The method involves activating a teaching program via a controller, and moving a tray toward production direction of a tray sealer (1) by a collection belt (5). The tray is transferred from the collection belt to a supply belt (4) in a velocity-synchronous manner. The supply belt is arranged upstream to the collection belt relative to the production direction. A position of the tray is detected by a sensor provided along the collection belt or the supply belt. Routing information of the tray is processed in the controller.