘pumped’ with flash-lamps (or semiconductor diodes today)

to create a lasing effect.

An important contrast between the two is that the CO2’s

beam wavelength is about 10 µm, solid-state lasers like Nd:YAG

about 1 µm. Engineers figured out how to deliver a 1-µm

beam through a fiber-optic cable, an important convenience

in machinery and around the shop floor. The 10-µm beam of

the CO2 must rely on comparatively clunky mirrors and optics.

The CO2 laser has a wall-plug efficiency of about 10–12% and

the Nd:YAG about 3% or less. CO2 lasers have improved from

500-W versions to 6 kW (or more) versions today for roughly the

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Direct-diode lasers have sufficient beam quality for a number of

applications, such as remote welding as shown in this LaserLine

installation for a body-in-white application.

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same price, with commercially available powers up to 20 kW.

Reliability for both has improved to the point that users see no

reason to replace existing lasers for years to come.

Energy in each wavelength interacts with material at dif-

ferent efficiencies. Tuning the wavelength to the application is

another important element in choice.

The Nd:YAG laser can deliver high-frequency,

modulated beams that have a very high peak power in

pulses measured in micro and picoseconds. “This de-

livers very high peak power, for example 30-kW peak in

a millisecond or less, even though the average power

could be between 20–600 W,” explained Tracey Ryba,

laser product manager for Trumpf (Plymouth, MI). Early

CO2 lasers were modulated with spinning mirrors,

but not at nearly the same frequency as modern CO2

lasers using high-frequency RF modulation in the kHz

range. In addition, they do not achieve the high peak

powers such as those seen in pulsed Nd:YAG.

Short and ultrashort-pulsed lasers are used for

fine cutting, drilling, and ablation. For example, fuel

injectors are drilled and heart stents cut with such de-

vices. An example of an ultrashort-pulse device is the

StarFemto released by Rofin-Sinar in

March. With an average power of only

20 W, it delivers up to 200 MW of peak

power and frequencies up to 2 MHz.

New Technology Advancements—

Better Solid-State Lasers

Not content with the status quo, la-

ser engineers continue to develop ways

to improve lasers. Solid-state lasers like

Nd:YAG experience thermal limitations,

limiting efficiency and average power.

As the lasing rods heat up during use,

they lose efficiency through thermal

lensing. If the lasing material is thinned

out into a disk and pumped with diode

lasers, the thin disk can be cooled bet-

ter and kept at a uniform temperature,

preventing thermal lensing. Enter disk

lasers, a prime offering from Trumpf.

These greatly improve efficiency and

peak power for laser beams in the

1-µm wavelength, while offering higher

power than Nd:YAG. The Trumpf disk

lasers produce power up to 16 kW.

High-beam quality means light cable

diameters measure as small as 50 µm,

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New applications for lasers will become economical as costs continue

to fall, as shown in this graphic from Trumpf.

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making them easy to attach to robots and other common

automation systems.

A related type of laser for industrial processing that

is gaining market share fast is the fiber laser. Instead

of a disk, diode lasers pump an optical fiber. This too

provides excellent cooling with a simpler construction

resulting in a more efficient laser than when using a

Nd:YAG lasing rod.

IPG Photonics (Oxford, MA) was a

pioneer in the development of high-

power fiber lasers. Offering a wide

range of such lasers, their YLS series

alone ranges from 500 W to 100

kW, operating in continuous wave or

modulated up to 20 kHz with wall-plug

efficiencies greater than 30%, accord-

ing to information from the company.

Fiber delivery cable diameters are as

small as 50 µm, depending on the

power delivered. Reflecting the grow-

ing importance of this class of laser,

companies like Trumpf and Rofin-Sinar

also offer versions of fiber lasers as

well. Both fiber and disk solid-state

lasers offer wall-plug efficiencies in the

30–35% range.

Both disk and fiber lasers are

pumped by a semiconductor laser,

the direct-diode laser. This begs a

question—why not use that as a laser

source? It boasts up to 40% wall-plug

efficiency and is less complicated to

use. Its downside is that it has poorer

beam quality, limiting its use to applica-

tions that need less beam quality.

