November 7, 2002
Editor's Note: This article is Part II of a four-part series covering flatness and stability in cut-to-length, slitting, and tension leveling operations. This article discusses flattening solutions and the anatomy of a bend. Part I, which appeared in the October issue of The FABRICATOR®, discussed how flat-rolled metal gets unflat; Part III in the December issue will address how coil processors can make metal flat so it stays that way; and Part IV in the January 2003 issue will discuss new applications and options in leveling equipment.
|While a worker prepares to remove parts from a dual-pallet laser at Hartzell Fan, Piqua, Ohio, the machine is cutting the next job. The company was able to replace an older laser and a plasma cutter with this new machine. The space saved contributed to better flow of material from the laser.|
By 1999 the throughput for an 8-year old laser cutter at Hartzell Fan's Piqua, Ohio, plant showed signs of becoming a serious obstacle to productivity and timely delivery.
"We were running approximately 20 hours a day and getting into six days a week; in some cases we would add a third shift, but still we couldn't keep up," recalled Dan Phillippi, manager of manufacturing at Hartzell.
Hartzell Fan Inc., one of three Hartzell companies, is a custom industrial fan builder. The company offers a range of fan types, with only a few of its products straddling the needs of both the industrial and commercial markets. It often builds larger, one-of-a-kind industrial fans or high-output fans. Hartzell also manufactures corrosion-resistant fans from a fiberglass material.
The company is primarily a sheet metal fabricator with engineering capability but makes its own propellers (fan blades) and wheels to force air. With its corrosion-resistant fans, however, it also has a foot in the fiberglass industry.
Hartzell's Piqua operation has 150 full-time hourly and salaried employees. The company designs and engineers its products itself and has its own sales department. The company also has another plant in Portland, Ind., that has an additional 40 people, and a shipping location in Aberdeen, Miss.
|According to Dan Phillippi, manager of manufacturing at Hartzell Fan, "Loading and unloading, basically from spark to spark, is about 20 seconds," on the dual-pallet laser. While operators now load and unload the machine, Phillippi said he likes the fact that he has the option to incorporate the machine into an automated flexible manufacturing system later.|
The plant needed a new laser to complement its turret punch press and plasma cutter. In its efforts to replace the ailing laser, Hartzell personnel looked at four laser vendors' products.
In the end, a new dual-pallet laser replaced both the old laser and the plasma cutter. This freed floor space in the plant and permitted the company to rearrange other equipment.
The newly opened floor space contributed to a better flow of product from the laser. Previously material moved from the shear operation to either the plasma operation or laser operation, and then perhaps to a punch press operation, with nearly all material going to the press brake or roll forming operation.
With the new laser, Hartzell has only three pieces of equipment feeding its secondary operations. In addition, while the shear operation remains, "the majority of our shear work has disappeared," Phillippi explained, "since the new laser is so fast that it almost competes with the shear with respect to setup. And when the safety factor is considered, handling a 1 D4-inch-thick plate is now a one-man operation on the laser."
Cutting a large steel sheet on the shear is a two-man operation with more possibilities for injuries, he added.
"When you get that down to a one-man operation, operating with a suction cup lift, it is both safer and faster." The shear continues to handle many alloys, specialty metals, and perforated metal used in the Piqua plant.
But ultimately, any equipment must justify itself on a company's bottom line, and Hartzell's management was watching its new laser.
"As a privately held company, we look pretty closely at value," said Dave Stonebraker, manufacturing engineering manager. He and Phillippi realized they'd need to "crunch the numbers," including as many variables as possible.
"We wanted to give several vendors an opportunity to demonstrate their equipment," he said. "We started by looking at literature and specifications sheets. We went to machine shows and narrowed it down to two machines. Then we went to those manufacturers' show rooms and a manufacturing plant for final evaluation." The research process took 15 to 18 months, Stonebraker said.
They realized that most of the newer equipment would outperform the old laser cutter. In some cases, as they found, those throughput speeds were up to four times greater.
"When we started crunching the numbers," Phillippi recalled, "one machine was about four times faster than our existing laser cutter—just in cutting speed." That machine was the Gemini 3015 from Amada. "In addition, it had a dual-pallet table—a shuttle table, which in essence made it eight times faster. Just in raw numbers, we were looking at increasing productivity probably fourfold."
He said his operation has not achieved that rate completely.
"We're in the neighborhood," he said. "Not only does our new machine run about 60 percent of the work from the old laser, it has taken on the plate cutting duties from the plasma cutter as well.
"We're already running anywhere from 130 to 190 percent on the new piece of equipment—pretty close to four times our previous productivity."
With the dual-pallet design, operators preload the free pallet for the next job. When the laser begins work on that pallet, they can unload the cut pieces and skeleton from the other.
"Loading to unloading, basically from spark to spark, is about 20 seconds; that is, the time to remove the cut material from the machine and begin cutting from the new pallet with the new piece of sheet metal," Phillippi said.
Phillippi said he likes the fact that his new machine gives him the option to expand to a flexible manufacturing system (FMS) at a later date.
"It is completely retrofitable to a fully automated system with one or two storage towers," he said. That type of growth flexibility is a good option to have, Phillippi said, but would require quite a change in the operating procedures at Hartzell.
"Considering the wide variety of materials we use, that would have been a big leap at one time, to go from loading a single sheet of whatever we need to a complete automated FMS. We went halfway, and perhaps eventually, depending on business volume, we may look further, but at least we have the option on the existing piece of equipment."
The new laser cutter replaced two pieces of equipment: the old 2,500-watt laser and a large-table plasma cutter used to cut thicker materials. Phillippi said his operation was able to replace both because of the new machine's capability to cut greater thicknesses, aided by a water-assisted cutting mode. It can cut mild steel a little more than 1 in. thick, enabling the company to get rid of its big plasma cutter as well.
The water-assisted cutting Phillippi referred to uses an adjustable water mist to absorb heat while cutting thick steel plate. As a result, higher power can be used without fear of excessive heat damaging affected areas, allowing for increased cutting speeds and improved material use and part yield.
"We use the water assist when cutting heavier material—from 5 D8, or 3 D4, or even 1 D2 in. It keeps the metal a lot cooler and gives a better, cleaner cut. We can space parts closer, since the material is not heating up as much."
The maximum wattage that can be used with the water-assist cutting is 4,000.
When asked by guests about the decision to move to the new laser cutter, Phillippi tells them it's a matter of assessment.
"What I try to impress on the visitors is that they must do their homework like we did."
Richard Herzfeld is a free-lance writer based in Milwaukee, Wis., and can be reached at e-mail firstname.lastname@example.org.
Ancel Thompson, manager, Laser Division, Amada America Inc., 7025 Firestone Blvd., Buena Park, CA 90621, phone 800-626-6612, Web site www.amada.com.
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