High-throughput manufacturing processes that produce millions of units per day often rely on sophisticated process equipment and control systems to ensure uninterrupted production. In such high-volume manufacturing applications, the effects of production stoppages can be crippling. In particular, unscheduled downtime, due to emergency stoppages and shutdowns caused by breaches of safety systems, can impact the company’s bottom line in a matter of minutes.
One company that is leading the way in high-volume manufacturing is global packaging giant Amcor, which produces a range of innovative packaging solutions using a variety of plastics, cardboards, glass and metals.
A significant proportion of Amcor’s Australasian operation is devoted to the manufacture of aluminum beverage cans. Its manufacturing facility in Revesby, New South Wales, is equipped to produce nearly 2.5 million aluminum cans per day, and is a vital element of the company’s global packaging network.
As part of the company’s ongoing commitment to safety, Amcor recently embarked on a safety upgrade at the Revesby facility. The upgrade included a transition to Allen-Bradley control systems, and the redesign and replacement of the facility’s legacy safety control system architecture. As the upgrade was to be implemented without impacting production, Amcor enlisted the engineering expertise of local system integrator, IGR Consulting to obtain a fast-tracked safety control solution.
Figure 1. The Revesby facility incorporates 12 bodymaker and trimming pairs. Control panels on each incorporate operator interfaces wired to distributed I/O, plus an InView message display.
Amcor’s Revesby facility employs the “draw and wall iron” (DWI) process to manufacture its aluminum beverage cans. This production method involves forming shallow cups from aluminum sheet, and stretching or drawing the cup’s walls to form an open-ended can. A combination of fast-moving precision machinery and sophisticated control systems is used to consistently manufacture large quantities of product.
Rolled aluminum sheet is fed into a press, which cuts out discs and forms them into shallow cups using a “blank and draw” die and “draw horn”. These shallow cups are conveyed to one of the plant’s 12 aluminum can bodymakers, where a can-shaped mechanical ram forces each individual shallow cup through a series of circular dies. This process elongates the cup’s wall and presses a dome shape into one end of the cup, forming an open-ended can. The bodymaker’s ram moves up and back at high speed, forming up to 250 cans per minute. Each time the can-shaped ram retracts, the can is stripped off the ram head and dispatched into a bucket elevator which transports it to the trimming machines.
The trimming machine’s roll-cutters trim the can wall to a predetermined height, leaving a smooth edge. A separate device is used to roll the freshly cut edge to form a flange, suitable to receive a lid or closure. The cans are then washed, etched, decorated, packed and shipped to various beverage manufacturers.
Figure 2. Amcor’s electrical supervisor, Sean Soulie inspects one of the GuardLogix control systems
The first stage of Amcor’s site-wide safety and control upgrade was completed mid-2008. Prior to the “in progress” upgrade, the plant’s 12 bodymakers and trimming machines were controlled using individual conventional programmable logic controllers (PLC). Each bodymaker/trimmer pair was equipped with its own PLC interlocked with a separate hard-wired safety control system. A second PLC was employed at each machine pair to accommodate high-speed control applications.
According to Chris Hilton, Amcor beverage cans engineering manager, the safety upgrade provided Amcor with the opportunity to implement a more streamlined safety control solution.
“Our legacy control system had served us well over the years, but we needed a more user-friendly system with advanced diagnostic and troubleshooting capabilities,” he says. “Our production schedule didn’t allow for a prolonged design and installation process, so we enlisted the services of control and automation specialists.”
IGR Consulting developed a new integrated safety and standard control solution, founded on the Allen-Bradley GuardLogix controller from Rockwell Automation. Featuring two-processor safety architecture, the Allen-Bradley GuardLogix controller provides integrated safety and conventional control within the one platform.
“This is a more elegant solution compared with the previous safety control architecture,” says Karl Schiesser, IGR Consulting project engineer. “Both standard and safety control of each of the 12 bodymaker/trimmer pairs will now be managed by 12 individual GuardLogix controllers. The high speed of the Logix platform means that the second PLC is no longer required. This integrated control architecture provides Amcor with increased levels of safety functionality and enables easy system expansion.”