Trends and Predictions

“The CO2 laser is not going to go

away anytime soon, but its market

share will decrease,” predicts Chris

Dackson, laser product manager for

Rofin-Sinar (Plymouth, MI). The long

10-µm wavelength of the CO2 actually

reacts less with most metals than the

1-µm beams, putting less energy into

them. Counterintuitively, that can be an

advantage, especially in welding. “The

CO2 beam spatters less and creates

a cleaner looking weld,” said Dackson

from Rofin-Sinar precisely because the




10-µm wavelength reacts less with metals. This makes it a

better choice for high-volume automotive powertrain parts,

where tiny bits of welding spatter could cause problems in

precision gearing, for example. “It is also important for stain-

less steel welding where simple cosmetics are important,

such as tubes used in appearance applications,” agreed

Ryba from Trumpf.

Another advantage for the CO2 laser is that it is ideal for

nonmetallic processing, such as wood, fabric, glass, or plas-

tics. “There is a huge market in low-power CO2 applications,

less than 2 kW, for plastic welding and cutting, as an exam-

ple,” explained Ryba, such as precision medical applications.

He also said there are new applications for the old workhorse

in making the next generation of computer chips. “CO2 is ideal

in exciting another element to create a shorter wavelength,

in the ultraviolet,” he said. As he describes it, the resulting

extreme UV light is ideal for the next generation of chipmaking

devices, allowing them to pack more transistors onto a chip.

“It will be a niche market, but an important one,” said Ryba.

Make no mistake, both Ryba and Trumpf see the future in

fiber and disk lasers. “This is because of their high efficiency

and simple delivery through a fiber-optic cable. They are the

preferred laser for most metal processing applications today,”

said Ryba. He also sees direct-diode lasers as achieving

the power and beam quality required for cutting and remote

welding in the next couple of years.

In this comparison between a nanosecond laser (ns) and

femtosecond laser (fs), it is easy to see that the ultrashort

pulse provides both more precision with no heat effect on

surrounding material.

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Learning and Matching Is the Key to New Lasers

“We currently sell about 50% of our laser systems

equipped with CO2 lasers and 50% with fiber lasers,” said

Matt Garbarino, marketing manager for Cincinnati Inc. (Har-

rison, OH). “The fiber laser share is

growing.” His company specializes in

laser cutting systems featuring flying

optics, where the material remains sta-

tionary and is cut by a moving beam.

They purchase a laser source and

integrate it into a platform. Incremental

improvements in CO2, he said, have

meant a slow evolution in improvement.

“What is different is that fiber lasers

are a revolution in technology, not an

incremental step,” he said.

As with other new technologies, fiber

lasers come with a higher purchase

price. A 4-kW fiber laser will cost more

to Cincinnati than a 4-kW CO2. “There

are a variety of reasons for that, but

against that we are seeing operating

costs for fiber lasers that are 60–70%

of that for a CO2, depending on the ap-

plication,” he said. The choice is in the

tradeoffs. “Fiber lasers excel in cutting

thinner materials fast, in some cases up

to twice as fast in thinner materials than

an equivalent CO2,” he explained. Not

so for thicker materials. “The breakpoint

[for choosing a CO2] is approximately

10 gage or thicker,” he said, which is

equivalent to about 4-mm thick. “Edge

quality is better with a CO2 [in those

thicker metals], that is why you do not

see everyone buying fiber lasers,” he

said. Garbarino related that applica-

tions like food industry equipment are

well suited for fiber-laser cutting, while

agricultural equipment and heavy-duty

machinery are at present well suited for

CO2. Thick versus thin.

Mazak Optonics (Elgin, IL) is another

machine provider specializing in laser

cutting applications for fabrication,

both 2D and 3D as well as tube and

pipe. “We make about 50 different models, and 60–70% of

our systems currently use CO2,” explained Mark Mercurio

applications and technical support manager for Mazak, with

the balance using fiber lasers. He also sees a trend towards

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more fiber lasers in just the last few years. The key is tuning

the laser to the application. “Our 4-kW fiber laser can now

compete with a CO2 laser cutting ¾" {19.1-mm] mild steel

plate,” stated Mercurio. “That will grab a wider segment of

the cutting market.”

