Flame-wielding Robots

Eissmann Group Automotive recently installed a flame-treating robotic work cell to increase productivity for interior components in high-end automobiles. The robot processes polypropylene parts, preparing the surfaces for adhesive application.

The ABB Robotics (new.abb.com/products/robotics) IRB 2600ID six-axis robot is methodically sweeping its arm through space over a large workpiece. While that isn’t unusual—thousands of robots are doing that every day—what is somewhat out of the ordinary is that the end-of-arm tooling, an Enercon 226 Series burner, produces a high-velocity blue flame curtain. That’s right: a robot wielding a flaming device. 

Eissmann Group Automotive (eissmann.com) didn’t install the system in some sealed room in its Pell City, Alabama, plant where it treats large polypropylene substrate parts for instrument panels, door trim and other interior components, but chose an open-cell setup to increase productivity for its Tesla, GM (Corvette), Mercedes, and Ford (Lincoln Navigator) customers. No, the robot is carefully controlled. But what’s it doing vis-à-vis the parts?

Polypropylene is used in many cases for the substrates found below leather-wrapped surfaces like instrument panels. But an issue is with an adhesive bonding to the surface of the plastic. So to prepare the part for better adhesion, flame treatment is often used to prepare the surface through oxidation. 

Eissmann had been using manually wielded propane torches or stationary flame-treating units to prep the parts. But as Barrett White, a manufacturing engineer at the Pell City plant, noted, “We began to get more full instrument panels, which are larger and more intricate than some of the other interior parts we were handling. The manual flame-treating process became difficult because the large parts are harder to maneuver and they typically have a lot of undulations and openings that need to be treated.”

Eissmann consulted with Fitz-Thors Engineering (fitz-thors.com) and Enercon Industries (enerconind.com) on a robotic solution. Rather than bringing the parts to the robot, the robot goes to the parts. A turntable holds three different fixtures on each side, allowing the station to process six different interior components. The turntable allows a part to be loaded, while the fixture on the other side holds a part in queue for the robot to approach for treatment. The other three stations each have a rigid fixture that holds one large component. ABB software provides additional safety features and collision control. Once the polypropylene substrates are flame treated, they are hung on a rack and routed to the adjacent glue spray booth, and then on to be wrapped with either padding or leather.

 “The cell has worked very well for us. It took two minutes on average to treat each part manually, and now it takes about 10 seconds with the robot,” said White. “The tolerance with the robot is 0.02 mm, which results in incredibly consistent coverage and far better adhesion.”

The robotic work cell produces 2,400 parts daily for the Chevrolet Corvette program, a feat impossible to duplicate with manual flame-treating. With such positive results, Eissmann has added an ABB robot for an airbag scoring and recently took delivery of a second flame-treating cell.