Figure 3. Manufacturing 2.5 million aluminum cans per day, Amcor’s Revesby facility is undergoing a safety control upgrade.
The GuardLogix controller is at the center of Amcor’s new integrated “safety-plus-standard” control solution: a seamless network of controllers, Category 4-compliant DeviceNet Safety communications and distributed I/O. EtherNet/IP connectivity provides interlocking between machines, and links the GuardLogix controllers to the factory’s supervisory control and data acquisition (SCADA) system. Several Allen-Bradley InView message displays connected to the GuardLogix controllers via an RS232 serial port, provide operators with detailed system diagnostics and allow straightforward monitoring.
“The InView message displays are configured to provide detailed system diagnostics,” says Hilton. “They allow on-site technicians to carry out fault analysis without having to directly access the GuardLogix program code.”
Previously, access to Amcor’s 12 bodymakers and trimmers was guarded by three separate hard-wired pneumatic guarding systems, each incorporating a series of relays and pneumatic switches.
“If a guard was opened, the air was cut off and the pressure switch was tripped, activating the safety response,” says Hilton. “On occasion, these pneumatic switches would fail in the open position, raise a ‘false alarm’ and cause the line to shut down.”
The legacy pneumatic safety system was replaced with a range of safety switches and devices wired back to local I/O, connected to GuardLogix controllers via a DeviceNet Safety communications network.
“With the GuardLogix integrated control system, troubleshooting false alarms and product jams is much easier,” says Hilton. “Previously, when a safety alarm was activated and the line shut down, a technician would have to visually inspect each machine guard in the group to locate the breach. Now, the GuardLogix controller allows us to immediately pinpoint the tripped switch. This means our response time is quicker and downtime is minimized.”
Programming and installation
According to Schiesser, the combination of distributed I/O and the DeviceNet Safety network dramatically improved site installation and wiring time.
“Using an integrated control solution like GuardLogix means that Amcor doesn’t have to duplicate its safety and standard inputs. This means less wiring and less I/O,” he says. “Local machine-mounted I/O and the use of a single communications network for both standard and safety communications also minimizes wiring and streamlines installation.”
The completely integrated nature of GuardLogix also provided Amcor with programming advantages.
“GuardLogix really is a step ahead of other systems. As the architecture is already set up, developing and expanding the system is uncomplicated,” says Hilton. “We were able to develop both the standard and safety control system code concurrently. This was a real time-saver.”
GuardLogix uses RSLogix 5000 programming software and allows users to program and manage their safety control system using familiar standard control methods.
“It actually provides us with real on-screen info – not a coded database hidden somewhere in systems like our previous PLCs,” explains Hilton. “With standard and safety control using the same (RSLogix 5000) programming environment, system configuration and troubleshooting are straightforward. It’s a piece of cake.”
With 12 GuardLogix -based control systems installed and online at the Revesby facility, Amcor has completed Phase 1 of its safety control upgrade. According to Hilton, the IGR Consulting team was a real key to the success of the project.
“They were on hand to install and commission the first system and train our technicians,” says Hilton. “This hands-on tuition has been invaluable, providing our on-site team with the necessary skills to successfully implement the remaining systems.”
“We understood the importance of making this plant-wide control transition as seamless as possible,” says Schiesser. “GuardLogix allowed us to simulate real-life control scenarios and view system architectures, without making any physical connections. This made it an efficient way to train Amcor staff during system design, set-up and commissioning.”
Hilton envisages further applications for the GuardLogix solution.
“Once again, we’ll be able to save time and resources by developing conventional and safety control concurrently, using the GuardLogix controller,” he says.
By implementing a transition to the Logix control platform, Amcor was able to leverage the benefits of Rockwell Automation’s GuardLogix controller, while fast-tracking a safety upgrade at its Revesby manufacturing facility. Instead of interrupting or slowing production, the transition has yielded optimized operational safety and efficiency.
For more information on Rockwell Automation products and services, visit the company’s Web site at www.ra.rockwell.com.