Just as products come in packaging of all shapes and sizes, so do today's demands on packaging machines. Although packaging is primarily there to protect the content, product presentation frequently boosts the incentive to buy and is constantly adjusted to meet point-of-sale requirements. Even when the packaging tasks are changed frequently, operators expect reliability, high cycle speeds and, in particular, flexibility from their packaging machines. Today's machines have a high degree of automation, which creates a need for intelligent, modular safety concepts that seek to maintain economic viability and deliver a competitive edge. With the configurable control system PNOZmulti Mini, the safety gate system PSENslock and the digital input modules PDP67 from Pilz, everything goes hand in hand.
These days there are an average of 18,000 products on a supermarket's shelves. In marketing, packaging is a powerful, sophisticated instrument, largely responsible for the product's success. The forms of packaging that product and packaging designers are coming up with are ever more refined; the task of creative engineers is to develop automated and productive packaging solutions to suit. Measures must be taken to counteract the risks to which machine operators or other people are exposed in areas where processes are semi-automated or fully automated. It's almost taken for granted that high-performance safety technology will not obstruct the production process and will work discretely in the background, so that operators don't even have to consider their physical safety.
Increased demands on safety and performance
Safety has been high on the list of priorities at the Oystar Group for many years. The company, whose origins date back to 1893, is based in Stutensee, Germany, and is one of the world's leading suppliers of packaging machines, including related technologies and a broad range of services. Oystar supplies stand-alone machines through to turnkey packaging lines via ten international production sites. Products include carton erectors, tray and case erectors, all-round packaging machines, high-performance packers, multifunctional packaging lines, palleting solutions and conveyor technology. The majority of packaging systems are used in the key industries of dairy, food, pharmaceuticals and cosmetics.
Oystar A+F, specialists for final packaging solutions, is equipped throughout with an open, flexible and decentralized safety system from Pilz, which boasts extensive diagnostics functions. So doors that have to be opened regularly or temporarily are fitted with safety gate systems designed for applications up to PL e of EN ISO 13849-1 and in many cases also have guard locking devices for process protection tasks. In the past, these tasks would have involved costly and labor-intensive cabling to install mechanical safety switches with guard locking devices, and signals would have been evaluated centrally via safety relays. Precise alignment between the switch and actuator was difficult because the mounting tolerances were low; diagnostics were not always reliable. This resulted in damaged switches and attempts to manipulate the safeguards.
Wanted: Open, decentralized safety concept
For a short while, Oystar A+F considered integrating the safety technology into the control systems of the various suppliers. This idea was soon shelved, however, because of the high level of complexity of the software tools for the various systems and the complicated software validation process involved. "Our primary aim was to define an open and decentralized safety concept that could be adapted to all control systems, that could not only be designed in accordance with protection type IP67 but could also be implemented with clear separation of responsibilities between safety and standard", says Manfred Schuster, Head of Electrical Design at Oystar A+F. Because the company was familiar with Pilz products and services following years of cooperation, it opted for the configurable control system PNOZmulti Mini in combination with decentralized periphery, the input modules PDP67.
As a central safety component, the configurable control system PNOZmulti Mini has every safety-related function in its sights. Installed in the main control cabinet, the PNOZmulti Mini base unit with 20 digital inputs and 4 digital semiconductor outputs monitoring the emergency stop button, reset button and mode selector switch, as well as taking control of the servo amplifier all the way to a safe operational stop.
Safety gate system PSENslock ensures higher productivity
The safety gate system PSENslock from Pilz monitors the machine access points via PNOZmulti Mini. Secure safety gate monitoring is combined with a non-contact magnetic interlock with either 500 N or 1000 N. Thanks to the flexible connection options, PSENslock can be used for safety gate monitoring up to PL e, both individually and in series, and guarantees maximum manipulation protection. The safety gate system passes the signals to the decentralized PDP modules / PNOZmulti Mini. Gates which do not require guard locking are fitted with the coded safety switch PSENcode. The connection is also made directly on-site via the decentralized PDP67 modules.
When plant and machinery are interlinked and when machines are assembled as modular systems, the PNOZmulti Mini systems are simply linked to each other, thereby guaranteeing that signals are exchanged safely. "By swapping the mechanical switches for the safety gate system PSENslock from Pilz, I can increase the productivity and reliability of my machines", Manfred Schuster explains.
The software tool PNOZmulti Configurator makes light work of the configuration of the entire system. The clearly structured, intuitive user interface speeds up the commissioning process. All the configuration and function elements are available either as icons or in selection menus. All inputs and outputs are free to select and can be linked using logic elements via a simple drag and drop function. Pre-defined, approved function blocks and menus make it easy for users. Safety functions require in-depth specialist knowledge, particularly during configuration and implementation, so the fact that certified safety blocks are already stored within the software tool helps tremendously in gaining approval for the machine.
The Safety Calculator PAScal from Pilz enables functional safety to be verified and documented simply and with ease. The calculation software calculates and verifies the key safety parameters such as Performance Level (PL) and Safety Integrity Level (SIL) for plant and machinery safety functions. The software can use a graphic editor to model safety functions and define not only their structure but also the usage pattern of the individual components. Given the extensive library functions, it is possible for users to import machine data in the standard library formats or to create and manage their own libraries. The result is compared with the safety parameters required for the safety functions and is displayed in graphic form.
A competent partner for every occasion
The close collaboration between Oystar and Pilz resulted in a system standard for safety, which can be adapted to cater to the individual needs and requirements of the various installations and machine types. Not only did Pilz supply the machines and systems but the company was also responsible for the design, product selection, commissioning, after-sales service and support. "For us it was an advantage that even during the commissioning phase we were able to call on Pilz's technical support at any time, and that support was always straight forward", Manfred Schuster stressed.
With their distributed structure, the products in the PNOZmulti range developed by Pilz are ideally suited to systems requiring a standardized solution, from the stand-alone machine right through to modular networks. The large number of different communication interfaces makes the configurable control system into a safety standard that can be applied all over the world because it can be used independently of any specific operating control system. "We were looking for a new, universal safety solution that could be clearly structured. And we found it, with the PNOZmulti Mini and the decentralized PDP67 modules", says Manfred Schuster, in summary.
>> For more information, click here
