Lean six sigma process improvement tools and techniques by donna summers chapter 20

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
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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
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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
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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

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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:
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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

1

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 1

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Element 2

Element 3

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 – (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 1
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.