Certified Quality Inspector & Reliability Engineer Flashcards

Which type of control chart is most appropriate for monitoring the number of defects per unit when the sample size varies?

Answer: u-chart

The u-chart monitors defects per unit and accommodates variable sample sizes, unlike the c-chart which requires constant sample sizes.

In reliability engineering, the 'bathtub curve' describes failure rate over time with three distinct phases. Which phase is characterized by a constant failure rate?

Answer: Useful life phase

The useful life phase exhibits a constant (random) failure rate, which is modeled by the exponential distribution.

A process has a Cp of 1.5 and a Cpk of 0.8. This indicates the process is:

Answer: Capable but not centered

Cp > 1.33 shows sufficient spread capability, but Cpk < 1.0 indicates the process mean is shifted toward a specification limit.

Which gauge R&R outcome indicates that measurement system variation is unacceptably large?

Answer: %GRR above 30%

Per AIAG guidelines, a %GRR above 30% indicates the measurement system is unacceptable and needs improvement.

In acceptance sampling, the Producer's Risk (α) is the probability of:

Answer: Rejecting a lot with quality at or better than the AQL

Producer's Risk (α) is the probability of rejecting a good lot whose quality meets or exceeds the Acceptable Quality Level.

A Pareto chart is used in quality inspection primarily to:

Answer: Identify and prioritize the most significant defect categories

Pareto charts apply the 80/20 principle to show which defect types account for the largest share of quality problems.

For a redundant system where two components each have reliability of 0.90 operate in parallel, what is the system reliability?

Answer: 0.99

Parallel system reliability = 1 − (1−0.90)(1−0.90) = 1 − 0.01 = 0.99.