This buyer guide helps you evaluate witness fat preparation and sign-off for export orders before committing capital to flexible packaging equipment. It focuses on scope, contract clarity, and acceptance discipline—not sales language.
Who this guide is for
Quality managers and project engineers defining FAT, SAT, and sign-off criteria with vendors.
Witness factory acceptance testing is the buyer's last structured checkpoint before serial equipment enters crating and sea freight. Poor preparation turns FAT week into argument over scope; strong preparation produces a signed record with measurable results, owned exceptions, and clear shipment authorization. Sign-off is a contract event—not a courtesy photo session.
Preparation begins at PO with FAT criteria attached to the technical schedule: substrate specification, ink or adhesive system, target speed duration, register and quality bands, changeover job if applicable, and who supplies test material. Buyers should confirm run-off bay reservation dates when deposit clears, especially for Q3 and Q4 export peaks when multiple witness visits compete.
Key decisions before you sign
Travel logistics matter for international witnesses. Visa lead time, hotel proximity to campus, and whether your team includes both quality and maintenance representation should be planned so one person is not forced to judge electrical and print quality alone. Request English or bilingual FAT checklists in advance to align on terminology before machines run.
Material readiness prevents false failures. Buyer-supplied film should arrive with conditioning notes, corona level if relevant, and width within agreed tolerance. Late or out-of-spec material forces vendors to argue whether a failed test counts against contractual acceptance—define retest rules before the first run.
FAT proves the machine at the factory; SAT proves it in your hall with your utilities and operators. Blending the two without written criteria invites argument.
Acceptance metrics should include register band, print density or coat weight, waste during ramp, and changeover time on agreed job families.
Buyer checklist
- Attach acceptance criteria to the purchase order or technical schedule.
- Define retest rules if FAT fails and who pays for re-witness.
- Record photos, torque sheets, and HMI recipe backups at sign-off.
- Separate FAT scope from SAT scope to avoid disputes after shipment.
Quotation, contract, and acceptance points
During witness days, record video and photos where contract permits, capture HMI trend data for speed and register, and log ambient conditions in the run-off hall. Subjective approval without files leaves SAT teams without baseline when drift appears after install.
Punch-list discipline defines sign-off integrity. Open items should list defect description, severity, owner, corrective action, and re-witness requirement. Signing full acceptance with verbal promises to fix later erodes leverage before balance payment. Critical safety or structural items should block crating regardless of schedule pressure.
Yaoshg FAT documentation packs align serial tracking across flexo, converting, and bag platforms so multi-machine projects hand over consistently. Buyers who complete sign-off with torque sheets, electrical test summaries, and spare parts kit verification typically shorten SAT punch-list closure compared with teams who treat FAT as a single signature line.
Define who owns rework if FAT fails: part replacement, re-witness travel, and schedule impact. Clarity here prevents relationship damage later.
Common mistakes and how to avoid them
Signing FAT under pressure with open punch-list items often becomes permanent tolerance of defects. Document exceptions with dates and owners.
Yaoshg sales and application teams can review your substrate list, layout sketch, and quotation scope before you finalize internal approval. Sharing structured questions early typically shortens FAT scheduling and reduces open items at SAT.