The automation of a paper reel handling process provided an ideal opportunity to push forward a new approach to safety from Omron at leading European packaging supplier DS Smith Converters’ Lincolnshire located corrugated board manufacturing plant.
The corrugated board manufacturing undertaken here is highly automated with employees focused on ensuring reels of paper are received and fed into the start of the process, overseeing the production process and transferring pallets of finished product to the storage areas. Automation at the plant was extended further through the installation of an automatic paper reel handling process, which transports paper reels weighing up to two and a half tonnes along a conveyor track set into the factory floor. Once the reel arrives, it is automatically picked and loaded onto one of five reel stands and then manually checked and spliced in order for the paper to be fed into the main corrugation machine in one seamless production process.
The process involves hazard
With the movement of large, heavy paper reels and the automatic handling processes, the production area when in full operation is hazardous to employees and, as the processes result in continuous movement, it is impractical to have fixed guards preventing employee access to restricted areas. DS Smith Converters were inspired by recently updated guidance notes with regards to safety from the Confederation of Paper Industries (CPI), of which it is an active member. The CPI was recommending the use of electro sensitive protection equipment (ESPE). The business was keen to explore these new options for safety around the new process and to build on an exceptional safety record.
Plant operations manager, Neil Osborne, commissioned integrator S Tech UK to lead the development of a safety system that would allow for the free flow of paper reels and the general movement of the automated process, but would shut down immediately if an employee mistakenly enters a restricted zone without first switching the process to manual operation.
Sean Scott, managing director of STech UK proposed an initial pilot project focused on installing a safety system onto one reel stand. Scott wanted a supplier partner who had a strong reputation for developing safety solutions for industrial automation processes – he engaged Omron whom he had successfully worked with in the past.
“Two senior members of Omron’s safety team visited the plant and after a wide-ranging consultation all agreed on the implementation of Omron’s safety network controller (SNC) in conjunction with a dedicated DeviceNet Safety network,” says Scott. The pilot scheme focused on a single reel stand with the installation of an Omron SNC contained in a master control unit with wiring running to a local I/O box close to the reel stand and Omron safety light curtains positioned either side of the conveyor transporting new paper reels into the machine. The use of mirrors around the perimeter of the machine ensured a completely protected area.
During the six months pilot, many benefits were evident to Scott. Omron’s safety curtains had an in-built ‘muting’ facility, enabling a paper reel to pass through the safety curtains, but shutting the system down if an employee passed through the curtain whilst the process was in operation. This muting functionality allows objects to pass through the safety curtains according to pre-defined dimensional parameters. It worked with 100% reliability.
System description
Once the safety curtains are triggered during automatic machine mode, the safety system is required to shut down the process. STech UK therefore needed to ensure the safety system networked into the wider automation process and also allowed the process to be stopped when a manual override of the safety system is requested.
DS Smith uses a total of 12 Omron PLCs to perform the major automation tasks across the plant. All PLCs communicate via a DeviceNet network with the DeviceNet cabling linked to local I/O boxes positioned along the production line. STech used the SNC linked to an Omron CJ1M PLC to communicate with the wider DeviceNet network. Scott teamed up with Frank Bauder from Omron’s Sensor and Safety business team to integrate the SNC and study the reel handling process. When an operator switches to automatic mode, the machine interlocking and safety curtain functionality are checked to ensure they are in an active state – if there is any discrepancy the machine goes into emergency mode. At the end of the process, the safety system is deactivated allowing the reel handler to feed in the next reel.
“The way we have programmed the SNC ensures a smooth, seamless process and clear visual indication shows employees whether the safety system is switched on or off. When the off light is shown, employees are confident it is safe to enter the reel stand area,” says Scott.
The Omron system features in-built maintenance counters to alert components reaching end-of-life, an Omron NS5 HMI provides visual indication of where maintenance is required. “From an integrator perspective, Omron’s SNC solution is affordable, flexible and highly configurable. Programming is straight forward with Omron’s user-friendly software tools. On the light curtains themselves the custom muting bar facility did not need any special configuration; it is an off-the-shelf Omron solution,” explains Scott.
After the pilot, DS Smith Converters was convinced STech’s Omron solution had shown its capability and gave the go ahead for the system to be integrated to the remaining four reel stands. This has now been successfully completed.
Osborne says that this is only Phase 1 of DS Smith’s enhanced safety system. “Due to the flexibility of Omron’s SNC solution we will be adding to existing safety systems over the coming months. This will give us total visibility over our safety solution.”
“Omron allows you to build a strong, flexible safety around existing systems and machinery that can be installed with minimum disruption due to its distributed network architecture. It only requires a modest level of investment and Omron’s people are on hand to help throughout,” adds Scott.
Mike Nichols, managing director of DS Smith Converters concludes: “We are not afraid to push for the very best systems in our plant if they support safer production as well as higher quality and quantity of product. The early adoption of Omron’s SNC has pushed the boundaries of what is achievable in terms of automation throughout the process. This in tandem with the ability to progressively update our systems as new technology emerges.”
For more information contact Terry McIntosh, Omron Electronics, 086 066 7661, [email protected], www.industrial.omron.co.za
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