GG Friction Antidote in ROLLER BEARING LUBRICATION APPLICATIONS

Major studies and independent sources prove this. The Society of Tribologists and Lubrication Engineers report more than 50% of all bearings failures are due to lubrication practices that don’t measure up.

Things break. No matter what you do, there is always a chance that products will fail. The same holds true for bearings, but that doesn’t mean that you can’t prevent many of the issues that result in costly downtime. A Best Practices Approach to Increase Your Company’s profits lowers operating costs, improves facility uptime and drives up profits by eliminating the cause of 50% of all industrial equipment failures, improper or outdated lubrication practices.

GG has the depth of detail needed to maximize the reliability of each machine in the plant. Reliability engineers rely on GG Friction Antidote as central to their equipment maintenance best practices programs.

Why Lubrication? When lubrication is done inconsistently or done incorrectly, it negatively impacts machine condition and equipment reliability plant wide.

Why GG? The best opportunity to save money and improve equipment uptime in maintenance is with well-executed lubrication reliability practices and management programs – and that means GG Friction Antidote. GG Friction Antidote lowers costs, improves uptime and increases profits by eliminating the cause of lots of industrial equipment failures.

This article is a guide to the major factors that can lead to bearing failure as well as how you can prevent the issues from happening. By learning more about these potential problems and knowing how to stop them, you can get the most life out of your bearings and make your application much stronger.

1. Lubrication Failure

According to a recent study, up to 80 percent of bearing failures are caused by improper lubrication. This includes insufficient lubrication, use of improper lubricants or excessive temperatures that degrade the lubricant.

What to Look for

Look for discolored rolling elements (such as blue or brown) and rolling-element tracks as well as overheating or excessive wear in the bearing.

How to Fix it

Use the appropriate type and correct amount of lubricant, avoid grease loss, and follow appropriate relubrication intervals.

2. Contamination

Contamination is caused by foreign substances getting into bearing lubricants or cleaning solutions. These include dirt, abrasive grit, dust, steel chips from contaminated work areas and dirty hands or tools.

What to Look for

Watch for denting of rolling elements and raceways that cause vibration.

How to Fix it

Filter the lubricant and clean work areas, tools, fixtures and hands to reduce the risk of contamination.

3. Improper Mounting

In most instances, bearings should be mounted with a press fit on the rotating ring.

What to Look for

A number of conditions can cause denting, wear, cracked rings, high operating temperatures, early fatigue and premature failure of bearings. These include mounting bearings on shafts by applying pressure or blows to the outer race, mounting bearings into a housing by pressing on the inner ring, loose shaft fits, loose housing fits, excessively tight fits, out-of-round housings and a poor finish on the bearing seat.

How to Fix it

Follow proper mounting instructions and provide training to ensure all employees understand the difference between a properly and improperly installed mounting.

4. Misalignment

Bent shafts, out-of-square shaft shoulders, out-of-square spacers, out-of-square clamping nuts and improper installation due to loose fits can cause misalignment, which may result in overheating and separator failure.

What to Look for

A wear path that is not parallel to the raceway edges of the non-rotating ring should be noted.

How to Prevent it

Inspect shafts and housings for runout of shoulders and bearing seats, and use precision-grade locknuts.

5. False Brinelling

Rapid movement of the balls in a raceway while equipment is idle wears away at the lubrication. In addition, a lack of rotation in the bearing does not allow fresh lubricant to return to the spot. Both of these conditions result in false brinelling.

What to Look for

You may see linear wear marks in the axial direction at the rolling-element pitch or no raised edges as opposed to marks due to incorrect mounting.

How to Fix it

Eliminate or absorb external vibration that could cause the balls to move. Also, be sure to use lubricants containing anti-wear additives.

6. Corrosion

Moisture, acid, low-quality or broken-down grease, poor wrappings and condensation from excessive temperature reversals can cause corrosion that is abrasive to the finely finished surfaces of ball and roller bearings.

What to Look for

Look for red and brown stains or deposits on rolling elements, raceways or cages, as well as increased vibration followed by wear, an increase in radial clearance or loss of the preload.

How to Fix it

Divert corrosive fluids away from bearing areas. Select integrally sealed bearings and consider external seals for particularly hostile environments. Using the proper bearing material, such as stainless steel, can help if you cannot avoid a corrosive environment.

7. Electrical Damage (Fluting)

Constant passage of alternating or direct current, even with low currents, can lead to electrical damage.

