Alpine uses automation to shorten lead-times, increase production capacity
July 11, 2006
Alpine Engineered Products had more business than it could handle: It was straining its resources and personnel in a way that made the company have to look outside its semiautomatic welding practices. Eventually robotic welding helped the company meet its production, lead-time, and turnover challenges—and keep the company growing.
|Robotic welding has helped Alpine Engineered Products improve productivity, weld consistency, and overall product quality; eliminate outsourcing; and cut lead-times for its line of truss fabrication tables. The company invested inrobotic welding equipment that performs 85 percent of the welding with one robot.|
Alpine Engineered Products Inc. had a good and a bad problem: more business than it could handle.
Demand for the company's truss fabrication equipment and other building components and services was increasing rapidly. For several reasons, this made for a challenging situation.
The first obstacle was production capacity: The company could produce 20 to 25 roof truss fabrication tables a month, and several outside vendors manufactured an additional 40. This situation was limiting, and so was the fact that Alpine had to perform rework on the items it purchased from outside vendors.
Lead-times, as long as 20 to 24 weeks, caused the company to lose orders to its competitors. The situation got worse when the company introduced the Alpine linear saw, which brought orders pouring in. At the same time, orders for the new RAM Easy Rider truss fabrication system went through the roof. The company's Grand Prairie, Texas, facility couldn't keep up with demand.
Turnover also was a problem—many welders suffered fatigue, especially when performing manual welding in the summer.
Managers looked at the situation and decided to see what automated welding might be able to do to help the company overcome its obstacles, as well as keep up with growth.
Assembly and fabrication tables used in Alpine's RAM Easy Rider equipment are 14 feet long, 7-1/2 ft. wide, and weigh about 5,400 pounds. Each table requires 660 single-pass welds, ranging from 1 in. to 6 in. long. Tables and subassemblies are 0.25- to 0.5-in.-thick mild steel. Each subassembly can weigh 400 lbs. to 500 lbs.
Gas metal arc welding (GMAW) machines and wire feeders with overhead swing arms and GMAW machines with wire feeders on portable carts were positioned around the workpieces. Welders had to lean into and climb onto the tables being welded.
Cranes and forklifts handled the workpieces, but significant handling and maneuvering were required, and parts didn't flow well through production.
This setup made it impossible for the company to keep up with increasing orders and offer its customers short lead-times.
Automation was the one avenue that made sense to investigate, according to Ted Martin, Alpine's fabrication manager.
Martin interviewed several vendors about different robot manufacturers to see what capabilities were available with different systems and how those capabilities matched what the company wanted to do by automating its welding.
One thing Martin realized through the process was that it took time even to see that automation couldwork for Alpine.
"Very few, if any, robotic sales presentations demonstrate large welding tasks," Martin said. "It leaves fabricators with the perception that if their product does not fit in a small rotating work envelope with large quantities, that robotic welding is not for them."
Then, once Martin started to see options for the types of work Alpine needed to accomplish with robots, most companies he talked to offered two or three—or in one case, up to six—robots to perform the work that Alpine wanted to do. With each robot, of course, came additional cost.
Martin then learned that a complete package—with one robot—from Motoman could meet most of Alpine's goals and challenges. Plus, he could get the package without having to work with multiple vendors.
"We liked the fact that we didn't need to involve an integrator to do systems integration or need to get any other parties involved," Martin said. "The Motoman MotoSweep™ workcells could do 85 percent of the welding they need to do with just one robot. This saved capital equipment cost."
So in July 2004 Alpine implemented its first robot: a six-axis Motoman UP20-6 in a FabWorld® system to weld subassemblies for the RAM Easy Rider tables. A month later the company added a second Motoman robot—a new, application-specific EA1900N arc welding model with integrated upper arm cabling. Invert-mounted from a MotoSweep transport beam, this welding robot processes the tables.
In May 2005 Alpine added a second FabWorld system for subassemblies—this one with another EA1900N robot. At the same time it added a second MotoSweep cell with an EA1900N robot, bringing the robot total in the facility to four.
All of the robots use Miller Electric's Auto-Axcess™ 450-amp power sources, air-cooled Motoman Tough-Gun® 500-amp torches, and barrel-fed 0.035-in. steel wire with an 80/20 mix of argon/CO2 shielding gas. Overhead cranes and forklifts move Easy Rider equipment in and out of the robot cells to be welded.
Although adding robotic welding equipment may sound seamless in this case, it didn't come without its challenges.
"Implementing robotic welding has required us to make some changes," Martin said.
A significant change, he said, was in the company's fixturing.
"We found that in order to weld with a robot, we had to make better fixtures—ones that hold everything just perfectly. A robot doesn't know how to fill weld, so the fixture must be as accurate as possible," Martin said. "We're in the process of adding more fixtures. Once we max out the capacity on these robots, we'll add more."
