RFID Helps ZF Speed Transmission Shipments

When containers are returned by truck and bus makers, they are typically stacked in a temporary holding area. A few days later, workers place the containers on a conveyor system that automatically moves them to a completely automated high-rack storage area. As a container moves along a track, an RFID reader made by FEIG Electronic is used to identify it. Based on tag location during reading, the system can determine if a container is in the correct position on the track, or if it must be rotated 180 degrees.

This is the single RFID read point in the entire application, except when new containers are introduced into the flow. Since containers are moved automatically throughout the process of filling and preparing orders for shipment, the computer system can calculate a container's location at subsequent points, based on the single identification. When new containers are added to the mix, employees initialize them using one of three handheld interrogators made by TDS Recon. The system assigns a container number to each tag, and that number plus a description of the carrier are encoded onto the tag, enabling ZF to track which containers went to which customers. Workers choose from an option menu to describe the container after visual identification. ZF uses nine types of containers.

As a container moves along the conveyor track, an RFID reader identifies it.

Workers who need to assemble a drive or part place an electronic order via the company's warehouse management system. The automatic system places the components in a tagged steel container—which can vary in size from 80 by120 centimeters (32 by 47 inches) to 80 by 160 centimeters(32 by 63 inches)— and moves the container to the proper position in the production area. Automation helps speed production and delivery, and is necessary because parts can be too heavy for workers to lift. As soon as the container's tag is identified upon its return—that is, once it is moved to the conveyor—the system is updated, allowing ZF to create a report about which containers are with which customers at that particular time.

ZF is considering changing the RFID system so the tag is interrogated automatically as soon as a customer returns a container to ZF's warehouse, rather than waiting for the container to pass an RFID reader along the conveyor track after spending a few days in the interim holding area. Interrogation would occur when the containers pass through an automated portal. Reading the tags earlier would afford the company a greater overview of the containers available.

During the first phase of the project, Tricon chronicled ZF's processes and tested RFID hardware before making a recommendation about the design of the RFID system. The biggest challenge Tricon faced was finding the right transponders to identify the containers, given the metallic and mechanical environment. The tags needed to provide a long read range—even when fixed to a metal surface—fit well on a container, and be easy to attach and cost-effective, given the application's high volumes. Tricon ultimately opted to use tags from Intermec that operate at 869 MHz and comply with the ISO 18000-6B standard.