The automation of a paper reel handling process provided an ideal opportunity to push forward a new approach to safety from Omron for a corrugated board manufacturing plant DS Smith Converters, a division of DS Smith plc - a global packaging business. At its sheet feeding plant located in Louth in Lincolnshire, two complete corrugators produce a wide range of corrugated board for the packaging market, and is one of the leading suppliers of board in Europe.
The corrugated board manufacturing process is highly automated; employees focus 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 storage areas. In 2005 it further extended automation at the plant 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 up and loaded onto one of five reel stands and then manually checked and spliced for the paper to be fed into the main corrugator machine, ensuring seamless production.
With the movement of large, heavy paper reels and automatic handling processes, the production area when in full operation is hazardous to employees. As the paper reel handling process results 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 DS Smith plc is an active member. The CPI was now recommending the use of Electro Sensitive Protection Equipment (ESPE). The business was therefore keen to explore the options for safety around the new process and to build on an exceptional safety record – it is not uncommon for the Louth plant to run for over 600 days with no injury or safety incident at all.
DS Smith Converters’ plant operations manager Neil Osborne commissioned integrator S Tech UK Ltd to lead the development of a safety system and which 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 Ltd proposed an initial pilot 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 who he had successfully worked with in the past.
“Two senior members of Omron’s safety team visited Louth and after a wide-ranging consultation we agreed on the implementation of Omron’s SNC (Safety Network Controller) in conjunction with a dedicated DeviceNet Safety network.” said Sean Scott. The pilot scheme focused on a single reel stand with the installation of an Omron SNC contained in a master control unit, wiring running to a local I/O box close to the reel stand and Omron safety light curtains (F3S-TGR-KXC) positioned either side of the conveyor transporting new paper reels into the machine and with the use of mirrors around the perimeter of machine ensuring a completely protected area.
During the six months pilot, many benefits were evident to Sean 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 facility allows objects such as a paper reel to pass through the safety curtains as the dimensions of the reel conform to pre-defined parameters. It worked with 100% reliability.
Once the safety curtains are triggered during automatic machine mode, the safety system needed to shut down the process. S Tech UK Ltd therefore needed to ensure the safety system networked into the wider automation process, and to also allow for the process to be stopped when a manual override of the safety system is requested. DS Smith uses a total of twelve Omron PLCs (Programmable Logic Controllers) performing all major automation tasks across the Louth plant – and all PLCs communicate via a DeviceNet network with the DeviceNet cabling linking to local I/O boxes positioned along the production line. STech used a SNC linked to an Omron CJ1M PLC which communicated with the wider DeviceNet network. Scott teamed up with Frank Bauder from Omron’s Sensor and Safety business team to integrate the SNC and involved studying 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 at all the machine will go into emergency mode. At the end of the automatic process, the safety system is deactivated allowing the reel handler to feed in the next reel.
Scott adds: “The way we have programmed the SNC ensures a smooth, seamless process, clear visual indication show employees when the safety system is switched on or off – when the off light is shown, employees are fully confident it is safe to enter the reel stand.”
The Omron system features in-built maintenance counters to alert components reaching end-of-life, linking in with an Omron NS5 HMI (Human Machine Interface) provides a visual indication where maintenance is required. Scott added “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 Omron off-the-shelf solution. ”
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 which has now been successfully completed.
DS Smith Converters’ plant operations manager Neil Osborne added that this is only Phase 1 of our enhanced safety system; due to the flexibility of Omron’s SNC solution we will be adding existing safety systems into the Omron system over the forthcoming months which will give us total visibility over our safety system.
Scott adds: “Omron allows you to build a strong, flexible safety system around existing systems and machinery. It can be installed causing minimum disruption due to its distributed network architecture, and requires only a modest level of investment. Omron’s people and products are on hand to help throughout.”
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, as well as higher quality and quantity of product. The early adoption of Omron’s SNC pushes the boundaries of what is achievable in terms of delivering automation throughout the process, in tandem with progressive updating of safety systems as new technology emerges.”