Transcript PowerPoint Presentations 19

19.1
Chapter 19
Risk management
Pearson Education Ltd. Naki Kouyioumtzis
19.1
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.2
Risk management
Operations
strategy
Design
Operations
management Improvement
Planning
and control
19.2
Operations
improvement
makes processes
better
Organizing for
improvement
Risk
management
stops processes
becoming worse
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.3
Key operations questions
In Chapter 19 – Risk management – Slack et al. identify
the following key questions:
• What is risk management?
• How can operations assess the potential causes of, and
risks from failure?
• How can failures be prevented?
• How can operations mitigate the effects of failure?
• How can operations recover from the effects of failure?
19.3
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.4
Why systems fail
Failures inside the
operation
Design failures
Supply failures
Facilities failures
Customer
failures
Staff failures
19.4
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.5
How failure is measured
Normal-life
stage
Wear-out
stage
Failure rate
Infant-mortality
stage
Time
19.5
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.6
How failure is measured (Continued)
Bath-tub curves for two parts of an operation. Curve A
represents a part with relatively predictable failure and curve
B represents a part with a more random failure pattern.
Normal-life
stage
Failure rate
Infant-mortality
stage
Wear-out
stage
Curve A
Curve B
X
19.6
Time
y
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.7
How failure is measured (Continued)
Service operations, after an early stage of failure
detection and improvement, may suffer from steadily
rising failure rates caused by increasing complacency.
Complacency
Failure rate
Early failure
detection and
improvement
Time
19.7
Chapter 19.
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.8
The three tasks of failure prevention and recovery
Failure detection
and analysis
Finding out what is going
wrong and why
Improving
system reliability
Stopping things going
wrong
19.8
Recovery
Coping when things do
go wrong
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.9
How failure is detected and analyzed
Failure detection
Failure detection mechanisms include:
– in-process checks;
– machine-diagnostic checks;
– point-of-departure interviews.
Failure analysis
Failure analysis procedures include:
– accident investigation;
– failure mode and effect analysis;
– fault-tree analysis.
19.9
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.10
Failure Management
Mitigation
Prevention
Normal
operation
19.10
Failure
Recovery
Severity of
consequence
Effect on
customer
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.11
Poka-Yoke (fail-safing)
File cabinets can fall over if too many drawers are
pulled out. For some file cabinets, opening one drawer
locks all the rest, reducing the chance of the file
cabinet tipping. It is a control method.
The window in the envelope is not only a labour
saving device. It also prevents the contents of an
envelope intended for one person being inserted in an
envelope addressed to another. It is a control method.
19.11
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.12
Controlled flight into terrain
What has to go wrong?
Flying at wrong altitude p = 0.001
Co-pilot fails to cross check p = 0.01
Air traffic control fail to notice p = 0.1
Pilots ignore warning alarm p = 0.5
Cumulative probability of occurrence = one in two million.
19.12
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.13
Failure modes effects analysis
Normal
operation
Probability of
failure
Failure
Severity of
consequence
Degree of
severity
Effect on
customer
Likelihood
of detection
Risk priority number
19.13
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.14
Fault-tree analysis
Food served to
customer is below
temperature
Food
is cold
Plate
is cold
Plate warmer
malfunction
Plate taken too
early from
warmer
Cold plate
used
19.14
Risk – below-temperature
food being served to
customers
Oven
malfunction
Key
AND node
Timing error
by chef
OR node
Ingredients
not defrosted
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.15
Fault-tree analysis (Continued)
Filter not replaced
when required
Automatic
cut-out fails
Signal
malfunction
Cut-out
disconnected
Risk – filter not replaced
when required
Inspection fails to
detect blocked filter
Inspection not
carried out
Key
AND node
Inspection
sequence violated
OR node
Disconnect
function failure
19.15
Particle
meter faulty
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.16
Maintenance modes
A mixture of maintenance approaches is often used – in an
automobile, for example.
Engine – Use
preventive
maintenance
Lights – Use
run-tobreakdown
maintenance
Tyres – Use
condition-based
monitoring
maintenance
19.16
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.17
Failure curve for two machines, A and B
Probability of failure
Machine A
Machine B
Machine A – breakdown
relatively predictable, so can
judge when to time preventive
maintenance.
19.17
Time
Machine B – breakdown
relatively unpredictable, so is
less easy to judge when to
time preventive maintenance.
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.18
Maintenance costs
One model of the costs associated with preventive
maintenance shows an optimum level of maintenance effort.
Costs
Total cost
Cost of
breakdowns
Cost of providing
preventive
maintenance
‘Optimum’ level of
preventive maintenance
Amount of preventive maintenance
19.18
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.19
Maintenance costs (Continued)
If preventive maintenance tasks are carried out by operators and if
the real cost of breakdowns is considered, the ‘optimum’ level of
preventive maintenance shifts towards a higher level.
Costs
Total cost
Cost of breakdowns
Cost of providing preventive
maintenance
Amount of preventive maintenance
19.19
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.20
Reliability centred maintenance
One part in one process can have several different failure
modes, each of which requires a different approach.
Failures
Shredding
process
Cutters
19.20
Cutter ‘wear out’
failure pattern
Time
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.21
Reliability centred maintenance (Continued)
One part in one process can have several different failure
modes, each of which requires a different approach.
Cutters
Failures
Shredding
process
Cutter ‘damage’
failure pattern
Time
19.21
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.22
Reliability centred maintenance (Continued)
One part in one process can have several different failure
modes, each of which requires a different approach.
Shredding
process
Failures
Cutters
Cutter ‘shake
loose’ failure
pattern
Time
19.22
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010
19.23
The stages in failure planning
Discover
• What’s
happened
• What
consequences
19.23
Act
• Inform
• Contain
• Follow up
Learn
Plan
• Find root
cause
• Analyze
failure
• Engineer
out
• Plan
recovery
Slack, Chambers and Johnston, Operations Management, 6th Edition,
© Nigel Slack, Stuart Chambers, and Robert Johnston 2010