A production schedule is useful only when the work can actually be performed. An attractive calendar can still allocate the same machine twice, start a job before its material arrives or assume a skilled operator is available during a break. Custom scheduling begins by making those constraints explicit.
What is the difference between planning and scheduling?
Production planning considers demand, materials and capacity over a period. Scheduling assigns particular operations to resources and time slots. Both need the same current orders, process information and resource calendars so the detailed schedule supports the wider plan.
Which constraints belong in the scheduling model?
- Process order: an operation begins only after its required predecessors and releases.
- Capacity: machines, tooling and shared resources cannot be used beyond their available limits.
- Working calendars: shifts, breaks, maintenance and approved downtime define usable time.
- Material readiness: stock must be available and cleared for use when required.
- Skills and alternatives: permitted operators and alternate resources depend on the operation.
- Setup and waiting: changeovers, handling and process-specific waiting periods affect the sequence.
Some constraints are mandatory. Others express a preference, such as reducing changeovers or keeping an order on its usual machine. Document that distinction. A preference should not silently override a mandatory process rule.
What should the system optimise?
Choose an objective with the planners. It might prioritise reducing late orders, controlling changeovers or protecting a bottleneck. Several objectives can conflict: a sequence with fewer setups may delay a high-priority order. The interface should expose those trade-offs and the assumptions used in the comparison.
Google's OR-Tools job-shop example illustrates operation precedence and exclusive machine use. It is a useful technical starting point; a real factory model also needs its own calendars, materials, process rules and business objectives.
Does a scheduling system need generative AI?
No. Rules and constraint optimisation can create and validate a schedule. Generative AI may help explain a change or summarise an exception, but a fluent explanation is not evidence that the plan respects capacity. Validate proposed assignments against the scheduling rules before publishing them.
Historical data may also support improved duration estimates. Keep the estimate and its assumptions visible, and review unusual jobs separately. A planner should be able to understand why the system suggested a particular allocation.
How should breakdowns and urgent orders be handled?
Update the changed constraint first. Preserve completed work and confirm what is already running. Compare alternate resources only when tooling, skills and material availability allow them. A planning freeze window can protect work that is too close to execution to change casually.
Show affected due dates before approval. Save the revised plan as a new version and communicate it through one agreed channel. Operators need to know which version is current, while the team still needs previous versions to understand deviations.
What happens when no feasible schedule exists?
The system should make the conflict visible rather than hiding it in an unrealistic date. The team may need to change a commitment, split an order, obtain material or approve extra capacity. Each option should preserve the underlying constraints and record the decision that made the revision possible.
How do you evaluate a scheduling pilot?
Replay representative past orders and known disruptions. Then run proposed schedules alongside the existing method. Check schedule adherence, predicted delivery risk and changes to already released work. Track planner overrides and their reasons; those reasons often reveal missing process knowledge.
Use a manageable pilot horizon and an agreed fallback plan. Clean routing data and timely progress updates matter as much as the solver. A schedule based on yesterday's status may be internally consistent yet operationally wrong.
Connect planning to the rest of the business
Explore Keen Systems' production planning and scheduling service for Sri Lankan factories. Read the breakdown rescheduling checklist, connect factory data and automation, or discuss your production constraints.