Case study: CO2 Lasers in job shops
Laser helps fabricator handle high-volume intricate parts
Wrayco Industries Inc., Stow, Ohio, a 20-year-old family-owned precision fabricating shop, produces steel fabricated fuel tanks, hydraulic reservoirs, and fenders for a leading heavy construction equipment manufacturer. The company employs 102 and has more than 100,000 square feet of manufacturing space.
Processing thousands of pounds of steel each day using its punch- plasma process required seven employees working in shifts around the clock to prepare part programs, sequence machinery, and load and unload material.
Wrayco was faced with a growing demand for high-quality, intricately configured parts produced in thicker materials. In addition, its largest customer was preparing to expand its product line.
"We began to see a demand for more intricate designs and shaped or curved parts from our customers," President Gary Gibb explained. "New fuel tank and fender designs can be very complicated, with the emphasis on improved part appearance and functionality.
"Fenders are more complex because they either mount, hold, or cover something," Gibb said.
Also, a trend toward more ergonomic principles has impacted part designs. Construction OEMs are designing products, such as parts with smooth, round corners, that are more sensitive to operator comfort and safety.
As parts became more complex, the company could not effectively meet production parameters for rectangular or highly contoured parts and for large sheets in thicknesses up to 1/4 inch with its existing equipment.
Rather than invest in the special tooling necessary for manufacturing each new component, the shop was outsourcing approximately $25,000 worth of work each month. It was outsourcing entire families of components, such as parts that called for slitting and removing 0.0010 in. of material in 0.125-in.-thick mild steel.
The company determined that it was not situated to handle the high volumes efficiently or to meet the cut quality and configurations the new parts required.
Exploring the Options
To address these production challenges, Wrayco began exploring equipment options. The company wanted the capacity to handle worksheets as large as 60 by 120 in. and to process parts in 1/8-, 3/16-, 1/4-, and 3/8-in. sheet thicknesses.
Automated material handling was a prerequisite, as the shop looked to keep production at a continuous pace with minimal operator intervention.
Gibb decided punching equipment would not best meet their needs because of the tooling investment required. He focused on a CO2 laser because he said it provided the most flexibility. He and his staff then spent three months researching CO2 laser systems.
Wrayco's quality control manager, chief engineer, and chief programmer were involved in the equipment evaluation process. The team reviewed equipment based on department needs and current and future requirements.
"As we looked at different equipment over a 90-day period, I would solicit input from the team and discuss equipment capabilities versus Wrayco's immediate and long-term needs," Gibb said.
The company's quality control manager evaluated equipment based on its repeatability and accuracy, and conducted capabilities studies on Wrayco's existing machinery for comparison.
The chief engineer looked at system functionality and considered the shapes and designs, such as slots and tabbing, that were required of its new parts. His goal was to have a machine that would give Wrayco's engineers the most flexibility in execution of a design.
The chief programmer wanted to simplify the programming process, taking into account DXF file importation, nesting, and DNC linking.
"We found a lot of similarity in laser system sizes and capabilities," Gibb said. "For us, the selection came down to material handling. We wanted a system that was heavy and robust enough to process heavier gauges and to handle large amounts of material daily."
The company also considered the machine footprint. It needed a fairly compact system, as well as the process for delivering material to the machine. According to Gibb, most machines were competitive in features and functions; therefore, cost was not an influencing factor.
Purchase and Installation
The company decided to purchase a Strippit®/LVD Axel 3015 L flying-optics laser system with multiple CNC automatic pallet stations. The 5- by 10-foot unit processes materials up to 1/2 in. thick using a 2-kW laser.
The laser's flying-optics design allows the cutting head to move freely on three axes. The workpiece does not move during cutting. Gibb felt the design was an advantage, as 60 to 70 percent of the workpieces Wrayco processes are large, up to 60 by 120 in., with significant travel distances from one cut to the next. The flying-optics system is designed to achieve axis positioning speeds of up to 170 meters per minute regardless of sheet size or weight.
The installation of the machine required minimal site preparation. A foundation was not required for the system; only isolating pads were installed.
Gibb also purchased the Strippit CADMAN-L CAD/CAM offline programming package. The software incorporates automatic nesting and is designed to optimize cutting and machine parameters to maximize sheet utilization. It automatically generates NC code and provides simulation of the laser path and calculation of production time. It also can be used for the importing of 2-D and 3-D DXF and IGES files, interactive CAD functions or generation of parametric shapes, and simplifying part programming.
Seven operators attended a week-long training session on-site.
Today the shop is handling a variety of part configurations, has eliminated its outsourcing, and handles a higher volume of work around the clock.