The two modified FabWorld workcells, known as cells 1 and 3, each have two rolling fixture tables on each side of a six-axis welding robot that's floor-mounted on a riser base. Fixture table movement is motorized but not yet automatic. Each holding fixture table has three zones, which allows Alpine to weld subassembly parts up to 15 ft. long using robot programs that are divided into A, B, and C portions. The robot always starts welding with the parts in the A position. Some fixtures are centered, and the table doesn't need to move. These workcells can run three different components in the three zones on each fixture table. Alpine runs approximately 20 different subassemblies of varying sizes in the smaller robot cells.
"End caps on rolls are really impressive to watch. That's the one we like to run when we have customers and visitors in for tours. The robot just smokes them," Martin said. "The 'wow factor' is an unexpected side benefit. When people toured the facility before we had the robots, they never wanted to tour the fabrication side—now it's their focus."
The two MotoSweep cells, known as cells 2 and 4, each have two stationary holding fixture tables, one per side. The robot in each workcell is invert-mounted from a transport beam controlled by the robot controller as an external axis. The robot can swing out of the way and weld on the opposite side of the workcell during loading and unloading to help increase productivity and also provide good reach and flexibility.
Operators load the subassembled weldments onto the fixtures. In the cells, operators load the workpiece tables with the tabletop surface upside down. This enables the robot to weld all the structural steel components and subassemblies that are added onto the underside of the workpiece table: tubes, flat bars, channels, and angles. Leg subassemblies that are previously welded in one of the workcells then are welded onto the workpiece tables in a secondary program.
Each workcell has two different work zones with a set of fixtures in each. The robot can process the same type of parts on both sides, or different parts can be run on opposite sides of the same workcell.
"We subassemble in the smaller robot cells and final weld in the bigger MotoSweep cells," Martin clarified. "The bigger cells have only about four different holding fixtures.
"We can also do some subassemblies in the MotoSweep cells if we have time. However, right now our huge priority is to get tables out, so we don't have time to do subassemblies on these cells," he said.
Fixturing is much stricter with the company's automated setup, Martin said. Although this helps ensure that every piece comes out precisely, it also requires special attention to fit-up.
"It's all fixtured very tight and very concisely to make sure everything comes out square and flat, but doing so leaves no room for error. Hot-rolled material varies enough to cause some grief. This material variation leads to fit-up problems that will sometimes cause the robot to miss a weld. Operators normally perform some secondary welding on the workpiece tables—primarily on the outside edges where the robot can't reach. At that time operators also visually inspect the robotic welds and touch up any that the robot didn't get," he said.
Even with a cautious estimate, return on investment has been quick for Alpine, according to Martin.
"Conservatively speaking, payback on the robot systems was less than half a year," he said.
Dan Rupe, vice president and general manager of Alpine's equipment division, also has noticed a direct impact of automating the company's welding procedures.
"By helping us cut our manufacturing costs, the Motoman robots have increased our profitability and contributed directly to the bottom line," he said.
Proof of this can be seen in the company's production capacity. Today Alpine produces three or three and a half tables per shift, or six or seven a day. In addition, the company has been able to bring all of its manufacturing back in-house, which means eliminating the rework it used to perform on outsourced parts.
Robotic welding also has improved the product quality, Martin said.
"We could see a big difference between the purchased items and the ones we made with the robots. Quality with the robots is much better—near-perfect and incredibly consistent," he said.
Increased production capacity and productivity also have helped the company shorten its lead-times.
"Our lead-time is now down to 16 weeks, and we're striving to get it down to eight weeks. We will be able to do that with the robots—without them, we wouldn't have a prayer," Martin said.
Currently the company runs two eight- to 10-hour shifts a day, five or six days a week. Martin said that once the company gets all of its fixtures in, the robots should be able to produce eight to 10 tables a day.
"Robotic welding the tables takes 20 to 30 minutes," Martin said. He added that employees are comfortable enough with the robots to turn them on and then leave to attend other tasks. "The hurdle now is to get the material in and out of the robot cell as quickly as we can. The robots weld much faster than we can get parts in and out."
Seeing how comfortable the employees are with the robotic welding equipment is encouraging, especially considering that many people worry that robots only replace people.
"When we first brought the robots in, everyone was afraid of losing jobs, but in our case, the opposite is true," Martin said. "We've added people because now we have greater capacity thanks to the robots. With the same two people, we can yield more, and it keeps going and going."
An added personnel benefit to investing in robots is reduced turnover and improved hiring.
"People want to work with new technology and progress. In the Dallas-Fort Worth area, employment is difficult because of the aircraft and automotive companies in the area that pay better. Before we had to hire someone that could weld—and skilled welders are at a premium anywhere, not just here," Martin said. "Now, with the robots, we can bring in welder trainees who can fit all the products without touching the welder. Then we can teach them welding. We don't have the turnover rate that we had previously because we give them a little technology, along with a salable skill—and it's a good thing."