Diode Diode Lasers

Direct benefits

Direct-diode laser technology offers edge quality comparable to CO2 and operating advantages similar to fiber

by Abbe Miller, editor-in-chief

 

 

 

Industrial fiber laser cutting has absolutely crushed CO2 laser cutting in terms of market share in the past few years. With its fast processing speeds, low maintenance and high wall-plug efficiency, fiber has basically relegated CO2 to the land of outdated cutting equipment. Fiber isn’t alone, however, in taking market share from CO2.

 

Direct-diode laser cutting, despite being a relative newcomer, might just be the technology to put the final nail in the CO2 coffin. It’s also proving to be a viable contender when put head-to-head with fiber.

 

For CO2, one of its final strongholds is the near-mirror edge quality it creates in thicker materials compared to fiber. Fiber, even though it might not produce the same level of edge quality, outperforms CO2 on nearly every other front. Direct-diode, however, is ready to tackle both technologies.

 

Its edge cuts in thicker materials are nearly indistinguishable from CO2 edge cuts and its speed in cutting thinner materials is giving fiber a run for its money. Not to mention direct-diode’s wall-plug efficiencies and minimal maintenance requirements, once major differentiators for fiber technology.

 

 

 

New, bright future

Direct-diode lasers aren’t new, but until Mazak Optonics Corp. announced its Optiplex DDL machine at Fabtech 2016, they hadn’t yet been packaged as turnkey systems.

 

Out of the box, the Optiplex DDL features flying optics, two pallet changer designs and a helical rack-and-pinion positioning system enabling higher cutting speeds. Within the DDL, users will find the benefits of fiber, such as high wall-plug efficiency and low maintenance requirements as well as the superior edge quality that comes with CO2.

 

“We’d shown fiber cut parts to plenty of job shops that said that the edge quality wasn’t good enough for their customers,” says Mark Mercurio, Midwest central regional sales manager at Mazak. “Most folks, but especially the thicker plate cutting guys, like those in the agricultural industry, had become accustomed to the smooth finish of a CO2, and they tended to shy away from thicker fiber cut parts because of it.

 

“Cuts from fiber were a little bit rougher in the thicker mild steels, but direct-diode technology is now able to achieve the smooth finish those customers had relied on with CO2,” Mercurio continues. “The guys that were unwilling to switch to a solid-state laser are now considering it with direct-diode technology. They get the benefits of solid state and still get the edge quality that they’re used to.”

 

Direct-diode technology is able to create faster cutting speeds and high-quality edges thanks to a combination of its wavelength and laser beam profile. The wavelength of a laser defines how well a laser can be absorbed into the metal. Better absorption results in faster cutting speeds. Additionally, the Optiplex DDL laser beam profile is similar to that of a CO2 beam. This helps produce an edge quality similar to that of the CO2.

 

Historically, with CO2 and fiber, a gain medium is required to excite the laser to a certain wavelength. With direct-diode lasers, no gain medium is required and virtually any wavelength can be created to address the absorption characteristics of various types of metals. This aids in the production of high-quality edges, but it also plays a big part in the speed that direct-diode is able to achieve.

 

 

 

Cut to the quick

The brightness – or wavelength – produced by direct-diode technology is well-suited for the full range of materials that metal fabricators and manufacturers typically work with. The better a metal can “accept” or “absorb” a certain wavelength, the faster the laser can cut through it.

 

Mercurio says that across the materials board, the Optiplex DDL has achieved feed rate increases in the ballpark of 15 to 20 percent. And that’s compared to the company’s own 4-kW fiber laser.

 

“The 4-kW fiber laser is a competitive machine, but we’re seeing the DDL with the same power level cutting faster than that machine in all materials,” he says. “Aluminum is one of the places where you get the benefit of the high end of that 15 to 20 percent range of increases. For mild and stainless steel, brass and copper, the DDL is averaging increases in feed rates at about 15 percent. And that’s significant.”

