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Laser Technology

Like peas & carrots

By Lynn Stanley

Above: An MC Machinery MSCIII tower feeds sheet metal to a Mitsubishi NXF-40 fiber laser and eX 4.5kW CO2 for higher output while shrinking Creative Metal Products’ equipment footprint.

Contract manufacturer pairs fiber and CO2 in one automated dual line

November 2016 - Fiber laser sales outsold CO2 machines in 2015, but Jeff Wolding, owner of Creative Metal Products, will tell you he has the best of both worlds. An automated dual line anchored by fiber and CO2 technologies is helping Creative boost output while shrinking its equipment footprint.

The Neenah, Wisconsin-based contract manufacturer serves a broad customer base by engineering and producing steel components and fabrications to specification. Since 1995, when Wolding founded the company, Creative has grown from 3,500 sq. ft. to 85,000 sq. ft. Its scale-up is due in part to some aggressive acquisitions of equipment and automation.

In 2013 Creative installed a Mitsubishi 5 ft. by 10 ft. MSCIII automated line with an eX 4.5kW CO2. Two years later the manufacturer sold an existing 4.5kW CO2 and loader and added a Mitsubishi NXF-40 fiber laser to the line. The new arrangement allowed Creative to reduce floor space by eliminating the standalone automated cell and feeding two lasers with one tower. Creative also has an older, manually operated 6 ft. by 12 ft. Mitsubishi  LV laser it uses for oversized jobs.

MC Machinery Systems Inc., part of Mitsubishi Corp., supplied Creative with its automated dual line. The Wood Dale, Illinois, supplier builds metalworking equipment ranging from simple fabrication applications to CNC-driven, automated manufacturing cells. 

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Creative uses the NXF-40 fiber laser to cut sheet metal up to 10 gauge and aluminum and stainless up to approximately ¼ in. thick.

Skin deep

Creative uses its eX CO2 to handle 7 gauge and heavier steel as well as stainless and aluminum 1⁄4 in. and thicker. The NXF-40 fiber cuts steel sheet metal up to 10 gauge and aluminum and stainless up to about 1⁄4 in. thick. The fiber laser can crank out two to three times the volume of parts on lighter gauge materials when compared to the CO2. But deciding whether a job goes to the CO2 or the fiber isn’t as simple as referring to a feed-rate chart, Creative’s Fabrication Manager Santy Vongkhamsaeng says. The fiber can cut a part faster, but the edge quality may not be as good as that achieved with the CO2.

“When you factor in a secondary operation to remove a hard burr, the CO2 may be the faster choice,” he says. A wide power door, safe wavelength and easy access to the cutting table make the CO2 the go-to machine for hand-loaded prototypes, regardless of thickness.

Assist gas selection is the main criteria for mild steel production. “If nitrogen makes sense from a cost perspective, then it belongs on the fiber,” Vongkhamsaeng says. “This is why nearly all of the work going across the fiber is cut with nitrogen. Conversely, the CO2 uses oxygen about 60 percent of the time and nitrogen approximately 40 percent of the time. The fiber can also oxygen cut steel, the CO2 just does a better job.”

When cutting thicker carbon on a CO2 there’s a lot of forgiveness, continues Vongkhamsaeng. “With a fiber [laser machine], conditions have to be just right or you can start to get a bad cut in a hurry.”

Balancing the efficiency of fiber against gas and electrical consumption—the main cost components of fiber laser operations—is another factor that influences Creative’s machine choices. To analyze real-world electrical consumption on its manufacturing floor, Creative had its electrician install meters on the dual line’s two fiber lasers [and chillers] to monitor cumulative draw over weeks of operation. The company turned to its supplier Praxair to take a deeper look at gas consumption.

Analysis showed the fiber laser used a lot less power, about a quarter of that of the CO2 laser. The CO2, however, demonstrated a lower gas consumption rate. “The fiber can cut the same material with a smaller diameter nozzle and lower flow,” says Vongkhamsaeng. 

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The eX CO2 laser cuts 7 gauge and heavier steel as well as stainless and aluminum ¼ in. and thicker.

Compare and contrast

Jerry Sackman, regional sales manager for Praxair, confirmed the findings stating, “Fibers cut with a thinner kerf and need a higher pressure.”

Creative found that its replacement of its previous CO2 system with the fiber laser caused nitrogen consumption to rise by 40 percent. “This increase is consistent with what I see from other customers who have switched to fiber,” says Sackman.  

While the CO2 requires laser gas [the fiber does not], the flow rate on the Mitsubishi cross-flow CO2 resonator is so low that Creative found the fiber laser still consumes significantly more gas overall. Wolding isn’t complaining. “The volume of parts is so much higher coming off the fiber that it’s worth it,” he says.

On thin materials, fiber’s higher speeds mitigate the cost of nitrogen per part. The speed advantage over oxygen decreases with thicker mild steel, making the CO2 the better choice. 

“It’s a lot cheaper and easier to oxygen cut 1⁄4-in. steel on the CO2 than to nitrogen cut it on the fiber,” says Vongkhamsaeng. “It takes about 42 cubic feet per hour of oxygen to cut 1⁄4-in. steel on a CO2 versus more than 2,000 cfh if you were to nitrogen cut the same material on a fiber.”

The speed of the fiber has also driven Creative’s choice to automate. “Some automation systems on the market struggle to keep pace with a fiber [laser],” notes Wolding. “It’s rare to see a tower supporting more than just one fiber but Mitsubishi’s high-speed MSCIII automation easily supports a variety of work on the fiber and the CO2.”

The automation cell’s “traffic cop” is a shop-floor line control software designed by Ncell for Mitsubishi. The software tracks a 12-shelf material tower with two load stations internal to the tower, two fiber lasers, two shuttle tables per fiber laser, four nest carts, and different materials running simultaneously on each fiber. “If the automation couldn’t keep up then the speed of the fiber would be wasted,” Vongkhamsaeng says. “Mitsubishi’s MSCIII automation in tandem with the line control pulls it off.”

Whether any given job is headed for the fiber laser or the CO2 machine, the Ncell offline programming system keeps operations simple by generating just one nest program. Cutting conditions specific to each machine are automatically assigned when a nest is posted. As a result, an operator can seamlessly switch a nest program to the fiber or the CO2 based on need.

Creative’s fiber and CO2 machines each have their production niche but the equipment also shares a number of common traits. Neither the Mitsubishi cross-flow CO2 resonator nor the fiber resonator contains turbine blowers or glassware. The design eliminates expensive resonator rebuilds and lowers cost of ownership. 

While the CO2 requires laser gas, its 3-liters-per-hour flow rate is one-tenth the requirement of some fast axial-flow CO2 lasers. The Mitsubishi CO2 is closer to the  zero liters per hour of a fiber than to other COmachines on the market. The laser gas pre-mix contains just 28 percent helium, unlike the traditional two-thirds helium (66 percent) of most CO2 laser gas mixes. Employing two technologies in the same line gives Creative Metal the flexibility to tailor each job to the strengths of its equipment based on cost, edge quality and finish. FFJ

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