# Production scheduling edge cases These are hypothetical planning patterns. No timing, capacity, certification, approval or predicted recovery is verified for a real factory. 1. **Shifting constraint.** Recheck the remaining mix, calendars, queues, blockage and staffing. A coating queue cannot simultaneously prove starvation on that same work. Compare a limited adjustment with a full replan and document impact; no universal three-hour threshold or highest-utilisation proof. 2. **Qualified operator absent.** Check actual training/competency records, shift coverage, rest and fatigue rules. Use an authorised qualified alternate or hold the operation. Do not label pharmaceutical packaging/labelling unregulated or claim FDA individually certifies coating operators. 3. **Two rush customers.** Present feasible schedules and commercial alternatives for management. Eight extra hours do not necessarily close a 16-hour shortage, and Saturday completion misses a Friday deadline. Separate dispatch and arrival dates and verify contracted penalties rather than promising both orders on time. 4. **Suspected phantom demand.** Trace pegging, BOM versions, open orders, stock, scrap, safety stock and lot sizes. A250 unit forecast times erroneous 12 yields 3000 gross units; the corrected component requirement is 250 before other demand and netting, not an automatically authorised 800 unit replacement. Hold suspicious release for engineering/planning correction and rerun, avoiding duplicates. 5. **Quality hold across WIP stages.** Contain all affected lots and trace downstream consumption/shipment. Quality/engineering approve rework and release. Sixty units at 0.5 person-hour require 30 person-hours, or 15 elapsed hours only if two independent qualified people/resources can work in parallel. Do not infer a next-day completion or authorise structural re-drilling from arithmetic. 6. **Constraint breakdown with a part in the machine.** Isolate hazardous energy; maintenance/engineering assess repair, datum preservation and safe validated restart. Never bypass safeguards to recover a part. Alternate machines, outsourced defence work or programmes need capability and data/product approvals. 7. **Wrong steel grade.** Stop affected use, preserve heat/lot traceability and quarantine. Reconcile the actual number of plates versus assemblies before replacement and disposition. A cut wrong-grade plate is not automatically scrap for every use, and supplier cost recovery depends on contract evidence. 8. **Overtime restricted.** Translate person-hours into actual fully staffed machine windows. Four workers each offering 5 hours do not automatically create 20 machine- hours if a crew works simultaneously. Include support/inspection coverage; do not pressure off-book work or count assumed setup savings as recovered hours. 9. **Specification changed mid-run.** Engineering and the customer approve the revision, affected serials and cost. Four unstarted plus one in-process unit can form the requested five modified units only if technically feasible. Four programme hours plus six fixture hours plus two machining hours are 12 resource- hours, not automatically 12 critical-path hours; model overlap and dependencies. 10. **NPI trials.** Schedule three trials and their actual setups/contingencies explicitly. Three 14-hour windows total 42 hours, not 14 every week for six weeks unless that reservation is intentional. At 120 hours/week,6 extra hours changes 88% to 93% utilisation, but the 120 hour assumption must be stated. Separate buffered run time from setup to avoid double counting; no fixed junior-operator penalty or automatic weekend availability. 11. **Material delay and leaking food retort.** Maintenance/food-safety owners determine whether operation is safe and the validated process remains met; scheduling cannot assume continued production. Increasing 40 to 45 minutes is a 12.5% cycle-time rise and 11.11% rate loss. An 8-hour repair with 40 hours remaining leaves 32 hours at 40 min/batch, or 48 batches, versus 40 hours at 45 min/batch, or 53.33 batch-equivalents without repair. That timing alone loses 5.33 batches rather than creating a 4.8-hour gain. Safety can require repair anyway; evaluate complete scenarios with actual batch timing. 12. **ERP cutover.** Use the approved continuity plan, controlled travellers, unique transaction IDs, traceability and reconciled physical counts. Stage materials physically if approved; do not post consumption before it occurs. Check migrated/already-captured transactions before replay and validate quality holds and qualifications throughout the outage. 13. **Supplier material advisory.** Trace affected raw material, WIP, finished and shipped units. Quality/regulatory owners determine containment, reporting, field action and release. A supplier pass does not itself release every lot; preserve investigation records and independent acceptance evidence. Apply the current QMSR framework where relevant, not an obsolete inspection procedure. 14. **Power curtailment.** Verify the utility baseline, interval demand limit and actual measured kW by time. Protect ventilation, heat stress, safe shutdown and process controls. Do not hold molten metal in improvised containers, assume thermal carryover for six hours or shift loads without engineering approval. Upstream shutdown can still starve the CNC despite its protected power supply. 15. **PM versus rush order.** Maintenance approves the safe work sequence and available crews. Reducing 10 hours to 6 recovers 4 hours, not 8. Friday 22:00 plus 10 hours ends Saturday 08:00; a continuous 18-hour run then ends Sunday 02:00 only with all resources and release available. Do not assume two-out tooling halves runtime without validated engineering and downstream capacity. 16. **Cross-site overflow.** Verify both sites' eligibility, capability and customer approval. At 120 hours/week and 122% load,146.4 hours are required. If 140 are truly available, gap is 6.4/week or 19.2 over three weeks. At 70% relative rate this needs about 27.43 hours at B across the same horizon, before transfer/setup losses; B's 33.6 headroom hours/week are a different time basis. No generic certificate automatically waives site qualification. 17. **Seasonal shared tooling.** Schedule each actual mould, technicians, machines, qualifications and demand. Six four-to-six-hour changes consume 24–36 machine- hours but only 4–6 elapsed hours if truly simultaneous and fully resourced. Phasing changes when capacity is lost; it does not inherently reduce total setup. Validate remaining summer demand and winter lead times rather than mandate fixed dates or speculative inventory. ## Review record For each disruption retain observed facts, uncertain estimates, containment, resource calculation, alternatives, approvals, revised version and next update. Never protect constraint output at the expense of a safety/quality obligation.