Quality control Flashcards
What is the definition of Quality Control (QC)?
A process that ensures that goods and services meet specific design specifications and customer expectations.
What is the objective of Quality Control?
To monitor, measure, and correct any deviations in quality.
List three importance factors of Quality Control.
- Improves customer satisfaction
- Reduces waste and costs
- Ensures regulatory compliance
What is the definition of Quality Management?
A systematic approach using policies, methods, and procedures to ensure quality.
What are the key areas Quality Management addresses?
- Product and service design
- Manufacturing and service delivery
- Customer satisfaction and expectations
Define Quality of Design.
Meeting intended specifications.
Define Quality of Conformance.
Ensuring products match design specifications.
What does Cost of Quality (CoQ) refer to?
Costs associated with achieving and maintaining quality or fixing poor quality.
What is the purpose of Cost of Quality (CoQ)?
Helps managers prioritize improvements and highlights cost savings from better quality control.
List the categories of Quality Costs.
- Prevention Costs
- Appraisal Costs
- Internal Failure Costs
- External Failure Costs
What are Prevention Costs?
Expenses to avoid defects before production.
Provide examples of Prevention Costs.
- Training employees
- Process control
- Quality audits
What are Appraisal Costs?
Costs to measure and monitor quality.
Provide examples of Appraisal Costs.
- Inspection/testing
- Equipment calibration
What are Internal Failure Costs?
Costs from defects found before reaching customers.
Provide examples of Internal Failure Costs.
- Scrap and rework
- Production delays
What are External Failure Costs?
Costs from defects after delivery.
Provide examples of External Failure Costs.
- Product recalls
- Warranty claims
- Customer complaints
What is the Total Cost of Quality?
The sum of all quality costs.
What does investing in prevention reduce?
Failure costs.
What is the process of Quality Control?
- Setting quality goals
- Measuring actual performance
- Comparing with set goals
- Correcting deviations
What does the 1:10:100 Rule illustrate?
Fixing an error at different stages: $1 in design phase, $10 during production, $100 after delivery.
What is Supplier Certification?
Ensures raw materials meet standards.
Define In-Process Control.
Detects defects during production.
What is Finished-Goods Control?
Final inspection before shipment.
What is Statistical Quality Control (SQC)?
Uses sampling to check quality instead of inspecting every unit.
List reasons for Sampling in SQC.
- Destructive Testing
- Time & Cost Efficiency
What is Acceptance Testing?
Evaluating a sample to decide if a whole batch meets quality standards.
What theorem is Acceptance Testing based on?
Central Limit Theorem (CLT).
What is the significance of a sample size greater than 30 in Acceptance Testing?
It follows a normal distribution.
What are common confidence levels used in quality estimation?
- 90% (Z = 1.64)
- 95% (Z = 1.96)
- 99% (Z = 2.58)
What is the purpose of Statistical Process Control (SPC)?
Monitors production quality over time.
Define Upper Control Limit (UCL).
Maximum acceptable variation.
Define Lower Control Limit (LCL).
Minimum acceptable variation.
What are Control Charts?
Graphs showing quality performance over time.
List types of Control Charts.
- X̄ Charts
- P-Charts
What indicates a shift in process according to SPC?
- 8 points above/below the centerline
- 10 of 11 points in the same direction
- 12 of 14 points trending up or down
- 4 out of 5 points near control limits
What do random variations indicate in process control?
Normal behavior; non-random trends indicate a process needs adjustment.
What is a Run Test?
Detect patterns in data.
What does a Z-test determine in Randomness Testing?
If |Z| > critical Z-value, then the process is not random.
Define Reliability.
The probability that a system performs without failure over a given time.
List factors affecting Reliability.
- Component Reliability
- System Design
What defines a Series System?
All components must work for the system to function.
What is the formula for Reliability in a Series System?
R = R1 × R2 × R3 …
What defines a Parallel System?
System works if at least one component functions.
What is the formula for Reliability in a Parallel System?
R = 1 - [(1 - R1) × (1 - R2)]
What are the implications for Quality Control in Series Systems?
Higher risk of failure; tighter quality controls needed.
What are the implications for Quality Control in Parallel Systems?
More reliable; can tolerate individual failures.
What is the overall purpose of Quality Control?
Ensures products meet customer expectations.
What does the Cost of Quality include?
- Prevention Costs
- Appraisal Costs
- Failure Costs
What is the role of Statistical Process Control (SPC) in quality detection?
Uses control charts to detect defects.
What does Acceptance Testing evaluate?
Samples to check quality.
What determines Reliability?
System design (series vs. parallel).
