Guide to Predictive Maintenance--Tribology

Tribology is the general term that refers to design and operating dynamics of the bearing-lubrication-rotor support structure of machinery. Several tribology techniques can be used for predictive maintenance: lubricating oil analysis, spectrographic analysis, ferrography, and wear particle analysis.

Lubricating oil analysis, as the name implies, is an analysis technique that determines the condition of lubricating oils used in mechanical and electrical equipment. It’s not a tool for determining the operating condition of machinery. Some forms of lubricating oil analysis will provide an accurate quantitative breakdown of individual chemical elements, both oil additive and contaminates, contained in the oil. A comparison of the amount of trace metals in successive oil samples can indicate wear patterns of oil-wetted parts in plant equipment and will provide an indication of impending machine failure.

Until recently, tribology analysis has been a relatively slow and expensive process.

Analyses were conducted using traditional laboratory techniques and required extensive, skilled labor. Microprocessor-based systems are now available that can automate most of the lubricating oil and spectrographic analysis, thus reducing the manual effort and cost of analysis.

The primary applications for spectrographic or lubricating oil analysis are quality control, reduction of lubricating oil inventories, and determination of the most cost effective interval for oil change. Lubricating, hydraulic, and dielectric oils can be periodically analyzed using these techniques, to determine their condition. The results of this analysis can be used to determine if the oil meets the lubricating requirements of the machine or application. Based on the results of the analysis, lubricants can be changed or upgraded to meet the specific operating requirements.

In addition, detailed analysis of the chemical and physical properties of different oils used in the plant can, in some cases, allow consolidation or reduction of the number and types of lubricants required to maintain plant equipment. Elimination of unnecessary duplication can reduce required inventory levels and therefore maintenance costs.

As a predictive maintenance tool, lubricating oil and spectrographic analysis can be used to schedule oil change intervals based on the actual condition of the oil. In mid size to large plants, a reduction in the number of oil changes can amount to a considerable annual reduction in maintenance costs. Relatively inexpensive sampling and testing can show when the oil in a machine has reached a point that warrants change.

The full benefit of oil analysis can only be achieved by taking frequent samples and trending the data for each machine in the plant. It can provide a wealth of information on which to base maintenance decisions; however, major payback is rarely possible without a consistent program of sampling.

LUBRICATING OIL ANALYSIS

Oil analysis has become an important aid to preventive maintenance. Laboratories recommend that samples of machine lubricant be taken at scheduled intervals to deter mine the condition of the lubricating film that is critical to machine-train operation.

Oil Analysis Tests

Typically, the following tests are conducted on lube oil samples:

Viscosity---Viscosity is one of the most important properties of lubricating oil. The actual viscosity of oil samples is compared to an unused sample to determine the thinning or thickening of the sample during use. Excessively low viscosity will reduce the oil film strength, weakening its ability to prevent metal-to-metal contact. Excessively high viscosity may impede the flow of oil to vital locations in the bearing support structure, reducing its ability to lubricate.

Contamination:

Contamination of oil by water or coolant can cause major problems in a lubricating system. Many of the additives now used in formulating lubricants contain the same elements that are used in coolant additives. Therefore, the laboratory must have an accurate analysis of new oil for comparison.

Fuel Dilution:

Dilution of oil in an engine, caused by fuel contamination, weakens the oil film strength, sealing ability, and detergency. Improper operation, fuel system leaks, ignition problems, improper timing, or other deficiencies may cause it. Fuel dilution is considered excessive when it reaches a level of 2.5 to 5 percent.

Solids Content:

The amount of solids in the oil sample is a general test. All solid materials in the oil are measured as a percentage of the sample volume or weight. The presence of solids in a lubricating system can significantly increase the wear on lubricated parts. Any unexpected rise in reported solids is cause for concern.

Fuel Soot:

Soot caused by the combustion of fuels is an important indicator for oil used in diesel engines and is always present to some extent. A test to measure fuel soot in diesel engine oil is important because it indicates the fuel-burning efficiency of the engine.

Most tests for fuel soot are conducted by infrared analysis.

Oxidation:

Oxidation of lubricating oil can result in lacquer deposits, metal corrosion, or oil thickening. Most lubricants contain oxidation inhibitors; however, when additives are used up, oxidation of the oil begins. The quantity of oxidation in an oil sample is measured by differential infrared analysis.

