Fiat Tackles Lighter Materials With New Robots

The automotive industry—long a leader in robotics use—is leveraging its robotic know-how to stay on top of changing production challenges.

With automotive manufacturers introducing new body materials to make their cars lighter-weight, they are also introducing new production challenges. All-aluminum, plastics, carbon fiber or dissimilar substrates are all real possibilities for automotive OEMs in their body-in-white and fabricating facilities.

Companies like Fiat Chrysler Automobiles (FCA) are examining their entire manufacturing processes and looking for new production applications to stay ahead of competitors. Recently, FCA implemented a remote laser welding application and a laser cutting operation at its plant in Melfi, Italy, with the help of robot manufacturer Comau.

“Over the years, we have developed several techniques for industrial applications based upon a variety of laser technologies, including brazing, welding and cutting,” says Andrew Lloyd, chief operating officer, Body Assembly Business Unit at Comau. “The industry’s future is tied to reducing investment costs within manufactured products.”

The recent update at FCA’s Melfi plant included three laser applications in its body-in-white facilities for the Jeep Renegade and the new Fiat 500X—a larger four-door vehicle. FCA commissioned a remote laser welding application, using Comau’s SmartLaser robot technology for door production, and a separate laser cutting process for the front end of the body frame.

FCA implemented these laser welding applications at its Melfi plant in 2014 as part of a larger global strategy that included plants in Brazil and China. Comau and its integrators implemented these two robotic cell applications in under eight months.

For the remote laser welding application, the complete system consists of a laser workstation that assembles front and rear door inner frames. In the first step, a rotary table holds doorframes while a robotic arm implements 100 laser dimples in about 13 seconds. This action enables the doorframes—inner and reinforcements—to be welded together in the next stage.

The remote laser application’s second stage includes a rotary table that moves the front and rear doors into the laser cabin where two SmartLaser robots join the materials together.

The increased positioning speed and accuracy with the remote laser application played a part in why FCA decided to move in this direction. Conventional robotic heads need to be repositioned to implement multiple welding stitches, while this robotic laser technology allows positioning to be modified by adjusting the working angle of the beam and its focal length. The result is a process that is faster than the traditional welding, providing two laser stitches per second.

Another reason is the reduction of material it enables for the doorframes. According to Comau, remote laser welding makes it possible to reduce the product flange width by up to 5 mm. This not only reduces part weight, but can also provide the manufacturer with other product characteristics, such as driver visibility in this case. The laser technology also allows for single-sided joining, providing manufacturers with alternative production techniques.

“One of the challenges that we face is to monitor the dimples being formed,” Lloyd says. “We have an external system for diagnostics that checks process parameters in real time and compares these against a control group of standards.”

The machine control, including the laser-head fixture and robots, are performed by a PLC on a Profibus network. There also is a supervisory PLC that oversees the production system performance and communicates data to FCA’s manufacturing execution system (MES). The MES oversees quality metrics, power, energy management of the laser, and safety and location settings.

The SmartLaser robots have a total of seven axes, with four tied to the robotic movement. The remote laser head also requires three axes. For the remote laser application, the robotic master control is done by a single C5G control unit with Profibus slave communication between the laser source and the head unit.

From a meter away, the integrated robotic laser system can move the 4 kW beam’s focus to produce a 6 mm-diameter weld. This range and efficiency produces fewer movements for the system, and increases the hot phases of the laser due to the speed of the optical cavity mirrors.

At the Melfi plant, this remote laser system produces 55 units per hour, with a cycle time of 62 seconds for this two-step process.

The third robotic application at FCA includes a dedicated laser cutting line for the car’s front-end body. Using integrated laser optics, two Smart5 NJ110 robots execute cutting paths within narrow tolerances.

With disruption in the global automotive industry, production methods are changing quickly and suppliers are showing that they can keep up on the technology side.

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