Redacted layout showing CTQ callouts, datums, and how pass/fail is stated.
Case study • CTQ evidence • Export-ready delivery
Case Study: Aerospace Assembly Tooling Plate (Datum Stability + Repeat Hole Patterns)
An anonymized tooling plate program where datum stability and repeat hole patterns were critical to assembly accuracy, with documentation to support supplier quality review.
Program snapshot
Customer: Aerospace manufacturing team (U.S. program; name withheld)
Part: Assembly tooling plate / fixture base used to locate parts during build
Why it mattered: Tooling errors amplify downstream assembly issues; hole pattern accuracy and stable datums are essential
SEMIX role: Machining planning, controlled datum strategy, and CTQ verification/reporting
| Field | Details (public) |
|---|---|
| Material / finish | Anonymized (share under NDA if needed) |
| Size envelope | Anonymized (available under NDA) |
| Qty range | Prototype to low-volume programs (anonymized) |
| CTQ focus | Datums + functional features (CTQs defined at RFQ) |
| Tolerance & verification | Tight/critical features verified on CTQ-focused report (ranges shared under NDA) |
| Lead time | Quoted per RFQ; schedule aligned to customer gate dates (ranges under NDA) |
| Evidence pack | CTQ report • CoC • material/finish certs (as applicable) • packaging notes |
Key requirements
| Area | Requirement |
|---|---|
| Datum stability | Stable primary datum surfaces to control hole-pattern locations |
| Hole patterns | Repeat hole patterns with positional integrity (per drawing CTQs) |
| Handling | Protection of reference surfaces during machining and packaging |
| Documentation | Inspection evidence aligned to hole-pattern CTQs |
| Schedule | Tooling delivered to match assembly milestone |
How we executed
SEMIX approached the build as a controlled workflow: confirm CTQs, plan measurement methods, and prevent revision drift.
- DFM review: confirmed datum strategy and how it would be maintained across operations.
- Setup strategy: minimized setups to reduce stack-up error on hole patterns.
- CTQ mapping: identified hole patterns and reference surfaces as inspection priorities.
- Inspection reporting: created a CTQ-focused report that supports quick supplier quality review.
- Packaging: protected reference surfaces to preserve accuracy through transit.
Quality evidence and documentation
To make receiving easy for a U.S.-based program, we shipped with evidence aligned to CTQs and revision control.
- CTQ inspection report emphasizing hole-pattern and datum surfaces
- CoC with revision references
- Packaging protection for reference surfaces
- Revision traceability to support supplier quality audit trails
Evidence pack preview (redacted)
On request, we can share redacted examples of the exact report formats our U.S. buyers receive—so your receiving team knows what to expect.
Revision- and PO-linked CoC format used for receiving acceptance.
Redacted packaging notes for protection, labeling, and kitted shipments (if applicable).
Outcome
- Tooling plate accepted quickly due to clear CTQ evidence
- Assembly fit issues avoided by protecting datum surfaces and hole-pattern integrity
- A stable process enabled follow-up tooling variants with shorter lead time
Outcome metrics are anonymized. The point is the workflow: stable routing, CTQ measurement, and receiving-ready documentation.
Outcome highlights
Evidence formatted for receiving review; CTQs highlighted to reduce back-and-forth.
CTQ inspection plan executed; CoC and required certs packaged with the shipment.
Delivery and documentation aligned to the customer’s internal gate / PO flow-down.
Deep dive (technical briefs)
If you want the engineering rationale behind the controls used in this program, start with these related briefs from our Technical Academy:
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ISO 230‑3 Thermal Effects | Warm‑Up Protocols That Protect Tolerances
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ISO 230‑2 / ISO 230‑4 CNC Accuracy Tests | Part‑Level Risk Control
How to use ISO 230‑2 positioning tests and ISO 230‑4 circular/contouring tests to manage tolerance risk, schedule verification, and prove CNC capability to U.S./EU buyers sourcing CNC machining in Vietnam.
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Decision Rules with Measurement Uncertainty | ISO 14253‑1 + ILAC G8 + GUM
Applied guide to uncertainty-based decision rules: guard bands, false accept/reject risk, and dispute-proof statements of conformity for precision CNC machining suppliers serving U.S./EU buyers.
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Gauge R&R for High‑Precision CNC | Practical Execution (NIST‑Aligned)
How to design Gauge R&R for tight-tolerance machining: artifact selection, fixturing, temperature discipline, CMM strategy, and actions that improve measurement reliability for U.S./EU buyer programs.
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Evidence patterns (technical case studies)
Incident-style write-ups that show how SEMIX handles common failure modes and prevents receiving disputes:
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Case Study (Semiconductor/Vacuum): Flatness Dispute Solved | Thermal State + Decision Rules
Flange flatness passed at supplier but failed at customer. Root cause traced to thermal-state mismatch and missing uncertainty-based decision rules. Includes corrective actions and reporting template.
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Case Study (Aerospace): Late‑Batch Reject Spike | Wear‑Driven Regime Change
Rejects appeared late in the batch. Root cause was wear-driven cutting regime change shrinking stability margins. Fix used wear gating plus EWMA/CUSUM drift detection.
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Documentation templates (print-to-PDF)
Want consistent receiving-ready evidence? These templates show typical formats SEMIX can provide with shipments (redacted samples available under NDA):
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Certificate of Conformance (CoC) template
Buyer-friendly CoC with clear scope, drawing revision reference, and statement of conformity.
Open template
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Inspection plan (CTQ) template
Characteristic table with method, sampling, decision rules, and reaction plans—built for high-trust programs.
Open template
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Final inspection report template
A report structure that reduces disputes: conditions, CTQ highlights, and declared decision rules.
Open template
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Packaging & shipping checklist template
Packaging spec, label control, photos, and shipment signoff for export-ready delivery.
Open template