Chapter 3

1. Chapter 3 Designing Quality into Products and Services Dr. Ayham Jaaron

2. Objectives • use the Management Tools to organize and communicate information. • discuss Quality Function Deployment (QFD) and its role in product and service design. • discuss Design for Six Sigma (DSS). • discuss Taguchi robustness concepts. • calculate reliability for a system. • discuss ways in which system reliability can be improved. • use the risk assessment tools of Fault Tree Analysis (FTA) and Failure Mode and Effects Analysis (FMEA).

3. Designing Quality into Products and Services • Must be designed to satisfy and delight the customer • Design begins with input from the customer • Two approaches: • Seven management tools • Quality function deployment • Reliability

4. The Seven Management Tools • Affinity Diagram • Tree Diagram • Process Decision Program Chart (PDPC) • Matrix Diagram • Interrelationship Digraph • Prioritization Matrix • Activity Network Diagram

5. Affinity Diagram • Similar to a cause and effect diagram • Organizes ideas and facts into categories • Ideas with affinities for each other are placed in the same category

6. Affinity Diagram Affinity Diagrams help to organize ideas and facts which have an affinity for each other into categories. In this example, Lower Price and No Delivery Charge have an affinity and are placed into the Cost category.

7. Tree Diagram Tree Diagrams facilitate planning actions shown on the affinity diagram.

8. Process Decision Program Chart (PDPC) • A framework for developing contingency plans • Starts with a tree diagram • Negative outcomes are considered for each branch • Contingency plans are listed

9. Process Decision Program Chart

10. Matrix Diagram • Graphically depicts relationships between concepts • Shows relationship between desired objectives and possible actions • Strength of relationship is indicated by shading

11. Matrix Diagram

12. Interrelationship Digraph • Depicts causal relationships among the categories in the affinity diagram • Arrows indicate which factors are drivers of other categories

13. Interrelationship Digraph

14. Prioritization Matrix • Allows the comparison of quantitative and qualitative data in the same analysis • Dimensions are the categories for the affinity diagram • Dimension must be assigned a weight • Each company is rated for the dimension on a scale of 1-10 with 10 being best

15. Prioritization Matrix

16. Activity Network Diagram • Also known as PERT and CPM • Program Evaluation & Review Technique (PERT) • Critical Path Method (CPM) • A project planning and control tool

17. Activity Network Diagram

18. Quality Function Deployment (QFD) • Developed in Japan by Professor Yoji Akao • Quality is defined by the customer • Customer’s definition of quality is considered in the product/service design process and production process

19. Quality Function Deployment (QFD) • West Wing-customer requirements • Second Floor-translates customer requirements into design requirements • Main Floor- correlation of design requirements with customer requirements • Attic-interrelationship of the design requirements (what are the tradeoffs)

20. Quality Function Deployment (QFD) • Basement-contains target values or specifications for the design requirements • East Wing-comparison of the product or service under design with leading competitors

21. Applying QFD House of QualityExample….climbing suit

25. QFD Example In the following example, the customer requirement of value is operationalized for a pizza in terms of meat, cheese, vegetables, and price. As the quantities of meat and cheese increase, customer value strongly increases. As the quantity of vegetables increases, customer value increases. As price increases, customer value decreases.

26. The House of Quality

27. QFD-Four-phased Approach • Uses a series of stages to translate customer requirements into: • Parts characteristics • Key process operations • Production equipment settings

28. QFD-Four-phased Approach Figure 3.9. Four-Phase QFD Model

29. Design for Six Sigma (DFSS) • Developed at General Electric in 1997 • An extension of the standard Six Sigma Methodology • Proactive • SIX SIGMA goal is 3.4 defects per million opportunity (DPMO) • No standard approach • 5-interconnected phases • Define, measure, analyze, design, & verify

30. Taguchi Robustness Concept • Advocated designing robustness into products and systems • Robustness: the condition of product/process design that remains relatively stable • Three steps • System design • Parameter design • Tolerance design • Results in more reliable products than can be produced economically.

31. Reliability • Key part of design process • Definition: The probability the product or service will perform without failure for a specified period of time. • 3 dimensions of reliability • Probability • Will perform on a given trial (successful trials) • Will last for a given length of time • Definition of failure • Prescribed operating conditions

32. Reliability Life Characteristic Concepts • Failure rate is the number of failures per unit of time • Graphically depicted failure is usually the bathtub curve • Early stage failure • Occurs early in the product/services life • These are usually the result of design, manufacturing or use error.

33. Reliability Life Characteristic Concepts • Expected Normal Life • A pattern of constant and relatively low failure rates • Usually result of design limitations, changes in the environment and damage from day-to-day use or maintenance • End-of-Life Failure • Product exceeds the intended life expectancy • Usually results from daily wear and stress

34. Bathtub curve

35. Mean Time Between Failures • The average time between failures • Can be modeled by a negative exponential distribution • Exponential distribution can determine: • Probability of failure before a certain time • Probability of a product lasting at least until a certain time

36. Mean Time Between Failures • To determine the probability that failure will not occur before a certain time: P(no failure before T) = e -T/MTBF Where: e = natural logarithm, 2.7183….   T = time in service before failure   MTBF = mean time between failures  

37. Risk Assessment Tools and Risk Prevention • Failure Mode and Effects Analysis • Used to examine a product at the system or subsystem levels • Can be expanded to include: • Safety • Effect on downtime • Access • Repair planning • Design changes

38. FMEA Worksheet

39. Risk Assessment Tools and Risk Prevention • Faulty Tree Analysis • A tool used to identify possible causes for potential operating hazards or undesired events. Can you suggest some examples?

40. Error Proofing • Japanese call it poka-yoke • Can be incorporated into services (e.g. failure to proceed in filling partial applications).

41. Class work (7 minutes) • In groups of 5 students, can you think of other three poke-yoke measures that can be used in products/services? • Share these with your colleagues.

42. Examples: • File cabinets. • Electric sockets • Cars electronic door lock; won’t operate if door is open. • Anti-Braking System. • Lawn mowers. • Washing machine won’t work if door is open to prevent injury.

43. Summary • Quality has to be incorporated into the design • First step is to focus on the customer • Seven Management Tools and Quality Deployment Function are tools to help incorporate customer input into the design process

44. Summary • Design for Six Sigma builds on traditional Six Sigma methodology • Robustness and reliability are related concepts • Reliability can be improved by: • Increasing reliability of individual components • Building redundancy into the system

45. Summary • Tools can address potential failure modes for products and services • Failure Mode and Effects Analysis • Faulty Tree Analysis