Every facility that produces a consumer product
has some requirement for maintenance or upkeep of their machinery. Depending upon the
product and, to some extent, the size of the facility, this maintenance activity may be
continuous in nature or periodic. Some maintenance activities may consume a significant
portion of the facility expenses and manpower.
Facility maintenance activities generally
fall into three categories: breakdown, preventive, and predictive. Each category has
particular costs associated and specific benefits.
Breakdown Maintenance
This method has no continuous activity associated with it. Essentially, no maintenance
activity is performed on machinery until it fails or produces unacceptable product. At
first impression this method seems the most cost effective because the manpower and their
associated costs are minimal.
But closer examination shows that when the machinery fails, considerable expense is
required to allocate manpower on an emergency basis, repair/replacement parts, and lost
revenues due to non-production can mount rapidly depending upon the manufacturing process
or product. Clearly, this method has the highest associated cost and maintenance is
unpredictable at best. In addition, an unexpected failure can be dangerous to personnel
and the facility.
Preventive Maintenance
An advancement on a breakdown maintenance program is a preventive program. This periodic
approach to maintenance has little continuous activity associated with it. It involves
scheduling a regular outage, usually on an annual basis, where the entire machine train or
plant is shutdown, or removed from production, for careful inspection and routine
replacement of specific parts.
This method has the highest cost for replacement
parts because the facility may have a separate program or department with the sole purpose
of maintaining an inventory of spare parts and scheduling outage activity. Maintenance
costs are reduced because the "annual outage" or "turn around" is
usually scheduled for a period when the product demand is low. Additional cost savings are
realized because manpower and any heavy equipment are scheduled.
Predictive
Maintenance
Throughout the decade of the 1980s many facilities began to seek solutions to high
maintenance costs and spare parts inventories. By adopting a continuous approach to
facility maintenance these reductions can be realized. Supporting this approach was the
profusion of portable data collectors and database software. As an extension or
enhancement to a portable data collector system, which can have an elevated associated
manpower cost, is a permanently installed monitoring system. Many of these systems can be
interfaced to advance software systems that can assist with signal analysis. The key to
this enhanced system is having the sensors installed which are available for signal
acquisition continuously.
Using these systems, and the appropriate training necessary for signal interpretation,
a facility can implement a predictive maintenance program. This method relies on the data
collected, either on a continuous basis or on a routine, periodic basis, to dictate the
required maintenance procedure and when to schedule the maintenance activity. Granted, the
scheduling is a subjective topic controlled by spare parts inventory, manpower
availability, and product demand. By evaluating all these parameters a scheduled outage
can be determined and all associated costs can be reduced.
Maintenance Method Checklist
- Breakdown Maintenance
- Preventive Maintenance
- Predictive Maintenance
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