Nitration:

Nitration results from fuel combustion in engines. The products formed are highly acidic, and they may leave deposits in combustion areas. Nitration will accelerate oil oxidation. Infrared analysis is used to detect and measure nitration products.

Total Acid Number (TAN):

The acidity of the oil is a measure of the amount of acid or acid-like material in the oil sample. Because new oils contain additives that affect the TAN, it’s important to compare used oil samples with new, unused oil of the same type. Regular analysis at specific intervals is important to this evaluation.

Total Base Number (TBN):

The base number indicates the ability of oil to neutralize acidity. The higher the TBN, the greater its ability to neutralize acidity. Typical causes of low TBN include using the improper oil for an application, waiting too long between oil changes, overheating, and using high-sulfur fuel.

Particle Count:

Particle count tests are important to anticipating potential system or machine problems. This is especially true in hydraulic systems. The particle count analysis made as a part of a normal lube oil analysis is different from wear particle analysis. In this test, high particle counts indicate that machinery may be wearing abnormally or that failures may occur because of temporarily or permanently blocked orifices. No attempt is made to determine the wear patterns, size, and other factors that would identify the failure mode within the machine.

Spectrographic Analysis:

Spectrographic analysis allows accurate, rapid measurements of many of the elements present in lubricating oil. These elements are generally classified as wear metals, contaminants, or additives. Some elements can be listed in more than one of these classifications. Standard lubricating oil analysis does not attempt to deter mine the specific failure modes of developing machine-train problems. Therefore, additional techniques must be used as part of a comprehensive predictive maintenance program.

Wear Particle Analysis

Wear particle analysis is related to oil analysis only in that the particles to be studied are collected by drawing a sample of lubricating oil. Whereas lubricating oil analysis determines the actual condition of the oil sample, wear particle analysis provides direct information about the wearing condition of the machine-train. Particles in the lubricant of a machine can provide significant information about the machine's condition. This information is derived from the study of particle shape, composition, size, and quantity. Wear particle analysis is normally conducted in two stages.

The first method used for wear particle analysis is routine monitoring and trending of the solids content of machine lubricant. In simple terms, the quantity, composition, and size of particulate matter in the lubricating oil indicates the machine's mechanical condition. A normal machine will contain low levels of solids with a size less than 10 microns. As the machine's condition degrades, the number and size of particulate matter increases. The second wear particle method involves analysis of the particulate matter in each lubricating oil sample.

Types of Wear:

Five basic types of wear can be identified according to the classification of particles: rubbing wear, cutting wear, rolling fatigue wear, combined rolling and sliding wear, and severe sliding wear. Only rubbing wear and early rolling fatigue mechanisms generate particles that are predominantly less than 15 microns in size.

Rubbing Wear. Rubbing wear is the result of normal sliding wear in a machine. During a normal break-in of a wear surface, a unique layer is formed at the surface. As long as this layer is stable, the surface wears normally. If the layer is removed faster than it’s generated, the wear rate increases and the maximum particle size increases. Excessive quantities of contaminant in a lubrication system can increase rubbing wear by more than an order of magnitude without completely removing the shear mixed layer.

Although catastrophic failure is unlikely, these machines can wear out rapidly.

Impending trouble is indicated by a dramatic increase in wear particles.

Cutting Wear Particles. Cutting wear particles are generated when one surface penetrates another. These particles are produced when a misaligned or fractured hard surface produces an edge that cuts into a softer surface, or when abrasive contaminant becomes embedded in a soft surface and cuts an opposing surface. Cutting wear particles are abnormal and are always worthy of attention. If they are only a few microns long and a fraction of a micron wide, the cause is probably contamination. Increasing quantities of longer particles signals a potentially imminent component failure.

Rolling Fatigue. Rolling fatigue is associated primarily with rolling contact bearings and may produce three distinct particle types: fatigue spall particles, spherical particles, and laminar particles. Fatigue spall particles are the actual material removed when a pit or spall opens up on a bearing surface. An increase in the quantity or size of these particles is the first indication of an abnormality. Rolling fatigue does not always generate spherical particles, and they may be generated by other sources. Their presence is important in that they are detectable before any actual spalling occurs. Laminar particles are very thin and are formed by the passage of a wear particle through a rolling contact. They often have holes in them. Laminar particles may be generated through out the life of a bearing, but at the onset of fatigue spalling the quantity increases.

