This buyer guide helps you evaluate sat vs fat: what gets tested on-site 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.
Factory acceptance testing and site acceptance testing serve different purposes but are often blurred in export contracts until a dispute forces clarity. FAT proves the vendor built and adjusted the machine against agreed criteria before shipment. SAT proves integrated performance in your hall with your utilities, operators, and material handling. Buyers who skip SAT because FAT passed—or who expect FAT to cover site variables—inherit predictable startup conflict.
FAT scope typically covers mechanical assembly verification, electrical safety checks, idle and load running, print or process quality on agreed material, speed and register bands in the vendor run-off bay, and optional changeover timing on reference jobs. FAT does not prove foundation leveling quality, your exhaust duct pressure drop, or operator skill on your shift pattern.
Key decisions before you sign
SAT scope should explicitly include site-specific items: web path through your building, splice discipline with your roll handling, integration with upstream and downstream partners, production-rate scrap during ramp, and repeatability across multiple shifts. SAT may reuse FAT metrics but measured under buyer ambient conditions and operator crew—not vendor specialists only.
Utility differences justify SAT even when FAT was flawless. Voltage variation, compressed air dew point, chill water temperature stability, and hall humidity affect drying, static, and adhesive open time. Contract language should state whether SAT retest uses buyer utilities as the governing condition for warranty performance claims.
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
Responsibility split must be written: who rigs and levels modules, who supplies SAT material, how many commissioning days are included, and whether failed SAT due to buyer-delayed civil works extends vendor obligation or triggers standby charges. Ambiguity here is more expensive than a longer technical schedule at PO.
Documentation handover bridges FAT and SAT. HMI recipes, register offsets, dryer profiles, and maintenance intervals validated at FAT should travel with the machine and be revalidated at SAT—not rediscovered from scratch. Buyers should require recipe backup files in the contract deliverables list.
Yaoshg commissioning teams typically propose SAT checklists derived from FAT records so site work focuses on integration gaps rather than repeating full mechanical proof. Buyers who define SAT success criteria before shipment align internal production deadlines with realistic ramp—not with the false assumption that FAT sign-off equals production-ready output on day one.
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.