Why Preventive Maintenance is Important
Excerpted from Preventive Maintenance (Maintenance Strategy Series) by Terry Wireman CPMM
Courtesy of Industrial Press
If you ask twenty different people to write their definition of preventive maintenance, you will get twenty different answers. The term has varied definitions. For the purpose of this text, preventive maintenance is defined as a fundamental, planned maintenance activity designed to improve equipment life and avoid any unplanned maintenance activity. In its simplest form, preventive maintenance can be compared to the service schedule for an automobile. Certain tasks must be scheduled at varying frequencies, all designed to keep the automobile from experiencing any unexpected breakdowns. Preventive maintenance for industrial equipment is no different.
The Importance of Preventive Maintenance
Preventive maintenance is the foundation of the entire maintenance strategy. Unless the PM program is effective, all subsequent maintenance strategies will take longer to implement, incur higher costs to implement, and have a higher probability of failure. This may seem to be an overstatement, but publications from authors around the world echo the same thought. Because the preventive maintenance program receives this type of solid endorsement from successful companies, it appears that companies would focus on their preventive maintenance programs, attempting to insure their success. However, this is not the case. Figure 1-1 shows the result of a survey that involved 5000 companies. As the figure highlights, the majority were not satisfied with the effectiveness of their preventive maintenance program. How is the effectiveness measured? Effectiveness occurs when 80% or more of the maintenance activities can be planned and scheduled at least one week in advance. This level is an indicator that the organization is moving from a reactive culture to a more proactive culture.
The results of another survey are highlighted in Figure 1-2. This figure shows that the percentage of respondents who believe their preventive maintenance program is ineffective is almost the same as reflected in the survey in Figure 1-1. The issue is that the two surveys were taken almost 40 years apart. Figure 1-1 was taken in 1965 and Figure 1-2 was taken in 2004. Why is there a lack of progress improving the number of companies with effective preventive maintenance programs? It is due to three major reasons.
The first is that companies do not focus on preventive maintenance activities because these activities are not "high profile" or "high visibility" activities. This obstacle is one of the first that companies need to overcome when moving from a reactive to a proactive culture. In a reactive culture, the "hero" technician (the individual who can fix problems quickly) is typically highly valued. The technicians then feel that the preventive maintenance activities are not valued; they will opt to focus instead on their "reactive" skills. This problem is not overcome until upper and mid level managers show they value the preventive maintenance activities more than the "fix it fast" activities. Without this management support, the technicians will always perform the activities that are perceived as the highest value.
The second issue is the pandemic originating from the lack of basic maintenance skills. In the majority of companies today, the maintenance technicians lack the skills to identify developing problems with equipment components. They are unable to perform basic lubrication tasks or even to make proper adjustments to their assigned equipment. This means that even when the organizational culture is conducive to change, the basic skills may still prevent the preventive maintenance program from being successful.
The third reason, the lack of a disciplined development process for preventive maintenance, will be discussed in Chapter 2.
Companies still try to excuse their lack of good preventive maintenance by making statements such as "Preventive Maintenance doesn’t work in our industry" or "Our customers don’t care about our maintenance practices." However, in every industry, there are excellent examples of companies with effective preventive maintenance programs. This calls to mind a quote from a classic textbook "Reengineering the Corporation" by Hammer and Champy. They wrote:
In almost every industry, under the same rules and with the same players, the successes of a few companies rebut the excuses of the many.
This quote is true of the maintenance/reliability business, but is especially reflective of preventive maintenance strategies. There are countless testimonials from companies that highlight the benefits of a good preventive maintenance program. The following material shows some examples from many different industries.
Concerning their equipment uptime, one discrete manufacturing company said: "We improved out equipment uptime from the 50%– 60% range to the 95% + range by instituting a preventive maintenance program." –85% uptime acceptable for the plant’s equipment. The Vice President changed the technician’s thinking by asking "What uptime do you expect from your Chevy Blazer?" Uptime at this manufacturing company now averages 94–97%.–$18 per installed horsepower per year–$13 per installed horsepower per year–$9 per installed horsepower per year—for example, the oil is never changed—it will have a shorter useful life. Because industrial equipment is often even more complex than the newer computerized automobiles, service requirements may be extensive and critical. Preventive maintenance programs allow these requirements to be met, reducing the amount of emergency or breakdown work the maintenance organization is required to perform. This same company continued on about the benefits by saying "Before the routine shutdowns for preventive maintenance, we were always behind in the production schedule. After we started regular preventive maintenance shutdowns, we began to increase our production efficiencies. As a result, all operations are now shut down one shift per week for preventive maintenance or to do something to improve the process."
