Glossary · System coordination, integration and orchestration
Downstream blocking
Also known as: blocking by downstream, output blocking
German: Blockierung durch nachgelagerte Station
In production line coordination, downstream blocking is the situation in which a machine must stop or wait because the machine or buffer after it cannot accept more product, so that the stoppage propagates upstream along the line.
- System integration
In one sentence
Downstream blocking occurs when a machine must wait because the next machine or buffer cannot accept product, spreading a stop upstream.
Example
When the palletizer stops, the accumulation conveyor fills within two minutes and then the case packer, the labeler and the filler stop one after another by downstream blocking.
How it applies
- Engineering: Buffers between machines decouple them and delay downstream blocking. Buffer size is a trade-off between floor space, product handling and the length of stoppages the line can absorb.
- Operation: Line performance analysis separates time lost to a machine's own faults from time lost to downstream blocking. Without that separation, the wrong machine gets blamed.
- Documentation: Machine documentation should describe the downstream-ready signal it expects and its behavior when the signal drops, for example finishing the current cycle and holding product safely.
Downstream blocking vs. upstream starvation
Downstream blocking spreads upstream from a stopped machine. Upstream starvation spreads downstream: machines after a stopped machine run empty. A single stop causes both, in opposite directions.