 

In the competitive realm of laser technologies, the increase in speed is turning the heads of fiber laser users. Direct-diode already boasted low maintenance and wall-plug efficiency, leaving speed as one of fiber’s only differentiators.

 

The Optiplex DDL delivers fast cutting speeds and high-quality edges due to a combination of its wavelength and laser beam profile.

 

 

Plugged in

To better understand how and why direct-diode is making such strides in the competitive laser field, Mercurio offers a quick history lesson on the progression of industrial laser technologies. The amount of electricity required to power a laser cutter has become less demanding throughout the years.

 

“Lasers have been around since 1986,” Mercurio says. “And the first generation laser – a CO2 laser – only had 10 percent wall-plug efficiency. CO2 lasers, even today, are very mechanical, so you have to turn on pumps, blowers and chiller units, just to name a few parts, to start cutting. The second generation were the fiber lasers and, as everyone knows, they come with a lot of benefits, including 35 percent wall-plug efficiency.

 

“The third generation of lasers, direct-diode lasers, can exceed fiber’s power efficiencies because no power is required to excite a gain medium,” Mercurio continues. “The wall-plug efficiency, therefore, can reach 45 percent. If we don’t talk about assist gas, one of the biggest expenses to run a laser is electricity. If you’re switching from a 4-kW CO2 machine to a 4-kW DDL, you’re able to replace 100-amp service with 40-amp service.”   

 

The new Optiplex DDL serves as a breakthrough laser platform, offering fabricators and manufacturers the utmost in performance and reliability. 

 

 

Full package

On top of speed, edge quality, wall-plug efficiency and low maintenance, Mercurio says that the Optiplex DDL machine offers a sophisticated interface that’s simple for operators to learn and use. It also boasts a robust frame that can sustain the speeds that direct-diode reach.

 

The Optiplex DDL’s Intelligent Multi-Control Torch HP-D and Nozzle Changer technology further increases productivity by automatically optimizing the torch setup, which improves cutting speeds and increases throughput with minimal operator intervention. Additionally, the entire package is housed in a cast machine, which is standard on all Mazak equipment.

 

“Mazak is a machining house, so they produce their fabrication machines just as robust as they build their machining centers,” Mercurio says. “That cast frame dampens vibration from the shop environment, which aids in the smoother edge quality. The DDL has higher acceleration rates; the machines are just faster – not only in cutting speeds but pure processing time. The cast frame, therefore, helps us sustain those speeds for longer periods of time.”

 

Furthermore, Mazak is still a family-owned business, so because the owners put their name on the machine, they will accept nothing but the most robust machine possible. Mazak took major care in not rushing to market with the machine. Two years prior, the company announced the development of its VCL, its first direct-diode laser machine for tube and pipe processing.

 

“When we introduced the VCL, it was a 2-kW machine; we didn’t have a 4-kW direct-diode machine yet,” Mercurio explains. “The flagship machine that gets purchased in the United States for fiber laser is typically a 4-kW. As that product was maturing, we were testing and running production on the 2-kW and then when the 4-kW was ready, we needed a period of time in our own technology centers and production facilities to run tests on the 4-kW DDL before we could introduce it into the marketplace.” 

 

Now that Mazak’s 4-kW DDL machine is on the market and fully vetted by the engineers at the company, users can relish in the benefits previously reserved for CO2 and fiber lasers. From reduced operator dependency to improved cut quality and increased productivity, direct-diode is a serious contender in terms of taking market share from legacy platforms. 

 

“In the past, two parts would be compared, one would be CO2 and one would be fiber,” Mercurio says. “For edge quality, customers would choose the CO2, but in that same breath, they’d equally want the benefits that came with fiber. Now, when we compare two parts, one CO2 and one direct-diode, even an experienced laser operator can’t tell the difference, meaning he can finally take advantage of the solid-state benefits.”

 

Mazak Optonics Corp.   

