Maintenance and Reliability
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The objective is
maintain the capability of the system
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Strategic Importance of Maintenance and Reliability
Reduced value of investment in plant and equipment
Profits becoming losses
idle employees
Dissatisfied customers
Profitability
Reputation
Operation
Failure has far reaching effects on:
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Maintenance and Reliability
Maintenance is
all activities involved in keeping a system’s
equipment in working order
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Maintenance and Reliability
Reliability is
the probability
that a machine will function properly for a specified time
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Important Tactics
Reliability
Improving individual components
Providing redundancy
Maintenance
Implementing or improving preventive maintenance
Increasing repair capability or speed
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Designing for reliability is an excellent place
to start reducing variability.
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Systems are composed of a series of individual interrelated components, each performing a
specific job.
If any one component fails to perform, for whatever reason,
the overall system (e.g., an airplane or machine) can fail
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Because failures do occur in the real world,
Understanding their occurrence is an important reliability concept.
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As the number of components in
a series increases,
The reliability of the whole system
declines very quickly
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Reliability
and so on
R2 = reliability of component 2
where R1 = reliability of component 1
Improving individual components
Rs = R1 x R2 x R3 x … x Rn
a system in which each individual part or component may have its own unique rate of reliability
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Example 1 Reliability in a Series
The Bank of Montreal’s loan-processing centre processes loan applications through
three clerks set up in series, with reliabilities of
0.90, 0.80, and 0.99.
The bank wants to find the system reliability.
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Reliability Example
Reliability of the process is
Rs = R1 x R2 x R3 = .90 x .80 x .99 = .713 or 71.3%
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A machine of n=50 interacting parts,
each of which has a 99.5% reliability,
overall reliability is 78%.
A machine has 100 interacting parts,
each with an individual reliability of 99.5%,
the overall reliability will be only about 60%!
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Product Failure Rate (FR)
Basic unit of measure for reliability
FR(%) = Number of failures
Number of units tested × 100%
FR(𝑁) = Number of failures
Number of unit−hours of operating time
Percent of failures
Number of failures during a period of time
Mean Time Between Failure MTBF
MTBF FR
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Failure Rate Example
20 air conditioning units designed for use in NASA space shuttles operated for 1000 hours
One failed after 200 hours and
one after 600 hours
Find:
Failure rate and MTBF
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Failure Rate Example
FR
FR(%)=Number of failures/Number of units tested %
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Failure Rate Example (1 of 2)
FR(𝑁) = 2
20 000 − 1200 = .000106 failure/unithr
MTBF = 1
.000106 = 9434hrs
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Failure Rate Example (1 of 2) Number of failures per operating hour:
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Failure Rate Example (1 of 2)
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Failure Rate Example
If the typical space shuttle trip lasts six days, NASA may be interested in the failure rate per trip:
• =(Failures/unit-hr)(24 hr/day)(6 days/trip) • =(0.000106)(24)(6) • =0.0153 failure/trip
Failure rate
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The technique here is to “back up” components with additional components.
This is known as putting units in parallel and is a standard operations management tactic.
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Providing Redundancy
Provide backup components to increase reliability
(Probability that first component works)
+
[(Probability that backup works) × (Probability that first component fails)
The resulting reliability
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Providing Redundancy
Provide backup components to increase reliability
𝑷𝒓𝒐𝒃𝒂𝒃𝒊𝒍𝒊𝒕𝒚
of first component
working
+
Probability of second
component working
×
Probability of needing
second component
If first component 80% and backup component 80%
The resulting reliability?
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Maintenance
Preventive maintenance – • routine inspection and
servicing to keep facilities in good repair
Breakdown maintenance – • emergency repairs on
failed equipment
Two types of maintenance
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Implementing Preventive Maintenance
Need to know when a system requires service or is likely to fail
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Implementing Preventive Maintenance
High initial failure rates….
infant mortality
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Implementing Preventive Maintenance
Once a product settles in,
MTBF (mean time between failures) generally follows a normal distribution
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Maintenance Costs
The traditional view attempted
to balance
preventive and breakdown
maintenance costs
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Maintenance Costs
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Maintenance Costs
Typically the previous approach fails to consider the true total cost of breakdowns
• Inventory • Employee morale • Schedule unreliability
Sample Solution
d found myself to be forceful which could’ve lead to staff conflict. I decided to complete the negotiation skills diagnostic again to explore different strategies and reflected on my previous supervisor role, as management skills are transferable in different environments.
4.2 Identify further improvements to professional skills and competencies:
My meeting was a success as my presentation was very clear and I was prepared with a compromising approach. This experience has highlighted areas I need to develop such as; Negotiating: Adapt to different techniques; soft and compromising not hard and forceful.
I obtain excellent communication skills however, when not prepared this was the opposite, therefore planning and preparing is very important to ensure a better delivery of objectives.
There was conflict with a member of staff, she thought all my workload would fall on her, I held a 1-2-1 meeting with her in my managers presence and cleared any misunderstanding in a calm rational way addressing her concerns, showed her how I have delegated my workload to the whole team, I changed my learning style to hers and noticed the positive difference in her reaction. My meeting was successfully lead and managed as the team understood my goal and how I intended to get there with their help. I now lead weekly staff meetings to be more involved in leadership and management activities and improve my negotiating and communication skills.
4.3 Review learning about SBM & relate to school setting:
As an aspiring SBM, this is the beginning of deepening my knowledge on behind the scenes of school business management, highlighting the importance of having an SBM in my school and areas where there is much scope for improvement such as; value for money (resources and services can be challenged regularly) identify areas where the school can save money. I have added on my PDP (Appendix 1) to conduct a monthly stock-take of stationery supplies eliminating surplus and unnecessary supplies, saving money for other resources promoting the schools vision.
I understand the importance of keeping up to date with policy changes and the necessity to adopt and adapt different learning techniques, also the positive impact of having an SBM on the Headteachers workload. Learning different analytical tools has made me notice areas of school improvement; what needs to be improved and how can it be improved. This course has helped me identify areas where I need to improve and enabled me to find ways of how I can develop myself further (Appendix 1). Also learnt how to use different learning techniques and negotiating skills and gained positive results, shadowing my manager is giving me valuable experience, I also made some suggestions she’s taken on board such as performance management should be throughout admin staff and training provided to staff to improve IT skills further for a more efficient service.
4.4 Priorities for further career development & professional learning:
My long-term career development is to secure an SBM position hopefully within my school. I need to further develop my leadership and management skills and believe this course, leading and completing my project along with the tasks I have undertaken will help me move up a tier on the NASBM standards. I also need to request to be involved in new projects assisting where possible. My PDP (Appendix 1) will help me to understand School Finance and Asset Management better. My new target (Appendix 1) will assist me in value for money, negotiation and d