CPM Quality Control and Process Optimization 2 — Questions and Answers
Question 1: A plant manager notices a process has a Cpk of 0.85. What does this indicate?
- The process is highly capable and centered
- The process is not capable and may produce defects (Correct answer)
- The process is exactly at the specification limit
- The process has zero variation
Correct answer: The process is not capable and may produce defects
A Cpk below 1.0 indicates the process is not capable of consistently producing parts within specification limits.
Question 2: Which DMAIC phase involves identifying root causes of defects using tools like fishbone diagrams?
- Define
- Measure
- Analyze (Correct answer)
- Improve
Correct answer: Analyze
The Analyze phase uses tools like fishbone (Ishikawa) diagrams, 5 Whys, and regression analysis to identify root causes.
Question 3: What is the primary purpose of a Gauge R&R study?
- To determine production throughput rates
- To evaluate measurement system variation (Correct answer)
- To calculate process capability indices
- To identify supplier quality issues
Correct answer: To evaluate measurement system variation
Gauge R&R (Repeatability and Reproducibility) quantifies the variation in a measurement system due to the gauge and the operators.
Question 4: In a Pareto analysis of defect types, 80% of defects come from 3 out of 15 defect categories. What should the plant manager do first?
- Address all 15 defect categories simultaneously
- Focus improvement resources on the 3 dominant defect categories (Correct answer)
- Eliminate the 12 minor defect categories from tracking
- Replace all equipment causing any defects
Correct answer: Focus improvement resources on the 3 dominant defect categories
Pareto analysis applies the 80/20 rule, directing resources toward the vital few causes that produce most of the problems.
Question 5: A control chart shows 8 consecutive points on one side of the center line. This is an example of:
- Common cause variation
- A special cause signal requiring investigation (Correct answer)
- Normal random variation
- An acceptable process trend
Correct answer: A special cause signal requiring investigation
Eight consecutive points on one side of the centerline is a recognized Western Electric rule signaling a special cause that needs investigation.
Question 6: Which quality cost category includes scrap, rework, and warranty returns?
- Prevention costs
- Appraisal costs
- Internal failure costs and external failure costs (Correct answer)
- Conformance costs
Correct answer: Internal failure costs and external failure costs
Scrap and rework are internal failure costs, while warranty returns are external failure costs — both are failure cost categories.
Question 7: What does OEE (Overall Equipment Effectiveness) measure?
- Total machine purchase and maintenance cost
- The combined impact of availability, performance, and quality on productive output (Correct answer)
- Energy consumption per unit produced
- Number of operators required per machine
Correct answer: The combined impact of availability, performance, and quality on productive output
OEE = Availability × Performance × Quality, providing a single metric for how effectively manufacturing equipment is utilized.
CPM Quality Control and Process Optimization 2
A plant manager notices a process has a Cpk of 0.85.
What does this indicate?