Quality Control & Reliability Engineering Flashcards

What does MTBF stand for in reliability engineering?

Answer: Mean Time Between Failures

MTBF (Mean Time Between Failures) is the average time elapsed between a failure and the next failure of a repairable system.

Which statistical distribution is most commonly used to model failure rates in reliability engineering over a product's useful life?

Answer: Exponential distribution

The exponential distribution is used during the useful life (constant failure rate) phase of a product's life, characterized by a constant hazard rate λ.

What is the primary purpose of a Pareto chart in quality control?

Answer: To identify the most significant causes of defects using the 80/20 rule

A Pareto chart prioritizes the most significant factors contributing to defects, based on the principle that 80% of problems come from 20% of causes.

In Six Sigma, what does the acronym DMAIC stand for?

Answer: Define, Measure, Analyze, Improve, Control

DMAIC is the structured Six Sigma problem-solving methodology: Define the problem, Measure current performance, Analyze root causes, Improve the process, and Control future performance.

In statistical process control (SPC), what condition indicates a process is 'out of control'?

Answer: A data point falls outside the upper or lower control limits

A process is considered out of control when a data point falls outside the upper control limit (UCL) or lower control limit (LCL), indicating a special cause of variation.

Overall Equipment Effectiveness (OEE) is calculated as the product of which three factors?

Answer: Availability, Performance, and Quality

OEE = Availability × Performance × Quality, providing a composite measure of how effectively manufacturing equipment is utilized.

What is the availability (A) of a system with an MTBF of 200 hours and an MTTR of 8 hours?

Answer: 0.96

Availability = MTBF / (MTBF + MTTR) = 200 / (200 + 8) = 200 / 208 ≈ 0.9615, which rounds to 0.96.