Single piece flow production is a manufacturing method where parts undergo each operations one at a time and and are passed on to the next operation with no waiting time.
Among the benefits of single piece flow are:
1) the quick detection of defects that prevent large batches of defective parts and allows immediate feedback of quality issues to previous operations,
2) shortened lead times for products due to the elimination of excess work in process inventory (WIP),
3) reduced material and inventory investment costs, and
4) design of equipment and workstations to minimal size.
Single piece flow can also effectively be used as an identifier of inherent waste in production by forcing a product to follow a one piece at a time processing sequence in operations that have traditionally practiced batch and queue production methods, and then addressing the obstacles that that exposes.
See this simple example of single piece flow being used for pipe fabrication.