Gauge R&R Type 1 Study.
Quick measurement system analysis (MSA) — measure one master part 25–50 times with one operator and one gauge. Computes Cg and Cgk capability indices to determine if the gauge is fit for the tolerance.
Known true value of the calibration master
Specification limits of the part being measured
25–50 readings recommended (AIAG MSA)
Cg — REPEATABILITY
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Cgk — REPEATABILITY + BIAS
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n (samples)
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Mean (x̄)
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Std dev (s)
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Bias (x̄ − ref)
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Tolerance
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%EV (study var.)
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Cg = 0.2 × Tolerance / (6 × s)
Cgk = (0.1 × Tolerance − |Bias|) / (3 × s)
%EV = 6s / Tolerance × 100
Pass criteria: Cg ≥ 1.33 and Cgk ≥ 1.33
Cgk = (0.1 × Tolerance − |Bias|) / (3 × s)
%EV = 6s / Tolerance × 100
Pass criteria: Cg ≥ 1.33 and Cgk ≥ 1.33
Acceptance criteria
| Cg / Cgk | Verdict | Action |
|---|---|---|
| ≥ 1.67 | Excellent | Use as is — gauge well within capability |
| 1.33 – 1.67 | Capable | Acceptable per AIAG MSA — use for production |
| 1.00 – 1.33 | Marginal | Acceptable for non-critical features only — investigate |
| < 1.00 | Not capable | Replace gauge or tighten the measurement procedure |