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Which Cut is Best, Water or Laser?

Geoff Giordano
By Geoff Giordano Contributing Editor, SME Media

Laser and waterjet are very different machines with very different — but perhaps complementary — capabilities

Laser cutting and waterjet cutting: two great technologies that go great together? Or best when they play solo? As ever, the answer is it depends—on what work a shop has coming in the door, what materials are being processed most often, operator skill levels and, ultimately, the available equipment budget.

“If I’m going to cut 3" by 1" circles out of ¼" mild steel, I’d probably prefer the laser (left) due to its speed and accuracy,” noted Application Specialist Tim Holcomb of OMAX. Waterjet cutting on right. (Provided by OMAX)

The short answer, according to a survey of major suppliers for each type of system, is waterjet is less expensive and far more versatile then laser in terms of materials it can cut. From foam to food, waterjets demonstrate an exceptional degree of flexibility. Lasers, on the other hand, offer unequaled speed and precision when producing high volumes of thinner metals up to 1" (25.4-mm) thick.

In terms of operating costs, waterjet systems consume abrasive materials and require pump rebuilds. Fiber lasers cost more initially but are less costly to operate than their older CO2 cousins; they also might require more operator training (although contemporary control interfaces shorten the learning curve). By far the most common abrasive used with waterjet is garnet; in the very rare cases when something more abrasive like aluminum oxide is used, mixing tubes and nozzles suffer more wear. Using garnet, waterjet components might cut for 125 hours; they might only last roughly 30 hours with aluminum oxide.

Ultimately, both technologies should be seen as complementary, according to Dustin Diehl, laser division product manager for Amada America Inc., Buena Park, Calif.

“When a customer has both technologies, they have tremendous flexibility on what they can bid,” Diehl explained. “They can bid any type of work because they have these two different but similar tools and can bid the whole package.”

For instance, one Amada customer with both types of systems performs blanking on a laser. “Right beside the press brake is a waterjet that is cutting a heat-resistant insulating material,” Diehl said. “As soon as the sheet is bent, they put the insulation in, bend it again and execute a hem or seal. It’s a neat little assembly line.”

In other cases, Diehl continued, shops indicate they would like to acquire a laser cutting system but feel they aren’t taking in the volume of work to justify the expenditure. “If you’re going to make a hundred parts and it’s taking you all day to do it, we ask them to look at the laser. We can get a sheet metal application done in minutes, not hours.”

Having run a shop featuring about 14 lasers and one waterjet, Application Specialist Tim Holcomb of OMAX Corp. Kent, Wash. recalled a poster he saw years ago at company that used lasers, waterjet and wire EDM. The poster listed the materials and thicknesses each type of machine could handle best—with the list for waterjet dwarfing the others.

Ultimately, “I’ve seen lasers try to compete in the waterjet world, and vice-versa, and they’re not going to win outside their respective niches,” Holcomb explained. He also noted that, because waterjet is a cold cutting system, “We can tap into more medical or defense applications because we have no heat-affected zone (HAZ)—we are microjet technology.” Minijet nozzles and microjet cutting “are really taking off for us.”

‘Swiss Army Knife’ of Machining

While lasers dominate in the cutting of mild ferrous steels, waterjet technology “is really the Swiss Army knife of the machine tool industry,” asserted Tim Fabian, vice president of marketing and product management at Flow International Corp., Kent, Wash., a member of Shape Technologies Group. It counts among its customers Joe Gibbs Racing.

Flow’s Dynamic Waterjet XD is fast, accurate, and flexible, according to the company.(Provided by Flow International)

“If you think about it, a race car manufacturer such as Joe Gibbs Racing would have fewer opportunities to use a laser machine because they’re often cutting limited quantities of parts from a lot of different materials, including titanium, aluminum and carbon fiber,” Fabian explained. “One of the needs they explained to us was that the machines they use have to be super easy to program. There are times when an operator might make a part out of ¼" [6.35 mm] aluminum and fit it on a race car, but then decide that part should be made of titanium, a thicker piece of carbon fiber or a thinner piece aluminum.”

On traditional CNC machining centers, he continued, “those sorts of changes are pretty major.” Attempting to change gears like that from material to material and part to part means changing tool bits, spindle rpms, feed rates and programs.

