The presentation describes the Preventive Maintenance feasibility, scheduling and the pros and cons for the same.

1. Preventive Maintenance
By
Manohar Tatwawadi
total output power solutions
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2. Agenda
• Definition of Preventive Maintenance (PM)
• Reasons for the increased need of PM
• Advantages of a PM system
• Risks of running a PM system
• When to use a PM system
• The law of PM
• Guide to a successful PM system
• Execution process
• Conclusion / Summery
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3. What is Preventive Maintenance?
• Preventive maintenance is a schedule of
planned maintenance actions aimed at the
prevention of breakdowns and failures.
• The primary goal of preventive maintenance is
to prevent the failure of equipment before it
actually occurs.
• It is designed to preserve and enhance
equipment reliability by replacing worn
components before they actually fail.
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4. Reasons for the need of a PM system
• Increased Automation
• Losses due to production interruptions / delays
• Production of a regular, reliable higher quality product
• Just-in-time manufacturing / delivering services
• Stores management / Increased costs of spares
• Need for a more organized, planned environment
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5. Advantages of a PM system
• Reduced production downtime, resulting in fewer
machine breakdowns.
• Better conservation of assets and increased life
expectancy of assets, thereby eliminating premature
replacement of machinery and equipment.
• Timely, routine repairs circumvent fewer large-scale
repairs.
• Reduced downtime and hence reduced costs
• Stores management at its best
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6. Continued -
• Reduced cost of repairs by reducing secondary
failures. When parts fail in service, they usually
damage other parts.
• Better quality products
• Identification of equipment with excessive
maintenance costs
• Improved safety and quality conditions
• Consumer satisfaction because of reduced failures /
breakdowns.
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7. Brainstorming Exercise
• Are there any risks of running a PM system?
• If there are risks when would it be a good time
to use PM?
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8. Potential errors or damage
of a PM system
• Damage to an adjacent equipment during a PM task.
• Reintroducing infant mortality by installing new parts
or materials.
• Damage due to an error in reinstalling equipment
into its original location.
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9. A real life example of a PM error
A review of the data from fossil-fueled power plants
that examined the frequency and duration of forced
outages after a planned or forced maintenance
outage reinforces our point.
The data collected from those plants showed that of
3146 maintenance outages, 1772 of them occurred
in less than one week after a maintenance outage.
Clearly, this is pretty strong evidence that suggests
that in 56% of the cases, unplanned maintenance
outages were caused by errors committed during a
recent maintenance outage.
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10. When Does Preventive Maintenance Make
Sense
• This is a logical choice that considers two
conditions
–#1. The component in question has an
increasing failure rate.
–#2. The overall cost of the preventive
maintenance action must be less than the
overall cost of a corrective action.
If both of these conditions are met PM
would make sense
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11. The Law of PM
• Higher the value of the plant assets and equipment
per square foot of plant, the greater will be the
return on a PM program.
E.g. - downtime in an automobile plant assembly line at one
time cost Rs.800,000 per minute. Relating this to lost
production time an automobile manufacturer reported that
the establishment of a PM program in their 16 assembly
plants reduced downtime from 300 hours per year to 25
hours per year.
With results such as this they can very well afford to develop a
PM program.
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12. How to determine the optimum age of
replacement?
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13. How to determine the optimum age of
replacement?
• A more technical approach.
Where:
• R(t) = reliability at time t.
• CP = cost of planned replacement.
• CU = cost of unplanned replacement
• CPUT(t) = The optimum replacement time
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14. The key for a successful PM system
• Scheduling – Should be automated to the maximum
extent possible
• Execution – Should be done before the actual break
down occurs.
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15. Execution
• The Bath Tub Model – Three
stages of new parts
1. Infant morality stage
2. A fairly long run stage
3. Wear out stage
• Traditional View according to
Bath Tub Model – Replace
components just before they
entered wear out stage
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16. Execution
• Traditional view says –
Wear out stage = Increased rate of failure.
• Point to Ponder –
Since, wear out stage represents increased rate of failure,
wouldn’t it be plausible to execute the PM program at this
stage?
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17. Execution
• United Airlines Research
Reliability Centered Maintenance based on research
done by United Airlines and the rest of the aircraft industry
showed that very few non-structural components exhibit
bathtub curve characteristics. Their research showed that only
about 11% of all components exhibit wear-out characteristics,
but 72% of components do exhibit infant mortality
characteristics. These same characteristics have been shown
to apply in Department of Defense systems as well as power
plant systems.
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18. What really should PM focus on?
• Cleaning Found through testing
• Lubrication and inspection
• And correcting deficiencies
Predetermined parts replacement should be minimal and done only where
statistical evidence clearly indicates wear-out characteristics
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19. In the absence of data
• Age exploration programs
• Statistical analysis
Cost shouldn’t be a primary factor in deciding against data
collection for a PM
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20. Motivating Preventive Maintenance
Workers
• Training programs – most effective
• Establish inspection and preventive
maintenance as a recognized, important part
of the overall maintenance program.
• Assign competent, responsible people to the
preventive maintenance program.
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21. Continued -
• Follow-up to assure quality performance and to show
everyone that management does care.
• Provide training in precision maintenance practices
and training in the right techniques and procedures
for preventive maintenance on specific equipment.
• Set high standards.
• Publicize reduced costs with improved up-time and
revenues, which are the result of effective preventive
maintenance
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22. Summary
• PM is not difficult to achieve.
• It is an essential part for cost reduction
• There is an element of risk involved in PM
• Careful planning and execution will reduce the risk of PM
• The biggest benefits of a PM program occur through
painting, lubrication, cleaning and adjusting, and minor
component replacement to extend the life of equipment
and facilities.
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