By MARY KAY MOREL, Motoman Inc.,
Edited by KIMBERLEY GILLES, associate editor

Jeff Tuttle, president of Tru-Form Steel and Wire Inc. of Hartford City, Ind., says automation keeps his company competitive. Tru-Form fabricates returnable metal racks that hold automotive parts such as windshields and powertrains, and also fabricates other equipment parts, such as heavy equipment buckets.

"Foreign competition, particularly with the Chinese, and the growing scarcity and high cost of skilled manual welders, are Tru-Form's two primary reasons for implementing robotic automation," says Monty Tuttle, vice president of the company and Jeff Tuttle's brother.

Tru-Form employs 100 people, and operates 2 eight-hour shifts for five, sometimes six, days a week. It currently has 13 Motoman robots in 12 workcells that operate in its three Indiana plants. Nine of the robots perform welding, while the remaining four are used for material handling and research and development operations.

"On average, the robotic welders replaced two human welders per cell," says Monty Tuttle. In some of the company's operations, the addition of a robot did not replace a person, but the use of the robot resulted in a more consistent product, he adds.

The newest robotic cell
The company, which began using robots in 1992, installed its newest robot cell in August 2006. The latest cell includes two Motoman six-axis HP50-20 robots and an NX100 DR2C controller, along with power sources from Miller Electric Mfg. Co. (www.millerwelds.com), pneumatic wire cutters and automatic torch cleaners.

Tru-Form designed and built all fixtures used in its robot cells, and views these fixtures as key cost-saving devices. Less-skilled operators can be used for the robot cells if fixtures are built so that parts can only be loaded correctly, says Monty Tuttle.

The newest robot cell includes two MHT-1500 headstock/tailstock positioners, each with a 6,614 lb. (3,000 kg) load capacity. The weld cell can handle parts to 11 ft. long (132 in.) and 80 in. wide, and that weigh as much as 3 tons.

"The dual robots start welding in the middle of the parts and work their way out. This cuts our cycle time in half," says Monty Tuttle.

He says the company also uses the new robots for pulse-welding 14-ga. and 16-ga. material. "Depending on the application, the robots have the flexibility to weave, touch-sense, seam-track, or do standard GMAW or pulsed-MIG welding," he adds.

Making racks
Parts are made primarily of mild steel, from 0.5-in. to 16-ga. thick. The fabricator generally uses standard 0.034-in. to 0.45-in. wire that is fed from a torch-mounted spool or 500-lb. bulk dispenser. The shielding gas mixture is 90 percent argon/10 percent CO₂.

In general, the robots produce single-pass welds that can range in size from ¹/₁₆ -in. to 12-in. long. A completed rack may have anywhere from 10 welds to 600 welds, depending on the product. But some of the welds can total 500-in. long, and some products can have more than 900 in. of weld.

The company does use some flat stock and sheet metal in its products, but it mostly uses tubing. So the robots must do a considerable amount of circumferential welding around the tubular parts.

"Welding different gage metals, like 0.025-in. material to 16-ga., can be challenging, especially on T-joints," says Monty Tuttle. He explains that the welding puts a great deal of heat into a product at one time, so the distribution of heat is critical. For that reason, the company developed a welding program that makes welds without distorting the tubes and doesn't twist the parts into pretzels.

"You can't just start at one end and weld like crazy or you'd never get the part out of the jig when it's done. Sometimes parts need to be pre-tacked in a certain way before we have the robots do the hard welding. Then, the robot might need to skip around a bit to avoid distorting the parts," he says.

Parts are batch run, and batch size varies widely. For example, the company may weld 25 or 30 different parts in its robot cells. A robot cell might run a hundred parts per batch, per robot, says Tuttle.

"All of the fabricating done for automotive suppliers is done on a just-in-time basis, so reliability is very important," says Monty Tuttle. He says the robots are reliable, so the company can produce consistent, high-quality parts that meet its customers' schedules.

An added bonus
"We are definitely pro-robot here," says Monty Tuttle. "Dad put me in college for robot technology, and bought the first K10MSB robot back in the early 1990s," he adds.

"Our people like the robots, too. Tru-Form gives its employees the opportunity to learn more of a skilled trade, and earn a higher pay. Getting involved with the robots really changes them. Instead of having to come in and weld every day, they get to learn about the robots. They can see how what they put in (programming) comes out," he adds.

The best success
Tuttle says training is most successful when it teaches welders, who already know welding processes, how to program robots. "Welding is all about angles, feeds and speeds, and it is easier to learn how to weld with a robot if they already know how to do it manually," Tuttle says, adding that welders appreciate being able to program a robot and see the weld being done at a faster rate than they can do it manually.