Freezing the Plan and Execution Feedback
In one sentence
A freeze window puts near-term change under a rule; when plan versions and actual events are stored together, the cause of a deviation can be measured.
By the end of this lesson
- Calculate the extra time load of 12 order changes and their effect on spare capacity.
- Separate a mandatory change from a deferrable request in the freeze window.
- Compare two change policies on the finite calendar and the delivery result.
- Design a feedback record that keeps the first plan, the current plan and the actual separate.
Why it matters
Freezing the plan does not mean declaring near-term work unchangeable; it means stopping execution of a change before its effect has been examined. As production approaches, material may have been prepared, workers assigned and the setup sequence built. A request that looks small can break these links and cause extra setup or rework. Adding every new request to the sequence immediately makes the plan look up to date, but it can reduce feasibility. The freeze window defines in advance which time range of changes needs special evaluation, on what grounds they can be accepted and with what capacity they will be met.
The window is not an excuse for postponing safety and quality requirements. Continuing hazardous or nonconforming work merely because the plan is frozen is not acceptable. In such a case the work is stopped or an approved safe practice is adopted; the time and delivery effect of the required correction is calculated openly. On the other hand, an optional adjustment that does not change the service condition can be left to the next suitable period. An exception must be kept apart from a habit. Labeling every request urgent means in effect abolishing the window. The acceptance decision rests not on the word priority but on a verified reason and an executable plan.
Actual feedback is not merely reporting the total quantity produced at period end. Start, finish, remaining work, stoppage and change events must be on the same time axis. A planned time difference and a scope added later are different deviations. Comparing a job that was lengthened by a change with the old time and declaring the worker inefficient gives a wrong result. In the same way, setting the time target equal to the actual is not proof of improvement. If scope and plan version are preserved, what changed, what could not be executed and what was assumed wrongly from the start can be examined separately.
Preserving the old plan is the basis of reliable measurement. The first plan, the current plan after the change and the actual record answer different questions. The first plan shows the initial commitment, the current plan the expected result under known conditions, and the actual what happened. If all three are continually changed in a single cell, plan success cannot be measured. Perfect conformity to a target created afterward does not prove that the initial delivery was kept. The version, the record time, the reason for the change and the affected order are therefore stored together. Feedback is used not to clean up history but to improve the assumptions of the next plan. For the numerical scenarios in the lesson quizzes as well: This dataset was generated synthetically for training; it does not represent a real business, employee or customer study.
Formula
Extra change load (min) = Sum of the extra times of accepted changes
Remaining capacity (min) = Available capacity − First plan load
Capacity overrun (min) = max(0, First load + Extra load − Capacity)
Run-time lateness (min) = If the finish exceeds the delivery, the open calendar time from the due time to the finish
otherwise 0
On-time delivery (%) = Orders finished on time ÷ Orders due × 100
Plan deviation (min) = Actual finish − Finish in the selected plan version, on the same time definition
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- Step-by-step instructions
- Worked example with real numbers
- Where the method misleads
- Common mistakes