Case Study: Process Lines to WIP Bins
The plant of a large, packaged food manufacturer contains multiple processing lines and a series of transfer lines to move the finished products into storage bins. Presently there are six process lines in operation but only four transfer lines, which limits the transfer from processing to storage. For example, if all four processing lines are running different products, it is impossible with the existing shared-transfer arrangement to simultaneously transfer all the products to the storage bins. The addition of two new transfer lines would establish one transfer line per process line, increasing flexibility in routing and ultimately increasing production capacity.
ECS undertook the project to install two new transfer lines, this project being carried out in three phases. Phase 1 added a transfer line dedicated to Process Line 5, Phase 2 added a transfer line dedicated to Process Line 6, and Phase 3 removed the shared functionality of the existing Process Lines and Transfer Lines 1-5. The installation of the new transfer lines included adding new conveyors, elevators, sifters, weigh scales, and slide gates for routing.
ECS Engineers completed all the required PLC programming, Ignition development, and hardware design for the new transfer lines and existing line upgrades in addition to the equipment upgrades, ECS also added programming for automatic transfer logic including product match interlocking. The company previously operated in a “semi-automatic” mode, manually instructing each conveyor group when to start up, but were unable to direct product from a given process line to a particular storage bin. After the programming for automatic transfer was added, operators can select a source and a destination. The program chooses the best path available based on product types in the process line, in the transfer line, and in the destination. The mixing of incompatible products on the conveyor or in the storage bins was a serious concern for the company, and in truth, this is more likely to occur unintentionally with manual operation.
The complete modifications introduced by ECS also included a “clean-out” function. If a new product type was selected to run on a Process Line, the system automatically dumped the old product from the line before allowing the new product to proceed. This additional functionality contributed to removing the need for manual operation intervention to prevent product mixing.
ECS engineers observed that with the addition of the automatic transfer control and product interlocks, there is potential for future integration potential with reporting services or even an MES system. The company is also using old versions of ControlLogix and old processors, much of which is close to the end of service life and upgrades should be considered in the near future.