QETPP flashcards
QETPP · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- PDCA Cycle
- Plan-Do-Check-Act: a four-step iterative management method for continual improvement; Plan sets objectives, Do implements, Check measures, Act standardizes or corrects.
- DMAIC
- Define, Measure, Analyze, Improve, Control: a Six Sigma methodology for improving existing processes by reducing variation and defects.
- DMADV
- Define, Measure, Analyze, Design, Verify: a Six Sigma methodology for creating new processes or products to meet customer requirements.
- Cp
- Process capability index: (USL - LSL) / (6σ). Measures potential capability if the process were centered; higher values indicate less variation relative to specifications.
- Cpk
- Process capability index accounting for centering: min[(USL - μ)/(3σ), (μ - LSL)/(3σ)]. Values below 1.33 often indicate a capable process is not achieved.
- Pp and Ppk
- Process performance indices using overall standard deviation instead of within-subgroup sigma; used for initial studies and compared with Cp/Cpk to assess stability.
- X-bar and R chart
- A pair of control charts for variables data: X-bar monitors subgroup means, R monitors subgroup ranges; used to detect shifts in center and variation.
- p-chart
- A control chart for attributes data that monitors the proportion of defective units in subgroups; subgroup size may vary; control limits computed from p-bar.
- c-chart
- A control chart for attributes data that monitors the count of defects per unit when the opportunity area is constant; assumes Poisson distribution.
- Western Electric rules
- A set of decision rules for detecting out-of-control patterns on control charts, including points beyond 3 sigma, runs, and trends; supplement basic control limits.
- Process capability vs control
- Control charts assess stability over time; capability indices assess ability to meet specifications; a process must be in statistical control before capability is meaningful.
- FMEA
- Failure Mode and Effects Analysis: a systematic method to identify potential failure modes, assess severity, occurrence, and detection, and prioritize actions to reduce risk.
- RPN
- Risk Priority Number: Severity × Occurrence × Detection in FMEA; ranges from 1 to 1000; higher RPN indicates higher priority for corrective action.
- Severity in FMEA
- A rating 1-10 of the seriousness of the effect of a failure mode on the customer; 10 is hazardous without warning, 1 is no effect.
- Occurrence in FMEA
- A rating 1-10 of the likelihood that a specific failure mode will occur, based on historical data or design/process knowledge; 10 is very high.
- Detection in FMEA
- A rating 1-10 of the ability of current controls to detect a failure mode before it reaches the customer; 10 means no detection.
- GR&R
- Gauge Repeatability and Reproducibility: a measurement systems analysis study that quantifies variation from the gauge (repeatability) and from operators (reproducibility).
- %GR&R
- The ratio of GR&R variation to total variation, expressed as a percentage; under 10% is acceptable, 10-30% may be acceptable, over 30% requires improvement.
- Bias in measurement
- The difference between the average of measured values and the reference or true value; a systematic error that affects accuracy, not precision.
- Linearity
- The change in bias over the operating range of a measurement instrument; assessed by comparing bias at multiple reference values.
- Stability in MSA
- The variation in measurements over time when measuring the same master part; indicates whether the measurement system drifts.
- Accuracy vs precision
- Accuracy is closeness to the true value; precision is closeness of repeated measurements to each other; a system can be precise but biased.
- AQL
- Acceptable Quality Level: the maximum percent defective that, for purposes of sampling inspection, can be considered satisfactory as a process average.
- LTPD
- Lot Tolerance Percent Defective: the quality level that is unacceptable and has a low probability of acceptance, often 10% in sampling plans.
- OC curve
- Operating Characteristic curve: plots the probability of accepting a lot versus the lot fraction defective for a given sampling plan.
- Type I error
- Producer's risk: rejecting a good lot; probability denoted alpha; in hypothesis testing, rejecting a true null hypothesis.
- Type II error
- Consumer's risk: accepting a bad lot; probability denoted beta; in hypothesis testing, failing to reject a false null hypothesis.
- 8D methodology
- Eight Disciplines problem solving: team, problem description, containment, root cause, corrective action, implementation, prevention, and recognition.
- 5 Whys
- A root cause analysis technique that repeatedly asks 'Why?' to drill down from a symptom to an underlying cause, typically five times.
- Pareto analysis
- A prioritization tool based on the 80/20 rule: 80% of effects come from 20% of causes; uses a bar chart sorted by frequency.
- Fishbone diagram
- Cause-and-effect diagram (Ishikawa) that organizes potential causes into categories such as Man, Machine, Material, Method, Measurement, and Environment.
- Kaizen
- Continuous improvement philosophy from Japan; small, incremental changes made by everyone, often using PDCA, to reduce waste and improve quality.