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. If you trigger SOP with unstable processes, you are merely scaling 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)

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).

If a process step is not in the Control Plan → Then it does not exist and cannot be enforced.

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

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)

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:

If Week 1 Yield > 98% → Then Release Week 2 Volume.

If Week 1 Yield < 98% → Then Hold Volume. Root Cause Analysis required.

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:

• 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

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:

• If > 20% of the line staff is new/temporary → Then Risk Level is High. Increase QC sampling to 100%.

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:

• Open Engineering Changes (ECOs): You cannot start production with pending design changes.
• Test Instability: If False Fail rate > 5%, SOP is denied.
• Material Shortages: No "partial builds" allowed for SOP.

The Sign-Off Artifacts

1. Yield Report: Final PVT data proving process capability (Cpk) and Yield targets.
2. Locked BOM: ERP system updated to "Production" status (no longer "Prototype").
3. Master Sample: Signed Golden Unit sealed in the QA cabinet.
4. Test Software: Checksum verified and locked (Read-Only).
5. Training Log: Signed roster of certified operators.

Final Checklist

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