Planning (MRP)
How demand turns into suggested jobs and purchase orders — and where that ends and scheduling begins.
Planning answers one question: what should we make or buy, and how much? Carbon's MRP looks at everything you owe and everything you have coming, and turns the gap into suggested orders — which you choose to act on.
Why it matters
Without planning you'd reorder by hand. MRP nets demand against supply across the whole bill of materials, so a shortfall on a top-level robot surfaces as the right quantity of every component, offset for its lead time — before you're caught short.
Two stages
Planning runs in two distinct passes, and conflating them is the usual mistake:
- MRP — explode and net. The engine explodes demand through bills of material, nets it against on-hand plus open jobs and purchase orders, and writes period-bucketed demand and supply forecasts. It does not apply reorder points and does not create orders.
- Planning views — suggest a quantity. The production and purchasing planning pages read those forecasts, project running stock week by week, and apply each item's reorder policy to propose a quantity to order.
MRP suggests, it never auto-orders. The engine only writes forecasts; turning a suggestion into a real job or PO is an explicit action you take on the planning page.
What feeds it
| Input | Source |
|---|---|
| Customer demand | Open sales-order lines, by promised date. |
| Production demand | Job material still to issue, offset by lead time. |
| Forecast demand | Manually entered demand projections. |
| Open supply | Open jobs and open purchase-order lines. |
| On hand | The item ledger balance. |
Reorder policy
Each item, per location, carries a reordering policy that decides how a suggestion is sized — Manual Reorder (suggests nothing), Demand-Based Reorder (the default), Fixed Reorder Quantity, or Maximum Quantity — tuned by reorder point, order quantity, accumulation period, and min/max/multiple rounding. See Reordering for the parameters in full.
From suggestion to order
An item's replenishment system routes where its shortfall shows up: Make items surface on the production planning page as suggested jobs, Buy items on the purchasing page as suggested POs. Choosing Order creates a real job or purchase order at status "Planned" — persisted from planning, but not yet released into the normal lifecycle.
"Planned" is a real, saved job or PO that came from a planning suggestion and is waiting to be released — distinct from a hand-started "Draft".
Planning vs scheduling
Planning decides what and how much; scheduling decides when and where. Once a job exists, the scheduling engine places its operations onto work centers and computes their dates — it never changes quantities. The two are separate subsystems that meet at the job: planning finalizes it, scheduling sequences it onto the floor.