What to Look for

Brownish marks may be observed parallel to the axis on a large part of the raceway or covering the entire raceway circumference.

How to Fix it

Prevent electrical currents from flowing through the bearing by grounding or using insulated bearings.

8. Fatigue (Spalling)

Spalling is often the result of overloading, an excessive preload, tight inner-ring fits and using the bearing beyond its calculated fatigue life.

What to Look for

Fatigue can be indicated by the fracture of running surfaces and subsequent removal of small, discrete particles of material from the inner ring, outer ring or rolling elements. Spalling is progressive and will spread with continued operation. It is always accompanied by a noticeable increase in vibration and noise.

How to Fix it

Replace the bearing and/or consider a redesign that uses a bearing with greater calculated fatigue life, internal clearances, and proper shaft and housing recommendations.

9. Overheating

Overheating is generally the result of excessive operating temperatures and improper lubrication. High temperatures can cause grease to bleed (purge the oil), which reduces the lubricant’s efficiency. In elevated temperature conditions, oxidation can lead to the loss of lubricating oils from the grease, leaving a dry, crusty soap that can seize the bearing. Higher temperatures also reduce the hardness of the metal, causing early failure.

What to Look for

Note any discoloration of the rings, rolling elements and cages. In extreme cases, the bearing components will deform. Higher temperatures can also degrade or destroy the lubricant.

How to Fix it

Thermal or overload controls, adequate heat paths and supplemental cooling are among the best options to mitigate overheating.

10. Excessive Loads

Putting too much load on a bearing is another common cause of failure.

What to Look for

You may see heaving rolling-element wear paths, evidence of overheating and widespread fatigue areas.

How to Fix it

Reduce the load or consider a redesign using a bearing with greater capacity.

11. Improper Storage and Handling

Improper storage exposes bearings to dampness and dust. Storing bearings in excessively high temperatures can also degrade a grease’s shelf life, so always check with the grease manufacturer for storage specifications. Handling bearings by opening boxes and tearing wrappings prematurely can let in dirt and expose bearings to corrosive elements.

What to Look for

Watch for dampness and temperatures that can cause rust and/or uncovered bearings in a storage area.

How to Fix it

Store bearings in a dry area at room temperature. Always cover bearings to keep them clean while in storage and take them to the installation site before unwrapping.

12. Fit

A tight fit can be caused by excessive loading of the rolling element when interference fits exceed the radial clearance at operating temperatures. Micro-motion between fitted parts where the fits are too loose in relation to the acting forces may result in a loose fit.

What to Look for

For a tight fit, look for a heavy rolling-element wear path in the bottom of the raceway, overheating or an inner-ring axial crack. For a loose fit, note any fretting (generation of fine metal particles), which leaves a distinctive brown color. Wear at the fitting surfaces can cause noise and runout problems.

How to Fix it

Make sure a proper clearance is selected to avoid fit issues. Refer to the manufacturer’s installation guide.

Preventing Failures

By becoming aware of the different problems that can cause a bearing failure and the signs to look for, you have already taken a big step toward limiting machine failures. Of course, you don’t have to wait for the symptoms of a bearing failure to take action. Regular preventive measures can keep your bearings at peak performance for as long as possible, saving your business time and money.

“A rather large number of factors influences lubricating oil degradation and, consequently, pump bearing life. If your centrifugal pumps are equipped with rolling element bearings, there is little doubt that medium viscosity turbine oils (ISO Grade 68) will perform better than the lighter oils originally specified by many pump manufacturers. But, by far, the most frequent cause of lube-oil-related failure incidents is water and dirt contamination. With only 20 ppm water in pure mineral oil, bearing surface and rolling element fatigue life is reduced by an incredible 48 percent. Although the fatigue life reduction is less pronounced with inhibited lubricants, there are always compelling reasons to exclude dirt and water from pump bearing housings. Lip seals are a poor choice for centrifugal pump installations demanding high reliability. Face seals represent superior, “hermetic” sealing and should be given serious consideration.

“On a related subject, have you explained to your operators and maintenance personnel that a full-bottle oiler is no guarantee of adequate lubrication? The height of the beveled tube determines the level of oil in the bearing housing, and all too often there will be costly misunderstandings. However, there are at least two considerably more elusive problems involving bottle oilers.

