Page 425 - Intro Predictive Maintenance

416 An Introduction to Predictive Maintenance

A major selling point of new automobiles is the elimination of ignition points that
require replacement and adjustment, the introduction of self-adjusting brake shoes and
clutches, and the extension of oil-change intervals.

18.9.4 Advantages and Disadvantages
Overall, preventive maintenance has many advantages. It is beneficial, however, to
overview the advantages and disadvantages so that the positive may be improved and
the negative reduced. Note that in most cases the advantages and disadvantages vary
with the type of preventive maintenance tasks and techniques used. Use of on-
condition or condition-monitoring techniques is usually better than fixed intervals.

Advantages

There are distinct advantages to preventive maintenance management. The primary
advantages include management control, reduced overtime, smaller parts inventories,
less standby equipment, better safety controls, improved quality, enhanced support to
users, and better cost–benefit ratio.

Management Control. Unlike repair maintenance, which must react to failures,
preventive maintenance can be planned. This means pre-active instead of reactive
management. Workloads may be scheduled so that equipment is available for pre-
ventive activities at reasonable times.

Overtime. Overtime can be reduced or eliminated. Surprises are reduced. Work can
be performed when convenient. Proper distribution of time-driven preventive main-
tenance tasks is required, however, to ensure that all work is completed quickly
without excessive overtime.

Parts Inventories. Because the preventive maintenance approach permits planning, of
which parts are going to be required and when, those material requirements may be
anticipated to be sure they are on hand for the event. A smaller stock of parts is
required in organizations that emphasize preventive tasks compared to the stocks
necessary to cover breakdowns that would occur when preventive maintenance is not
emphasized.

Standby Equipment. With high demand for production and low equipment avail-
ability, standby equipment is often required in case of breakdowns. Some backup
may still be required with preventive maintenance, but the need and investment will
certainly be reduced.

Safety and Pollution. If there are no preventive inspections or built-in detection
devices, equipment can deteriorate to a point where it is unsafe or may spew forth
pollutants. Performance will generally follow a sawtooth pattern, as shown in Figure
18–5, which does well after maintenance and then degrades until the failure is noticed