Combined Rolling and Sliding Wear. Combined rolling and sliding wear results from the moving contact of surfaces in gear systems. These larger particles result from tensile stresses on the gear surface, causing the fatigue cracks to spread deeper into the gear tooth before pitting. Gear fatigue cracks don’t generate spheres. Scuffing of gears is caused by too high a load or speed. The excessive heat generated by this condition breaks down the lubricating film and causes adhesion of the mating gear teeth.

As the wear surfaces become rougher, the wear rate increases. Once started, scuffing usually affects each gear tooth.

Severe Sliding Wear. Excessive loads or heat causes severe sliding wear in a gear system. Under these conditions, large particles break away from the wear surfaces, causing an increase in the wear rate. If the stresses applied to the surface are increased further, a second transition point is reached. The surface breaks down, and catastrophic wearenses.

Normal spectrographic analysis is limited to particulate contamination with a size of 10 microns or less. Larger contaminants are ignored. This fact can limit the benefits derived from the technique.

Ferrography

This technique is similar to spectrography, but there are two major exceptions. First, ferrography separates particulate contamination by using a magnetic field rather than by burning a sample as in spectrographic analysis. Because a magnetic field is used to separate contaminants, this technique is primarily limited to ferrous or magnetic particles.

The second difference is that particulate contamination larger than 10 microns can be separated and analyzed. Normal ferrographic analysis will capture particles up to 100 microns in size and provides a better representation of the total oil contamination than spectrographic techniques.

Oil Analysis Costs and Uses

There are three major limitations with using tribology analysis in a predictive maintenance program: equipment costs, acquiring accurate oil samples, and interpretation of data.

The capital cost of spectrographic analysis instrumentation is normally too high to justify in-plant testing. The typical cost for a microprocessor-based spectrographic system is between $30,000 and $60,000; therefore, most predictive maintenance pro grams rely on third-party analysis of oil samples.

Simple lubricating oil analysis by a testing laboratory will range from about $20 to $50 per sample. Standard analysis normally includes viscosity, flash point, total insolubles, total acid number (TAN), total base number (TBN), fuel content, and water content. More detailed analysis, using spectrographic or ferrographic techniques, that includes metal scans, particle distribution (size), and other data can cost more than $150 per sample.

A more severe limiting factor with any method of oil analysis is acquiring accurate samples of the true lubricating oil inventory in a machine. Sampling is not a matter of opening a port somewhere in the oil line and catching a pint sample. Extreme care must be taken to acquire samples that truly represent the lubricant that will pass through the machine's bearings. One recent example is an attempt to acquire oil samples from a bullgear compressor. The lubricating oil filter had a sample port on the clean (i.e., downstream) side; however, comparison of samples taken at this point and one taken directly from the compressor's oil reservoir indicated that more contaminants existed downstream from the filter than in the reservoir. Which location actually represented the oil's condition? Neither sample was truly representative. The oil filter had removed most of the suspended solids (i.e., metals and other insolubles) and was therefore not representative of the actual condition. The reservoir sample was not representative because most of the suspended solids had settled out in the sump.

Proper methods and frequency of sampling lubricating oil are critical to all predictive maintenance techniques that use lubricant samples. Sample points that are consistent with the objective of detecting large particles should be chosen. In a recirculating system, samples should be drawn as the lubricant returns to the reservoir and before any filtration occurs. Don’t draw oil from the bottom of a sump where large quantities of material build up over time. Return lines are preferable to reservoir as the sample source, but good reservoir samples can be obtained if careful, consistent practices are used. Even equipment with high levels of filtration can be effectively monitored as long as samples are drawn before oil enters the filters. Sampling techniques involve taking samples under uniform operating conditions. Samples should not be taken more than 30 minutes after the equipment has been shut down.

Sample frequency is a function of the mean time to failure from the onset of an abnormal wear mode to catastrophic failure. For machines in critical service, sampling every 25 hours of operation is appropriate; however, for most industrial equipment in continuous service, monthly sampling is adequate. The exception to monthly sampling is machines with extreme loads. In this instance, weekly sampling is recommended.

Understanding the meaning of analysis results is perhaps the most serious limiting factor. Results are usually expressed in terms that are totally foreign to plant engineers or technicians. Therefore, it’s difficult for them to understand the true meaning of results, in terms of oil or machine condition. A good background in quantitative and qualitative chemistry is beneficial. At a minimum, plant staff will require training in basic chemistry and specific instruction on interpreting tribology results.

