15S
Maintenance
McGraw-Hill/Irwin
Copyright © 2007 by The McGraw-Hill Companies, Inc. 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
 Reasons for maintenance




To avoid production or service disruptions
To not add production or service costs
To maintain high quality
To avoid missed delivery dates
15S-4
Reactive vs Proactive
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-5
Maintenance Reasons
 Reasons for keeping equipment running




Avoid production disruptions
Not add to production costs
Maintain high quality
Avoid missed delivery dates
15S-6
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-7
Total Maintenance Cost
Table 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 S-1
Frequency of breakdown
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 S-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