Download Chapter 22

Chapter 22
Miscellaneous Issues
Learning From Failure
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Technicians in an ambulance taking a heart attack
victim to a hospital lost use of their heart machine
every time they attempted to use their radio
transmitter. (Unshielded RF interference) The
patient died.
Thalidomide was sold in Europe in the late 1950s,
causing over 8,000 births of malformed children.
The drug had not been tested adequately prior to
market release.
Design for Failure
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Should consider and plan for failure
For safety and convenience
Safety Considerations
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Sprinkler Systems – the increase in
temperature due to a fire causes melting of
a metal plug and the opening of a sprinkler
or gas quenching system to put out the fire
In the event of a power failure, a lead shield
drops in front of a cobalt therapy delivery
unit
Design for Convenience
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Postage Stamps – sheets of postage stamps
typically contain individual stamps separated by
perforations. A slightly skilled user can easily
separate out an individual stamp by causing
failure along the perforations.
Scoring of a surface to enhance breakage is a
common way to ensure easily opened bags of
coffee and pop-top cans of various designs
Product Life Issues
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Necessary to determine how a product is
performing during actual use
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Analysis of field service reports
Failure analysis of failed units
Warranty analysis
Analysis of Field Service Reports
(FSR)
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Type of Product
Serial #
Date of Service Activity
Symptom of the problem
Diagnosis
List of parts replaced
Labor hours required
Service representative
Data Analysis
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Determine most significant problem
information & trend causes
Pareto Analysis – a histogram of problems
Graphical Plots
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Determine what pt in life cycle
Determine efficiency of manufacturing process
Useful for analyzing warranty costs
Failure Analysis of Field Units
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Focus on cause of problem based on
symptom
Fault- tree analysis
Warranty Analysis
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Warranty cost as a % of sales
Warranty cost per unit
Installation cost per unit
% of shipped units experiencing problems
Product Testing Issues
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HALT Testing – may indicate problems
early in testing that would take some time
to occur in the field.
More severe parameters
Misuse of product (type & severity testing)