To better tune lasers to applications, Mazak developed a

multifunction torch. “Its function is to make the process more

consistent by removing the operator from the process, allow-

ing the machine to do the setup rather than the operator,” he

explained. Engineering the beam that the fiber laser delivers

for optimal cutting is the key. Thick cutting requires a different

beam shape than thinner material.

However, he also predicts CO2 remaining a viable solution

for some time to come. His perspective is that both CO2

and fiber lasers cut materials in the ½–¾" thickness almost

identically, with similar edge quality and speeds. “But the

CO2 is quite a bit less expensive. If I am cutting 1/2" [12.7-

mm] thick material all day long, the CO2 is cost-effective,” he

said. Where fiber lasers really become attractive is when they

can cut faster, say in 20 gage material where the feed rate

is 2400 ipm [61 m/min]. “The CO2 may only cut at 800 ipm

[20.3 m/min] in that application,” he said, making the fiber

laser the clear choice.

Mark Barry, vice president of sales and marketing, Prima

Power Laserdyne (Champlin, MN) is direct in his enthusiasm

for fiber lasers—they are increasingly the tool of choice today.

His company also delivers turnkey laser systems

for cutting, welding, and drilling. “A laser is like an

electric motor, it is useless without a machine to

enable it to do something,” he said. “From that

perspective, the fiber laser is often a better engine.

There are things I am doing today with a fiber laser

that are vastly superior to what we were doing with

a CO2 or an Nd:YAG.”

Further advancements will lie in controlling

the laser beam rather than in choosing the laser

itself. An example Barry pointed out is Laser-

dyne’s SmartRamp software recently installed in

their controllers for consistent endpoint control

during laser welding. SmartRamp controls laser

parameters in conjunction with the motion of the

beam to eliminate depressions at the end points of

welds. Depressions are a common occurrence in

laser welding because the power is ramped down

at the end of welds after the start point has been

overlapped. It is more than aesthetics, these can

be leak points in hermetically sealed devices.

Future Developments—Direct Diodes

As convenient as fiber and disk lasers are, the

technology to watch is direct-diode lasers. While still

considered under development, there is evidence

that direct diodes are gaining ground even now.

They offer better efficiency, smaller footprint, and

less complexity. “We are seeing the laser market for

material processing increasing by 10%, but the business for

our diode lasers increased by 25% last year and we are aiming

for that in 2015 again,” said Wolfgang Todt vice president US

operations for Laserline (Santa Clara, CA), a company that

specializes in what it terms as fiber-coupled diode lasers.

Laserline’s LDF series of fiber-coupled diode lasers ranges

from 3 to 25 kW in power, though the beam quality decreas-

es as power increases. For example, the 3-kW version of


Table I Summary of most common laser types.


Laserline’s LDF system has a beam parameter product (BPP)

of 20 mm-mrad, the 6-kW version is only 40 mm-mrads,

compared with single-digit BPPs for fiber or disk lasers.

Note: a smaller BPP means finer beam quality.

Still, for a number of applications—

especially outside of cutting—direct-di-

ode lasers are often competitive. “There

are a number of industries where we are

seeing the same competitive situations

pop-up time and again, with custom-

ers comparing disk lasers, fiber lasers,

and direct diodes,” he said, where all

three are competitive at some level.

Todt shared that their prices have come

down 10–15% in the last year as well,

driven by higher production volumes

and decreasing cost in components.

His company’s direct diodes are

continually improving, now boasting a

top power range of 40 kW with a 220

mm-mrad BPP first introduced in 2014.

“This is aimed at high-speed cladding

operations or deep welding,” he said.

He said to look for a new product fam-

ily announcement in 2015 that will reduce the physical size of

their diode lasers with even better beam quality. The aim is to

make direct-diode lasers competitive in applications where a

brilliant beam quality matters.

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Laser Technologies Offer a Growing Array of Choices L - …€¦ · Laser Technologies Offer a Growing Array of Choices Bruce Morey Contributing Editor When it comes to cutting, welding,