Measurement Systems Analysis Flashcards

According to the AIAG MSA manual, a Gauge R&R result is generally considered acceptable when % Gauge R&R is:

Answer: Less than 30%, where under 10% is ideal and 10–30% may be acceptable based on application

The AIAG MSA manual classifies % Gauge R&R under 10% as acceptable, 10–30% as marginal (may be acceptable based on importance and cost), and over 30% as generally unacceptable.

The 'number of distinct categories' (ndc) in a Gauge R&R study indicates:

Answer: The number of non-overlapping categories the gauge can reliably distinguish within process variation

The ndc represents how many statistically distinct groups can be detected within the process variation; a value of 5 or more is required for the gauge to be considered adequate.

The %P/T ratio in measurement systems analysis compares:

Answer: Measurement system variation to the engineering specification tolerance

The %P/T (Precision-to-Tolerance) ratio expresses the gauge's measurement variation as a percentage of the specification tolerance, showing how much of the tolerance band is consumed by measurement error.

The standard design for a crossed Gauge R&R study per AIAG MSA guidelines typically includes:

Answer: 2 or 3 operators, 10 parts, and 2 or 3 measurement trials per part per operator

AIAG recommends 2–3 operators, 10 parts, and 2–3 trials, providing sufficient data to estimate both repeatability and reproducibility while remaining practical to conduct.

Compared to the Average and Range method, the ANOVA method in Gauge R&R analysis provides the additional ability to:

Answer: Detect and quantify the operator-by-part interaction effect

The ANOVA method partitions variance into repeatability, reproducibility, and the operator-by-part interaction term, providing richer information about how operator and part effects combine.

When parts are destroyed during the measurement process, the appropriate MSA study design is:

Answer: A nested (destructive) Gauge R&R study where parts are nested within operators

A nested (destructive) Gauge R&R is used when parts cannot be re-measured; different but similar parts are assigned to each operator so repeatability and reproducibility can still be estimated.

When % Gauge R&R falls in the marginal range of 10–30%, the key factor in deciding acceptability is:

Answer: The importance of the characteristic, cost of gauge improvement, and risk of measurement error

AIAG MSA guidance states that for marginal gauges, the decision depends on practical factors including the criticality of the characteristic, the cost of a better gauge, and the risk posed by measurement-driven errors.