How 11 Cobots Help Build the Fiat 500 Electric Car
Stellantis N.V. is a Dutch multinational automaker formed by the merger of PSA and Fiat Chrysler Automobiles. The company has installed 11 collaborative robotic arms from Universal Robots (UR) at its Mirafiori plant in Turin, Italy, to automate a number of complex operations on the assembly line and quality control of the new Fiat 500 electric car.
Collaborative applications developed at Mirafiori have delivered significant benefits in precision and quality of work, and have also improved the ergonomics of several operations that were previously performed by hand.
Challenge
On the Fiat 500 electric car production line, some assembly and quality control processes required special automation technologies to ensure the quality and repeatability needed to meet product standards. In addition, given the fairly high average age of factory workers, ergonomic well-being was a pressing concern.
Solution
Stellantis decided to use UR cobots several years ago. Collaborative automation freed operators from repetitive and physically demanding manual tasks, so they can be deployed in processes with greater added value.
11 UR cobots now automate the following tasks:
- Applying waterproofing to car doors (two UR10e cobots working in parallel)
- Positioning the soft top (activating the primer track and visual inspection to ensure correct extrusion of the adhesive tape around the perimeter) (one UR10e)
- Checking the dimensions of the folding roof frame (one UR10e)
- Riveting the trunk door with blind rivets on the trunk frame (one UR10e)
- Fastening the hood (one UR10)
- Tightening the rear side door hinges (one UR10)
- Fastening the fender liners (two UR5 cobots and two UR10 cobots)
UR cobots at the Mirafiori plant were introduced gradually so that operators could fully understand how the automated processes work.
“As a first step, we decided to install a UR cobot in the company canteen to hand out cups of water to employees during their lunch break. This allowed line workers to see for themselves the safety and collaborative nature of cobots and to overcome any concerns about the safety of later applications”
Results
Following the success of this initial trial, UR cobots were installed to perform tasks on the 500 electric car production line:
Applying waterproof coating to vehicle doors
Two UR10e cobots work in parallel on the door assembly line. A machine vision system detects the arrival of a door and activates the cobot, which uses a roller attached to its wrist to apply constant pressure to the fabric, pressing it against the door panel.
This application is particularly demanding, as it requires the cobot to follow a complex path in a confined space, avoiding the protrusions of the panel's pressure pins and ensuring a complete seal of the insert to prevent water ingress. The cobots work with millimeter precision, guaranteeing repeatability of +/- 0.05 mm.
“The UR cobot significantly improved the ergonomics of this application. Applying the insert required the operator to maintain constant pressure with a torque-controlled roller, a task that over the long term could damage the joints of the hands and cause musculoskeletal disorders. Thus, the cobot delivered two advantages: high precision and quality of work, as well as improved ergonomics and comfort for our operators”
Soft top assembly
Two UR10e cobots work on the assembly line for the folding roof of the Fiat Cabrio 500. The first cobot performs two different operations. Using a pad supported by a special gripping device, the UR10e cleans and prepares the primer track, onto which adhesive is later applied to attach the soft top to the frame.
The second operation is quality control, in which a machine vision system checks the geometric continuity and dimensions of the adhesive tape. The second cobot works in synergy with an anthropomorphic robot.
Once the soft top is assembled, it is opened on a special support and then lifted by a robot. At this point, the second UR cobot checks the size of the folding roof frame (via the machine vision system) to confirm the dimensions match. After conformity is confirmed, the soft top is removed from the line by an anthropomorphic robot.
This application offers a range of performance and quality benefits. The cobots verify the correct application of adhesive and check the dimensions of the folding roof frame.
Riveting the rear door
On the door assembly line for the Fiat 500 electric car, a UR10e cobot was configured to press 10 blind rivets that fasten the trunk hinge reinforcement to the trunk frame. The operator loads the rear door frame and hinge reinforcements onto the workstation, then leaves the cobot to position and press the rivets.
The use of the cobot provides productivity and ergonomic benefits. At the same time, constant monitoring of the workstation's input and output parameters ensures higher and more stable process quality.
Fastening the hood
For this application, the car body reaches the workstation with the hood installed in the closed position and hinge screws inserted by operators at the previous station. Once the hood geometry is set, the cobot (UR10) moves into position and tightens four screws to the correct torque.
The main benefits of this application are quality, efficiency and ergonomics, given that the body reaches the station in the closed position, which makes correct tightening extremely difficult. Because the hinge screws that need to be tightened are not visible, an operator can easily miss one or tighten it incorrectly. The cobot also improves working ergonomics by freeing operators from working in awkward positions.
Additional tightening of door hinges
The Fiat 500 model with an additional rear side door required an automated application capable of performing a complex tightening cycle. Using an advanced automated tool fitted with a cobot, the door is correctly positioned on the car body. The cobot then performs the tightening operations at the rear.
The cobot meets two different technological requirements: it frees the operator from tightening hinges in an awkward posture, when they cannot see the correct position inside the car body, and it prevents the recoil of the tightening tool (which operates at 75 Nm of torque) from striking the operator's hand.
Fastening the fender liners
At this station on the sheet metal line, the frame arrives with the right and left fender liners already installed. Two UR5 cobots and two UR10s cobots are mounted on a platform that lowers along the Z axis relative to the body. The platform wings close to fix the geometry and activate the tightening of 24 screws that secure the fender liners. Each of the four cobots is equipped with an automatic torque-controlled screwdriver.
The application offers several advantages. Collaborative automation ensures ergonomic benefits for operators, who no longer have to work under the car body. Because the screws are tightened to a set torque, tensile stress on the sheet metal parts is eliminated. In addition, cycle time is reduced, which increases the productivity of the entire station.