Machine of the Month - September/October 2016

 

 

Mazak Optonics Corp.’s Versatile

Compact Laser-Tube 100

The Mazak Optonics VCL-T100 is an affordable tube production laser that utilizes direct-diode laser technology, which delivers higher efficiency and reliability than traditional fiber or other solid-state laser generation systems. This is the first in a series of machines to be engineered and produced in North America to meet the specific demands of the local market.

 

Machine Advantages:

• VCL-T100 has been designed as a cost-effective solution for low- to midvolume tube components up to 4 in. round, 3 in. square and standard lengths up to 12 ft. (24 ft. optional).

• The machine also cuts flat sheets up to 20 in. by 24 in. and 1/4 in. thick.

• The VCL-T100 utilizes direct-diode laser technology, which is the next generation of solid-state laser technology. VCL-T100 includes a fiber delivery system and a generator that offers unique advantages, including more efficient operation.

• As a direct-diode laser, the VCL-T100 delivers better performance when cutting aluminum compared to other technologies. It also offers enhanced modular flexibility over other fiber laser generators.

• The machine is engineered and produced in North America Mazak's Mfg. campus in Florence, Ky.

Direct benefits

At Fabtech 2015, direct diode lasers were presented, proving their enhanced cutting speed and quality

by Bryce Samson, director of business development, TeraDiode Inc.

 

 

 

The recent annual gathering in Chicago for Fabtech 2015 was considered a huge success by everyone involved, gathering an international list of exhibitors and attendees at North America's largest metalforming, fabricating, welding and finishing event. Covering the latest advances in all of these fields, the recent shift toward laser processing of metals in particular was obvious from the increased number of exhibitors in that field.

 

Among those processes, high-power, high-brightness direct diode laser technology has been the holy grail – for those visiting Fabtech as well as those who did not attend the annual event. Offering higher efficiencies and reliability at a lower cost when compared to the current state-of-the-art disk and fiber laser, TeraDiode Inc., a company that presented its recent products based on direct diode laser systems for cutting and remote welding at Fabtech, has been the first and only company to commercialize direct diode technology.

 

TeraDiode offers powers as high as 4 kW and BPP less than 4 mm.mrad that have been successfully used for cutting of metals with results showing superior speeds and edge quality. The company’s innovations have also been applied to remote welding of metals on sectors such as the automotive industry.  This has been in collaboration with Panasonic Welding System Co. Ltd.

 

 

Performance improvements

The introduction of direct diode lasers into the cutting and remote welding application space, which was pioneered by Teradiode using patented technology from MIT Lincoln Labs, came with many benefits. These improvements in cutting performance over the existing fiber and disk lasers were highlighted by the benchmarking of cutting speed and quality presented by Teradiode at Fabtech. 

 

In the company’s Fabtech presentation, titled “High Brightness Multi-kilowatt Direct Diode Laser Applications Using Wavelength Beam Combining Technology,” the latest results using
2- and 4-kW TeraBlade direct diode laser for metal processing applications were presented, comparing them against other conventional near infrared lasers.

 

An example of the improvement in cutting speed is shown in Figure 1 on the following page where the speed of cutting aluminum using a 1-kW direct diode laser at 970 nm is compared with an industry standard fiber laser with similar beam quality (BPP~2.5mm.mrad). Clearly, the increase in cutting speed associated with the DDL (twice as fast at a thickness of 1mm) can be seen and is associated with the optimized laser wavelength for this material. Other materials show improvements in cutting speed although not as dramatic as the case of aluminum, where a 1-kW direct diode is cutting as fast as a 2-kW fiber.

 

Direct diode laser cutting of aluminum can double the process speed compared with typical fiber laser performance.

 

 

Improvements in cutting quality for thicker materials is also noted by many users of direct diode lasers and additional features incorporated into the direct diode laser, such as continuously variable BPP, further enhance these improvements in cut quality particularly for the thicker cross sections of materials such as mild steel.

 

An example of the cutting speed optimization obtained by varying the BPP is shown in Figure 2 on the following page, where a 50 percent increase in cutting speed for stainless steel (6- and 8-mm) is obtained by optimizing the BPP from the laser source, a 2-kW direct diode laser in this case. Variable BPP from the same laser, allows faster cutting speed of thin cross sections to be combined with the process optimization needed for thick materials.

