7. Making: work orders

The loop

1. Raise a work order: make N of part X, from components at location A, output to location B, by this date, at this priority. It is a draft; adjust freely.
2. Release it. The part's routing is snapshotted into the order's own steps — editing the routing tomorrow does not rewrite the job on the bench today. No routing means one step, Build.
3. Steps are worked in sequence. A step is ready when every earlier step is finished and its materials are on hand at the component location or anywhere beneath it. Each step's card lists what it consumes, per unit and for the quantity still to do, with a short flag where the shelf is thin.
4. An operator starts a step on a workstation from its group (the station goes busy) and, when done, completes it with a quantity — the whole remainder, or fewer for a partial run.
5. Completing backflushes: the step's materials for that quantity are issued from the component location and the locations beneath it, biggest pile first, as ledger movements referencing the step. On the last step, the output is received into the output location. Not enough on the shelf refuses the completion and names the part.
6. When the last step's done quantity reaches the order's, the order is complete.

Why per step

Because that is where the truth is. Materials leave the shelf when the operation that uses them happens, not when the order is raised and not when it is all over. The ledger ends up recording the build the way it actually went — including a run that stalled at lacing for a week because the rims were late — and the inventory records MRP depends on stay accurate because of production.

The wheel, end to end

Two front wheels. Release: four steps. Hub build is ready (bearings on the shelf); Joe starts it on stand 1, completes 2 — four bearings and two hubs are issued. Lacing: rims and spokes issued. Truing: consumes nothing; Mike completes it. Tyre fitting: one tyre on the shelf, two needed — the step shows short and refuses a completion of 2; Sarah completes 1, one tyre is issued and one wheel received; the order sits at 1 of 2 until the tyre delivery is received, then the second wheel completes the order.

That is the whole system exercised in one job: routing, allocation, readiness, backflush, partial completion, receipt.

Things to know

• One component location per order, and it is a subtree. Name the site (or the area) the order is built at, and everything on any shelf beneath it counts. Name a shelf only when you mean that shelf. A part at another site shows as short: transfer it, or raise the order from there.
• Skip passes a pending step without doing it; Cancel closes an unfinished order — what was consumed stays consumed.
• Priority (1 urgent … 4 low) and due date decide the order in which stations are offered work.
• A released order whose next step is short raises a task naming the component.

Services and repairs

Not every job makes something. A scheduled service on a boat occupies the same people and stations as a build, uses grease and antifoul, and sometimes eats a gearbox. It is a work order like any other, for a part that is not stocked:

1. Create a part per kind of job ("Class 1 service"), not stocked. Give it a routing (the procedure, step by step, with the groups that do it) and a BOM of what every such job uses.
2. Raise a work order for it, with a reference saying which boat. The order appears on the capacity chart beside the builds, because it is competing with them.
3. Completing steps consumes the BOM as usual. Completing the last step receives nothing: there is nothing to put on a shelf.
4. A part found worn out is drawn under Extra parts on the order. Stock drops, and if that part has a minimum stock the next planning run proposes its replacement.

Another system can raise these through the API: POST /api/work-orders.

Automatic stations

A workstation of kind automatic is driven by something else — a 3D printer's manager, say. It asks the API what should I do now, gets a step only when it is idle and the step is ready, reports busy, completes with a quantity, and goes idle. When a printer needs a human — a bed to clear — it goes blocked and pushes a task; the human clears it and taps Ready on the workstation page; the next poll gets a job. The system knows nothing about printers, and does not need to.

Next: attention.