The plan is in one person's head and on one wall
The whiteboard by the office door has a column for each machine and magnets for each job. The production manager moves them around every morning based on who is in, what material has arrived and which customer rang yesterday. It works, mostly. Then the production manager is off for a week and nobody else can read it.
Or a rush job arrives, gets squeezed onto the five axis, and the job that was already there slides a week without anyone telling the customer.
Why the scheduling module in your MRP sits unused
Most MRP systems can schedule, in theory. In practice they treat machines as interchangeable work centres with a number of hours per day. A subcontract machine shop does not work like that. The job that fits on the Mazak will not fit on the smaller vertical, the long shaft needs the lathe with the tailstock, and running two jobs with the same soft jaws back to back saves a whole setup.
- Machine capabilities are not recorded: axes, travel, spindle speed, bar capacity, probing.
- Setup time depends on the job before, not just the job itself.
- Material arrival, tooling and outside processing dates are not visible to the plan.
- Operator skills limit which machine can run on which shift.
- Due dates change and nobody sees the knock on effect.
What it costs to plan by memory
Late deliveries that could have been seen coming weeks earlier. Machines left idle because the next job's material has not arrived. Setups repeated that could have been grouped. And a production manager who spends the first hour of every day replanning, and cannot take a holiday without the shop drifting.
The loading board we build
- Each machine is described properly: type, axes, working envelope, bar capacity, tool magazine size, probing, pallets, and which operators can run it.
- Each job, pulled from your MRP or job list, carries its operations, the machines able to do each one, estimated setup and cycle time, material status and due date.
- The board shows machines as rows and time as columns. Jobs are dragged into place, and the board refuses or warns when a job is put on a machine that cannot do it or when material will not be there in time.
- Jobs that share a fixture, soft jaws or material are highlighted, so the manager can group them to save setups.
- Any job that will finish after its due date shows in red the moment the plan changes, with a list of which customers are affected.
- Operators see their own machine's queue on a screen or tablet, in the order the manager set.
| Constraint | Held in the board |
|---|---|
| Machine capability | Machine record: axes, envelope, bar size |
| Setup grouping | Shared fixtures, jaws and material flagged |
| Material ready | Linked to purchase orders and goods in |
| Outside processing | Expected return date from the processor |
| Operator skills | Who can set and run each machine |
We do not try to replace the production manager's judgement with an optimiser. The board does the checking; the person decides.
How the mornings change
The plan can be read by anyone. When a rush job comes in, you can see which jobs move and by how much before you say yes to it. Material shortages show up days ahead instead of at the machine. Customers whose parts will be late get a call before they have to make one.
Is your machine loading held together by one person?
- The schedule is a whiteboard, a spreadsheet or a notebook.
- Nobody else can plan when the production manager is away.
- Rush jobs push other work late without anyone noticing.
- Machines stand idle waiting for material or tools.
- Your MRP's scheduling screen has never been used.