CPM Quality Control and Process Optimization 3 — Questions and Answers
Question 1: A plant implements poka-yoke on an assembly line. What is the primary goal of this approach?
- Increase production speed by removing quality checks
- Prevent defects by making errors impossible or immediately detectable (Correct answer)
- Reduce operator training time
- Automate all inspection processes
Correct answer: Prevent defects by making errors impossible or immediately detectable
Poka-yoke (mistake-proofing) designs processes or fixtures so that errors either cannot occur or are detected immediately when they do.
Question 2: In process optimization, what is the difference between efficiency and effectiveness?
- They are interchangeable terms for the same concept
- Efficiency is doing things right; effectiveness is doing the right things (Correct answer)
- Effectiveness relates to speed; efficiency relates to quality
- Efficiency is a strategic measure; effectiveness is an operational measure
Correct answer: Efficiency is doing things right; effectiveness is doing the right things
Efficiency measures how well resources are used (output per input), while effectiveness measures whether the right outcomes are being achieved.
Question 3: Which of the following best describes a Type II error in acceptance sampling?
- Rejecting a good lot (producer's risk)
- Accepting a bad lot (consumer's risk) (Correct answer)
- Sampling more units than required by the plan
- Setting the AQL too low for the process capability
Correct answer: Accepting a bad lot (consumer's risk)
A Type II error in sampling occurs when a defective lot is accepted, representing the consumer's risk or beta risk.
Question 4: A plant manager wants to reduce changeover time using SMED. What does SMED stand for?
- Standard Manufacturing Equipment Design
- Single-Minute Exchange of Die (Correct answer)
- Systematic Methods for Equipment Downtime
- Six-Month Equipment Deployment
Correct answer: Single-Minute Exchange of Die
SMED (Single-Minute Exchange of Die) is a lean methodology targeting changeover times of less than 10 minutes to increase flexibility.
Question 5: What is the purpose of the control phase in a Six Sigma DMAIC project?
- To identify the problem and define project scope
- To sustain improvements and prevent regression to old performance levels (Correct answer)
- To collect baseline data on the current process
- To generate and test potential solutions
Correct answer: To sustain improvements and prevent regression to old performance levels
The Control phase implements monitoring systems, control plans, and standardized procedures to maintain gains achieved in the Improve phase.
Question 6: When applying Design of Experiments (DOE) in process optimization, what is a 'main effect'?
- The total cost impact of a process change
- The average change in output when a factor shifts from low to high level (Correct answer)
- The interaction between two or more variables
- The residual variation not explained by any factor
Correct answer: The average change in output when a factor shifts from low to high level
A main effect is the average response change attributable to changing a single factor from its low to its high level, independent of other factors.
Question 7: A process produces 45 defects per million opportunities. What sigma level does this approximately correspond to?
- Three sigma
- Four sigma
- Five sigma (Correct answer)
- Six sigma
Correct answer: Five sigma
Approximately 233 DPMO corresponds to 5 sigma; 45 DPMO is between 5 and 6 sigma, closest to 5 sigma in standard tables.
CPM Quality Control and Process Optimization 3
A plant implements poka-yoke on an assembly line.
What is the primary goal of this approach?