01Verify the comparison reference
Record golden-sample ID, product revision, approval scope, date, condition and linked specification. Check for fading, wear, battery aging, scent loss, deformation or software changes before using it. If buyer and supplier references differ, reconcile identity and hierarchy before evaluating production.
02Choose characteristics vulnerable to scale-up
Review material lots, tooling cavities, equipment, process windows, software loading, manual assembly, print, finishing and pack-out. Select measurable or observable outputs connected to those risks. Do not invent material or performance claims simply to create a metric; use the approved product requirements and qualified test methods.
03Define method and acceptable variation
State instrument, fixture, conditioning, environment, lighting, orientation, timing, units, number of repeats and acceptance limit for each characteristic. Distinguish bilateral tolerances, one-sided limits, boundary samples and descriptive criteria. Ensure the measurement process is suitable enough to distinguish real product variation from measurement noise.
04Sample the production structure
Select units across early, middle and late output plus relevant shifts, lines, cavities, stations, material lots and variants. Preserve lot identity. A convenience sample from one finished carton can miss cavity-specific, time-dependent or rework-related drift. Use an applicable sampling plan when making lot-acceptance decisions.
05Review individual results and distribution
Record each result and calculate summaries only when method and data support them. Look for range, clusters, trend, location by cavity or time and outliers as well as average. Compare with requirement and historical production, not only the approved sample's single value. One prototype cannot define process capability by itself.
06Separate reference, method and process causes
When a difference appears, verify sample condition, instrument status, setup, operator method, environment and data entry before altering production. Then investigate materials, tool wear, parameters, software, assembly, finish and packing. Record both occurrence and escape causes when nonconforming output passed earlier controls.
07Disposition and control the next version
Identify affected lots and choose hold, sorting, rework, concession or rejection through the agreed authority. Repeat measurements after correction and monitor later output. If the business wants a changed appearance or performance, use formal change control and approve a successor reference; never relabel drift as the new standard after production.