Assembly in Action: Robots, Machine Vision Cut Defect Rates
February 20, 2009
The Meister Group (Sprimont, Belgian) manufactures components for the automotive industry, including steering systems, injectors, valves and safety systems. At its plant in Haute-Savoie, France, the company produces electric valve parts for use in anti-lock braking systems.
The valves, which require both machining and assembly, must be produced to very high tolerances if they are to function correctly in the field. Historically, the company used human operators to check for damage, metal shavings, and loose or missing components. However, the system became unworkable due to the high volumes involved-approximately 120,000 parts each day, or nearly 40 million parts per year.
To reduce the number of defective parts getting through, Meister installed a pair of automated checking and sorting systems employing a trio of In-Sight 1000 machine vision systems from Cognex Corp. (Natick, MA) and a pair six-axis ARC Mate 100iB robots from Fanuc Robotics (Rochester Hills, MI).
In operation, the valves are first placed in a kind of mesh-style packaging by the robot and then transferred to the test station. After the valves are in place, the robot picks up one of the cameras and performs the inspection. The system then sends the inspection data to the robot controller and the robot removes any defective parts, placing them in one of a number of chutes depending on the nature of the defect.
One of the test benches is outfitted with two In-Sight 1000 systems and processes up to 6,000 parts per hour. The other system employs a single sensor and processes about 4,000 parts per hour.
Since putting the systems in place, the number of defective parts shipped has dropped from about 1 per 1,000 to 40 per million. With the help of the In-Sight systems’ processor algorithms and their ability to “learn” how to identify faulty parts, Meister’s engineers are working to further reduce the defect rate to less than 20 parts per million.
“We were concerned that these test systems would slow down production rates. We have noted with satisfaction that the implementation of these industrial vision solutions do not have a negative effect on production,” says Jean-Marc Sermet, technical director of Meister France. “[Our system] appears to be particularly stable, and the operators do not have any need to intervene.”
For more on robotic systems, visit www.fanucrobotics.com or call 800-iQ-ROBOT.
For more on machine vision, call 508-650-3000 or www.cognex.com.