Lean initiative highlights validation gap
Torque measuring and handling of related information are key to a robot process at one the world's largest and most diversified suppliers of automotive parts, Delphi-Delco (Troy, MI). The company designs, engineers, and manufactures a variety of components, integrated systems, and modules. It has pioneered many automotive interior design innovations, such as incorporating radios and tape and CD...
Torque measuring and handling of related information are key to a robot process at one the world's largest and most diversified suppliers of automotive parts, Delphi-Delco (Troy, MI). The company designs, engineers, and manufactures a variety of components, integrated systems, and modules. It has pioneered many automotive interior design innovations, such as incorporating radios and tape and CD players into the dashboard.
Diagram shows how Delphi-Delco’s lean manufacturing process incorporates new barcodes; robotic screwdriver; HMI; and remote monitoring, automation, and data acquisition system.
Design and production of these interior panels and components naturally involves the use of complex and diverse manufacturing systems and equipment. One such system is a robotic screwdriving machine designed for Delphi-Delco by Janome America Inc. (Mahwah, NJ). Janome, which was best known as a manufacturer of sewing machines for home and industrial use, supplied Delphi-Delco with a small, custom-built robot equipped with multiple bits for driving screws and assembling various automotive panels and components.
The relationship between the two companies grew out of Delphi-Delco's lean manufacturing initiative (reducing waste in materials and time associated with non-value-added processes), through which Delphi-Delco sought to optimize performance of manufacturing systems and equipment. This lean initiative brought to light a manufacturing procedure which involved designating the amount of torque to be applied by the robotic screwdriver to each specific automotive component, then verifying the torque.
This required means for Delphi-Delco to identify individual components on the assembly line so that the screwdriver torque could be adjusted appropriately. It also meant that the company would need to measure, capture, and record the actual amount of torque applied and use the data for manufacturing validation.
Legacy programmable logic controllers (PLCs) at Delphi-Delco, though capable of communicating with the robot to specify the required torque, could not capture and deliver the needed data to the enterprise databases used by Janome for verification. Because most PLCs are designed to perform rudimentary logic and execute associated control functions, they are not typically used for data acquisition. To bridge this communication gap, Delphi-Delco employed Opto 22's Snap Ultimate I/O system for automation, remote monitoring, and data acquisition.
Key to the new robotic screwdriver process is the application of barcodes to ensure that appropriate parts are assembled properly. Prior to implementation of the Snap system, Delphi-Delco had no way of reading bar codes on each part to get this process started, requiring engineers to read the codes and reprogram the robotic screwdriver's torque manually.
Now, as the individual automotive components reach the robotic screwdriver, a barcode reader scans the part's barcode. The reader sends an ASCII string identifying the part to the Snap Ultimate I/O unit via an RS-232 serial connection. Using a preprogrammed lookup table within ioControl—Snap Ultimate I/O's flowchart-based control programming software—the system confirms that each part is correct and matches it with the corresponding torque. The Snap system then communicates with a host, which directs the amount of torque to be applied by the Janome robot.
Once screws are applied, a torque meter measures the actual amount of torque applied. This information is also sent to the Snap Ultimate unit and then passed on to the host application. This type of validation is critical in the automotive manufacturing industry due to self-imposed and regulatory standards. Without this verification, no parts can leave the factory.
Delphi-Delco also uses OptoTerminal-G70, a small operator interface that managers and other workers on the plant floor use to access data or locally start and stop assembly processes. The terminal is mounted on the Janome robot, giving assembly floor workers access to any needed process information without accessing a PC.
By implementing these new technologies, Delphi-Delco's assembly processes are well on the way to reaching goals from its Lean Manufacturing initiative. First-time quality analyses (which means no rehandling by operators) increased from 87-92% to 99%.