Manufacturing Operations · Quality management · Component
The capability measure
Whether the process can hold the specification consistently — a question about the process rather than about today’s output.
The deliverable
What it is
Inspecting output tells you about today. Capability tells you whether tomorrow’s output will conform without being sorted.
A capable process produces conforming output by default; an incapable one produces it by inspection, which is a permanent cost.
One level in
What it is made of
Each element is a constituent part of the component. Follow one to see the attributes it carries.
The variation
How much the process output actually varies.
3 attributes: Spread · Sample size · Sampled across
LearnThe centring
Where the process output sits relative to the middle of the tolerance.
3 attributes: Process mean · Target · Offset
LearnThe stability
Whether the process behaves consistently over time.
3 attributes: Stable · Observed over · Instability source
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Establish stability before assessing capability. Capability calculated on an unstable process describes nothing.
The other components in quality management
The specification
What output must meet, in measurable terms, with tolerances derived from what the next step actually needs.
LearnThe root cause record
Why defects occurred and what was changed as a result — the step that turns a defect record into an improvement.
Learn