Open Lines

In an open asynchronous line a new job may enter at the first station of the line whenever it, the first station, finishes its current job and is not blocked (i.e., it's upstream buffer is not full).  Thus, the WIP level in the line can vary over time. Because inputs to the line are governed by upstream information (e.g., the production schedule) this type of line is typically termed a  push system.

Depending on the capacity of the inter-station buffers, open asynchronous lines can be further classified as::

• Infinite Buffer: if the inter-station buffers never become full (i.e., they are infinite in size or simply large enough to prevent filling them up).. The key feature of an infinite buffer line is that no station ever gets blocked (although stations certainly may become starved). 
  
  
• Finite Buffer: if any of the buffers in the line has the possibility of getting filled up.  A finite buffer line can have stations become both blocked and starved periodically.