Classification of Serial Production Lines
Most production systems are made up of serial production lines, in which jobs are passed from one workstation to the next along a routing. But there are different types of serial production line. (See overview for a classification diagram.) A fundamental distinction is between synchronous and asynchronous lines.
In an asynchronous line, jobs are permitted to transfer between the stations independent of one another (i.e., not necessarily at the same time). Because arrivals to a station may not be coordinated with departures from that station, asynchronous lines may have buffers between the stations to hold intermediate inventory. A job is transfered from a station whenever it is completed at that station and the next station is idle or the buffer is not full. If the buffer is full and the station can not transfer the job the station is said to be blocked. Similarly, if a station finishes its job but does not receive a new job from its upstream station, then the station is said to be starved.
Depending on how the input of raw material into the line is controlled, asynchronous lines may be further classified as:
In a synchronous production line all jobs in the line are transferred from one station to the next at the same time. This is generally accomplished through the use of a fixed conveyor, which ensures synchronization between the transfers. Synchronous lines can be further classified as:.