A production plan groups what you intend to build over a window, explodes the BOMs to find what components are needed, compares that with stock, and raises the work orders.
Manufacturing → Planning → New plan: Name, Plan date *, Build window from / to, Components from (the warehouse), Sub-assemblies (build sub-assemblies as their own orders, or issue them as parts), Notes, and one row per Product with the Quantity, the warehouse to Stock into and a Start date.
The plan page shows What to build, Sub-assemblies, and a Materials table with what is required, what is available (on hand less held bins, sales-order holds and what other work orders still need), what is projected (available plus what is on order, in production or requested by the end of the build window) and what is to buy — the shortage is measured against the projection, so a component already on its way is not asked for twice. Buttons: Edit, Confirm (freezes the plan), Raise work orders (creates one work order per product and sub-assembly), Cancel plan. Statuses: Draft → Confirmed → In progress → Completed; Cancelled.
When components are short, the Materials tab shows how many and roughly what they cost, with a Create requisition button: one purchase requisition carrying every short component at its shortage quantity, due by the build window's start. From there it goes out as an RFQ to several vendors or straight to a purchase order — see Chapter 6.10.
A reorder rule can also plan for you: with Replenish by: Make (section 10.8) the replenishment run drafts a work order for the item when its projected stock falls below the minimum, and refreshes that draft until you release it.