Fluid Contaminant Control as Essential Technique to Implement Proactive Maintenance for Bearing Elements
Fluid Contaminant Control as an Essential Technique
to Implement Proactive Maintenance for Bearing Elements
PT. Filtagreen Global, Indonesia
Maintenance brings a work to ensure bearing element runs as its function. A good
maintenance management system is able to prevent health and safety problems, result in low
cost, and high quality of life. On the other hand, proactive maintenance is not like
predictive/preventive maintenance due to proactive maintenance is aimed for failure root
cause, not just symptoms. According to the bearing division of TRW that contamination is
the number one cause of bearing damage that leads premature removal. Furthermore, the
amount of damage caused by solid contaminant passing between the rolling and sliding
surface of an anti-friction bearing is proportional to the size and concentration of
contaminants. Therefore, this is important to do particle counting on lube oil samples. Fluid
contaminant level must be frequently monitored to verify filter performance and to provide
the essential “feedback” that gives integrity to a contamination control program.
: Fluid contaminant control, proactive maintenance, failure root cause, particle
counting, filter, bearing element
Commonly, operation and maintenance are an integrated process that covers the
performance of work to deliver a proper function of bearing element. Maintenance brings a
work to ensure the bearing element runs as its function. The maintenance scheme forms a
maintenance management that covers planning, organizing, monitoring, and evaluating
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maintenance activities and their costs. Therefore, a good maintenance management system is
able to prevent health and safety problems, result in lower cost, and higher quality of life.
On the other hand, the symptom of failure in the bearing element masks the root cause of
failure. For example, a sudden bearing failure is often blamed on poor quality lubricant. In
the fact, the root cause is often contamination in lubricant (bad filter) of bearing (Figure 1).
According to the bearing division of TRW that contamination is the number one cause of
bearing damage that leads premature removal. Furthermore, Machine Design Magazine
reports that less than 10 percent of all rolling-element bearings reach the fatigue limit because
contamination usually causes wear earlier. Therefore, fluid contamination level must be
frequently monitored to verify filter performance and to provide the essential “feedback” that
gives integrity to a contamination control program.
Figure 1. Contamination in lubricant (Harker., 2001)
Commonly, there are three categories in the maintenance such as corrective, preventive,
and predictive maintenances. Corrective maintenance is intentionally withheld until bearing
element stops working or starts falling, where maintenance is then performed as necessitated
such as lubricate bearing when they become noisy or vibration occurs. In the corrective
maintenance, a conscious decision is made to neglect bearing element falls. This maintenance
strategy is referred to as “Run to Failure” (RFT). Whereas, preventive maintenance is a
planned maintenance such as cleaning of machine, fuel, and oil. On the other hand, predictive
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maintenance is condition based maintenance such as indicator of oil pressure (lubricant stop).
In the preventive maintenance, the bearing element is subjected to a regular of
maintenance tasks such as inspections, cleaning, lubrication, and adjustment. The frequency
of preventive maintenance is generally constant and is usually based on the expected life of
the component being maintained. The preventive maintenance is carried out at predefined
intervals in attempt to reduce bearing element failure or to ensure a consistent appearance of
bearing element. As the bearing element age, the frequency and number of checkpoints may
need to be re-evaluated.
On the other hand, the predictive maintenance (also known as condition monitoring)
delivers additional benefit over preventive maintenance. The main benefit of predictive
maintenance is the availability of earlier warning reduces the number of breakdown
catastrophic failure. Predictive maintenance is usually implemented concurrently with
Furthermore, the proactive maintenance is the most important to achieve the predictable
cost and better performance. The approach of proactive maintenance replaces the
maintenance philosophy of “failure reactive” to be “failure proactive”. Proactive maintenance
is not like predictive/preventive maintenance due to proactive maintenance is aimed at failure
root cause, not just symptoms.
Physically, wear occurs as a result of contamination due to dust, metallic particle, or
condensation. Contaminant is inevitable in any non-sealed lubrication system. High
contamination level is linear to the level of wear which cause a premature failure. Therefore,
the increase of wear metal causes the abrasive process to be irreversible. The exorbitant wear
metal level should have been detected after catastrophic failure.
There are many types of contaminant-induced failures in machinery and the most
common are wear, erosion, and corrosion. Contaminant involved includes solid particle,
moisture, air, chemicals, and other materials foreign to the system (Figure 2). However,
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abrasive wear caused by solid particle is the result of particles (too small to be seen) that cut
plow and sliding surfaces.
Figure 2. Contamination in lubrication system (TESTOIL., 2012)
Furthermore, contaminant is clearly the most common and serious failure culprit.
According to Caterpillar that dirt and contamination are far the number one causes of
hydraulic system failures. The amount of damage caused by solid contaminant passing
between the rolling and sliding surface of an anti-friction bearing is proportional to the size
and concentration of the contaminants. Therefore, J. I. Case states that the bearing element
must be kept clean (spotlessly clean) in order to achieve the productivity they are capable of.
Whereas, Oklahoma State University reports that when fluid maintained 10 times cleaner
then hydraulic life can be extended by 50 times.
In the fact, most machinery is fluid dependent system. Whereas, there are many types of
contaminant-induced failures in machinery such as wear, erosion, and corrosion. Fluid (such
as lubricant, hydraulic fluid, coolant, fuel, and air) brings contaminants into the bearing
element and transports the contaminant within the bearing element. The most serious of
contaminant is abrasive wear caused by solid particles. The abrasive wear is the result of
particles (too small to be seen) that cut and plow rolling and sliding surfaces.