“The first of these is that bottle oilers may malfunction unless suitably large bearing housing vents are provided. With a relatively viscous oil and close clearance at the bearing housing seal, an oil film may exist between seal bore and shaft surface. Good lube oils have a certain film strength and under certain operating conditions, this sealing film near the bearing end cap may break only if the pressure difference bearing housing interior-to-surrounding atmosphere exceeds 3/8 inch of water column.

“If now, the bearing housing is exposed to a temperature increase of a few degrees, the trapped vapors – usually an air-oil mix – floating above the liquid oil level will expand and the pressure may rise 1/4 inch of water column. While this would not be sufficient to rupture the oil film so as to establish equilibrium between atmosphere and bearing housing interior, the pressure buildup is nevertheless sufficient to depress the oil level from its former location near the center of a bearing ball at the 6 o’clock position to a new level now barely touching the extreme bottom of the lowermost bearing rolling element. At that time, the bearing will overheat and the lube oil in contact with it will carbonize. An oil analysis will usually determine that the resulting blackening of the oil is due to this high temperature degradation.

“The second of the elusive oil-related problems often causes the contents of bottle oilers to turn grayish color. This one is primarily observed on ring-oil lubricated rolling element bearings.

“Suppose you have very precisely aligned the shafts of pump and driver; nevertheless, shims placed under the equipment feet in order to achieve this precise alignment caused the shaft system to slant 0.005″ or 0.010” per foot of shaft length. As a consequence, the brass or bronze oil slinger ring will now exhibit a strong tendency to run “downhill.” Thus bumping into other pump components thousands of times per day, the slinger ring gradually degrades and sheds numerous tiny specks of the alloy material. The specks of metal cause progressive oil deterioration and, ultimately, bearing distress.

“Pump users may wish to pursue one of two time-tested preventive measures. First, use properly vented bearing housings or, better yet, hermetically sealed bearing housings without oiler bottles. The latter are offered by some pump manufacturers and incorporate bull’s-eye-type sight glasses to ascertain proper oil levels.

“The second preventive measure would take into account the need for radically improved pump and driver leveling during shaft alignment or, even more desirable, apply flinger spools. Of course, oil mist lubrication or direct oil injection into the bearings would represent an altogether more dependable, long- term satisfactory lube application method for centrifugal pumps.

Understanding the Differences between Automotive and Industrial Greases

In regards to grease and its application, there are critical elements used in the formulation process that must be considered. These elements include the thickener type and concentration, lubricant type, viscosity and additive package. Greases are rated by the National Lubricating Grease Institute (NLGI) and range from 000 through 6. An NLGI 2 grade is typically the specification used in automotive greases.

One of the only differences between industrial and automotive greases is that a two-letter designation is often used in the automotive industry to specify the type of grease to employ. For example, greases may be rated as GC or LB. GC is recommended for axle and wheel bearing grease, while LB is the industry standard for chassis grease used on tie-rod ends, ball joints, U-joints and control-arm shafts.

Regardless of the application, greases should reduce friction and wear, protect against corrosion, seal bearings from water and contaminants, and resist leakage. While one of the main reasons for grease failure is selecting the wrong type of grease for the intended application, there may also be other causes, such as incompatibility resulting in excessive softening of the grease, contamination leading to excessive wear or applying too little or too much grease for the application.

For instance, in off-road equipment, the environment generally is harsh with a variety of factors to take into account including water, dirt, poor seals and heavy loads. In this type of situation, grease selection is key. You will need a grease with good rust protection, film strength and water resistance.

Bearings normally see less contamination but often experience wide variations of speed and temperature. In this case, you should choose a grease with excellent oxidation stability, exceptional mechanical stability and good performance over a wide temperature range.

In summary, the constituents of industrial and automotive greases may be quite similar and should be treated as such. The point is that no matter the application in which grease is used, it is critical to know how to properly select a grease while keeping in mind all of the important parameters.

Grease Selection: Lithium vs. Lithium Complex

According to a recent NLGI Grease Production Survey, approximately 70 percent of the grease sold worldwide is based on either simple lithium soap or lithium complex thickener. You might ask, “Why are those thickener types so popular?” and “How do I decide which one is best for my application?” This article will provide answers to these and a few other questions.

First, let us take a historical perspective. Clarence E. Earle, an American chemical engineer, was granted U.S. Patent No. 2,274,675 on March 3, 1942, for an invention called “Lubricant Containing Lithium Salts.” This is the first description in the patent literature of a grease based on simple lithium soaps. Although the soaps described in the patent are the types typically used to produce lithium-soap-based greases today, the lithium greases described by Earle ushered in a new era in the lubricating grease industry.

