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Safety light curtains with multiple scans increase machine availability

21 June 2018

At Automatica 2018, the Schmersal Group presented safety light grids and safety light curtains from the product series SLC/SLG 445 which, due to their integrated multiple scan function, are suitable for demanding environmental conditions, in particular also for welding robots.

With these non-contact devices, a protective field composed of infrared beams is emitted by the transmitter and evaluated by the receiver. In the case of the SLC/SLG 445, multiple scanning evaluates each infrared beam six times in succession within the reaction time. This increases the response time from 10 to 20ms.

The Schmersal Group says the advantage is that brief interruptions of individual beams in the protective field – for example due to small particles, chips or, in the case of welding robots, due to glow sparks or the influence of high light energy – do not automatically result in the protective device being switched off. The multiple scan thereby contributes to increased machine availability.

Due to the multi-scan function for the prevention of interferences, the SLC/SLG 445 product series is an effective safety solution for areas of application with high contamination, such as wood or stone processing, outdoors where there are insects and birds, or for work areas in which water vapour and splash water are commonplace, for example in food processing. 

Another feature of this series is the integrated muting function, which distinguishes between human and material and hence also contributes to increased productivity. In addition, the SLC/SLG 445 offers an integrated setup aid with status display. It indicates to installation personnel whether the emitting and receiving units are precisely aligned with one another. This reduces the assembly effort and lowers the installation costs.These and many other useful functions of the SLC/SLG 445 can be configured quite simply and without software and so offer a high degree of adaptability for flexible machine concepts.

Opto-electronic protective devices are a space-saving and economical solution for protecting robot workstations. Safety light grids and safety light curtains allow a clear view of the process and offer additional productivity-enhancing functions. Moreover, robot systems are often walkable. Measures must therefore be taken to prevent hazardous movements from starting while persons are in the hazardous area. The integrated 'double acknowledgement' function of the SLC/SLG 445 product series prevents unintentional restart of the machine in difficult-to-see production areas.