1. 15S
Maintenance

2. 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

3. Introduction Maintenance Two basic categories
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

4. Goal of Maintenance
To keep production systems in good working order at minimal cost

5. Maintenance Reasons Reasons for keeping equipment running
Avoid production disruptions
Avoid adding production costs
Maintain high quality
Avoid missed delivery dates

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

7. 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

8. Total Maintenance Cost
Figure 15S.1
Total Cost
Cost
Preventive maintenance cost
Breakdown and repair cost
Optimum Amount of
preventive maintenance

9. 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

10. Example 15S-1 Frequency of breakdowns
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?
Number of breakdowns 1 2 3
Frequency of occurrence
.20
.30
.40
.10

11. Example 15S-1 Solution Number of Breakdowns Frequency of Occurrence
Expected number of 1 2 3
.20
.30
.40
.10
1.00
.80
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

12. 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

13. 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

14. Replacement Trade-off decisions When is it time for replacement?
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?