Concerning their equipment uptime, one discrete manufacturing company said: "We improved out equipment uptime from the 50%– 60% range to the 95% + range by instituting a preventive maintenance program." –85% uptime acceptable for the plant’s equipment. The Vice President changed the technician’s thinking by asking "What uptime do you expect from your Chevy Blazer?" Uptime at this manufacturing company now averages 94–97%.–$18 per installed horsepower per year–$13 per installed horsepower per year–$9 per installed horsepower per year—for example, the oil is never changed—it will have a shorter useful life. Because industrial equipment is often even more complex than the newer computerized automobiles, service requirements may be extensive and critical. Preventive maintenance programs allow these requirements to be met, reducing the amount of emergency or breakdown work the maintenance organization is required to perform.
This same company continued on about the benefits by saying "Before the routine shutdowns for preventive maintenance, we were always behind in the production schedule. After we started regular preventive maintenance shutdowns, we began to increase our production efficiencies. As a result, all operations are now shut down one shift per week for preventive maintenance or to do something to improve the process."
The magazine Engineered Systems presented a feature article on maintaining properly levels of humidity in a facility (a typical preventive maintenance function). The article noted, "Both people and equipment can cost companies thousands, if not millions, of dollars if the relative humidity is not maintained within the recommended guidelines." This article provides good insight into the ancillary financial contributions that an effective preventive maintenance program can have on a company’s bottom line.
The magazine Business Week featured an article on an electronic manufacturer, where it was observed "By developing a fixed pattern for preventive maintenance chores and reinforcing them through constant repetition, the company slashed electrical breakdowns by 80% since 1990 and saved millions of dollars." This observation provides yet another example where preventive maintenance contributes to a company’s profitability.
In an anecdotal story, a maintenance technician told one company’s Vice-President of Operations that he considered 80
Certainly, this was one Vice President who knew how to communicate the equipment uptime to the technicians. The value of extending the equipment life by performing proper preventive maintenance was highlighted in an article where it was explained that "Without proper preventive maintenance, the usable life of any piece of equipment is much shorter than its design life, sometimes by as much as 30%." For a company to maximize its return on investment in an asset, it needs to have an effective preventive maintenance program.
Early replacement of expensive assets will force a company to increase its capital appropriations budget. This unnecessary expense detracts from the company’s profitability.
In the facilities sector, energy usage is a large portion of a company’s budget. However, there are large financial impacts that an effective preventive maintenance program can have on energy expenses. For example, consider some statistics for Heating, Ventilation, and Air Conditioning:
- Controls for HVAC that are malfunctioning or simply out of calibration place excessive demands on equipment, causing up to a 20% greater energy demand.
- A condenser surface fouled with 0.015" of scale will increase energy usage by 11%.
- An improperly-tuned boiler will require as much as 25% more fuel to operate.
- A sluggish purge system on a chiller can boost energy consumption by as much as 10%.
If these items are not addressed on a proper preventive maintenance program, the energy consumption is higher than it needs to be (on average by 5% to as much as 10%) for the entire facility or plant.
In another facility example, the following parameters were given:
- 100,000-square-foot building
- 300-ton chiller, 200-hp boiler
- Air volume is 90,000CFM
With this established as a baseline for the size of the facility, the following typical equipment conditions were established:
- Refrigeration condenser are slightly scaled
- Coils and filters in air handlers are dirty
- Purge unit is not fully removing non-condensing gasses
- Controls is not functioning to specifications
- Boiler controls out of trim by 4%
- Cooling tower fans and nozzles are inefficient
All of these conditions are typical when a company does not have a good preventive maintenance program. The results were calculated and it was determined that the facility would be wasting approximately $25,500 per year in energy costs.
Another interesting study, published by the magazine Preventive/Predictive Maintenance Technology, categorized companies into three major classifications. These were:
- In a breakdown mode
- In a preventive mode
- In a predictive mode
After classifying each of the organizations, the installed horsepower for each of the plants was determined. The installed horsepower was then used in the denominator to calculate the maintenance cost (the numerator) per installed horsepower. The results were:
- In a breakdown mode, $17
- In a preventive mode, $11
- In a predictive mode, $7
This clearly shows that the more advanced a company becomes in their maintenance practices, the lower the overall maintenance costs become. While it may seem apparent that the maintenance costs (numerator) was impacted, the installed horsepower (denominator) was also lowered. The reason is the well-maintained and reliable equipment requires less redundancy. For example, the company may only need two compressors at the plant instead of three due to the reliability of the primary compressors.