 

With power levels covering the range 500 to 8-kW, direct diode laser technology is now poised to meet many of the key market segments currently covered by fiber and disk and offer an alternative to these technologies. Together, with higher wall plug efficiency and back-reflection insensitivity (making processing of reflective materials easier), the process improvements highlighted should further encourage migration to the latest industrial laser technology.

By optimizing the BPP for the process, improvements of 50 percent in cutting speed can be obtained.  This tunable BPP option is available on standard Teradiode high power lasers.

 

 

Competitive edge

“Other advantages to direct diode lasers abound,” says Francisco Villarreal, Ph.D., senior director of laser application developments at TeraDiode. “They are unaffected by back reflections and include a pluggable fiber optic and field replaceable laser power modules. Ease of integration also comes as a standard on the TeraBlade laser systems together with a very competitive pricing schemes, all together making our laser an attractive choice to machine integrators and end users that are looking for a distinctive competitive edge, high performance product for their systems.”

 

At Fabtech, TeraDiode released the extended catalog of products that include the 6- and 8-kW direct diode systems with a BPP in the range of 6 mm.mrad using 120-micron fiber delivery cable. The company also released 1- and 2-kW laser systems with a BPP of 2.5 mm.mrad using a 50-micron fiber. All lasers are offering power conversion efficiencies of 45 percent. 

 

At the same venue, TeraDiode also released the continuously variable BPP (CVBPP) optional feature to its lasers. That allows the end user to fine tune the BPP delivered on the workpiece to further enhance the edge quality and thickness range for a given laser power. 

 

TeraDiode Inc. presented its recent products based on direct diode laser systems for cutting and remote welding at Fabtech and has been the first and only company to commercialize direct diode technology.

 

 

Teradiode was formed in 2009 and has been delivering high-power direct diode laser systems into the industrial laser market for the last three years, including 4-kW direct diode systems to Panasonic welding systems in Japan for incorporation into the LAPRISS remote welding system, most commonly deployed in automotive part manufacturing. In addition to Panasonic, other customers were also exhibiting cutting systems using high-power direct diode laser technology at the Fabtech event in Chicago this year.

 

Like many of the exhibitors at Fabtech, TeraDiode is a leader in its space. It has been since its conception of its laser innovation and will continue with this trend as many technological advances go through the company’s pipeline. On the scope of things to come, TeraDiode engineers plan to extend the technology to other wavelengths and to further increase power and beam quality. 

 

TeraDiode Inc.

Direct Cutting

TeraDiode talks about its technology and how it can change the future of laser metal cutting.



Many consider direct-diode lasers the future of industrial laser metal cutting. Laser experts have long recognized that direct-diode lasers can offer advantages over other laser technologies because of their efficiency, reliability, compactness and low cost. However, applications for direct-diode lasers have been limited because there has always been a trade-off between high power and high beam quality.

Enter TeraDiode Inc., a company that has commercialized high-brightness direct-diode laser technology for metal cutting. TeraDiode has developed the first direct-diode lasers that are bright enough to cut metal while having the highest electrical efficiency available.

Shop Floor Lasers recently spoke with Robin Huang, Ph.D., vice president and a co-founder of TeraDiode, to discuss the TeraDiode technology and its future. Prior to joining TeraDiode in October 2009, Huang was a technical staff member at MIT Lincoln Laboratory.

Robin Huang, Ph.D., is the vice president and a co-founder of TeraDiode. Prior to joining TeraDiode, Huang was a technical staff member at MIT Lincoln Laboratory.



Shop Floor Lasers: Why is there a need for direct-diode laser metal cutting?

Huang: For many years, the market was dominated by CO2 lasers, which are large and inefficient. A CO2 laser machine, even at 2 kW or 4 kW, is big. It takes up a huge amount of a room and also requires a lot of water cooling and electricity. It also requires a lot of maintenance to keep replenishing the CO2 gas so there are a variety of operational costs involved. CO2 lasers are considered the first generation of laser technology.

