Blog · Production & Procurement
Why your production plan needs frozen days.
A plan that can change every hour is not flexible; it is unreliable. We think every plant should decide which days are committed, and stop the plan from moving inside them.
There is a common belief that the best production plan is the one that updates the moment anything changes. A new order arrives, the plan reshuffles. A line slows down, the plan reshuffles. On a screen this looks responsive. On the floor it looks like chaos.
What a late change really costs
Think about a bakery plant with a bread line, a cake line and a cookie line. By the afternoon, tomorrow’s bake is already in motion in ways the plan does not show:
- Flour has been drawn from the silo and the mixing schedule set.
- Fat, sugar and flavours for the cake batter have been issued from stores.
- Wrappers and cartons for specific SKUs are staged near the packing hall.
- Shift supervisors have assigned people to lines.
- Dispatch has told outlets and distributors what is coming.
Move tomorrow’s sponge cake to Friday at 6 pm and every one of those steps has to be undone. Materials go back, people move, dispatch makes calls. Some of it cannot be undone at all: a dough already mixed has to be baked. The plan changed in a second; the plant pays for it all night.
The idea of frozen days
A frozen period is a stretch of days, usually the nearest ones, that the plan is not allowed to change except by a deliberate decision. Outside that window, the plan stays fluid and reacts to new orders freely. Inside it, the plant gets stability.
| Window | What the plan does | Who can change it |
|---|---|---|
| Today and tomorrow | Frozen: committed to the floor | Plant head or planner, with a recorded reason |
| Rest of the week | Firming up: changes allowed, but visible | Planner |
| Beyond the week | Fluid: re-planned from demand each morning | The system’s suggested plan |
The right length depends on the plant. A line with long changeovers or long material lead times needs a longer frozen window than one that can switch products in minutes. The table is a starting point, not a rule.
“But we must react to customers”
Of course. Frozen days do not stop a plant from accepting an urgent order. They change how it happens. Instead of the plan silently reshuffling, someone decides to break the freeze, knows what it will disturb and owns the call. Most urgent orders can then be placed in the first open day after the frozen window, which is often soon enough. The ones that truly cannot wait get a conscious exception, not an accidental one.
Frozen days also make other numbers honest. If the plan for tomorrow cannot drift, then tomorrow’s plan versus actual is a fair test of the line. And procurement can buy against a plan that will still be the plan when the material arrives. The raw material planning guide shows why that matters for order-by dates.
How the planner handles it
In the production planner, the suggested plan is rebuilt each working day: due SKUs take capacity in priority order, then pull-ahead fills what is left, line by line against the calendar. On the daily plan, planners can override any cell and freeze days that are already committed, with targets shown alongside. Planners and admins have those rights; viewers can read the plan but not change it. Overrides are recorded in the audit log with who and when. The plan can still be downloaded to Excel from every screen, so the floor keeps the sheet it trusts.
Where to start
Look at last month and count how often the next day’s plan changed after mid-afternoon, and what each change disturbed. If the answer is “often” and “a lot”, a frozen window will do more for the plant than a faster plan. More on planning practice is in the production planning guides.
Questions
What are frozen days in a production plan?
The nearest days of the plan that are committed to the floor and do not change except by a deliberate, recorded decision. Days beyond them stay open to re-planning.
Do frozen days stop a plant from taking urgent orders?
No. They make breaking the freeze a conscious decision with a known cost, and most urgent orders can go into the first open day after the frozen window.
Can the planner freeze days?
Yes. Planners can override any cell on the daily plan and freeze days that are already committed; overrides are recorded in the audit log.
See it on your own data. Production & Procurement — Plan the line, buy on time. Book a 30-minute working session with an engineer.