1. Today we are going to learn the basics
of maintenance & the method for the
accountability of losses & the method
to over come those losses by
appropriate maintenance activity.
By,
Raghuttam Jorapurkar
2. What is Maintenance?
Maintenance is defined as engineering actions
which are necessary for retaining or restoring an
equipment, machine or system to the specified
condition to achieve its maximum useful life.
3. Types of Maintenance
There are major three types of maintenance
1. Preventive Maintenance
2. Breakdown Maintenance
3. Corrective Maintenance
4. 1. Preventive Maintenance
It includes two types of Maintenance
1.1 Periodic Maintenance
(TBM : Time Based Maintenance)
1.2 Predictive Maintenance
(CBM : Condition Based Maintenance)
5. 1.1 Periodic Maintenance (TBM)
In this type of maintenance, spares / consumable
replacement activity of the equipment or machine
is carried out as per predefined time period.
Disadvantage : Spare cost become high
Note : TBM is only spare part replacement activity
6. 1.1 Periodic Maintenance (TBM)
A Periodic time based maintenance plan is
to be prepared for our company.
7. 1.2 Predictive Maintenance (CBM)
It is the determination of the condition of in-service
equipment in order to predict when maintenance
should be performed
This maintenance can be easily carried out by
electronic equipment like bearing echo meter,
multimeter, IR temperature meter etc.
Advantage : Cost effective & utilization of spares
can be achieved up to 99%
8. 1.2 Predictive Maintenance (CBM)
A Periodic condition based
maintenance plan is to be prepared
for our company.
9. 1.2 Predictive Maintenance (CBM)
While performing this type of maintenance, check sheet
should be updated for further analysis. Machine /
equipment history card is to be updated regularly for
analysis & timely action.
10. 2. Breakdown Maintenance
This maintenance is carried out on all items
where the time of failure or wearing out are
not yet captured in history of the machine or
equipment.
The maintenance activity conducted to
bring back the machine / equipment in
working order which has worn out or failed.
11. 3. Corrective Maintenance
To improve reliability & maintainability,
corrective maintenance is must
It can be achieved by implementation of
kaizens on :
a. MTBF improvement
b. MTTR reduction
13. Minor Stoppage
If downtime is less than or equal to 10 minutes
due to equipment problem, it is “minor stoppage”
14. Mean Time To Repair (MTTR)
• It is a basic measure of the maintainability of
repairable items.
• It represents the average time required to repair the
equipment
Total Breakdown Time
Total Breakdown Incidences
M. T. T. R. =
15. Mean Time To Repair (MTTR)
• It can be measured in minutes, hours or days
• It should be very low & ideally it should be zero
• While calculations of MTTR, there is no
consideration of minor stoppages
16. Mean Time To Repair (MTTR)
Question : Calculate MTTR for the month of May 2014
in which there were 2 breakdowns of 65 & 75 min
17. Mean Time To Repair (MTTR)
According to formula of
Total Breakdown Time
Total Breakdown Incidences
MTTR =
65 min + 75 min
2
MTTR =
18. Mean Time To Repair (MTTR)
140 min
2
MTTR =
70 min=
70/60 hours=
1.16 hours=
19. Mean Time Between Failure (MTBF)
It is nothing but the average time between
failures of the system/equipment
Total Working Time – Total Breakdown Time
Total Breakdown Incidences
MTBF =
20. Mean Time Between Failure (MTBF)
• It can be measured in minutes, hours or days
• It should be very high & ideally it should be infinite
• There is no consideration of minor stoppages
21. Mean Time Between Failure (MTBF)
Question : Calculate MTBF for the month of May 2014
in which there were 2 breakdowns of 111 & 222
min
(Given : No. of working days were 24)
22. Mean Time Between Failure (MTBF)
Working time = Working Days X 24 hours
Working time = 24 days X 24 hours
= 576 hours
23. Mean Time Between Failure (MTBF)
Breakdown time= 111 min + 222 min
Breakdown time = 333 min
= 333/60 hours
= 5.55 hours
24. Mean Time Between Failure (MTBF)
Now as per formula of MTBF
Total Working Time – Total Breakdown Time
Total Breakdown Incidences
MTBF =
576 – 5.55
2
MTBF =
285.22 hoursMTBF =
25. Uptime
It is a measure of the time a machine has been
up without any downtime
It is measured in percentage
Available Time – Breakdown Time
Available Time
Uptime = X 100
26. Uptime
Suppose, available time is 24 day & breakdown
time is 4 hours, then uptime will be
Available Time – Breakdown Time
Available Time
Uptime = X 100
(24 X24) – 4
(24 X 24)
Uptime = X 100
Uptime = 93.31 %