SETTING UP AN EFFECTIVE PROGRAM

Many plants have implemented oil analysis programs to better manage their equipment and lubricant assets. Although some have received only marginal benefits, a few have reported substantial savings, cost reductions, and increased productivity. Success in an oil analysis program requires a dedicated commitment to understanding the equipment design, the lubricant, the operating environment, and the relationship between test results and the actions to be performed.

In North America, millions of dollars have been invested in oil analysis programs with little or no financial return. The analyses performed by original equipment manufacturers or lubricant manufacturers are often termed as "free." In many of these cases, the results from the testing have little or no effect on the maintenance, planning, and/or evaluated equipment's condition. The reason is not because this service is free, or the ability of the laboratory, or the effort of the lubricant supplier to provide value-added service. The reason is a lack of knowledge-a failure to understand the value lost when a sample is not representative of the system, and the inability to turn equipment and lubricant data into useful information that guides maintenance activities.

More important is the failure to understand the true equirements and operating characteristics of the equipment. This dilemma is not restricted to the companies receiving "free" analysis. In many cases, unsuccessful or ineffective oil analysis programs are in the same predicament. Conflicting information from equipment suppliers, laboratories, and lubricant manufacturers have clouded the true requirements of equipment to the maintenance personnel or individuals responsible for the program.

The following steps provide a guideline to implementing an effective lubricating oil analysis program.

Equipment Audit

An equipment audit should be performed to obtain knowledge of the equipment, its internal design, the system design, and the present operating and environmental conditions. Failure to gain a full understanding of the equipment's operating needs and conditions undermines the technology. This information is used as a reference to set equipment targets and limits, while supplying direction for future maintenance tasks.

The information should be stored under an equipment-specific listing and made accessible to other predictive technologies, such as vibration analysis.

Equipment Criticality:

Safety, environmental concerns, historical problems, reliability, downtime costs, and repairs must all be considered when determining the equipment to be included in a viable lubricating oil analysis program. Criticality should also be the dominant factor used to determine the frequency and type of analyses that will be used to monitor plant equipment and systems.

Equipment Component and System Identification:

Collecting, categorizing, and evaluating all design and operating manuals including schematics are required to understand the complexity of modern equipment. Original equipment manufacturers' assistance in identifying the original bearings, wear surfaces, and component metallurgy will take the guesswork out of setting targets and limits. This information, found in the operating and maintenance manuals furnished with each system, will aid in future troubleshooting. Equipment nameplate data with accurate model and serial numbers allow for easy identification by the manufacturer to aid in obtaining this information.

Care should be exercised in this part of the evaluation. In many cases, critical plant systems and equipment has been modified one or more times over their installed life.

Information obtained from operating and maintenance manuals or directly from the original equipment manufacturer must be adjusted to reflect the actual installed equipment.

Operating Parameters:

Equipment designers and operating manuals reflect the minimum requirements for operating the equipment. These include operating temperature, lubricant requirements, pressures, duty cycles, filtration requirements, and other parameters that directly or indirectly impact reliability and life-cycle cost. Operating outside these parameters will adversely impact equipment reliability and the lubricant's ability to provide adequate protection. It may also require modifications and/or additions to the system to allow the component to run within an acceptable range.

Operating Equipment Evaluation:

A visual inspection of the equipment is required to examine and record the components used in the system, including filtration, breathers, coolers, heaters, and so on.

This inspection should also record all operating temperatures and pressures, duty cycles, rotational direction, rotating speeds, filter indicators, and the like. Tempera ture reading of the major components is required to reflect the component operating system temperature. A noncontract, infrared scanner may be used to obtain accurate temperature readings.

Operating Environment:

Hostile environments or environmental contamination is usually not considered when the original equipment manufacturer establishes equipment operating parameters.

These conditions can influence lubricant degradation, eventually resulting in damaged equipment. All environmental conditions such as mean temperature, humidity, and all possible contaminants must be recorded.

Maintenance History:

Reliable history relating to wear and lubrication-related failures can assist in the decision-making process of adjusting and tightening targets and limits. These targets should allow for advanced warnings of historical problems and possible root-cause detection.

Oil Sampling Location:

A sampling location should be identified for each piece of equipment to allow for trouble-free, repetitive, and representative sampling of the health of the equipment and the lubricant. This sampling method should allow the equipment to be tested under its actual operating condition while being unobtrusive and safe for the technician.

