One of the critical aspects of Del Monte’s set-up was to synchronize the labelers to the pack speed so that the switch-over labeler applies the label precisely. When the labeler is activated it must instantly match the speed of the conveyor the pack is traveling on regardless of what that is. That’s done via encoder cables from the conveyor to each labeler.
The main reason to change labelers is the exhaustion of a label roll on one of the units. The labelers will also perform an automatic switch-over when needed such as when the active labeler experiences a problem. For example a photoeye senses if there is a label missing on the roll or if the web breaks. The programmable logic controller then signals the applicators to switch. Both label applicators are interconnected through a PLC from Aromat (New Providence NJ). Each labeler is topped with a light “tree” that serves as a visual indicator of the labeler status: on off or problem.
In a demonstration for Packaging World a single label was removed from the roll on the upstream unit. Sure enough the missing label was detected and the system prompted the downstream labeler instantly into action to label the pack that had been “missed.” It continued labeling while the roll on the other labeler was fixed. Obviously this works only when the upstream unit misses a label rather than the downstream unit.