Drives & Controls Magazine November/December 2022

n SAFETY Tray-former safety system is the right package F or more than 35 years, the German machine-builder Sema Systemtechnik has been manufacturing machines for the semi-finished goods and packaging industries. It focuses on machines for packaging, transportation, palletising, straightening and re-packing, particularly of primary packaged dairy products. The company, which has round 100 employees, offers services ranging from design and production, through to commissioning and line integration. Sema’s 1200 s tray-forming machine is characterised by its extreme flexibility and fast operation. Cardboard blanks are fed in at one second intervals and folded, glued and sealed in several production stages. A risk analysis performed when designing the machine revealed that an effective safety system was needed for the situation where there was no cardboard in front of the feed opening. It was essential that this system did not restrict either the operator or the process. Sema opted for a TÜV SÜD-certified safe cardboard feed system. Two optical sensors are installed above the feed opening to scan it. If they detect that there are insufficient cardboard blanks in the infeed, a Pilz PNOZmulti 2 compact safety controller triggers an immediate stop of the hazardous movement. Once the cardboard stocks have been refilled, the machine can be restarted. There's no need for rigid safety barriers such as tunnels, so operators have the flexibility to feed the machine from either side. Because many of the blanks are smaller than the opening on the tray former, a precisely contoured perspex screen seals off the uncovered area. This is called up by a tamper-proof, coded safety switch – a Pilz PSENcode device – which increases process efficiency and reduces downtime on the tray former. The configurable safety controller monitors the tray-forming machine’s safety functions. The TÜV-certified safety system allows safe, efficient feeding of cardboard stock that complies with PL d / SIL 2. n A German packaging machine is using a configurable safety controller, sensors and coded safety switches to ensure that feeding of cardboard blanks can be done safely without affecting the machine’s operation. Sema’s tray-forming machine uses a safety system to check that carboard blanks are available to feed into the machine