An automated machine has three loading stations. As parts move down the line, an operator adds a stamped metal part to the welded assembly. To avoid injury, the operator should not put his hands into the active loading area. To ensure safety, the operator must walk through a light curtain that disables the power and pilot air (only to the redundant pneumatic valves controlling the moving components in the work station), preventing unwanted motion. He loads the part into a fixture, walks back out through the light curtain, initiates operation, and the machine restarts.
The operator’s safety must be guaranteed while in the loading zones per the Machine Directive and ISO 13849-1. The conventional way to implement a safety function would be to have one manifold dedicated to the safety circuit in the first loading station. Feeding that manifold would be an expensive redundant safety dump valve. A duplicate manifold and dump valve would be installed for the safety circuits in the second and third loading zones, as well.
With a zoned safety approach, a much simpler design is possible that allows safety operation without the need to dump air to the entire manifold. Three independent zones within a single Numatics 500 Series manifold would independently control the safety function in the three loading stations. The additional manifolds, dump valves, and fieldbus nodes would not be required.
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