1. 4s-1 McGraw-Hill/Irwin Operations Management, Seventh Edition, by William J. Stevenson Copyright © 2002 by The McGraw-Hill Companies, Inc. All rights reserved. Reliability Chapter 4 Supplement Reliability

2. 4s-2 McGraw-Hill/Irwin Operations Management, Seventh Edition, by William J. Stevenson Copyright © 2002 by The McGraw-Hill Companies, Inc. All rights reserved. Reliability Reliability : The ability of a product, part, or system to perform its intended function under a prescribed set of conditions Failure : Situation in which a product, part, or system does not perform as intended Normal operating conditions: The set of conditions under which an item’s reliability is specified

3. 4s-3 McGraw-Hill/Irwin Operations Management, Seventh Edition, by William J. Stevenson Copyright © 2002 by The McGraw-Hill Companies, Inc. All rights reserved. Reliability Probability that the product or system will: – Function when activated – Function for a given length of time Independent events Redundancy Reliability is a Probability

4. 4s-4 McGraw-Hill/Irwin Operations Management, Seventh Edition, by William J. Stevenson Copyright © 2002 by The McGraw-Hill Companies, Inc. All rights reserved. Reliability Example 1: Reliability Determine the reliability of the system shown.98.90.92.95

5. 4s-5 McGraw-Hill/Irwin Operations Management, Seventh Edition, by William J. Stevenson Copyright © 2002 by The McGraw-Hill Companies, Inc. All rights reserved. Reliability Example 1 Solution The system can be reduced to a series of three components.98.90+.90(1-.90).95+.92(1-.95).98 x.99 x.996 =.966

6. 4s-6 McGraw-Hill/Irwin Operations Management, Seventh Edition, by William J. Stevenson Copyright © 2002 by The McGraw-Hill Companies, Inc. All rights reserved. Reliability Failure Rate Few (random) failures Infant mortality Failures due to wear-out Time, T Figure 4S-1

7. 4s-7 McGraw-Hill/Irwin Operations Management, Seventh Edition, by William J. Stevenson Copyright © 2002 by The McGraw-Hill Companies, Inc. All rights reserved. Reliability Exponential Distribution Reliability = e -T/MTBF 1- e -T/MTBF TTime Figure 4S-2

8. 4s-8 McGraw-Hill/Irwin Operations Management, Seventh Edition, by William J. Stevenson Copyright © 2002 by The McGraw-Hill Companies, Inc. All rights reserved. Reliability Normal Distribution Reliability 0z Figure 4S-3

9. 4s-9 McGraw-Hill/Irwin Operations Management, Seventh Edition, by William J. Stevenson Copyright © 2002 by The McGraw-Hill Companies, Inc. All rights reserved. Reliability Availability The fraction of time a piece of equipment is expected to be available for operation MTBF = mean time between failures MTR = mean time to repair

10. 4s-10 McGraw-Hill/Irwin Operations Management, Seventh Edition, by William J. Stevenson Copyright © 2002 by The McGraw-Hill Companies, Inc. All rights reserved. Reliability Improving Reliability Component design Production/assembly techniques Testing Redundancy/backups Preventive maintenance procedures User education System design