Reliability Management Benbow and Broome (Ch 1, 2, and 3)

1. Reliability ManagementBenbow and Broome (Ch 1, 2, and 3) Presented by Dr. Joan Burtner Certified Quality Engineer Associate Professor of Industrial Engineering and Industrial Management

2. Overview • Chapter 1 Strategic Management • Definition of reliability • Interrelationship of quality and reliability • Role of reliability in the organization • Chapter 2 Reliability Program Management • Terminology • Elements of a reliability program • Product life cycle and costs • Chapter 3 Product Safety and Reliability • Roles and responsibilities • Ethical issues • Elements of a system safety program Dr. Joan Burtner, Associate Professor of Industrial Engineering

3. Reliability Definition • Reliability is defined as the probability that an item will perform a required function without failure under stated conditions for a specified period of time. • Reliability statement components • Probability (at least ___ %) • Required function (by part, subassembly and assembled product) • Stated conditions (may be mandated by industry/government regulations such as Underwriters Laboratory or Energy Star Program) • Specified period of time (duration in terms of hours, miles, cycles, etc) Dr. Joan Burtner, Associate Professor of Industrial Engineering

4. Quality vs. Reliability • Strongly interrelated • Continuous improvement • Meet or exceed customer requirements • Important role in the design phase • Distinctions noted in the text • Design process inputs • Quality – within tolerance at a reasonable cost • Reliability – functional for a longer period of time • Data collection • Quality – focus on manufacturing process • Reliability – focus on manufactured product • In the workplace, functions often overlap. Dr. Joan Burtner, Associate Professor of Industrial Engineering

5. Role of Reliability in the Organization • Traditionally, the focus of reliability engineering is on product reliability, not human reliability. • What is the useful lifetime of the product? • What is the failure rate of in-house components and products? • What is the failure rate of suppliers’ components? • Reliability techniques are also useful in other areas • Marketing and advertising (especially warranties) • Product liability (mitigate safety and health hazards) • Manufacturing processes (Do processes impact product failure rates? How can preventive maintenance and spare parts inventories improve reliability? Etc) Dr. Joan Burtner, Associate Professor of Industrial Engineering

6. Related I.A. Body of Knowledge Topics • Reliability in product and process development is increasingly being implemented in the spirit of concurrent engineering • Reliability engineers need to examine the consequences of failure, as opposed to a narrow focus on estimates of the probability of failure • Reliability engineers need to take the long-term view and find cost-effective ways to reduce lifecycle costs. • Listening to the Voice of the Customer applies to internal and external customers (beta testing, QFD). • Reliability professionals must have a working understanding of project management tools. Dr. Joan Burtner, Associate Professor of Industrial Engineering

7. Reliability Terminology 1 • Mean life definitions • Average time to failure of identical products operating under identical conditions • Expected time to failure • Mean time to failure (MTTF) • Applies to non-repairable products • Assumes the underlying failure distribution is exponential and the failure rate is constant • Mean time between failures (MTBF) • Applies to repairable products • Assumes the underlying failure distribution is exponential and the failure rate is constant Dr. Joan Burtner, Associate Professor of Industrial Engineering

8. Reliability Terminology 2 • Censored data • Exact failure times (See Example 2.1) • Right-censored data (only known might have failure happened after a certain time) because item is still functioning when test is concluded) • Left-censored data (only known failure happened before a certain time because items were not checked at the beginning of the test period) • Interval-censored data (only known failure happened between two times) • Minitab users see caution on page 19 • Mean time to repair (MTTR) is the average time it takes to return the product to operational status • Failure rate (lambda) is the mathematical reciprocal of mean life: 1/MTBF or 1/MTTF Dr. Joan Burtner, Associate Professor of Industrial Engineering

9. Reliability Terminology 3 • Maintainability • Probability that a failed product will be repaired within a given amount of time once it has failed • May be expressed as a function such as M(3) = .95 • Interpretation: There is a 95% probability that the product will be operable with three units of time (hours, days, etc) • Maintenance definition should include a specific maintenance action such as rebuild time or per procurement time • Availability (equations on pp. 19-20) • Probability that a product is operable and in a committable state when needed • Probability that item has not failed or is not being repaired • Takes into account an item’s reliability and maintainability Dr. Joan Burtner, Associate Professor of Industrial Engineering

10. Six Elements of a Reliability Program • Established reliability goals and requirements • Minimum reliability requirements time dependent (reliability changes throughout life of product) • Product design • Reliability requirements documented for each stage • Process design • Reliability requirements linked to process parameters • Validation and verification • Validate that requirements produce desired product reliability • Verify that production can ‘deliver’ the valid requirements • Post-production evaluation • Production samples, customer feedback, field service/warranty records • Training and education Dr. Joan Burtner, Associate Professor of Industrial Engineering

11. Product Life-Cycle and Costs for Hardware • Three stages • Early failure (infant mortality or decreasing failure rate) • Useful life stage (constant failure rate stage, random causes stage) • Wear-out stage (fatigue stage, increasing failure rate stage) • See Bathtub Curve figure on page 23. • Note that random causes are generally present during all three stages. • Change the curve / improve the product • Shorten the length and flatten the slope of early failure • Decrease the constant failure rate • Delay the onset of the wear-out stage and reduce the slope Dr. Joan Burtner, Associate Professor of Industrial Engineering

12. Product Life-Cycle and Costs for Software • Two stages • Test phase • Useful lifetime • See typical reliability curve on page 24. • It is better to prevent errors than to detect faults. • Change the curve / improve the software code • Make it modular • Keep it simple • Document, document, document Dr. Joan Burtner, Associate Professor of Industrial Engineering

13. Design Evaluation • Important at various stages throughout the life-cycle • Failure prevention approaches for early stages • Fault tolerance – redundant systems • Fault avoidance – design for more than minimum reliability • Derating (“the practice of using components for lower stress levels than specified by the standards” p. 128) • Evaluation for later stages (See page 26) • Environmental stress screening • Reliability development/growth tests • Reliability qualification tests • Production reliability acceptance tests Dr. Joan Burtner, Associate Professor of Industrial Engineering

14. Three Elements of a System Safety Program • Identification of safety hazards • “The reliability engineer must be innovative and diligent in the discovery of all possible ways … present a safety hazard to personnel.” • Risk analysis • Use standard analysis techniques such as FMEA,FMECA, FTA,STA,FRACAS, and PRAT(production reliability acceptance test) • Use results to establish prioritized list to help resolve root causes • Correction and prevention • Implement change requests as necessary • Use mistake-proofing techniques • Physical barriers to errors such as shapes • Visual reminders for users • Use of automated equipment to mitigate a detected error • Standardizing operations for similar parts Dr. Joan Burtner, Associate Professor of Industrial Engineering

15. References • Course Text: • Benbow, D.W. and Broome, H.W., Ed. (2009). The Certified Reliability Engineer Handbook . Milwaukee,WI: ASQ Quality Press. • Additional Sources • Westcott, R.T., Ed. (2006). Certified Manager of Quality/Organizational Excellence Handbook (3rd ed.). Milwaukee: ASQ Quality Press. Dr. Joan Burtner, Associate Professor of Industrial Engineering

16. Contact Information • Email: Burtner_J@Mercer.edu • US Mail: Mercer University School of Engineering 1400 Coleman Avenue Macon, GA • Phone: (478) 301- 4127 Dr. Joan Burtner, Associate Professor of Industrial Engineering