Page 80 - Intro Predictive Maintenance

Benefits of Predictive Maintenance 71

on the survey results, major improvements can be achieved in maintenance costs,
unscheduled machine failures, repair downtime, spare parts inventory, and both
direct and indirect overtime premiums. In addition, the survey indicated a dramatic
improvement in machine life, production, operator safety, product quality, and overall
profitability.

Based on the survey, the actual costs normally associated with the maintenance opera-
tion were reduced by more than 50 percent. The comparison of maintenance costs
included the actual labor and overhead of the maintenance department. It also included
the actual materials cost of repair parts, tools, and other equipment required to main-
tain plant equipment. The analysis did not include lost production time, variances in
direct labor, or other costs that should be directly attributed to inefficient maintenance
practices.

The addition of regular monitoring of the actual condition of process machinery and
systems reduced the number of catastrophic, unexpected machine failures by an
average of 55 percent. The comparison used the frequency of unexpected machine
failures before implementing the predictive maintenance program to the failure rate
during the two-year period following the addition of condition monitoring to the
program. Projections of the survey results indicate that reductions of 90 percent can
be achieved using regular monitoring of the actual machine condition.

Predictive maintenance was shown to reduce the actual time required to repair or
rebuild plant equipment. The average improvement in mean-time-to-repair (MTTR)
was a reduction of 60 percent. To determine the average improvement, actual repair
times before the predictive maintenance program were compared to the actual time
to repair after one year of operation using predictive maintenance management
techniques. The regular monitoring and analysis of machine condition identified the
specific failed component(s) in each machine and enabled the maintenance staff to
plan each repair. The ability to predetermine the specific repair parts, tools, and labor
skills required provided the dramatic reduction in both repair time and costs.

The ability to predict machine-train and equipment failures and the specific failure
mode provided the means to reduce spare parts inventories by more than 30 percent.
Rather than carry repair parts in inventory, the surveyed plants had sufficient lead time
to order repair or replacement parts as needed. The comparison included the actual
cost of spare parts and the inventory carrying costs for each plant.

Prevention of catastrophic failures and early detection of incipient machine and
systems problems increased the useful operating life of plant machinery by an average
of 30 percent. The increase in machine life was a projection based on five years of
operation after implementation of a predictive maintenance program. The calculation
included frequency of repairs, severity of machine damage, and actual condition of
machinery after repair. A condition-based predictive maintenance program prevents
serious damage to machinery and other plant systems. This reduction in damage
severity increases the operating life of plant equipment.