Furthermore, they may not need a third air compressor because the preventive maintenance program eliminates air leaks, reducing the demand form compressed air.
Finally, one other area of consideration covers the legal ramifications for companies without good preventive maintenance programs. For example, Modern HealthCare’s magazine Facility Operation highlighted an article about hospitals with poor preventive maintenance program. In part, it noted "There are three hospitals with lawsuits filed against them, which had weak or no preventive maintenance programs at all." This statement highlights the fact that good preventive maintenance programs are essential to maintain a good standing in the community, whether a company is a hospital or any industrial type of a plant.
Additional Justification for Preventive Maintenance
Increased automation in industry requires preventive maintenance. The more automated that the equipment is, the more components there are that and fail and cause the entire piece of equipment to be taken out of service. Routine services and adjustments can keep the automated equipment in the proper condition to provide uninterrupted service.
Just-In-Time manufacturing (JIT), which is becoming more common in the United States today, requires that the materials being produced into finished goods arrive at each step of the process just in time to be processed. JIT eliminates unwanted and unnecessary inventory. However, JIT also requires high equipment availability. Equipment must be ready to operate when a production demand is made; it cannot break down during the operating cycle. Without the buffer inventories (and high costs) traditionally found in U.S. processes, preventive maintenance is necessary to prevent equipment downtime. If equipment does fail during an operational cycle, there will be delays in making the product and delivering it to the customer. In these days of intense competitiveness, delays in delivery can result in lost customers. Preventive maintenance is required so that equipment is reliable enough to develop a production schedule that, in turn, is dependable enough to give a customer firm delivery dates.
In many cases, when equipment is not reliable enough to schedule to capacity, companies will purchase another identical piece of equipment. Then if the first one breaks down on a critical order, they have a back-up. With the price of equipment today, however, this back-up can be an expensive solution to a common problem. Unexpected equipment failures can be reduced, if not almost eliminated, by a good preventive maintenance program. With equipment availability at its highest possible level, redundant equipment will not be required.
Reducing insurance inventories has an impact on maintenance and operations. Maintenance carries many spare parts in case the equipment breaks down. Operations carry additional spare parts in process inventory for the same reason. Good preventive maintenance programs allow the maintenance departments to know the condition of the equipment and prevent breakdowns. The savings from reducing (in some cases, eliminating) insurance inventories can often finance the entire preventive maintenance program.
In manufacturing and process operations, each production process is dependent on the previous process. In many manufacturing companies, these processes are divided into cells. Each cell is viewed as a separate process or operation. Furthermore, each cell is dependent on the previous cell for the necessary materials to process. An uptime of 97% might be acceptable for a stand-alone cell. But if ten cells, each with a 97% uptime, are tied together to form a manufacturing process, the total uptime for the process is only 73% (see Figure 1-4).
This level is unacceptable in any process. Preventive maintenance must be used to raise uptime to even higher levels. Performing needed services on the equipment when required leads to longer equipment life. Returning to an earlier example, an automobile that is serviced at prescribed intervals will deliver a long and useful life. However, if it is neglected
Preventive maintenance reduces the energy consumption for the equipment to its lowest possible level. Well-serviced equipment requires less energy to operate because all bearings, mechanical drives, and shaft alignment receive timely attention. By reducing these drains on the energy used by a piece of equipment, overall energy usage in a plant can decrease by 5% to as much as 11%.
Quality is another cost reduction that helps justify a good preventive maintenance program. Higher product quality is a direct result of a good preventive maintenance program. Poor, out-of-tolerance equipment never produces a quality product. World class manufacturing experts recognize that rigid, disciplined preventive maintenance programs produce high quality products. To achieve the quality required to compete in the world markets today, preventive maintenance programs are required. If operations or facilities were organized and operated the way the majority of maintenance organizations are, we would never get any products or services when we needed them. An attitude change is necessary to give maintenance the priority it needs. This change also includes management’s viewpoint. Modern management tends to sacrifice long-term planning for short-term returns. This attitude causes problems for maintenance organizations, leading to reactive maintenance with few or no controls.
When maintenance is given its due attention, it can become a profit center, producing positive, bottom line improvements to the company. No preventive maintenance program will be truly successful without strong support from the facility’s upper management. Many decisions must be made by plant management to allow time to perform maintenance on the equipment instead of running it wide open. Without upper management’s commitment to the program, PM will either never be performed, or it will be performed too little, too late. Thus, management support is the cornerstone for any successful PM program.