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Bringing Waterjet Cutting Inhouse--a Lucrative Decision

Sunday, April 01, 2012
 

When wind-turbine manufacturer Kronos Energy Solutions, Cordova, TN, sought to improve its own level of green-fabricating processes, it turned to waterjet cutting to take on a portion of its production, custom and prototyping work. Kronos designs and manufactures small vertical-axis turbines. Company president and CEO John Bogensberger launched Kronos in 2009; prior to that, he worked for a high-production manufacturing company fabricating primarily sheetmetal. “I first saw waterjet-cutting machines at an IMTS show in 1998,” Bogensberger says. “I was intrigued with the process because it produced no toxic gases, dust nor dangerous chemicals. But I felt I couldn’t justify the machines in a high-production environment cutting sheetmetal.”

Kronos Energy Solutions vertical axis turbines
Kronos Energy Solutions designs and manufactures small vertical-axis turbines. Company president and CEO John Bogensberger launched Kronos in 2009, initially outsourcing fabrication work such as oxyfuel cutting of turbine components.
When Bogensberger launched Kronos Energy Solutions, he outsourced most fabrication work, including oxyfuel cutting (OFC) of turbine parts. Outsourcing, he felt, offered a cost-effective for his new company to have parts cut and machined without the upfront capital investment. However, outsourcing can cause production delays, particularly when design changes occur. And, Bogensberger found that the secondary processing required to remove the heat-affected zone and dross caused by the OFC process was time consuming, as was deburring of stamped parts. He decided to outsource cutting work to a shop using waterjet-cutting machines, which eliminated the need for secondary processing. “However, there still was taper to contend with,” says Bogensberger. “We use a specialized gear configuration in the wind turbines that requires very tight tolerances and required secondary machining of the waterjet-cut parts.”

Bogensberger took a fresh look at waterjet cutting—and began to think seriously about bringing the work inhouse—after attending the FABTECH 2010 show in Atlanta. There he was introduced to a new waterjet-cutting machine, the Mach 4 model from Flow, outfitted with the company’s Dynamic Waterjet XD technology. “We’ve als known that the waterjet-cutting process is extremely flexible, but when I experienced the speed and accuracy possible with the Mach 4, we knew we had to have one.”

Victory Over Stream Lag and Taper

Two types of part-quality issues typically plague abrasive waterjet cutting: stream lag and taper. Both of these accuracy hurdles can be cleared by significantly reducing cutting speed, but cycle time and cost per part rise with equal significance.

Stream lag—evidenced by the exit point of the waterjet lagging behind the entrance point—causes geometry errors as it sweeps out cone shapes instead of circles, and causes corner wash-out on inside corners. And, V-shaped taper naturally occurs as the power of the waterjet dissipates during cutting. The faster the cutting speed the greater the kerf-taper error, which can be as much as 0.01 in. per side. As with stream lag, slowing cutting speed will minimize taper, but will restrict productivity and increase garnet consumption per inch of cut.

Kronos FlowJet waterjet-cutting system
Since Kronos installed this Mach 4 FlowJet waterjet-cutting system—outfitted with a 13- by 6.5-ft. table—costs compared to outsourcing work have reduced dramatically, allowing the company to pass savings directly onto its customers.

Flow’s Dynamic Waterjet with Active Tolerance Control avoids taper and stream lag during flat-stock cutting, says the company, maximizing cutting speed. The technology combines control software with precision machine-tool design and an articulated end-of-arm wrist.

Ownership Has its Advantages

Since Kronos installed its Mach 4 FlowJet waterjet-cutting system, outfitted with a 13- by 6.5-ft. table, costs compared to outsourcing its cutting work have reduced dramatically. “For example,” says Bogensberger, “we had previously outsourced work to a gear manufacturer at a cost of $103.00 per gear. With our FlowJet, cutting the same gear now costs about $1.40, without the need for any secondary machining. That’s savings we can pass directly onto the customer.”

Additionally, Kronos can easily scale ring gears for its wind turbines, or the vane head size, to meet specific customer performance requirements or space constraints. And with its waterjet-cutting machine, it can make such product-design and configuration changes up to the last minute without the delay or extra charges when outsourcing.

The flexibility of the waterjet-cutting process allows the company to cut virtually any material, whether stainless or carbon steel, aluminum alloys or rubber. “We made a Lexan display case with interlocking joints,” says Bogensberger, “and didn’t have to use even a single screw to assemble the case. We waterjet-cut slot and peg configurations instead, also avoiding the need for fixturing during assembly.”

Sales director Frank Garavelli describes another waterjet-cutting success story. “We have a new customer that was purchasing raw material, sending it to a blanker and then onto a metal-processing facility,” he says. “Parts fabricated on a punch press required secondary deburring, and the parts had a 0.030-in. dimensional variance from top to bottom. In all, six different operations performed by various suppliers were required to produce parts to print.

“Now, fabricating the parts on our FlowJet,” continues Garavelli, “we simply order the raw material, cut and form the parts and they’re ready for assembly. There’s no need to deburr or hone down uneven edges.”

Support for Other Green Applications

Since adding waterjet cutting to its inhouse resume of fabricating processes, Kronos has been able to expand its customer base beyond the wind-energy market and into other green markets. For example, it’s fabricating aerodynamic skirt-side fairings for long-haul trucks, to reduce drag and improve gas mileage.

“With our FlowJet, we can customize the look to meet trucker or fleet-design requirements,” says Bogensberger. “Whether it’s a logo, contact information or an applique to match artwork on the truck, we can quickly meet customer expectations.” Other new ventures have included custom flooring applications and even cutting 5-in. concrete for a church sculpture.

“The bottom line is that the FlowJet has expanded our capabilities and improved our net income by at least 20 percent,” surmises Bogensberger. “Due to our ability to prototype and offer design flexibility for our wind turbines, as well as perform custom work, we calculate our return on investment at 22 months.” MF

Article provided by Flow International, Kent, WA; 253/850-3500, www.flowwaterjet.com.

 

See also: Flow International Corp.

Related Enterprise Zones: Fabrication

 


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