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Physically, high contamination is a correctable condition. The abnormal presence of
contamination is a system can be described as an incipient failure, where the machine is not
currently experiencing loss of performance or component degradation (the condition that
leads to failure and shortened service life are present and untenable). On the other hand, the
U.S. Department of Defense states that approximately 30 percent of all engine failure is
caused by metal particulate contamination in lubricating oil system. The oil film thickness,
between which particles can reach and attack surface are typically in the 10-micron range.
Whereas, according to Cummins Engine, particles smaller than 10 microns generated about
3.5 times more wear (rods, rings, and main bearings) than 10 microns. In addition, in diesel
engine, high local stresses associated with sliding contact wear in abrasive removal of
material surface. When load is concentrated on the effective area of a small particle, the
resulting surface stresses can be greater than 500,000 psi, far beyond the elastic limit of
substrate materials. Therefore, filter with high efficiency is specified for engine lube oils
(Figure 3). The lube oil contamination is the primary cause of engine wear that begins what is
referred to as the chain reaction to failure.
Figure 3. Filter for engine lube oils with high efficiency (TESTOIL., 2012)
There are some considerations filter such as temperature change, fluid viscosity,
pressure, flow (surge), vibration, and fatigue. Therefore, fluid contamination level must be
frequently monitored to verify filter performance and to provide the essential “feedback” that
gives integrity to a contamination control program. On the other hand, the challenge task is to
remove particle from fluid at the same rate which they are entering (ingression). Other
common problems such as filter bypass valves that get stuck open, damaged or missing filter
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gaskets, and filter which installed backward or crooked. The logical first-approach to
proactive maintenance is the implementation of rigorous contamination control programs for
lubrication fluid, hydraulic fluid, coolant, air, and fuel.
Simplify, this is important to do particle counting on lube oil samples. Furthermore, wear
metal analysis and elemental analysis are too often confused as being indicative of actual
particle sizes and concentrations in lube oils. Therefore, only accurate particle counting
devices can determine this.
The fundamental purpose for contamination control and contamination monitoring is to
achieve greatly extended mean time between failures (MTBF). Furthermore, there are three
baselines in the system monitoring, such as:
1. Routine contaminant monitoring to deliver the major system monitoring
2. Set the contaminant level scale to represent the abnormal condition for further
3. Description of the contamination source
Steps to implement proactive contamination control maintenance
Furthermore, there are four steps to implement proactive maintenance, such as:
1. Using the Contamination Life Index to assist the target fluid cleanliness level
2. Select and install filtration system to achieve the target cleanliness level
3. Monitor fluid cleanliness at regular intervals to verify that target is achieved
4. Adjust filtration to stabilize the target cleanliness
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Result and discussion
This paper appears that the contaminant level is extremely dynamic. Whereas, fluid
contaminant monitoring can be accomplish in the field or plant by extracting samples of fluid
into bottles for lab analysis or by portable instruments used at the machine. Recently, there
has been a trend away from bottle sampling and lab analysis for routine contaminant
monitoring due to costly, reduced accuracy, and time delay. The use of portable monitors that
receive fluid directly delivers on-the-spot analysis. For example, the digital Contam-Alert
(dCA) from Diagnestic is a portable instrument for routine contamination monitoring. This
instrument allows a small sample of fluid to flow into the sensor for particle counting. The
result of particle counting will be sent to computer through satellite connection (Figure 4).
Figure 4. Contamination monitoring using portable instrument through satellite connection
(Murakami et al., 2002)
Furthermore, the unit can be used with a variety of different fluids such as lube oils,
hydraulic fluids, and coolants. After each test, the handle on the sensor is depressed to expel
the sample which making it immediately ready for reuse. Finally, the result of particle
counting can be easily stored in the computer, print out with a portable printer, and
downloaded into a personal computer.
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Proactive maintenance is presented as an important mean to cure failure root causes and
extend machine life. In the implementation, contaminant monitoring is being a key to achieve
proactive maintenance through its contamination control. Therefore, fluid contaminant
control is established as an essential technique to implement proactive maintenance.
On the other hand, the use of real time or portable instrument for contaminant monitoring
has been effective to recognize the symptoms of impeding machine failure. Expert system
software combined with strategically located sensor and transducer to provide a
comprehensive contaminant monitoring for sophisticated machines and applications.
Furthermore, outside of its usefulness as a proactive maintenance tool, contaminant
monitoring can be equally effective as a first-alert to impending machine failure. Therefore,
the use of portable contaminant monitor provides easy in-the-plant or in-the-field proactive
maintenance for bearing elements.
Chichester, Chad., “Lubrication beyond Oil and Grease: How Anti-Seize Pastes and
Anti-Friction Coatings Reduce Wear, Optimize Friction and Perform Under Extreme
Environmental Conditions”, Dow Corning Corporation, 2012
Fitch, J. C., “Proactive Maintenance Can Yield More Than a 10-Fold Savings Over
Conventional Predictive/Preventive Maintenance Programs”,
Technical Information Document., “Maintenance Management System”, RPS for INAC
, TID-AM-01, October 2000
Information Bulletin., “What is Maintenance”, Vol. 5
Murakami, Taku., Saigo, Takaichi., Ohkura, Yasunori., Okawa, Yukio., Taninaga,
Tadashi., “Development of Vehicle Health Monitoring System (VHMS/WebCARE) for
Large-Sized Construction Machine”, KOMATSU, Technical Report, 2002
TEST OIL., “Filter Debris Analysis Report”, 2012
Harker, D. E., “Lubrication of Clarifier Drives, Why Oil is Preferred over Grease”,
Walker Process Equipment, Division of McNish Corporation, 2001
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