15S
Maintenance
Copyright © 2014 by McGraw-Hill Education (Asia). All rights reserved.
Learning Objectives
 Explain the importance of maintenance in
production systems
 Describe the range of maintenance activities
 Discuss preventative maintenance and the
key issues associated with it
 Discuss breakdown maintenance and the
key issues associated with it
 State how the Pareto phenomenon pertains
to maintenance decisions
15S-2
Introduction
 Maintenance

All activities that maintain facilities and
equipment in good working order so
that a system can perform as intended
 Two basic categories


Building and grounds
Equipment maintenance
15S-3
Goal of Maintenance
 To keep production systems in good working
order at minimal cost
15S-4
Maintenance Reasons
 Reasons for keeping equipment running




Avoid production disruptions
Avoid adding production costs
Maintain high quality
Avoid missed delivery dates
15S-5
Breakdown Consequences
 Production capacity is reduced

Orders are delayed
 No production


Overhead continues
Cost per unit increases
 Quality issues

Product may be damaged
 Safety issues


Injury to employees
Injury to customers
15S-6
Two Basic Options
Reactive Maintenance:
 Breakdown maintenance

Reactive approach; dealing with breakdowns or
problems when they occur
Proactive Maintenance:
 Preventive maintenance

Proactive approach; reducing breakdowns
through a program of lubrication, adjustment,
cleaning, inspection, and replacement of worn
parts
15S-7
Total Maintenance Cost
Figure 15S.1
Cost
Total Cost
Preventive
maintenance cost
Breakdown and
repair cost
Optimum Amount of
preventive maintenance
15S-8
Preventive Maintenance
 Preventive maintenance: goal is to
reduce the incidence of breakdowns or
failures in the plant or equipment to
avoid the associated costs
 Preventive maintenance is periodic

Result of planned inspections

According to calendar

After predetermined number of hours
15S-9
Example 15S-1
Frequency of breakdowns
Number of breakdowns
Frequency of occurrence
0
1
2
3
.20 .30 .40 .10
If the average cost of a breakdown is
$1,000, and the cost of preventative
maintenance is $1,250 per month, should
we use preventive maintenance?
15S-10
Example 15S-1 Solution
Number of
Breakdowns
0
1
2
3
Frequency of
Occurrence
.20
.30
.40
.10
1.00
Expected number of
Breakdowns
0
.30
.80
.30
1.40
Expected cost to repair = 1.4 breakdowns per month X $1000 = $1400
Preventive maintenance = $1250
PM results in savings of $150 per month
15S-11
Predictive Maintenance
 Predictive maintenance

An attempt to determine when best to
perform preventive maintenance activities
 Total productive maintenance

JIT approach where workers perform
preventive maintenance on the machines
they operate
15S-12
Breakdown Programs
 Standby or backup equipment that can
be quickly pressed into service
 Inventories of spare parts that can be
installed as needed
 Operators who are able to perform minor
repairs
 Repair people who are well trained and
readily available to diagnose and correct
problems with equipment
15S-13
Replacement
 Trade-off decisions





Cost of replacement vs. cost of continued
maintenance
New equipment with new features vs.
maintenance
Installation of new equipment may cause
disruptions
Training costs of employees on new equipment
Forecasts for demand on equipment may
require new equipment capacity
 When is it time for replacement?
15S-14