Certified Quality Inspector & Reliability Engineer Flashcards

When constructing an X-bar and R chart with a subgroup size of 5, which constant is used to calculate the upper control limit for the R chart?

Answer: D4

UCL_R = D4 × R-bar, where D4 is the control chart constant for the upper range limit at n=5 (D4 = 2.114).

Which document formally specifies the characteristics that a product must possess to be considered acceptable?

Answer: Product specification

A product specification defines all required characteristics, dimensions, materials, and performance requirements a product must meet.

The Weibull distribution is widely used in reliability engineering because it can model:

Answer: All three phases of the bathtub curve depending on the shape parameter β

The Weibull shape parameter β 1 models wear-out, making it extremely versatile.

In a hypothesis test, a quality engineer sets α = 0.05. This means:

Answer: There is a 5% probability of rejecting the null hypothesis when it is actually true

The significance level α is the probability of a Type I error — concluding a difference exists when the null hypothesis is actually true.

A quality inspector uses GO/NO-GO gauges primarily to:

Answer: Verify a part conforms to upper and lower specification limits

GO/NO-GO gauges quickly verify whether a feature falls within its tolerance limits without providing a variable measurement.

Mean Time To Repair (MTTR) is a key metric of which reliability-related concept?

Answer: Maintainability

Maintainability is measured by MTTR — the average time required to restore a failed system to operational status.

Which corrective action tool requires teams to identify all potential root causes of a problem using categories such as Machine, Method, Material, Man, Environment, and Measurement?

Answer: Cause-and-Effect (Ishikawa) Diagram

The Ishikawa (fishbone) diagram organizes potential causes into the 6M categories to systematically identify root causes.