The second generation of laser technology was really heralded by fiber lasers and disc lasers. These are the diode-pumped solid-state lasers that use diode lasers to pump, or excite, the lasing medium. They introduced considerable improvements over CO2 lasers in that they offered fiber coupling as a solution, allowing the user to have flying optics and so forth. The gantry system had a fiber laser attached to it, so you could just bring the fiber to a processing head and then do the work right there. And wall-plug efficiency was improved. CO2 lasers are in the range of 10 percent efficient while fiber and disc lasers are in the 25 to 30 percent range.

SFL: How does the direct-diode laser technology compare?

Huang: We consider the TeraDiode technology to be third-generation technology. It is a new type of solid-state system that is lower in cost, has comparable brightness to fiber and disc lasers, and has a simpler, more robust architecture. We say that it removes the middleman. There is no intermediate solid-state gain medium. We just have these relatively low-cost diodes and the so-called brightness converter.

TeraDiode recently announced the signing of a purchase and supply agreement with Panasonic Welding Systems for its 4-kW high brightness TeraBlade laser engines.


SFL: What is a brightness converter and how does it fit into the direct-diode laser technology?

Huang: We use technology that was pioneered at MIT Lincoln Laboratory over the last decade or so that combines multiple laser beams into a single output beam. In layman’s terms, it is something like the Death Star’s ray in Star Wars. Wavelength beam combination (WBC) technology enables the combination of energy from thousands of individual emitters into a single output beam while preserving the beam quality needed for cutting metal.

And it has additional advantages because we can actually build lasers at different wavelengths. That is important because the shorter the wavelength, the more types of metals you can address. Aluminum, for example, has a very strong absorption, which goes to 800 nm, and we can make lasers at that wavelength.

In a traditional direct-diode laser setup, the beam quality degrades when beams are combined. This is because when identical wavelengths combine, they don’t travel in the same direction or merge neatly to produce a small spot size. This becomes more significant as more diodes are ganged together for more power. The TeraDiode technology combines the similar but slightly different wavelengths from an array of diodes into one powerful beam with waves going the same direction and to the same spot.

And the technology exhibits 40 percent efficiency compared with the 10 percent efficiency of CO2 lasers and the 25 to 30 percent of fiber and disc lasers.

TeraDiode uses technology pioneered at MIT Lincoln Laboratory that combines multiple laser beams into a single output beam. The company sells its laser source to system integrators and directly to end users.



SFL: Are other laser manufacturers working on direct-diode laser cutting?

Huang: Using conventional techniques of diode combining, the best they can do today is not very good brightness. There are many outstanding laser manufacturers out there, but the best they can do are low-brightness applications, such as brazing, heat treating and paint removal. Their penetration into metal cutting has been poor.

To cut metal, you really need extraordinary brightness. In the units of beam parameter produced, you need something in the range of 3 to 4 mm mrads. Today’s diodes are in the range of 20 mm mrads, so that means in reality they are about 50 to 100 times lower in brightness than what TeraDiode can do. It will probably take more than five years, in my opinion, for direct diodes to really get to the level that they could cut metal using the conventional techniques that are out there.

SFL: Is TeraDiode more of an R&D company or a manufacturer?

Huang: We started out as an R&D company in some sense, but we are now a manufacturing company under the management of our CEO Parviz Tayebati, who brings tremendous manufacturing experience. We have a very impressive production line for building these direct-diode lasers. We have produced a large number of units that have already shipped to customers.

We are actually competing against, in some sense, other laser manufacturers, but we are going to be potentially selling TeraDiode products to system integrators to incorporate into their technology. We are making the laser source that comes into a system that others integrate. So we sell to system integrators and directly to end users.

As TeraDiode continues to make inroads with its direct-diode technology with new partners like Panasonic Welding Systems, the team at Shop Floor Lasers will be sure to keep our readers in the know. Stay tuned!

TeraDiode

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