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    Skody AI
    GlossaryScheduling Concepts

    Manufacturing Variability

    Definition

    Manufacturing variability is the unpredictable variation in setup time, run time, scrap rate, material arrival, labor availability, and machine uptime that makes any deterministic schedule drift from reality as the day progresses. It is not noise to be eliminated — it is the fundamental physics of a discrete manufacturing floor. The job of a scheduler is to absorb variability, not pretend it doesn't exist.

    Why it matters

    A scheduler that assumes setup is always 30 minutes when it actually ranges 20 to 60 will be wrong on every operation. Compounded across a day, the schedule diverges from reality by hours. The solution is not better point estimates; it is a scheduling architecture that replans as actuals arrive, so the schedule walks alongside reality instead of trying to predict it.

    Common failure mode

    The standard time for an operation is 4 hours. Actuals range 2 to 7 hours. The schedule assumes 4 every time. By the end of the week the published completion times are off by half a shift on average. Customers receive optimistic promises that are systematically missed.

    How Skody approaches it

    Skody learns from actuals — setup, run, and queue times per operation, per machine, per operator — and updates its scheduling model as those actuals land. Variability is absorbed by event-driven replanning rather than by inflating buffers. The result is a schedule whose accuracy improves with use.

    Related terms

    Dynamic Replanning
    Recalculating the production schedule continuously as floor conditions change.
    Queue Time
    The time a job waits in front of a work center before it actually starts processing.
    Schedule Instability
    When the schedule changes so often that the floor cannot rely on it.
    Finite Capacity Scheduling
    Scheduling that respects the real, limited capacity of each machine, operator, and tool.
    Bottleneck
    The resource whose limited capacity governs the throughput of the whole factory.

    Questions

    Some variability you can attack at the source — standard work, setup reduction, preventive maintenance. The rest is inherent to high-mix discrete manufacturing and must be absorbed by the scheduling system through event-driven replanning, not by adding buffer time to every operation.

    Yes, periodically — but standard times will always be a point estimate against a distribution. The bigger lever is to feed actuals back into the scheduler, so the schedule reasons about reality rather than about the standard.

    Inflated buffers expand lead times for every customer, while still failing on the worst jobs. They optimize for the average case and miss the long tail. Event-driven replanning addresses the tail directly — when an operation runs long, the downstream sequence adjusts instead of relying on a global buffer.

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