Analysis of Transfer Lines

Abstract

Transfer lines are common in industries such as food, automotive, electronics, and pharmaceutical, among many others. A transfer line is a synchronous production line consisting of several work stations in series integrated into one system by a common transfer mechanism and a control system. Each station is a stopping point at which operations (machining, inspection, etc.) are performed on the work pieces. The main feature of transfer lines is that the machines are connected through conveyors and the units on the entire conveyor system move one slot at a time synchronously. The transfer points in time are determined by the maximum of the unit processing times at all the stations, which is referred to as the cycle time. Typical examples of these systems are filling and packaging lines in the pharmaceutical and food industries, and the assembly lines in various other industries. Transfer lines operate like a single machine when all the machines are up and producing one unit per cycle. However, they experience failures like any other production line. Different manufacturing practices may necessitate different line designs. Also, the procedures as to what to do when a failure occurs may vary from one manufacturing environment to another. For instance, the entire system may stop, or parts of the system may remain unaffected by a failure and may continue to operate utilizing the conveyor segments and the buffer storages. The units on failed machines may be discarded, reworked, or processed further for the remaining unfinished work after the repair is completed. In food and pharmaceutical manufacturing facilities, depending on the cost and the perishability concerns, the unit on a failed machine may be removed and discarded.