New Oil Baseline:

A sample of the new lubricant is required to provide a baseline or reference point for physical and chemical properties of the lubricant. Lubricants and additive packages can change over time, so adjusting lubrication targets and alarms should reflect these changes.

Cooling Water Baseline:

A sample of the cooling water, when used, should be collected, tested, and analyzed to obtain its physical and chemical properties. These results are used to adjust the lubricant targets and to reflect and provide early warnings of leaks in the coolers.

Targets and Alarms:

Original equipment manufacturing (OEM) operating specifications or the guidelines of a recognized governing body can be used in setting the minimum alarms. These alarms must be set considering all of the previously collected information. These set tings must provide early detection of contaminants, lubricant deterioration, and present equipment health. These achievable targets should be set to supply an early warning of any anomalies that allow corrective actions to be planned, scheduled, and performed with little or no effect on production schedules.

Database Development:

A database should be developed to organize equipment information and the collected data along with the equipment-specific targets and alarms. This database should be easy to use. The end user must have control of the targets and limits in order to reflect the true equipment-specific conditions within the plant.

In ideal circumstances, the database should be integrated into a larger predictive maintenance database that contains all information and data that are useful to the predictive maintenance analysts. Combining vibration, lubricating oil, infrared, and other predictive data into a single database will greatly enhance the analysts' ability to detect and correct incipient problems and will ensure that maximum benefits are obtained from the program.

Lubricant Audit Process

Equipment reliability requires a lubricant that meets and maintains specific physical, chemical, and cleanliness requirements. A detailed trail of a lubricant is required, beginning with the oil supplier and ending after disposal of spent lubricants. Sampling and testing of the lubricants are important to validate the lubricant condition through out its life cycle.

Lubricant Requirements:

Information from the equipment audit supplies the physical and chemical requirements of the lubricant to operate within the equipment. After ensuring that the correct type of lubricant is in use, the audit information ensures that the correct viscosity is used in relationship to the true operating temperature.

Lubricant Supplier:

Quality control programs implemented by the lubricant manufacturer should be questioned and recorded when evaluating the supplier. Sampling and testing new lubricants before dispensing ensures that the vendor has supplied the correct lubricant.

Oil Storage:

Correct labeling, including materials safety display system (MSDS), must be clearly installed to ensure proper use of the contents. Proper stock rotation and storage methods must be considered to prevent the possibility of the degradation of the physical, chemical, and cleanliness requirements of the lubricant throughout the storage and dispensing phase.

Handling and Dispensing:

Handling and dispensing methods must ensure that the health and cleanliness of the lubricant meet the specifications required by the equipment. All opportunities for contamination must be eliminated. Pre-filtering of all lubricants should be performed to meet the specific equipment requirements. Preventive maintenance activities involving oil drains, top-ups, sweetening, flushing, or reclaiming. Information should be recorded and forwarded to the individual responsible for the oil analysis program group in a timely manner. Record keeping of any activity involving lubricant consumption, lubricant replacement, and/or lubricant top-ups must be implemented and maintained.

Waste Oil:

Oil deemed unfit for equipment usage must be disposed of in the correct storage container for that type of lubricant and properly marked and labeled. The lubricant must then be classified for the type of disposal and removed from the property without delay. Long storage times allow for the introduction of contaminants and could result in reclassification.

Baseline Signature

The baseline signature should be designed to gather and analyze all data required to determine the current health of the equipment and lubricant in relationship to the alarms and targets derived from the audit. The baseline signature or baseline reading requires a minimum of three consecutive, timely samples, preferably in a short duration (i.e., one per month) to effectively evaluate the present trend in the equipment condition.

Equipment Evaluation:

Observing, recording, and trending operating equipment along with the environmental conditions, including equipment temperature readings, are required at the same time as the lubricant sample is obtained. This information is used in troubleshooting or detecting the root-cause of any anomalies discovered.

Sampling:

A sampling method will be supplied to extract a sample for the equipment that will be repetitive and representative of the health of the equipment and the lubricant. Improper sampling methods or locations are the primary reason that many oil analysis programs fail to generate measurable benefits. Extreme care must be take to ensure that the correct location and best sampling practices are universally applied and followed.

Testing:

Equipment-specific testing assigned during the audit stage will supply the required data to effectively report the health of the lubricant and equipment. This testing must be performed without delay.

