I. Quantifying Acceptance Prerequisites
Prerequisite: Full quantification of standards. Industry experience dictates that acceptance criteria must be 100% quantifiable. Core metrics—such as cycle time, yield rate, equipment utilization rate, critical dimensional accuracy, and equipment failure rate—must specify exact numerical values, testing methods, and testing tools, eliminating any ambiguous wording.
Any requirements extending beyond the technical agreement must undergo a formal written change process, clearly outlining the scope of change, pricing, and timeline; the change becomes effective only after being signed and stamped by both parties. Quantifiable metrics are the primary rule for acceptance.
II.
Four-Stage Acceptance
Phased acceptance across four stages.
Industry practice divides the acceptance of non-standard conveyor lines into four stages: Delivery Acceptance involves random sampling of profile wall thickness, chain specifications, and sensor brands, verified via vernier calipers and multimeters; Installation Acceptance checks track levelness, height differences at connection points, and drive synchronization; Operational Acceptance entails continuous full-load operation for 72 hours, recording failure frequency, positioning accuracy drift, and noise levels;
Final Acceptance requires all metrics to meet the technical agreement before signing off on payment—avoid signing off on the entire project at once; instead, use phased acceptance.
III.
FAT and SAT
Dual acceptance: FAT and SAT. According to industry standards, the FAT (Factory Acceptance Test) takes place at the manufacturer’s facility: it includes at least two hours of no-load operation (recording vibration, temperature, and noise), cyclic testing of all operating modes, simulation of alarms and faults, and actual measurement and sign-off of cycle times. The SAT (Site Acceptance Test) occurs at the customer’s site: it involves re-running tests based on FAT protocols, end-to-end trial production, and personnel training.
FAT verifies if the equipment is capable of performing the task, while SAT confirms its usability on-site—verify before shipment, confirm upon arrival.
IV. Core Quantitative Metrics
Core quantitative metrics.
Based on industry benchmarks, key acceptance indicators include: a First Pass Yield (FPY) of no less than 95%; a Process Capability Index (Cpk) for critical dimensions of no less than 1.33; an Overall Equipment Effectiveness (OEE) of at least 65% (calculated as availability × performance × quality; e.g., 62.5% × 75% × 95% results in only ~45%, which fails to meet the standard); a production line cycle time measured over 100 consecutive units;
and a PLC response latency (from trigger to command execution) of no more than 50 milliseconds—all of which must be stipulated in the technical agreement.
V.
Safety and Stability Standards
Safety and stability standards: In accordance with industry norms, safety must comply with relevant national standards (such as GB/T 20818-2018), covering requirements such as an emergency stop response time of no more than 0.5 seconds, insulation resistance of at least 2 MΩ, grounding continuity resistance of no more than 0.1 Ω, protective guard impact strength of at least 50 Joules, and verification of safety light curtain interlocking functions. Stability is assessed via Mean Time Between Failures (MTBF) and Mean Time To Repair (MTTR), requiring 72 hours of continuous, fault-free operation.
Safety indicators must be tested and certified by CMA/CNAS-accredited institutions.
Conclusion
What are the acceptance standards for a custom-built assembly line? The answer lies in a “four-stage acceptance process combined with eight quantitative indicators”: incoming goods spot checks (wall thickness, chain specifications, sensor brands) → installation inspection (levelness, height variance, synchronization) → 72-hour full-load operation acceptance (failure count, accuracy drift, noise levels) → final documentation review (drawings, installation and commissioning records, inspection reports, certificates of conformity, electrical schematics, spare parts lists). Key indicators include cycle time, FPY ≥ 95%, Cpk ≥ 1.33, OEE ≥ 65%, emergency stop response ≤ 0.5 seconds, insulation resistance ≥ 2 MΩ, and metrics for MTBF/MTTR alongside the 72-hour fault-free operation requirement.
In accordance with industry practice, Party A, Party B, and the designer jointly sign off on the acceptance results; deadlines for rectifying non-compliant items are clearly stipulated, and the final payment is released only after standards are met.
Acceptance criteria are not merely verbal agreements but hard terms within the technical agreement that specify exact values, testing methods, and testing tools.
