Robotic welding material handling improve quality in auto industry.

To day's car buyers expect quality, not only in performance and reliability but also in the aesthetics of their vehicles. "Customers look for reliability and a good-looking product," said Wilfried Eberhardt, vice president of sales and marketing for KUKA Robotics Corp. "Consumers want to know

how reliable is the product, how long they can use it without it having problems. They also care about how it looks and feels. Does it look plastic, are there gaps, does the paint look good? That might not affect reliability, but more and more it's how consumers feel about the product. Products can't look cheap."

Automobile OEMs long have relied on robotics to achieve higher quality, among other benefits, generally in welding and material-handling applications. As auto makers continue to outsource more work to their suppliers, those suppliers also are increasingly using robotics to achieve the quality the OEMs demand.

"OEMs are getting more complete subsystems from suppliers, so you have fitup issues," said CarlTraynor, director of marketing for Motoman Inc. "Parts coming in from tier suppliers have to fit the vehicle. Quality is making all those components come together."

Tier One suppliers, those companies that are supplying the more complete subsystems like complete dashboards or seats, are also pushing for higher quality from their suppliers.

"The OEMs are outsourcing more and more components," Eberhardt said. "Japan and Europe more and more are using tiers to supply more complete systems. An extreme example of that is outsourcing the complete body, which is what Mercedes is doing with one model. The body will be done by another company completely, and Mercedes is only responsible for the final assembly. That's why suppliers have to supply the same level of quality. And the Mercedes plant in Alabama is telling its suppliers they have to use same the processes to achieve that quality. There's no way not to use robots."

And, according to Mike Bomya, executive vice president, engineering and manufacturing, for Nachi Robotic Systems: "The lower tiers, in the past, were manually intensive. Now they're becoming more automated and quality is a driver. Ultimately, the auto companies are looking for part traceability. They want to know how the part was manufactured and whether it conforms to all requirements. Naturally, the way to get that traceability is to automate and have the automation keep those records for you. When the automated tooling is qualified, and you qualify your part off your tooling, you can have good confidence that what you're manufacturing is good."

Auto makers and their suppliers use robots mainly for spot and arc welding and material-handling applications, such as tending machine tools; loading, unloading and transferring parts at stamping presses; moving parts on and off conveyors; and reorienting parts between processes.

"We're also now seeing a lot of. part-to-process robotic applications," Traynor said. "In the past, a conveyance system would carry parts down the line and the robot would do its thing to the part. Now we're using robots to pick up the part, carry it to a fixed tool or another robot. The robot is now acting as part conveyor and part fixturer."

ROBOTIC WELDING

Welding in the auto industry is one of the more mature robotic applications and one that has a major impact on the quality of components and the finished product.

"The location of the spot weld definitely affects quality," Traynor said. "The fact that robots are very repeatable means that weld is always in the right place."

"You also have very crisp control of consumables," added Erik Nieves, senior manager of technology advancements at Motoman. "With robots, you can optimize deposition, which is hard to do with manual welding."

Robotic welding has become so commonplace in the auto industry that Eberhardt said "it's almost impossible to build a car body without robots. Humans can't achieve the same precision and repeatability. The variations are too small. And to achieve the required stiffness of a car body, you have to deal with heavy weld guns, which people can't handle."

Another recent trend in the auto industry that will have a direct effect on quality is the replacement spot welds with arc welds, said Nieves.

"The general trend in Europe is to do more arc welding because arc welding makes for a more rigid structure," he said. "You don't spot-weld a NASCAR automobile. Some OEMs are going to go toward arc welding with some critical welds."

In addition, robots are now being used to hold parts for other robots doing the welding, which eliminates fixtures. While that may not directly affect quality, it does save money on fixturing. "So instead of turntable with a fixture, advanced users have one robot with end-of-arm tooling that is fixture quality presenting parts to a welding robot," Bomya said.

MATERIAL HANDLING

On the material-handling side, a robot can be used for just about any process in which a part is moved from one place to another, such as in and out of a machine tool or press. Robots also are used to reorient parts between processes.

"In a lot of assembly processes among suppliers, you have to handle parts automatically even if you don't use robots directly for assembly," Eberhardt said. Think about the assembly of electronic components or transmissions. You need a lot of parts at precise locations, and the best way to achieve it is using robots."

And lately, auto suppliers are starting to use robots to move parts from one job to the next, essentially acting as a flexible conveyor.

"Many robots are adding material handling to whatever other process they're doing," Bomya said. "In production, two things have to occur: the process, such as welding, and moving the part to the next job. If the robot can take over part transfer, potentially conveyors can be eliminated at a cost saving. I think we'll see wholesale applications of that in the future."

Material-handling robots also eliminate ergonomic problems that human workers are susceptible to, such as repetitive stress injuries and back injuries.

As automobile CEMs continue to stress higher quality, and insist on it from their suppliers, the use of robotics will continue to increase in the auto industry. And the benefits, some tangible and some intangible, will continue to accrue.

"Robotics help the auto industry and suppliers be more competitive and meet the growing customer needs, which are growing because we're never satisfied with what we have; we always want something better," Eberhardt said. "Quality is essential to selling your product over your competitor, and robots are absolutely supporting that because they're achieving current and future quality demands of the market."