This presentation is about the basic Maintenance, objectives, Types & its description, as well as equipment performance evaluation technique.

1. Presentation By
Rahmat Ullah
B. Tech. (E.I.E)

2.  Introduction - Plant Maintenance
 Objectives of the Maintenance
 Types of Maintenance
 Corrective Maintenance
 Types of Corrective Maintenance
 Breakdown Maintenance
 Breakdown Classification
 Preventive Maintenance
 PM - Cycle
 PM - Benefits
 Preventive Maintenance - Category
 Evaluating Equipment Performance
 Mean Time To Repair (MTTR)
 Mean Time Between Failure (MTBF)
 Uptime (Availability)

3.  Plant maintenance is defined as a set of
activities that are necessary to keep machinery,
parts & types of equipment in good operating
conditions to avoid production stoppage and
loss with minimum cost acquired.
 It helps in maintaining and increasing the
operational efficiency of plant facilities.
 The general aim of plant maintenance is to
create a productive working environment that is
also safe for workers.

4.  To achieve minimum breakdown and to keep the plant in good
working condition at the lowest possible cost.
 Machines and other facilities should be kept in such a condition
which permits them to be used at their optimum (Profit Making)
capacity without any interruption.
 Minimizing the loss of production time due to equipment
failure
 Improving equipment efficiency & reducing scrap rate.
 Improve the quality of the product and to improve productivity
 Helps to reduce the total maintenance cost of repair, preventive
maintenance & inventory carrying a cost due to a spare part
inventory.

5. 1) Corrective Maintenance (Planned)
2) Breakdown Maintenance (Unplanned)
3) Preventive Maintenance
◦ Scheduled/Periodic Maintenance (TBM - Time
Based Maintenance)
◦ Predictive Maintenance (CBM - Condition Based
Maintenance)
◦ Performance Maintenance

6.  Corrective Maintenance is a maintenance task
performed to identify, isolate and rectify a fault
so that the failed equipment, machine or
system can be restored to an operational
condition within the tolerance or limits.
 Corrective maintenance is maintenance which is
carried out after failure detection and is aimed
at restoring an asset to a condition in which it
can perform its intended function.
 Corrective Maintenance = After a failure has
occurred.

7. i. Scheduled Corrective Maintenance
ii. Unscheduled Corrective Maintenance
i. Scheduled Corrective Maintenance:
Maintenance that is needed, but not required
to be performed immediately.
e.g. A spray nozzle becomes clogged causing
lubricant to stop flowing through the nozzle.
A work order is created to clear the blockage
or replace the nozzle head at the time of next
inspection.

8. ii. Unscheduled Corrective Maintenance:
Maintenance that is required due to a critical
failure that must be corrected without delay.
e.g. Mineral build-up from hard water
collects in a pipe, increasing the pressure and
causing it to burst. The pipe must be
replaced as soon as possible.

9.  Breakdown maintenance implies that repairs are
made after the equipment is out of order and it
cannot perform its normal function any longer,
e.g., an electric motor will not start, a belt is
broken, if a critical piece of machinery breaks etc
 It occurs when work gets stopped because of a
machine breakdown. The maintenance activity
conducted to bring back the machine / equipment
in working order which has worn out or failed.
 Breakdown maintenance, sometimes called run-to-
failure maintenance.

10.  This may also called corrective maintenance,
but basic difference is, CM can planned & but
breakdown must be rectify on emergency basis.
 Breakdown maintenance is costly and affects
productivity as it can put a halt to your entire
production if any critical equipment
breakdown.

12.  It is based upon the principle that ‘prevention
is better than cure’.
 Preventive Maintenance is the regular & routine
maintenance of equipment, machine and assets
in order to keep them running and prevent any
costly unplanned downtime from unexpected
equipment failure.
 Preventive Maintenance = Before a failure has
occurred.

13.  Preventive Maintenance follows PDCA cycle.
◦ P (Plan: Making a machine inspection plan)
◦ D (Do: Executing machine inspection)
◦ C (Check: Identifying and diagnosing portions where a failure
or fault is anticipated, based on the results of inspection)
◦ A (Action: Repairing failed
or damaged portions as
planned).

15.  Preventive Maintenance is done in 3-ways.
◦ Time Based (Scheduled/Periodic Maintenance)
 Weekly, Monthly, Quarterly, Yearly
◦ Condition Based (Predictive Maintenance)
 Temp, Pressure readings or when machine is not
working up to the mark.
◦ Performance Based
 (500hrs, 1000hrs, 2000hrs)

16.  To improve reliability & maintainability,
maintenance activity is must.
 It can be achieved by implementation
a) MTBF improvement
b) MTTR reduction

17.  It is a basic measure of the maintainability of
repairable items.
 It represents the average time required to
repair the equipment.
 MTTR = Total Breakdown Time
 Total no of breakdown happened

18.  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.

19.  Question : Calculate MTTR for the month of
October 2019 in which there were 4 breakdowns
of 65, 35, 20 & 75 min.
 According to formula of
MTTR = Total Breakdown Time
Total no of breakdown happened
= 65+35+20+75
4
= 195
4
= 48.75 min
= 48.75/60 hr
= 0.81 hrs

20.  It is a basic measure of the reliability of
repairable items.
 It is nothing but the average time between
failures of the system/equipment.
 MTBF = Total Working Time – Total Breakdown Time
Total no of breakdown happened

21.  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.

22.  Question : Calculate MTBF for the month of
October 2019 in which there were 4
breakdowns of 65, 35, 20 & 75 min.
(Given : No. of working days were 27)
 Working Time = Working Days x 24 hrs
Working Time = 27 days x 24 hrs
= 648 hrs

23.  Breakdown Time = 65min+35min+20min+ 75min
= 195 min
= 195/60 hrs
= 3.25 hrs

24.  According to formula of:
MTBF = Total Working Time – Total Breakdown Time
Total no of breakdown happened
= 648 – 3.25
4
= 644.75
4
= 161.18 hrs

25.  It is a measure of the time a machine has been
up without any downtime.
 It is measured in percentage.
 Uptime = Available Time – Breakdown Time x 100
Available Time
= MTBF – MTTR
MTBF

26.  Suppose, available time is 27 days &
breakdown time is 5 hours, then uptime will
be
 Uptime = Available Time-Breakdown Time x 100
Available Time
= 27x24 – 5 x 100
27x24
= 648-5 x 100
648
Uptime = 99.22%

27. Feedback to improve…
rahmateie@gmail.com