Applicable instances are the number of a work center's machines a specific routing step is allowed to use, which can be fewer than the total available. A work center may hold several identical machines, but not every one is always suitable for every operation. Applicable instances lets a step say "use only this many," so the engine spreads that step's work across the right subset rather than the whole cell. EDGEBIC by User Solutions reads applicable instances per step so a routing reflects which machines can genuinely run each operation.
How it works
A work center has a total number of instances, meaning how many identical machines physically exist there: a drilling cell with four presses has four. A routing step then carries applicable instances, meaning how many of those machines this particular step may actually use. When the two match, the step can spread across the whole cell. When applicable instances is lower, the step is limited to that many.
The reason to limit a step is that "identical" machines are not always interchangeable for a given part. Two of the four presses might hold the fixture the part needs, or only two might have the right tooling. Applicable instances captures that constraint without pretending the other machines do not exist: they remain available to other jobs, just not to this step.
The count shapes elapsed time. A step that may use four machines finishes in roughly a quarter of the time of a single machine, because the work runs in parallel. Cut applicable instances to two and the same work takes roughly twice as long as the four-machine case, because half the parallel capacity is off the table. That is the deliberate trade-off: honesty about which machines can run the step, at the cost of some parallel speed.
A concrete example
Think of a bakery with four ovens. All four are the same model, so in principle a big batch could bake across all of them at once. But this particular product needs a specific rack that only two ovens have. So for that product, the applicable ovens are two, even though the total is four.
The bakery does not remove the other two ovens; they keep baking everything else. This product simply spreads across the two racked ovens and therefore takes about twice as long as it would across all four. The count reflects a real limit, not a shortage of ovens.
In the plant, a drilling cell with four presses whose fixture fits only two sets that step's applicable instances to two. The work spreads across those two, the elapsed time reflects two-way parallelism, and the other two presses stay free for parts they can run.
How EDGEBIC uses it
Applicable instances is a value on the routing step, set alongside the work center assignment. The step-by-step is in how to set the applicable instance count on a step in EDGEBIC, and the broader configuration of instances and utilization is in how to configure instances and utilization.
Because the count controls how much parallel capacity a step can draw on, it feeds directly into the multi-machine allocation the engine performs. The underlying concept of a single physical machine within a work center is the companion glossary term machine instance, and the failure mode of two steps fighting over the same machine is covered in what is an instance collision.
Set applicable instances honestly and the plan matches the floor: the right machines carry the step, the wrong ones stay open, and elapsed times stop pretending the whole cell can run every part. For the wider vocabulary, see the manufacturing glossary, and to see instance-aware scheduling in a live plan, explore EDGEBIC.
Expert Q&A: Deep Dive
Q: Our drilling cell has four presses but only two hold the fixture this part needs. How do I stop the schedule from spreading the job across all four?
A: Set that step's applicable instances to two. The work center still has four machines in total, but the step will only be spread across the two that can hold the fixture, matching what the floor can actually do. The engine will not book the other two presses for this operation, so they stay available for parts that can run on them. Without this, the plan would assume four-way parallelism the fixture does not allow, and the real job would fall behind.
Q: If I set applicable instances higher than the machines that physically exist, what happens?
A: That would tell the engine to use more parallel machines than the work center actually has, which the plan cannot honor. Applicable instances is meant to be less than or equal to the total number of instances at the work center. Keep it within the real machine count: if the cell has four machines, the largest sensible value is four, and you lower it only when fewer are suitable for the step. Setting it above the physical count invites a schedule that assumes capacity you do not own.
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