Exception Testing

Sample data that report an abnormal condition or an alarm or target that has been exceeded requires exception testing. This will help pinpoint the root-cause of the anomaly. The oil analysis technician should authorize these tests, which are not to be considered as routine testing.

Data Entry:

The recorded data should be installed into a system that allows for trending and future reference, along with report-generation opportunities.

Baseline Signature Review:

After all tests are performed, the data are systematically reviewed. Combining the hard data gathered in the system audit with experience, the root-causes of potential failures can be pinpointed. A report should then be generated containing all test results, along with a list of recommendations. This report should include testing frequencies and any required improvements necessary to bring the present condition of the lubricant and/or the operating conditions to within the acceptable targets.

Monitoring

These activities are performed to collect and trend any early signs of deteriorating lubricant and equipment condition and/or any changes in the operating environment.

This information should be used as a guide for the direction of any required maintenance activities, which will ensure safe, reliable, and cost-effective operation of the plant equipment.

Routine Monitoring:

Routine monitoring is designed to collect the required data to competently inform the predictive maintenance analysts or maintenance group of the present condition of its lubricants and equipment. At this time, observations in the present operating and environmental conditions should be recorded. This schedule of the routine monitoring must remain timely and repetitive for effective trending.

Routes:

A route is designed so that an oil sample can be collected in a safe, unobtrusive manner while the equipment is running at its typical full-load levels. These routes should allow enough time for the technician to collect, store, analyze, and report anomalies before starting another route. If the samples are sent to an outside laboratory, time should be allocated for analyzing and recording all information once the data are received.

Frequency of Monitoring:

The frequency of the inspections should be based on the information obtained in the audit and baseline signature stages of program development. These frequencies are equipment specific and can be changed as the program matures or a degrading condition is observed.

Tests:

Testing the current condition of critical plant equipment is the goal of the oil analysis program. Technicians who report alarms proceed into exception testing mode (i.e., troubleshooting) that pinpoints the root-cause of the anomaly. At this stage of inter facing, other predictive technologies should be implemented, if applicable. Testing by the maintenance group or the laboratory group requires a maximum of a 24-hour turnaround on exception tests. A 48-hour turnaround on routine tests supplied by the laboratory would be considered acceptable.

Post-Overhaul Testing:

After completing an overhaul or replacement of a new component, certain oil analysis tests should be performed to ensure that the lubricant meets all equipment requirements. These tests become a quality check for maintenance activities required to perform the overhaul and supply an early warning of problem conditions.

Contractor Overhaul Templates:

Components not overhauled in an in-house program should have a guideline or tem plate of the overhaul procedures and required component replacement parts. These templates are a quality control measure to ensure that the information in the audit data base is kept up-to-date but also to ensure compatibility of components and lubricants presently used.

Data Analysis:

After all data are collected from the various inspections and tests, the alarms and targets should alert the technician to any anomalies. Instinct combined with sensory and inspection data should warrant further testing. Using the technicians' wealth of equipment knowledge along with the effects of the operating environment, is critical to the success of this program.

Root-Cause Analysis:

Repetitive failures and/or problems that require a solution to alleviate the unknown cause require testing to identify the root-cause of the problem. All the data and information collected in the audit, baseline signature, and monitoring stages of the program will assist in identifying the underlying problem.

Reports:

All completed routes, exception testing, and root-cause analysis require a report to be filed with the predictive maintenance specialist outlining the anomaly identified and the corrective actions required. These reports should be filed under specific equipment cataloging for easy, future reference. The reports should include:

• Specific equipment identification

• Data of sample

• Date of report

• Present condition of equipment and lubricant

• Recommendations

• Sample test result data

• Analyst's name

Use of a computerized system allows the reports to be designed as required and, in many cases, will provide an equipment condition overview report.

Program Evaluation

Predictive maintenance tasks are based on condition measurements and performance on the basis of defects before outright failure impacts safety and production. Well managed predictive maintenance programs are capable of identifying and tracking anomalies. Success is often measured by factors such as number of machines monitored, problems recognized, number of saves, and other technical criteria. Few maintenance departments have successfully translated technical and operating results gained by predictive maintenance into a value and benefits in the financial terms necessary to ensure continued management support. Without credible financial links to the facility and organization's business objectives, technical criteria are essentially useless. As a result, many successful predictive maintenance programs are being cur tailed or eliminated as a cost-savings measure. Dedication to an oil analysis program requires documenting all the obtained cost benefits associated with a properly implemented program.

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