Maintenance and Reliability

 

 

 

17 – 2

The objective is

maintain the capability of the system

17 – 3

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:

17 – 4

Maintenance and Reliability

Maintenance is

all activities involved in keeping a system’s

equipment in working order

17 – 5

Maintenance and Reliability

Reliability is

the probability

that a machine will function properly for a specified time

17 – 6

Important Tactics

Reliability

Improving individual components

Providing redundancy

Maintenance

Implementing or improving preventive maintenance

Increasing repair capability or speed

17 – 8

Designing for reliability is an excellent place

to start reducing variability.

17 – 9

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

17 – 10

Because failures do occur in the real world,

Understanding their occurrence is an important reliability concept.

17 – 11

As the number of components in

a series increases,

The reliability of the whole system

declines very quickly

17 – 13

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

17 – 14

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.

17 – 15

Reliability Example

Reliability of the process is

Rs = R1 x R2 x R3 = .90 x .80 x .99 = .713 or 71.3%

17 – 16

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%!

Copyright © 2020 Pearson Canada Inc. 17 – 17

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

17 – 18

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

17 – 19

Failure Rate Example

FR

FR(%)=Number of failures/Number of units tested %

17 – 20

Failure Rate Example (1 of 2)

FR(𝑁) = 2

20 000 − 1200 = .000106 failure/unithr

MTBF = 1

.000106 = 9434hrs

17 – 21

Failure Rate Example (1 of 2) Number of failures per operating hour:

17 – 22

Failure Rate Example (1 of 2)

17 – 23

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

17 – 24

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.

17 – 25

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

17 – 26

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?

17 – 27

Maintenance

Preventive maintenance – • routine inspection and

servicing to keep facilities in good repair

Breakdown maintenance – • emergency repairs on

failed equipment

Two types of maintenance

17 – 28

Implementing Preventive Maintenance

Need to know when a system requires service or is likely to fail

17 – 29

Implementing Preventive Maintenance

High initial failure rates….

infant mortality

17 – 30

Implementing Preventive Maintenance

Once a product settles in,

MTBF (mean time between failures) generally follows a normal distribution

17 – 33

Maintenance Costs

The traditional view attempted

to balance

preventive and breakdown

maintenance costs

17 – 34

Maintenance Costs

17 – 35

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

This question has been answered.

Get Answer
WeCreativez WhatsApp Support
Our customer support team is here to answer your questions. Ask us anything!
👋 Hi, Welcome to Compliant Papers.