3.3 SOP readiness & transfer to volume
Start of Production (SOP) is the specific moment where the project transitions from an Engineering Cost Center to an Operational Profit Center. It is not a date on a calendar; it is a certified state of readiness. Triggering SOP with unstable processes merely scales up defect generation. At this stage, the focus shifts from “Making it work” (Engineering) to “Making it repeatedly at target cost” (Operations).
The control plan baseline (the constitution)
Section titled “The control plan baseline (the constitution)”The Control Plan is the governing document of the production line. It dictates exactly how quality is maintained at every step. Once SOP is signed, the Control Plan is Locked. Any change requires a formal Process Change Notification (PCN).
Action: Process steps not explicitly defined in the Control Plan are considered non-existent and cannot be enforced by the quality team. Strict adherence is mandatory.
Baseline requirements:
Section titled “Baseline requirements:”- IQC (Incoming Quality Control): Sampling plans (AQL) for raw materials.
- IPQC (In-Process): Critical parameters (Torque, Temperature, Time) monitored during assembly.
- OQC (Outgoing Quality Control): Final audit criteria before sealing the box.
Sample control plan extract
Section titled “Sample control plan extract”| Step ID | Process Name | Control Characteristic | Specification | Sample Size | Reaction Plan |
|---|---|---|---|---|---|
| SMT-04 | Reflow Soldering | Peak Temperature | 245°C ± 5°C | Continuous (Profiler) | Stop Line. Quarantine last 2 hrs. |
| ASY-10 | Screw Assembly | Torque Value | 3.5 kgf-cm ± 0.2 | 100% (Smart Tool) | Tool auto-locks. Rework manually. |
| FQC-01 | Cosmetic Check | Scratches/Gaps | Limit Sample Set | AQL 0.65 Level II | Sort 100% of lot. |
Pro-Tip: The most critical column is the “Reaction Plan.” Operators know how to check things; they often do not know what to do when a check fails. Explicitly define “Stop Line” triggers to prevent creating a pile of scrap.
Capacity lock & ramp plan (safe launch)
Section titled “Capacity lock & ramp plan (safe launch)”Do not flip the switch to 100% volume on Day 1. Use a “Safe Launch” or “Early Production Containment” strategy to protect the customer from latent defects.
The ramp logic
Section titled “The ramp logic”- A Week 1 Yield exceeding 98% authorizes the release of Week 2 Volume.
- A Week 1 Yield below 98% necessitates a hold on volume increases and requires a Root Cause Analysis (RCA) before proceeding.
The safe launch plan
Section titled “The safe launch plan”| Phase | Duration | Volume (% of Peak) | Control Level | Exit Criteria |
|---|---|---|---|---|
| Safe Launch | Weeks 1 – 2 | 10% – 25% | 100% OQC Inspection. Engineers on-site. | 5 consecutive lots defect-free. |
| Ramp Up | Weeks 3 – 4 | 50% – 75% | Standard AQL Sampling. | Cₚₖ stable. Cycle time met. |
| Steady State | Week 5+ | 100% | Audit / Skip-lot sampling. | Process validated. |
Capacity verification:
Section titled “Capacity verification:”- Headcount: Is the 2nd shift hired and trained?
- Equipment: Are testers duplicated to meet Takt time at full volume?
- Supply Chain: Is the ERP driven by “Firm Orders” rather than “Forecast”?
Training & certification
Section titled “Training & certification”A Work Instruction posted on a wall is not training. Training is demonstrated competence.
Requirement:
- Certification Matrix: Every operator on the SOP line must have a “Green” certification level for their specific station.
- The “Shadow” Rule: New operators must shadow a certified trainer for 3 shifts before touching production units.
Decision Logic:
- A line staff composition exceeding 20% new or temporary personnel elevates the risk level, requiring an increase in QC sampling to 100% until process stability is demonstrated.
SOP sign-off pack (the handover)
Section titled “SOP sign-off pack (the handover)”This is the formal transfer of liability. Once this pack is signed, the Project Manager (Engineering) steps back, and the Operations Manager takes command.
The “no-go” triggers:
Section titled “The “no-go” triggers:”- Open Engineering Changes (ECOs): You cannot start production with pending design changes.
- Test Instability: A False Fail rate exceeding 5% results in SOP denial.
- Material Shortages: No “partial builds” allowed for SOP.
The sign-off artifacts
Section titled “The sign-off artifacts”- Yield Report: Final PVT data proving process capability (Cₚₖ) and Yield targets.
- Locked BOM: ERP system updated to “Production” status (no longer “Prototype”).
- Master Sample: Signed Golden Unit sealed in the QA cabinet.
- Test Software: Checksum verified and locked (Read-Only).
- Training Log: Signed roster of certified operators.
Final Checkout: SOP readiness & transfer to volume
Section titled “Final Checkout: SOP readiness & transfer to volume”| Control Point | Passing Criteria | State |
|---|---|---|
| ERP Status | Part numbers valid, BOM costs rolled up, routing active. | Active |
| Packaging | Drop test passed; palletization pattern defined. | Passed |
| RMA Process | Return address and “Return for Repair” code created. | Defined |
| Spare Parts | 2% spare pool (or agreed %) set aside for immediate support. | Stocked |
| Emergency Contact | 24/7 Escalation list (Operations & Quality) shared. | Shared |