Planning

Master production schedule

The MPS is the statement of what finished goods will be built, in what quantity, in which period, at which plant. It sits between demand and MRP so that the plant commits to a build plan it can actually hold, and MRP works from that commitment instead of from raw demand swings.

• Time fences: inside the demand fence the schedule is frozen and changes need a named approval; inside the planning fence MRP may propose but not move; beyond it the engine plans freely.
• Available to promise is computed from the MPS, so sales quotes a date the plant has agreed to.
• Rough-cut capacity checks the MPS against critical work centres before it is released.

MRP run

The planning run explodes every top-level demand through the bills, nets each item against on-hand stock, reservations, open purchase orders and open work orders, applies the item’s lead time and lot sizing rule, and proposes:

• Planned purchase orders for bought items, with a suggested supplier and a release date that respects lead time.
• Planned work orders for made items, dated back from the need date through the routing.
• Exception messages: expedite, de-expedite, cancel, past due, and the shortage list that no manufacturer can run without.

The run can be regenerative (rebuild the whole plan) or net change (only items with new demand or supply since the last run). Output is pegged: open any planned order and see the demand that caused it, level by level.

Capacity

Capacity requirements planning takes the released and planned work orders, walks their routings, and loads each work centre by period in hours. The load profile shows where the plan breaks. The planner then moves orders, adds shifts, chooses an alternate routing or outsources an operation, and re-runs. Finite scheduling is available per work centre for the bottlenecks where infinite loading lies.