Flow’s Mach 500 is available in a range of sizes and is designed with options that include the Dynamic Waterjet head, five-axis, dual gantry, and multiple cutting heads. (Provided by Flow International)

“One of the things they really push us on with waterjet is to create libraries of different materials they use so all they have to do is perform a couple of mouse clicks that let them switch from ¼" aluminum to ½" [12.7 mm] carbon fiber,” Fabian continued. “Clicking the mouse again, they go from ½" carbon fiber to 1/8" [3.18 mm] titanium.” Joe Gibbs Racing is “using a lot of exotic alloys and things that you don’t always see your average customer using. So we spend a lot of time helping to create libraries with these advanced materials in cooperation with them. We have hundreds of materials in our database, and there is a simple process where a customer can add to their own unique materials and expand this database even further.”

Another high-end user of Flow waterjets is Elon Musk’s SpaceX. “We have quite a number of machines at SpaceX to make rocket ship parts,” Fabian said. Blue Origin, another aerospace exploration manufacturer, also uses Flow machines. “They are not making 10,000 of anything; they are making one of these, five of those, four of something else.”

For typical shops, “anytime you have a job and you need 5,000 of something out of ¼" steel, a laser is going to be tough to beat,” Fabian noted. “But if you need two steel parts, three aluminum parts or four nylon parts, you’re likely not going to consider a laser over a waterjet. With a waterjet, you can cut anything from thin gauge steel up to 6" to 8" [15.24 to 20.32-cm] thick metal.”

Trumpf’s Tale of the Tape

With laser and machine tool divisions under its umbrella, Trumpf has its feet planted clearly in the laser and traditional CNC worlds.

In the narrow window in which waterjet and laser are most likely to overlap—metals just over 1" [25.4 mm] thick— waterjet holds the clear edge.

“For very, very thick metals—1.5" [38.1mm] and greater—a waterjet will not only give you better quality, but the laser may not be able to process the metal,” according to Brett Thompson, laser technologies and sales consulting manager. Afterward, the divide is clear: Nonmetals are likely to be processed on a waterjet, while for any metal 1" thick or less, “a laser is a no-brainer. Laser will cut much, much faster, particularly amongst the thinner and/or harder materials—for example, stainless steel compared to aluminum.”

Trumpf’s Highspeed Eco process can increase feed rate and sheet throughput by up to 100 percent, the company says. The nozzle design reduces nitrogen consumption by an average of 70 percent. (Provided by Trumpf)

With part finish, particularly edge quality, the advantage again goes to waterjet as materials get thicker and heat input becomes a factor.

“This can be a place where a waterjet may have an advantage,” Thompson acknowledged. “The range of thicknesses and materials exceeds that of a laser with less heat-affected zone. Although processing is slower than laser, waterjets will also give consistently nice edge quality. You’ll tend to have very good perpendicularity with a waterjet as well—even at thicknesses counted in inches, and all with no burr to worry about.”

The edge in automation goes to the laser in terms of integration into extended production lines, Thompson added.

“With a laser, complete integration is possible: load material on one side, and out the other side of an integrated cutting and bending system you’ll have a finished cut and bent part. A waterjet would likely still be a poor choice in such a scenario—even if there was a good system for material management—because the parts are cut much more slowly, and obviously you’d have to deal with the water.”

Thompson asserted that lasers are less expensive to operate and maintain, as “the consumable items used are relatively limited, particularly with fiber lasers.” However, “the overall overhead costs of a waterjet have the potential to be less due to the lower machine dynamics and relative simplicity. It really comes down to how well engineered and maintained either piece of equipment is.”

The Reality In the Shop

When OMAX’s Holcomb was running a shop in the 1990s, he recalled, “any time I had a part or a blueprint come across my table, my initial thought was, ‘can I do it on the laser?’ But before I knew it we were getting more and more projects exclusively for the waterjet. Those were the thicker-gauge materials and some types of parts because with the laser’s heat-affected zone, we can’t get into a corner really tight; it would blow out the corner, so we would lean toward the waterjet—and that’s even with material thicknesses that the laser normally would do.”

And while single sheet was quicker on the laser, sheet stacked up to four high went faster on the waterjet.

“If I’m going to cut 3" by 1" [76.2 by 25.4-mm] circles out of ¼" [6.35-mm] mild steel, I’d probably prefer the laser due to its speed and accuracy. The finish—the side-cut profile—is going to be more of a glassy finish, very smooth.”

