An introduction to predictive maintenance
Maintenance costs are a major part of the total operating costs of all manufacturing or production plants. Depending on the specific industry, maintenance costs can represent between 15 and 60 percent of the cost of goods produced. For example, in foodrelated industries, average aintenance costs represent about 15 percent of the cost of goods produced, whereas maintenance costs for iron and steel, pulp and paper, and other heavy industries represent up to 60 percent of the total production costs.
These percentages may be misleading. In most American plants, reported maintenance costs include many nonmaintenance-related expenditures. For example, many plants include modifications to existing capital systems that are driven by market-related factors, such as new products. These expenses are not truly maintenance and should be allocated to nonmaintenance cost centers; however, true maintenance costs are substantial and do represent a short-term mprovement that can directly impact plant profitability.
Recent surveys of maintenance management effectiveness indicate that one-third—33 cents out of every dollar—of all maintenance costs is wasted as the result of unnecessary or improperly carried out maintenance. When you consider that U.S. industry spends more than $200 billion each year on maintenance of plant equipment and facilities, the impact on productivity and profit that is represented by the maintenance operation becomes clear.
The result of ineffective maintenance management represents a loss of more than $60 billion each year. Perhaps more important is the fact that ineffective maintenance management significantly affects the ability to manufacture quality products that are competitive in the world market. The losses of production time and product quality that result from poor or inadequate maintenance management have had a dramatic impact on U.S. industries’ ability to compete with Japan and other countries that have implemented more advanced manufacturing and maintenance management philosophies.
The dominant reason for this ineffective management is the lack of factual data to quantify the actual need for repair or maintenance of plant machinery, equipment, and systems. Maintenance scheduling has been, and in many instances still is, predicated on statistical trend data or on the actual failure of plant equipment.
Until recently, middle- and corporate-level management have ignored the impact of the maintenance operation on product quality, production costs, and more important, on bottom-line profit. The general opinion has been “Maintenance is a necessary evil” or “Nothing can be done to improve maintenance costs.” Perhaps these statements were true 10 or 20 years ago, but the development of microprocessor- or computerbased instrumentation that can be used to monitor the operating condition of plant equipment, machinery, and systems has provided the means to manage the maintenance operation. This instrumentation has provided the means to reduce or eliminate unnecessary repairs, prevent catastrophic machine failures, and reduce the negative impact of the maintenance operation on the profitability of manufacturing and production plants.