Full definition
The operational activities and techniques used to verify that products, processes, and services meet defined specifications and requirements — the "check" in the Plan-Do-Check-Act quality cycle. QC encompasses: (1) Incoming inspection — verify raw materials and purchased components meet purchase specifications (hardness, tensile, dimensions, certificates). (2) In-process inspection — monitor manufacturing parameters (temperature, time, pressure, dimensions) during production using control charts and process capability indices (Cp/Cpk ≥ 1.33 = capable process). (3) Final inspection — verify finished product meets all customer requirements before shipment (dimensional, visual, functional, testing). (4) Acceptance sampling — inspect a statistical sample from each batch per AQL (Acceptable Quality Level) tables (ANSI/ASQ Z1.4). Key QC tools: control charts (X-bar/R, p-charts — detect process drift), measurement system analysis (Gage R&R — verify measurement reliability), histograms, Pareto charts, and root cause analysis for nonconformances. Per ISO 9001 Clause 8.6 (release of products and services), IATF 16949 (automotive — additional QC requirements), and ASTM testing standards for material verification. For rubber products: incoming QC typically includes hardness testing (every batch), tensile/elongation (periodic or per lot), and dimensional verification.