Finite Capacity Load Planner

How this works

Checking each order's own math against its own due date misses a common failure mode: orders share the same capacity pool, so a later order's real completion date depends on everything scheduled ahead of it. This engine loads orders in the priority order you give them, accumulating units against your daily capacity, and reports each order's actual completion date and buffer, not just what it would look like in isolation.

Assumptions

• Capacity is constant across the period
• Orders load strictly in the given priority order, with no splitting or interleaving
• Calendar days, not a working-day calendar (see Production Completion Date Planner for working-day-aware single-order scheduling)

Limitations

• Up to three orders only
• Fixed priority order, not a dispatch-rule comparison
• Does not account for changeover time between orders

Sources

Follows finite capacity scheduling and load-based sequencing in Vollmann, Berry, Whybark, and Jacobs, Manufacturing Planning and Control for Supply Chain Management (6th edition).

Worked example

Starting September 1 with 50 units/day of capacity, Order A (300 units, due September 10) looks comfortably feasible on its own, finishing September 7 with 3 days to spare. Order B (400 units, due September 14) would also look feasible if it had the capacity to itself. But loaded after A, B's completion lands on September 15, one day past its due date, because A's 6 days of capacity use pushed B's start back. The queue is infeasible even though neither order looks infeasible in isolation.

Common use cases

• Sequencing two or three orders that compete for the same production line or work center
• Catching a due-date miss that only shows up once orders are loaded together
• Deciding which order in a queue needs expediting or a capacity increase
• Testing whether adding a new order breaks an already-committed queue