The drive for lighter materials in vehicle production has been a consistent trend for years, and it has picked up more speed over the past 10 years with regulations pointing toward higher fuel efficiencies. Though some state and national requirements have now been revised downward, lightweight material strategies are still in place for automakers.
Advanced materials—including aluminum, carbon fiber and lighter steel—are being used in many different areas within a vehicle, such as body panels, engines, brackets and doors. This new approach coincides with new production and flexible manufacturing approaches for the automotive industry. For example, many automakers have realized record high plant utilization rates across multiple car models on one manufacturing platform strategy.
One luxury automaker taking on this advanced materials challenge is Fiat Chrysler Automobiles with its famous Maserati brand and its introduction of the company’s first sports utility vehicle (SUV), the four-door Levante. The crossover SUV—a hot-selling auto segment—employs front and rear aluminum doors to reduce vehicle weight and provide better miles per gallon (MPG) rates.
With the introduction of aluminum doors, Maserati wanted “a scalable production workcell that allows the ability to add a second model while leveraging the capital investment and guaranteeing the Maserati-backed quality that its clients expect,” the company said.
Maserati turned to Comau, a global robotics and automation supplier for a range of industries, to design and implement an aluminum door production cell that mixes manual and robotic components, while also including a robotic roller-hemming system with advanced materials. Comau’s RHEvo roller hemmer, introduced in 2014, offers an end-of-robotic-arm roller that exerts force on the aluminum door’s outer panel to bend and fold over a flange on the inner panel.
To save on commissioning time and raw material costs at the plant, Comau used its extensive design and simulation experience to work through challenges before implementation at the Maserati plant. One challenge with door hemming can be the springback effect, where the material doesn’t fold over the inner panel and can cause production line inefficiencies.
“The Pam-Stamp simulation of the hemming, from the ESI Group, allowed us to determine the most optimal trajectories while anticipating and fixing defects that would have required significant time and resources at the site,” says Giovanni Di Stefano, head of process technologies at Comau.
The design of the aluminum door workcell at Maserati includes both manual and automated systems. In the first section of the production line, workers receive the die-cast aluminum sheets and hand assemble the inner door panels. Once finished, the operators move the doors to the decoupling buffer, where they are manually fed into the fully automated assembly process using a flexible batch production strategy.
The entire automated assembly system for the aluminum doors consists of five articulated robots from Comau that execute part handling, riveting, sealing, marriage, roller hemming and spot welding of the Levante’s front and rear aluminum doors. The design has the robots working in a single direction to perform predetermined sequences, such as the handling and positioning of the inner and exterior door panel, spreading adhesive, fastening the two panels together and riveting.
“The biggest challenge with advanced materials and complex processes is process monitoring,” Di Stefano says. “This is especially true with a batch, luxury production line that combines manual and automatic processes.”
The system design features process monitoring capabilities that allow operators to control the hemming process in real time as needed, as speeds reach up to 750 mm/s. The hemming monitoring provides access to real-time process parameters, creating alarms for process variations in the production workcell that can be sent to tablets and smartphones.
“The entire monitoring platform oversees the robots, rotary tables, grippers and auxiliary processes and produced analytics for predictive maintenance needs,” Di Stefano says. Line data is automatically gathered and cross-referenced using advanced pattern recognition algorithms and graphically represented in a fast and user-friendly manner, according to Comau.
Maserati can also scale the robotic assembly production by adding another set of rotary tables next to the current five robots and provide bidirectional manufacturing. The bidirectional manufacturing design allows each line to reach 6 jobs per hour (JPH), but with a capacity to reach 9 JPH while accommodating two distinct vehicles.
The successful implementation of Maserati’s aluminum door workcell is an essential milestone for the Italian carmaker as more advanced material applications keep gaining momentum in the ever-changing world of automobiles.