Machine builder safety system protects workers, simplifies design
Every roll of bathroom tissue and paper towels is cut from a far more massive spool of paper that’s also wound around a cardboard core. But this core is a Goliath compared to the tiny ones tossed in household garbage bins every day.
Weighing in at 100 lb with a 16-in. dia., each of these industrial-strength cardboard cylinders can carry a roll of paper up to 30 ft in circumference. Paper manufacturers reuse these cores repeatedly to avoid the high costs of disposal and replacement.
Traditionally, salvaging these cores has been a difficult and potentially dangerous process. To avoid damaging valuable machines by exposing them to the rigid core, manufacturers stop short of using the entire spool of paper. This sizable “spent” left on the core can weigh anywhere from 200 lb to 300 lb, and must be removed for recycling.
Automatic Handling International, a builder of innovative roll-handling and packaging systems, saw its existing end users manually cutting the leftover paper off each core with knives, creating a safety hazard for workers. This manual method also led to accidental scoring of the cardboard. These and other human errors damaged cores, rendering them unusable and forcing manufacturers to purchase new cores.
Automatic Handling, based in Erie, Mich., recognized an opportunity to make this process safer and less costly. For more than 40 years Automatic Handling has designed and patented handling and packaging systems for the pulp and paper, converting, tissue, and nonwoven industries. With these experiences, engineers created the first-of-its-kind, fully automated core-cleaning and joining system to help improve worker safety, enhance productivity, and dramatically reduce scrap.
The system consists of several machines that together automatically clean the remaining paper off cardboard cores and transport them to a core joiner. The joiner removes damaged ends of cores, joins good portions of sequential cores, and cuts renewed cores to length.
While engineers customize each system for the unique needs of the end user, every part of the core management system must be seamlessly integrated. That includes the crane that hoists the used core from the previous machine and positions it in the automatic core cleaner, as well as the roll loader, buffer crane, and core joiner.
The new system also connects to machines upstream and downstream to help ensure uninterrupted production. For example, the converting process that turns the paper into the final product happens upstream from the core cleaner, and must operate continuously to ensure production keeps up with demand.
To easily connect multiple machines in the process, Automatic Handling needed a control solution that tightly integrates safety, motion, discrete, and drive control. Such a solution would also reduce the time engineers require to design, develop, and deliver the completed system.
Risk assessments, training
Automatic Handling decided several years ago to switch automation suppliers for more reliable training services and support, a network of local specialists, and distributors available for end users, globally. Also, major end users also sought specific automation platforms and expertise with safety regulations and risk assessments.
Automatic Handling engineers collaborated with the automation vendor on the initial design and implementation of the safety-control system. An integrated safety system that allows safety and standard control on one platform alleviated complicated hardwiring and reduced engineering time.
As part of an integrated software programming and hardware environment, the safety programmable automation controllers use the same configuration, networking, and visualization environment as the rest of the system. This integration provides end users with fewer spare parts to maintain, while the control platform’s openness helps ensure easy integration with third-party components in a plant. In addition, safety I/O modules communicate with the safety controllers using the Common Industrial Protocol (CIP) safety protocol over EtherNet/IP (both managed by ODVA), streamlining control and information flow.
“Designing the safety system presented many challenges—namely due to the size of the system,” said Dan Pienta, president, Automatic Handling. “Altogether, it’s more than a thousand square feet in size and requires multiple entry points and zones. Traditional hardwired safety circuits would be too cumbersome and significantly complicate troubleshooting and future adjustments for end users. The new integrated safety system eliminates these issues.”
Another problem with conventional hardwired circuits: A safety event in one section of a machine can force operators to shut down the entire machine because the standard system has limited knowledge of the safety event. But the new system relies on EtherNet/IP, allowing the control and safety systems to coexist on the same network, and share data between the safety and standard applications. This enables engineers to perform “zone control,” where one area of the machine is brought to a safe state while others continue to operate.
Unlike hardwired systems, the integration of safety and standard control systems provides operators and maintenance personnel with visibility to all machine events, including safety events, via a human-machine interface. Knowledge and insight provided by the integrated system allows plant personnel to respond quickly and return the machine to full production.
Automatic Handling also updated its motor control solution for the new core cleaning and joining system to the ac drives, which have a safe-off function. Servo drives precisely manage all the machines’ motion axes and reside on the same EtherNet/IP network as the ac drives, simplifying machine design. In addition, engineers configure, program, and control the servo and ac drives using the same embedded instruction sets for standardized operation and consistent behavior.
No high risk, manual cleaning
Automatic Handling now delivers a fully integrated, automated core cleaning and joining system that doesn’t require manual core cleaning. Now end users can assign their labor force to less hazardous areas of the plant.
End users also can reuse more cores, reducing scrap by approximately 80% and contributing to long-term sustainability efforts. Automatic Handling estimated the new system also can save end users millions of dollars per year because the company can reuse the core many more times through the process. Troubleshooting and maintenance is greatly simplified because the system communicates with the main computer system in a mill, for example, and other machines in a production line.
“We’re using the integrated safety technology to improve safety but also to increase productivity for our customers,” said Dave Pienta, vice president and director of sales and marketing, Automatic Handling. “Our own productivity, efficiency, and quality have increased as well, and we’ve significantly reduced the time required to deliver a new system.”
Automatic Handling saves hundreds of engineering hours on each project, and estimates the new modular programming and design software cut design time in half.
“We’re able to go from the proposal phase to having complete drawings of a machine in half the time” with hardware standardization, Dave Pienta said. “We’ve only added a couple of engineers to our staff in recent years, but our business has more than doubled.”
The new system also makes it easy for Automatic Handling to standardize moving forward. The integrated safety system reduced wiring efforts by 75% and makes changes during factory acceptance testing take hours rather than days or weeks. End users are familiar with the control platform, easing troubleshooting and maintenance.
“Sometimes people think regulatory changes and risk-assessment documentation make upgrading safety automation systems complex,” Dan Pienta said. This safety system is “a flexible solution and makes designing a safer, more productive system much easier,” he added.
– Tim Roback is manager of marketing for safety systems, Architecture & Software Group, Rockwell Automation. Edited by Mark T. Hoske, content manager, CFE Media, Control Engineering and Plant Engineering, email@example.com.