Assembly in Action: RFID Keeps Vehicle Seats in Order
To meet NUMMI’s needs, Johnson Controls makes up to 12 daily deliveries to the plant, where the seats are unloaded directly onto the production line.
Johnson Controls receives seat orders from NUMMI every hour in the form of a serial number list. This list determines the order in which seats are loaded onto the trucks at Johnson Controls. The loading must correspond with the vehicle production order in the NUMMI plant.
Johnson Controls has two separate seat production lines. One produces truck cab seats, and the other produces car seats. When the seats reach the inventory and packing stage, these two lines become one, mixing truck and car seats together on the same conveyer. If the NUMMI plant has an order that goes: car, truck, car, and Johnson Controls loads a delivery truck in the order of: car, truck, truck, NUMMI’s production line will be brought to a standstill.
Fred Zaske, electrical engineer at Johnson Controls, explains the problems that the production plant was experiencing: "Our previous identification system involved clipboards and checklists, located with operators at each station of production, inventory and shipping. The main reason we invested in radio frequency identification (RFID) was to eliminate the human error that was prevalent with a manual identification system." NUMMI allows only a certain amount of mistakes each year, and Johnson Controls was barely able to keep itself from going over the allotted error margin. To keep its contract from being closed, a new system was needed.
The company contacted Escort Memory Systems (Scotts Valley, CA) to set up an RFID system for tracking seats. Initially, Johnson Controls installed the HMS system on the truck seat production line, as well as the inventory and shipping sections.
On the truck seat production line, HMS tags are installed on the bottom of the truck seat pallets. In the first stage of production, recipe information is added to the tags. In subsequent stations, as the seat continues down the production line, the pallet passes over an HMS827-04 antenna at each operator station. Operators reference a touchscreen at their station that indicates seat type, as well as needed alterations. If a seat requires work, the operating system won’t let the seat continue down the line until the operator has made and verified all adjustments. The antenna then writes to the tag, updating it with whatever modifications have been made to the seat. This process continues at each modification station until it reaches the final station where the seat’s recipe is verified with the actual modification record. If they match up, the seats are transferred to the storage and shipping area.
The company’s seat storage area, like the truck seat line, was outfitted with several HMS827-04 antennas, directly on the conveyer line. Once final inspection is completed, a fully automated system moves these stored seats to create a lineup to be loaded into the trucks. This lineup matches NUMMI’s serial number sequence request.
A final HMS827-04 reader was installed on the conveyer leading into the back of the trucks. This antenna serves as a final checkpoint. Before an operator can load a seat into the delivery truck, he must pass the seat over the conveyer with the installed antenna. The operator’s host touchscreen computer displays the type of seat being loaded and references the serial number lineup NUMMI has provided to ensure they match.
"RFID has provided us with significant time savings and flexibility. We can produce multiple models of car and truck seats on their respective lines, without worrying about grouping or order until they have reached the final stages of the inventory and shipping line," explains Zaske.
For more information on radio frequency identification, call 800-626-3993 or visit http://www.ems-rfid.com.