Manufacturing resource planning: closing the loop between the sales plan and the shop

The master schedule is a commitment, not a wish

Somewhere between the commercial forecast and the detailed materials calculation sits a statement of what the plant intends to build, in what quantity, in which period. That statement is the master schedule, and its defining property is that somebody personally owns it and can refuse to change it. Where it does not exist, sales promises become the plan by default and every disappointment is blamed on manufacturing. Where it exists but is rewritten on request, it is decoration. The master scheduler's authority is the whole mechanism: they hold the near horizon steady, absorb changes further out, and force the trade-off conversation when both cannot happen.

The capacity check people skip because it is approximate

Before a schedule is released for detailed calculation it is worth testing against the handful of resources that actually limit output — the heat treatment furnace, the paint line, the test rig, the two people qualified to do final adjustment. This is deliberately coarse work using approximate load factors rather than a full model, and its value is that it happens early enough to change the schedule cheaply. Plants skip it because it feels unscientific, then discover the constraint in the last week of the period when every option is expensive. A rough answer available in time beats a precise one that arrives after commitment.

The loop only closes if execution reports back

Closed loop means the next planning cycle knows what the last one actually achieved: which orders finished, which slipped, what the yield really was, where the hours went. Without that return path the plan is regenerated from the same optimistic assumptions each time, and the difference between intention and outcome is absorbed silently by expediting and overtime. Feedback also has to include the reasons, because a schedule missed through a supplier failure calls for a different response from one missed through a changeover taking longer than the routing claims. That distinction is what turns reporting into planning improvement rather than into a performance discussion.

One set of figures for operations and for finance

A genuine attraction of the closed-loop model is that the operating plan and the financial plan are derived from the same product structures, routings and standards. Volumes become hours, hours become absorbed cost, material requirements become spend, and the budget conversation stops being an unrelated exercise conducted in a spreadsheet. The catch is that this only holds while both functions accept the same underlying records. As soon as finance maintains a private view of standard hours because it does not trust the routings, the plant has two planning systems and no reconciliation, and the monthly variance meeting becomes an argument about whose data is wrong.

The software gets blamed for a process nobody runs

Every element of this depends on a governance rhythm: a scheduled review where the demand picture, the plant plan and the constraints are examined together, with named people who can commit. Buy the modules, skip the rhythm, and the visible result is a system producing plans that participants privately regard as fiction. The tell is easy to spot — attendance at the planning review drifts down to planners only, senior people stop coming because nothing is decided there, and firefighting resumes as the real coordination mechanism. Restoring the rhythm is a management task that no configuration change substitutes for.

Frequently asked questions

How is this different from just running the materials calculation?

The materials calculation answers one question: what to order and when, given a demand statement it does not question. The wider closed-loop model asks whether that demand statement is deliverable, checks it against limiting resources before releasing it, feeds actual results back into the next cycle, and derives financial numbers from the same records. In other words the calculation is a component inside it. Plants that run the calculation without the surrounding discipline get orders they cannot make on time.

Who should hold the master scheduler role?

Someone senior enough to say no to a commercial request and be supported when they do, with enough plant knowledge to know which constraints are real. Placing the role under sales produces a schedule that reflects hopes; burying it deep in production produces one nobody outside the plant respects. Many manufacturers put it in a planning function reporting to operations, with an explicit escalation route when commercial and manufacturing cannot agree. The role fails when it becomes clerical order entry rather than a decision-making position.

Does a small manufacturer need this whole apparatus?

The mechanism matters more than the module list. A modest plant can hold a credible master schedule in a simple tool, check its bottleneck by hand, and review outcomes weekly with the people who run the floor. What cannot be skipped is single ownership of the schedule, a horizon that is protected from constant change, and honest feedback about what was achieved. Buying a large planning suite before those habits exist tends to automate the confusion rather than remove it.