Parts cut on OMAX waterjet machines. (Provided by OMAX)

But to get the laser to perform at that level of precision, he added, “you had to be an expert on frequencies and wattages. We were very good at it, but you had to dial it in really tight; with a waterjet it’s first time, first try. Now, we have a CAD system built into all our machines. I can design a part right at the machine.” This comes in handy for prototyping, he added. “I can program right there at the waterjet and change material thicknesses and settings so much easier.” And job setup and changeover “is comparable; I’ve seen some changeovers on a waterjet very similar to a laser.”

Now, for smaller jobs, prototyping or educational uses —even for a hobby shop or garage—OMAX’s ProtoMAX features a pump and cutting table on casters for easy relocation. Work material is submerged under water for quiet cutting.

Regarding maintenance, “typically I can train someone on waterjet in a day or two and send them off into the wild pretty quickly,” Holcomb asserted.

OMAX’s EnduroMAX pumps are designed to use less water and allow quick rebuilds. The current version features three dynamic seals. “I still tell people to be meticulous with maintaining any pump, not just mine. It’s a high-pressure pump, so take your time and get trained properly.”

The Final Analysis

For Amada’s Diehl, waterjet and laser can indeed be used in complementary fashion.

“Waterjet is a great stepping stone to get into blanking and fabrication, and maybe your next move will be a laser,” he suggested. “That gets people cutting parts. And press brakes are pretty affordable, so they can cut and bend them. In a production environment, you’ll probably lean to laser.”

While fiber lasers offer the flexibility to cut non-steels—copper, brass, titanium—waterjet allows cutting of gasket material and plastics thanks to having no HAZ.

Operating the current generation of fiber laser cutting systems is “so intuitive now to where production is being dictated through the program,” said Diehl. “Operators are simply loading workpieces and hitting start. I came from shops where, in the CO2 days when optics would start to age and deteriorate and cut quality would suffer, you were considered a good operator if you could diagnose those issues. Today’s fiber systems are kind of cookie cutter, and they don’t have those consumables so they’re on or off—cutting parts or not. That takes a little bit of that skilled operator need out of the equation. That said, I think going from waterjet to laser would be a smooth and easy transition.”

Diehl estimates a typical fiber laser system can be run at $2 to $3 per hour, vs. in the neighborhood of $50 to $75 an hour for waterjet, taking into account abrasives consumption (e.g., garnet) and scheduled pump rebuilds.

With laser cutting systems rising in kilowatt power, they are increasingly an alternative to waterjet in a material like aluminum.

“It used to be that with thick aluminum, waterjet would have [the] advantage,” Diehl explained. “Lasers didn’t have the power to get through something like 1" aluminum. We didn’t mess in that world for a long time in the laser world, but now with the higher-wattage fibers and advancements in laser technology, 1" aluminum is not an issue anymore. If you did the cost comparison, it might be cheaper on the waterjet for the initial investment on the machine. Laser might cut 10 times as many parts, but you’re going to have to be in that volume environment to make that cost up. When you’re running a higher mix of low volumes of parts, that’s where there might be some advantages to the waterjet—but certainly not in a production environment. If you’re in any type of environment where you need to run hundreds or thousands of parts, that’s not a waterjet application.”

Illustrating the increase in available laser powers, Amada’s ENSIS technology is topping out at 12 kW, up from the 2 kW at its 2013 introduction. On the other end of the scale, Amada’s VENTIS machine—launched at Fabtech 2019—allows for a broader variety of material processing thanks to a beam that moves in the diameter of the nozzle.

“We can execute different techniques with back-and-forth motion, up and down, side to side or figure eights,” Diehl said of the VENTIS. “Something we learned from the ENSIS technology is that every material has a sweet spot—a way that it likes to be cut. We did that with different types of mode and beam shaping. With the VENTIS, we can go back and forth almost like a saw; as the head moves, the beam is going back and forth, so you get very smooth striations, great edge quality and sometimes speed increases.“

In the same vein as OMAX’s small-footprint ProtoMAX waterjet system, Amada is preparing a “very small footprint fiber system” for smaller shops or “R&D prototype shops that don’t want to break into their production department when they just need to prototype some parts.”

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