Maintenance Management
In the past thirty years, executive management has focused increasingly on short-term profitability, sacrificing their physical assets
to do so. Best Practice companies have taken advantage of this trend to develop strategic plans, building strong, complete organizations.
One of the foremost areas of focus for these companies has been the maintenance/asset management function. important to being competitive in the world market. But have the majority companies followed their lead? The answer for the majority, sadly, is no. I have seen plants where one day the maintenance force is required to work on sophisticated electronic systems and the next day to perform janitorial service in the lavatories.
Equipment service level indicates the amount of time the equipment is available for its intended service. The amount of service required from the equipment, along with its resultant costs, determines the type of maintenance philosophy a company will adopt. Five common
philosophies are:
In far too many cases, equipment is run until it breaks down. There is no preventive maintenance; the technicians react, working only on equipment that is malfunctioning. This approach is the most expensive way to coordinate maintenance. Equipment service level is generally below acceptable levels, and product quality is usually impacted.
Corrective maintenance activities are generated from PM inspections, routine operational requests, and routine service requirements. These activities make up the maintenance backlog and should be planned and scheduled in advance. This approach is the most cost effective way to perform maintenance, reducing performance costs by 2 to 4 times compared to reactive maintenance. When the majority of maintenance activities fall into this category, equipment service levels can be maintained.
Preventive maintenance includes the lubrication program, routine inspections, and adjustments. Many potential problems can thus be corrected before they occur. The methods for organizing and developing PM programs will be detailed in Chapter 7. At this level of maintenance, equipment service levels enter the acceptable range for most operations.
Predictive maintenance allows failures to be forecast through analysis of the equipment’s condition. The analysis is generally conducted
through some form of trending of a parameter, such as vibration, temperature, and flow. Preventive maintenance differs from
predictive maintenance in that it focuses on manual tasks whereas predictive maintenance uses some form of technology. Predictive
maintenance allows equipment to be repaired at times that do not interfere with production schedules, thereby removing one of the largest
factors from downtime cost. The equipment service level will be very high under predictive maintenance.
An extension of predictive maintenance is condition-based maintenance, which is maintenance performed as it is needed, with the equipment monitored continually. Some plants have the production automation system directly connected to a computer system in order to monitor the equipment condition in a real-time mode. Any deviation from the standard normal range of tolerances will cause an alarm
(or in some cases a repair order) to be generated automatically. This real-time trending allows for the maintenance to be performed in the most cost effective manner. Condition-based maintenance is the optimum maintenance cost vs. equipment service level method available. The startup and installation cost can be very high. Nevertheless, many companies are moving toward this type of maintenance.
Source: Terry Wireman(2015). Benchmarking Best Practices for Maintenance, Reliability and Asset Management.