Handling Intricate Parts
The company now can accommodate its customers' needs for intricately shaped parts, Gibb said. "Different sizes and shapes that used to be very difficult are now not a problem."
The shop achieves accuracies of ±0.004 in. Prior to the use of the laser, its accuracy was ±0.020 in. The laser uses high-pressure nitrogen assist gas to produce a sheared edge cut quality without dross or burn marks. The quality of the cut has improved the integrity of secondary welding operations, which Gibb considers especially important since Wrayco implemented a robotic welding system.
"Parts must be made accurately for them to weld well. Your upstream operations such as parts cutting have to be improved when you introduce robotics," Gibb said.
Accurately cut parts also reduce welding time, keep the setup consistent, and help components fit together during assembly.
24/7 Operation, Higher Throughput
Two weeks after the laser system was installed, the shop was producing 24 hours a day, seven days a week. As a result, the shop now can process 50,000 pounds of sheet metal daily.
"Having the ability to run the system unattended appeals to me," Gibb said. "I can place 10,000-lb. bundles at each load station and let the system run around the clock without supervision."
The multipallet CNC load and unload system enables loading and unloading functions to be performed independently with a load-unload time of 40 seconds. This frees the laser operators to perform other tasks, including programming the next group of parts, removing a table of finished parts, or receiving incoming material. The loading mechanism handles plates up to 3/4 in. and stack heights up to 6 1/2 in. per station.
A tipping motion lays the cut parts onto the table, preventing damage to the sheet material. Cut parts are deposited on a scissors table with a 5-ton capacity and a 12-in. stacking height. The unattended operation has proved a savings for the company, which has reduced its labor requirement within the past six months. It needs only two workers to operate the system, instead of the seven formerly required.
"There are very few disadvantages of running around the clock—the profitability is high," Gibb said. "But when you're operating 24/7, you need to build time into the schedule to maintain and monitor the machine.
"The misconception is that "lights out' means 'hands off,'" Gibb said. "It's important that you spend time to properly maintain the machine. If you do, it's very manageable. When you ignore maintenance procedures, you will have problems."
On a weekly basis the company shuts down its laser an average of eight to 10 hours to perform routine maintenance. Maintenance tasks typically include cleaning mirrors, checking focal lengths, changing filters and slats, and general machine cleanup.
The shop has improved work floor safety. According to Gibb, the incidence of injuries was higher before it introduced automated material handling. Wrist and hand injuries from part handling and shearing operations have been reduced. Workers no longer contend with part burrs, the sharp edges of which could result in cuts or injuries to fingers and hands.
The automated laser operation also facilitates just-in-time (JIT) production. Parts can be cut overnight, and bending, welding, or assembly operations can begin the next morning.
Before using a laser system, the shop was obtaining 60 percent sheet utilization. Currently it has increased utilization to as much as 90 percent and reduced material requirements by 20 percent.
"At present business levels, $250,000 per month is spent on sheet steel,"Gibb reported. 'We are saving about $30,000 to $40,000 in steel with that 15 percent improvement. We know there is a direct payback here."
Wrayco maximizes material usage and productivity by using automatic nesting and common-line cutting. The shop uses its offline programming system to nest parts automatically, combining assemblies on a sheet. Before the laser, the shop could not nest parts efficiently on its punch-plasma equipment without reducing machine productivity because of the changing customer demands for more intricate parts.
In addition, the company is employing double-cut processing in which one cut produces two parts. The double-cut technique has reduced laser cutting time as much as 20 percent.
For Wrayco, the technology has broadened the shop's capabilities and its opportunities.
"Before the laser, we would try to lead customers away from special sizes and shapes because we knew that those types of designs would require significant nibbling and deburring time,"Gibb said. "Now our only question is, How are the files being supplied? The technology has changed how we look at parts."
The company now is also more involved in its customers' design process.
"We can go back to our customers and make suggestions—we're actively involved in the process and it's more creative than ever before," Gibb said. "Our customers are soliciting that kind of information and are looking for suppliers to bring new processes to the table."
While laser system automation generally is more easily cost-justified in the manufacturing sector, shops such as Wrayco are investing in CO2 laser cutting systems with automation and high-power laser resonators to meet throughput and material capacity requirements.
Loretta DeGasperi is public relations specialist for Strippit/LVD, 12975 Clarence Center Road, Akron, NY 14001, phone 716-542-4511, fax 716-542-7225, e-mail email@example.com, Web site www.lvdgroup.com.Strippit/LVD manufactures a range of metal fabricating equipment, including turret punch presses, press brakes, lasers, shears, flexible fabricating systems, automation programming software, and press brake tooling.
Photos courtesy of Strippit/LVD, Akron, N.Y., and Wrayco Industries Inc., Stow, Ohio.
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