Manufacturing approximately 1,200 vehicles per day, the AutoAlliance facility in Flat Rock, MI makes extensive use of CC-Link networking. The Ford Mustang and Mazda6 are manufactured at this location, which employs 3,700+ employees. More than 400 robots make over 6,000 body welds on each vehicle; 61 robots and 10 automatic paint machines apply sealants, sound deadening material, and 19 paint colors.
The ease of assembly line start-up and excellent reliability of CC-Link have translated into a highly productive manufacturing facility. The speed at which these new lines were installed and commissioned resulted in significant savings in comparison to networked systems used previously. Control engineers at AutoAlliance have commented that they have had no CC-Link network failures, but that they have experienced failures with Ethernet networks and with two other commonly used fieldbus networks.
Conveyor System
A series of CC-Link-controlled conveyors move car bodies through the numerous welding, assembly, and painting stations. Each vehicle travels approximately 13 miles during production. The motors that power the conveyors throughout the facility are controlled by Mitsubishi VFD Drives, communicating via CC-Link. It’s interesting to note that Power and Free (P&F) conveyors are, mechanically, essentially the same as they were on Henry Ford’s early assembly lines. However, the sophistication of the control system has changed greatly -- for example, the load on one particular conveyor line requires two motors, each with its own networked Mitsubishi VFD drive, in order to deliver sufficient power to the line. The Mitsubishi controller must coordinate the drives to accomplish proper load-sharing between the two motors so that each provides an equal amount of torque to the conveyor line.
Typical Control Panel
The control panel for the Mustang sub-assembly within the body shop at AutoAlliance handles control for assembly of the driver’s side panel of the auto body. This panel includes a Mitsubishi Q Series Controller with five CC-Link network masters. One of the five networks provides communication among other control panels within the body shop. The other CC-Link networks handle control of the material handling equipment, robots, and welding operations. The Mustang Body Shop uses approximately 125 control panels of this type; the Mazda Body Shop uses an additional 125 control panels for Mazda assembly.
Body Panel Assembly and Welding Operations
CC-Link networking also handles communication and controls for the VFD drives that power the motors for moving a JIG bed. A JIG is a large fixture with remote pneumatic I/O that can clamp, fold, and hold a section of the auto body. Mounted on the JIG and connected to CC-Link are Mitsubishi IP67-rated I/O modules that control the various clamps and actuators. Since different JIG beds are used for different auto body assembly functions, there are numerous fixed and movable JIG beds.
Only one remote JIG bed communicates with the controller at a time. When its time comes, a bed is automatically plugged into the network via a large connector. At this point the remote I/O on the JIG bed receives power and is connected to CC-Link to receive commands from the Q Series Controller. After the JIG bed completes its portion of the assembly operation, it is automatically unplugged and removed from the network. The tight motor control necessary to plug and unplug each JIG bed from the network is communicated to the VFD drives via CC-Link.
A CC-Link network also handles communication and coordination of the Kawasaki robots within a specific manufacturing cell. Some move parts within the cell and others weld body panel assemblies. The CC-Link network initiates and stops robot movement and also enables the robots to communicate their positions to one another in order to avoid collisions. Approximately 400 robots in the Body Assembly area are each connected to a Mitsubishi controller via the CCLink network. One network typically controls between 10 and 12 robots. In addition, Mitsubishi VFD drives control the pumps that provide coolant water to the robot welding guns.
Typical Operator Interface Panel
Numerous Mitsubishi GOT operator interface panels depict production information and status on their LCD screens. The VFD drives and operator interface panels communicate to the PLC controllers via CC-Link. Upwards of 95% of the controls within the Body Assembly area are connected via CC-Link.
Application of Sound-Deadening Material; Paint Line
CC-Link-controlled ABB robots apply the LASD (Liquid Applied Sound Deadening) material and joint sealant within the body of the car prior to painting. Five different body types can be run through this line (Mustang Coupe or Convertible and Mazda6 Wagon, Hatchback, or Sedan). Each body style requires a different material application routine. Depending on the type of auto frame, the LASD and joint sealant can be applied to 12 different areas of the vehicle. As within the body shop, the CC-Link network tells the robots when and where to apply the material. It also provides a method of communication among the robots in order to prevent collisions while operating.
Mitsubishi PLCs control the paint line where state-of-the-art Fanuc P500 robots apply one of 24 different finish colors. Finally, another line of robots sprays two coats of clear paint over the vehicle body.
Pollution Abatement
The AutoAlliance facility also uses the latest in pollution abatement equipment. The strong fumes generated during the body paint process are incinerated to neutralize harmful compounds before being vented to the atmosphere. The process is called RCO for Regenerative Catalytic Oxidizer. A Mitsubishi PLC controls the RCO process and communicates, via CC-Link, to 5 Mitsubishi VFD drives. Each VFD drive controls a 500 hp fan. The process involves exhausting the fumes from the paint line and passing the fumes through a catalytic oxidizer. There are 6 oxidizer beds (2 incinerators, 2 regeneration, 2 standby).
The CC-Link network used in the RCO process also includes a Mitsubishi 800 Series GOT Operator Interface to display current system status and to allow the operator to interact with the control system.