Preformed three-compartment trays used for Reichel Foods’ snacks are filled with a variety of components. Monday it might be meat cheese and crackers Wednesday nacho chips and salsa and Friday peanut butter jelly and pizza bread.
The trays are filled by a semi-automatic depositor but some compartments are fed by hand. No two operators load trays at the same pace so filled trays in their eight lanes head toward the lidding machine randomly. The task of evacuating backflushing and lidding these trays is performed by an intermittent-motion machine that Craig Reichel describes as one of a kind.
“We needed automated equipment that would accept randomly fed trays in multiple lanes” says Reichel. “Most machinery builders who said they could design such equipment wanted a sizeble financial commitment from us before they would even show us what their solution was.”
Considering that his was a small firm in start-up mode such an arrangement was less than ideal. One equipment builder however willing to design machinery on acceptable terms was Orics Industries (Flushing NY). The eight-lane system installed by Orics in 1998 uses eight-cavity-wide carrier plates 23 plates in all to take trays through a lidding chamber. Arranged like the treads of a tank in a long oval path the carrier plates come up to receive filled trays at the infeed end of the oval travel through the lidding chamber discharge lidded trays at the discharge end of the oval and then travel beneath the machine before coming back up at the infeed end.
Immediately upstream from this part of the system is a robotic pick-and-place tool and just ahead of that an eight-lane infeed device. The robot has eight pairs of end effectors. When a filled tray reaches the transfer position a sensor signals the central PLC to actuate a mechanical device that elevates the tray slightly. This puts the tray into the pick position. Also triggered is a mechanical stop that prevents trailing trays in that lane from advancing. When all eight lanes have a tray in the pick position the servo-driven robot’s eight pairs of end effectors pick up their assigned trays and load them into an eight-cavity carrier plate.
The carrier plate takes the trays into the sealing chamber. Just ahead of this chamber eight fiber-optic sensors detect when containers are present. A signal is then sent to the PLC indicating that the sealing chamber is to be activated.
Inside the sealing chamber says Reichel “A lot of things happen.” The first thing once the chamber is closed is evacuation. Next is backflushing with a modified atmosphere followed by heat sealing of lid to tray and finally cutting of the lidding material around the tray perimeter. With all these tasks performed the lidding chamber opens and all eight trays are discharged onto a takeaway conveyor leading to an automatic cartoner. Reichel runs the machine as fast as 120 trays/min.
“One of the nice things about the machine is that the carrier plates move independently of the film feed” says Reichel. “Film is only drawn from the roll when it’s needed. The carrier plates just keep steadily cycling through the lidding chamber while the infeed section waits for all eight pick stations to be occupied by a tray. Only then will trays be advanced and lidding material drawn. It’s a very clever solution that accommodates our random-feed requirement without wasting lidding material.”