Robotics in ABS Manufacturing: A Case Study
Stäubli Robotics Posted 01/30/2013Automotive manufacturers demand ever-increasing precision in their antilock braking system (ABS) components. This became a problem for one global manufacturer of ABS systems which needed a unique solution to its manufacturing processes. Its plants in China, Germany, and the United States had manual production lines that were no longer accurate enough, and increasingly difficult to adapt to the customers’ changing designs. This was costing time, money, and future business.
Their answer was to install flexible robotic systems. The manufacturer turned to Advanced Automation, Inc., of Greenville, South Carolina, to design a robotic version of their assembly lines. Advanced Automation, a robotics systems integrator, in turn, approached Stäubli Robotics in nearby Duncan, South Carolina for assistance.
“The accuracy of Stäubli robots was a major factor in choosing them,” says Robert Belk, Controls Group Manager at Advanced Automation. “Their precision solved the problem of positioning parts more accurately and repeatedly.” Belk also says, “Stäubli robots have zero gear backlash and we didn’t want to take a risk of it not being repeatable. In addition, the robot’s cycle time studies were very impressive.”
Likewise, Bill Hein, Project Manager at Advanced Automation, asserts, “Because the robots are pressing parts together, they need to maintain tolerances within a few microns. We were very concerned with the precision and repeatability required, which is the main reason we preferred Stäubli.” Hein adds, “Their performance and accuracy contributed greatly to the value of our designs.”
Three Different Lines
Bill Hein describes the ABS project as; “The end-user has robots on three individual assembly lines to automate the manufacturing of antilock brake systems. Robots place the parts into position for different operations and processes.” The tasks involve gauging, screw driving, and pressing of parts into an assembly.
The units used in these operations are the Stäubli RX160 and TX90L models, both are six-axis pedestal mounted. Advanced Automation chose these particular models due to their inherent adaptability and long reach. Hein mentions, “We needed to flip the part; operations are performed on all six sides. Six-axis robot models gave us that flexibility.”
While throughput on the automated lines today matches that of the previous manual version, the new lines can adapt to the many requirements expected in the future by the manufacturer and their customers. Some of these needs were not even foreseeable during the planning phase of the project, but the manufacturer wanted to have the flexibility to meet any eventuality that might arise in the competitive world of automotive parts manufacturing. “The manual system was very rigid, not at all adaptable. Advanced Automation went with a very flexible robotic design to allow changes in product types,” notes Hein. “And of course our system offers them considerable labor savings, compared to the manual line.”
The three new ABS lines are not all exactly the same. “The production line in Germany is totally automated, so it naturally includes more robots,” says Bill Hein. “The China and U.S. production lines have some variations of the line in Germany but include some manual loading operations.” Hein explains that the reason those production lines are less automated than their German counterpart has nothing to do with technical issues, but was a capital expenditure decision.
Justin Nardone, a Project Manager and Hein’s colleague at Advanced Automation, adds, “The parts running through the lines are similar, but have variations for different vehicles. That further highlights the flexibility the end-user required.” The major difference is the size of parts produced, although they go through comparable processes.
Hein says that the manufacturer expects to upgrade the lines in China and the U.S. eventually. “Initially, those lines didn’t need the full production rate, so they decided to go with a manual station in each of them,” Hein states. “They are outfitted to accommodate full automation, though. Advanced Automation can duplicate some of the subassemblies at each of the stations without too much effort.”
During the design phase of the project, the integrator carefully considered how the robots were going to grasp the components. “Once the robot gripped the part, we didn’t want it to let go while the part was being brought to a station, flipped, moved, and rotated. This would help to maintain both flexibility and speed,” recalls Bill Hein. “We were also challenged with securing the part while being pressed. We talked with Stäubli about how much pressure could be applied without damaging the robot arm.” Hein reports that some flexure of the arm does occur, but Advanced Automation and Stäubli worked jointly to achieve a creative and reliable solution.
Robert Belk remarked on the grippers as well. “They are pneumatic, some of which have vacuum cups. While Advanced Automation bought some of the grippers, we fabricated the others ourselves.”
Vision and Software
A vision system locates and inspects parts during production. Justin Nardone explained the vision system’s role on the production lines. “Vision is needed for locating the product due to random arrangement on the pallets. It also scans the product to be sure it’s the correct part for the process.” Nardone adds, “The camera is mounted on the end of the robot arm, not stationary over the conveyor. A photograph is taken to locate identifying features of the part, and the gripper position is tweaked based on feedback from the vision system.”
Robert Belk noted that the system’s camera functions well in the brake parts manufacturing environment. “Although some dirt and fluids are present, keeping the camera clean is not an issue.”
Software plays a big role in making the robots perform their tasks properly and consistently. Again, Justin Nardone: “The production lines are software-intensive because they are very database heavy. Each part has its own identity within the database. When the part arrives at a work station, software gauges that part, sets the database interface, and takes full control of the robot.”
The robot controller is not being used as a work cell controller. According to Belk, “The robot is a slave where tasks are programmed into it. Commands are issued to run specific tasks from the work cell controller.” Device Net is used to communicate with the robot, which only interfaces with what a PLC allows.
Getting a Brake with Robotics
Installation of the Advanced Automation systems using Stäubli robotics solved the inflexibility, inconsistency and lesser quality inherent in the manufacturer’s manual production operations. The robots can be reconfigured to run ABS parts that have yet to be designed. With these systems, the manufacturer now has a cost-effective means to accommodate whatever the market throws at it.
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Stäubli Robotics (USA)
Stäubli Corporation Marketing Manager
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About Stäubli: Textile Machinery, Connectors and Robotics
Stäubli is a mechatronics solution provider with three dedicated divisions: textile machinery, connectors and robotics. With a workforce of 4000, Stäubli has a presence in 25 countries and agents in 50 countries around the world.