What Is a Continuous-Process Work Center?

A continuous-process work center produces flowing product that cannot be counted in discrete transfer batches, so the schedule overlaps its steps with a time-lag model instead of a piece count. Reactors, extruders, ovens with continuous throughput, and liquid filling stages all fit this description: there is no tray of finished parts to hand to the next step, only a continuous flow. Flagging a work center as continuous-process tells the engine which lot-streaming model to apply. EDGEBIC by User Solutions reads the flag on every work center so process stages and discrete-parts stages each overlap the way their physics allows.

How it works

Lot streaming lets a downstream step start before the upstream step finishes, overlapping the two to shorten the total run. There are two ways to express that overlap. The piece-count model moves a defined number of finished parts, a transfer batch, to the next step as soon as they exist. The start-to-start lag model overlaps the steps by a time offset instead, letting the successor begin a set amount of time after the predecessor starts.

The piece-count model only makes sense for discrete parts. You cannot move a "batch of 25" of a flowing liquid or a continuous extrusion. So when a work center is flagged continuous-process, the engine always uses the start-to-start lag model on steps routed there, and it ignores any transfer batch size that happens to be set on those steps. The work center's flag wins over the step's batch, which is the safeguard that keeps a discrete-parts rule from being applied to a process that has no discrete pieces.

The flag is a property of the machine, not the product or the routing, because the machine's physical character does not change from job to job. A reactor is continuous by nature; a mill is discrete by nature. Setting the flag once per work center is all it takes.

A concrete example

Think about serving food two different ways. At a bakery, finished loaves come out in countable units, so you can carry a tray of 25 to the packing table as soon as those 25 are baked. That is piece-count streaming: real, countable parts moving downstream.

Now think about a juice line. The juice flows continuously through pasteurizing and into filling; there is no tray of finished juice to carry, only a continuous stream. You overlap those stages by starting the filling a set time after pasteurizing begins, not by counting units. That is the start-to-start lag model, and the juice line is a continuous-process work center.

In the plant, a chemical reactor that continuously processes product is continuous-process: you cannot count transfer batches of liquid, so the engine overlaps it by lag. A machining center feeding an assembly station is discrete, so it overlaps by moving trays of finished parts.

How EDGEBIC uses it

The continuous-process flag is set on each work center. The step-by-step is in how to mark a work center as continuous-process in EDGEBIC, and the wider picture of when and why to use it is in continuous-process work centers.

Because the flag selects the lot-streaming model, it interacts directly with the piece-count settings. A transfer batch entered on a step routed to a continuous-process work center is ignored on purpose, which is the exact scenario explained in my transfer batch size was ignored and reported by the continuous-process model mismatch check. The full overlap mechanism, both models side by side, is covered in EDGEBIC lot streaming.

The flat handling lag that can sit on top of either model is the companion term transfer delay. For the wider vocabulary, see the manufacturing glossary, and to see process and discrete stages in one plan, explore EDGEBIC.