Reliability Chapter 20 Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 2011 Pearson Higher Education, Upper Saddle River, NJ 07458 • All Rights Reserved Reliability • Reliability and Maintainability are key ingredients to preserving production efficiency Properly managed, they lead to lower total life cycle costs, helping organizations maintain a competitive edge Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 2011 Pearson Higher Education, Upper Saddle River, NJ 07458 • All Rights Reserved Reliability • Reliability is the probability that machinery/equipment/system can perform continuously, without failure, for a specified time interval when operating under stated conditions Increased reliability implies less failure and consequently less downtime and loss of production Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 2011 Pearson Higher Education, Upper Saddle River, NJ 07458 • All Rights Reserved Reliability • Maintainability is a characteristic of design, installation, and operation, usually expressed as the probability that a machine can be retained in, or restored to, specified operable condition within a specified interval of time when maintenance is performed in accordance with prescribe procedures Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 2011 Pearson Higher Education, Upper Saddle River, NJ 07458 • All Rights Reserved Reliability • Reliability engineering provides the theoretical and practical tools used to determine the capability of parts, components, equipment, subsystems and systems to perform their required functions without failure for specified periods in specified environments Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 2011 Pearson Higher Education, Upper Saddle River, NJ 07458 • All Rights Reserved Reliability • Life Cycle Curve Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 2011 Pearson Higher Education, Upper Saddle River, NJ 07458 • All Rights Reserved Reliability • Causes of Unreliability – – – – – – – – – Improper design Improper materials Manufacturing errors Assembly and inspection errors Improper testing Improper packaging and shipping Improper start-up User abuse misapplication Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 2011 Pearson Higher Education, Upper Saddle River, NJ 07458 • All Rights Reserved Reliability • Infant Mortality Failure Causes – – – – – – – – – – – – – Inadequate test specifications Inadequate quality control Inadequate manufacturing processes or tooling Inadequate materials Improper handling or packaging Marginal components Overstressed components Improper setup or installation Improper use procedures Power surges Inadequate marketing Inadequate training Incomplete final testing Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 2011 Pearson Higher Education, Upper Saddle River, NJ 07458 • All Rights Reserved Reliability • Random Failure Causes – Insufficient design margins – Misapplication: overstress – Use in wrong environment – Predictable failure levels – Intermittent failures – Inherent manufacturing failures Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 2011 Pearson Higher Education, Upper Saddle River, NJ 07458 • All Rights Reserved Reliability • Wearout Failure Causes – – – – – – – – – Scratching Material wear Aging Incipient stresses Limited-life components Inadequate or improper preventive maintenance Assembly interference fits Loose hardware Misalignments Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 2011 Pearson Higher Education, Upper Saddle River, NJ 07458 • All Rights Reserved Reliability • Reasons for Reliability Programs – Successful companies are able to control the reliability of their products – Increasing complexity of products requires higher component reliability – Consumers are becoming more reliability conscious Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 2011 Pearson Higher Education, Upper Saddle River, NJ 07458 • All Rights Reserved Reliability • Basic functions of a reliability program – – – – – Establish reliability in design Assure reliability by proper manufacturing Assure reliability through quality assurance Verify reliability by well designed test programs Maintain reliability by proper packaging and shipping methods – Assure reliability by proper field service and training – Improve reliability through feedback to design, engineer, purchase, manufacture, package, ship, sell, and service Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 2011 Pearson Higher Education, Upper Saddle River, NJ 07458 • All Rights Reserved Reliability • A well thought out reliability program will include the areas of design, testing, manufacture, raw material and component purchases, production, packaging, shipping, marketing, field service, and maintenance Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 2011 Pearson Higher Education, Upper Saddle River, NJ 07458 • All Rights Reserved Reliability • A sound reliability program will consider: – – – – – – – The entire system The humans in the system Maintenance of the system Simplicity of design Redundant and fail-safe designs Manufacturing methods and purchasing requirements Maintenance of complete product or system performance records – Communication Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 2011 Pearson Higher Education, Upper Saddle River, NJ 07458 • All Rights Reserved Reliability • Reliability testing: – Failure terminated tests – Time terminated tests Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 2011 Pearson Higher Education, Upper Saddle River, NJ 07458 • All Rights Reserved Reliability • Measures of Reliability: time dependent – Failure Rate λestimated = number of failures observed sum of test times or cycles – Mean Life θestimated = – Availability λ θestimated Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers sum of test times or cycles = number of failures observed © 2011 Pearson Higher Education, Upper Saddle River, NJ 07458 • All Rights Reserved Reliability • Calculating System Reliability – Reliability in Series Element – Element Element Rs = R1 x R2 X R3 Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 2011 Pearson Higher Education, Upper Saddle River, NJ 07458 • All Rights Reserved Reliability • Calculating System Reliability – Reliability in Parallel – Rp = – (1 – R1)(1 – R2) Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 2011 Pearson Higher Education, Upper Saddle River, NJ 07458 • All Rights Reserved Reliability • Calculating System Reliability – Reliability of Redundant or Back-up components Element Element backup – Rb = R1 + Rb(1 – R1) Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 2011 Pearson Higher Education, Upper Saddle River, NJ 07458 • All Rights Reserved  ... reliability implies less failure and consequently less downtime and loss of production Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 201 1 Pearson Higher Education,... and inspection errors Improper testing Improper packaging and shipping Improper start-up User abuse misapplication Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 201 1... material and component purchases, production, packaging, shipping, marketing, field service, and maintenance Lean Six Sigma: Process Improvement Tools and Techniques Donna C Summers © 201 1 Pearson