What Is Lot Streaming in Manufacturing Scheduling?

Lot streaming is overlapping two sequential routing steps by transferring partial batches from the upstream step to the downstream step before the upstream step finishes the whole lot. Rather than waiting for every piece to clear one operation before the next begins, work moves in smaller transfer batches so the two operations run partly in parallel. The result is a shorter total lead time for the job, because the second step no longer waits idle for the first to complete the entire batch.

This entry defines lot streaming and shows how it behaves inside EDGEBIC by User Solutions. For the wider index of planning terms, see the manufacturing glossary, and for the piece-count unit that drives it, read what is a transfer batch.

How it works

The mental picture is a conveyor assembly line. Without lot streaming, the painter stands idle until the cutter has finished cutting the entire batch, then starts. With lot streaming, the painter starts on the parts the cutter has already finished while the cutter keeps working on the rest. The two operations overlap, so the whole job clears faster.

There are two common ways to express the overlap. The first is a piece-count transfer batch: the downstream step may start as soon as a set number of pieces, say 25, has cleared the upstream step. This is the industry-standard model for discrete parts, and a transfer batch of one is the extreme case of one-piece flow. The second is a start-to-start lag in hours: the downstream step may start a fixed number of hours after the upstream step begins, independent of piece counts. This suits continuous processes and simple overlaps where counting trays does not apply.

Either way, a separate handling delay can sit on top. Even after a transfer batch is ready, it may take time to load the tray and move it to the next station, so a flat transfer delay in hours can be added before the downstream step actually starts. Lot streaming shrinks the wait between steps; the handling delay is the honest cost of physically moving the parts.

A concrete example

A job runs 200 parts through cutting, then drilling. Cutting takes ten hours for the full batch, and drilling takes eight. Without lot streaming, drilling cannot start until hour ten, when all 200 are cut, and finishes at hour eighteen. The two steps run strictly end to end.

Now set a transfer batch of 25. As soon as the first 25 parts are cut, roughly one and a quarter hours in, they move to drilling and drilling begins. From then on the two steps run largely in parallel, with drilling trailing cutting by about one transfer batch. The job now finishes close to the length of the longer step plus that one-batch lead, rather than the ten-plus-eight total. The saving is real work in process that never sat waiting, and a completion date pulled meaningfully earlier.

How EDGEBIC uses it

EDGEBIC supports lot streaming per routing step, with the model chosen automatically from the step and work center settings. When a step carries a piece-count transfer batch and its work center is a discrete process, the engine uses the piece-count model: the downstream step becomes schedulable once the transfer batch worth of pieces has cleared upstream. A transfer batch of zero means no streaming, so the downstream step waits for the full lot, which is the default for every step until you opt in.

When the work center is flagged as a continuous process, the piece-count model does not fire, because counting transfer batches of a flowing product is meaningless. There the engine uses a start-to-start lag in hours instead, letting the downstream step begin a configured number of hours after the upstream step starts. A separate flat transfer delay, in hours, can be added on top of whichever model applies to account for the real material-handling time of moving a batch between stations.

Because streaming is opt-in per step, no existing routing changes behavior until you set a transfer batch or a lag on it, so you can introduce overlap selectively on the operations where it pays. To understand the piece-count unit behind it, continue with what is a transfer batch. For the buffer time that composes with streaming between steps, read what is queue time in manufacturing scheduling. And for the finite engine that places these overlapped steps, see what is advanced planning and scheduling.