01 September 2003
PC control helps Trane track manufacturing totals
Manufacturing air conditioners involves casings, condensers, fans, valves, electronic controls, heat dissipaters, and other components—all with individual production rates that must correspond and integrate smoothly for the final assembly process. Plant personnel need to accurately track real-time production information for productivity trends and downtime analysis. If production of one component stalls, it can have an impact on the entire manufacturing process.
Trane's Tyler, Texas, air-conditioner plant wanted to track information about specific machines in its assembly line, giving management and plant floor operators real-time information. Then they would know more about production totals, uptime/downtime, and most importantly, why a machine would fail to work at the optimum level in the first place. If they could reduce service failure rates to roughly 3.4 failures per million opportunities, they would reach Six Sigma status—a superior quality achievement. The answer? Install a new control system and software to track information from controllers and other devices on the assembly line.
Trane focused first on its spine-fin wrapping section of the plant—the area with the most potential to disrupt the entire production process and reduce finished product assembly rates if not running correctly. Each of Trane's 60 spine-fin wrapper machines continually wraps and glues a 0.0005-inch by 1-inch band of ribbon around a 3/8-inch pipe that runs up through the center of the wrapping machine. The finished product is a continuous length of pipe with a ribbon edging fanning out perpendicular to the pipe (similar to the fanned edge on a car's radiator).
Under the previous system, analog counters measured the linear amount of wrapped pipe produced by each spine-fin wrapping machine. But this system could be inaccurate and offered no mechanism for measuring or capturing a machine's uptime and downtime. Manufacturers manually controlled each spine-fin wrapper with individual control panels not integrated with any other wrapping machine.
Trane wanted to collect production data from each spine-fin wrapping machine and display it in real-time for the machine operators on the plant floor. The data would appear in HTML format on the company intranet, where management could easily access the information and track production progress. To make this as seamless as possible, they would have to integrate machines.
A SOFT SELL
Although PLC-based control could control the system, developers decided a soft controller, such as Allen-Bradley's SoftLogix, would be a better solution. The PC-based controller takes control functions normally found on a dedicated programmable controller, encapsulates the functions in software, and runs on a commercial operating system. More control system users are applying PC-based control, because it combines human-machine interface (HMI), programming, control, and enterprise integration on a single hardware platform. Monitors stationed at each bank of wrappers give operators easy access to the system data so they can monitor the entire system via operator interface stations running the HMI software.
The soft controller controls operations for each of the spine-fin wrappers—linked together with an architecture that includes DeviceNet, ControlNet, and Ethernet to help the company configure devices and collect data more efficiently. DeviceNet, used for device-level control, is a single cable that connects Trane's industrial devices, eliminating the need for hardwired I/O. It can transfer real-time information from the devices on the DeviceNet network to the soft controllers, which in turn track and analyze the data. The ControlNet network connects each of these controllers to monitor time-critical applications in the plant. It also configures and collects data without impacting the scheduled control and I/O communications. Ethernet links large amounts of production data to the site management network that controls all the raw materials in and out of the site. The combined use of DeviceNet, ControlNet, and Ethernet networks provide seamless integration throughout the assembly process and enable operators to view the status of devices and the entire line via the monitors or remotely via the Internet.
The transaction-manager software interfaces between the soft controller and a Microsoft SQL Server database running in the engineering department. The transaction manager transfers information from the wrapping machine—production totals, uptime, and reason codes—into the database where it can be stored and analyzed. The historian helps manufacturers understand how each process is performing.
Information is also available at every level of the plant. Operators can monitor real-time information on displays and HMI stations on the floor, engineers can view and analyze information from the databases, and managers can view and analyze information via the Web, wherever they are located.
Source: Rockwell Automation
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