Run-to-Failure Management

The logic of run-to-failure management is simple and straightforward: When a machine breaks down, fix it. The “If it ain’t broke, don’t fix it” method of maintain-ing plant machinery has been a major part of plant maintenance operations since the first manufacturing plant was built, and on the surface it sounds reasonable. A plant using run-to-failure management does not spend any money on maintenance until a machine or system fails to operate.

Run-to-failure is a reactive management technique that waits for machine or equip-ment failure before any maintenance action is taken; however, it is actually a “no- maintenance” approach of management. It is also the most expensive method of maintenance management. Few plants use a true run-to-failure management philoso- phy. In almost all instances, plants perform basic preventive tasks (i.e., lubrication, machine adjustments, and other adjustments), even in a run-to-failure environment. In this type of management, however, machines and other plant equipment are not rebuilt, nor are any major repairs made until the equipment fails to operate. The major expenses associated with this type of maintenance management are high spare parts An Introduction to Predictive Maintenance inventory cost, high overtime labor costs, high machine downtime, and low produc-tion availability.

Because no attempt is made to anticipate maintenance requirements, a plant that uses true run-to-failure management must be able to react to all possible failures within the plant. This reactive method of management forces the maintenance department to maintain extensive spare parts inventories that include spare machines or at least all
major components for all critical equipment in the plant. The alternative is to rely on equip ent vendors that can provide immediate delivery of all required spare parts.

Even if the latter option is possible, premiums for expedited delivery substantially increase the costs of repair parts and downtime required to correct machine failures. To minimize the impact on production created by unexpected machine failures, main- tenance personnel must also be able to react immediately to all machine failures. The net result of this reactive type of maintenance management is higher maintenance cost and lower availability of process machinery. Analysis of maintenance costs indicates that a repair performed in the reactive or run-to-failure mode will average about three times higher than the same repair made within a scheduled or preventive mode. Sched- uling the repair minimizes the repair time and associated labor costs. It also reduces the negative impact of expedited shipments and lost production.