Greases based on lithium soap possess many improved properties compared to the other alkali metal soaps that existed in 1942. They have better water resistance properties compared to sodium soap greases, better high-temperature properties compared to calcium soap greases, and excellent mechanical properties (both resistance to shearing and good ability to be pumped). Although they are more expensive to manufacture than other grease types, lithium soap greases offer so many advantages compared to sodium and calcium soap thickeners that extra cost is offset by improved performance, fuel and oil savings and improved uptime.

Lithium complex greases were developed in the late 1940s. U.S. Patent 2,417,428 was granted to Lester W. McClennan on March 18, 1947. This is one of the first patents to describe complex soap greases. However, it wasn’t until the early 1980s that lithium complex greases entered the market in large volumes and started to displace the simple lithium soap greases that had been the mainstay of the industry since the 1950s.

Lithium complex greases possess many of the properties of simple lithium soap greases and also have higher dropping points, allowing the greases to be used at higher temperatures.

The dropping point of lithium complex greases is higher than that of simple lithium soap greases due to the presence of a second thickener component, known as the complexing agent. Modern lithium complex greases typically use a shorter chain-length difunctional carboxylic acid, such as azelaic acid or adipic acid. The lithium salt of these materials is typically present in a significantly lower proportion compared to the simple lithium soap thickener. An alternate material used as a complexing agent is boric acid. The use of this material also results in an elevated dropping point.

Mechanical stability, also known as shear stability, is the ability of grease to maintain consistency when subjected to mechanical shear forces. Simple lithium greases have good resistance to breakdown due to shear, and lithium complex greases also exhibit good resistance to shear. This property makes both simple lithium and lithium complex greases popular for use in a wide range of applications.

The water resistance of simple lithium and lithium complex greases is related to the solubility of the thickener. Lithium hydroxide has limited solubility in water (about 10 percent), and the thickeners based on it also have limited solubility. This provides good resistance to both washing by water and the absorption of water. Although other thickener types (calcium, barium) have better inherent water resistance compared to lithium and lithium complex thickeners, those products have negative aspects that make them less desirable for many applications. In addition, the water resistance properties of simple lithium and lithium complex greases can be enhanced by the addition of polymer additives in small concentrations.

The oil separation properties of a grease relate to both the product’s lubrication ability and storage stability. The grease must release enough oil in the contact zone of the application (bearings, gears), while not releasing so much oil during storage to cause the product to become unusable. If the oil separates excessively during storage, the grease may not be able to be remixed and used.

Property                                          Lithium Grease                                Lithium Complex Grease
Dropping Point	˜385°F / 195°C	˜500°F / 260°C
Mechanical Stability	Good	Very Good
Water Resistance	Good	Very Good
Oil Separation Resistance	Good	Very Good

Table 1. Properties of Lithium and Lithium Complex Greases

Now, to answer the questions posed at the start: Why are the lithium and lithium complex thickener types so popular? It’s the versatility of the thickeners, making greases containing them suitable for use in a broad range of applications. Which one is best for your application? The thickeners are similar in many properties, so the best way to determine which to specify is the operating temperature of the application. Many prefer lithium complex greases as general-purpose lubricants, and that is a good approach, since they can be used in a wide range of applications and over the widest range of temperatures. However, for specific applications, simple lithium soap greases are often the most economical choice.

Storing Grease to Avoid Bleed and Separation

When storing grease and even during use, a certain amount of oil bleed will develop. Although it is common, the rate at which this bleeding occurs can be controlled through proper storage and usage techniques. Before looking at these strategies, it is important to understand the make-up of grease and the types of oil release that can take place.

Grease Composition

Grease = 70 to 95 percent base oil + 3 to 30 percent thickener system + 0 to 10 percent additives.

In general, a grease is a solid to semifluid product that consists of a dispersion of a thickening agent in a liquid lubricant. This thickener system can be made up of either simple or complex metal soaps of lithium, calcium, aluminum, barium or sodium, or non-soap such as clay (bentone) or polyurea. The thickener system can be thought of as a sponge that contains a matrix of fibers or platelets with a high surface area forming a dense network of micro-asperities (voids) or fibers. It is in these voids or fiber structure where the base oil and additives are stored until they are needed for lubrication.

Just like a sponge that releases water when it is squeezed, the grease releases its base oils from the thickener system when it is squeezed or stressed. The stresses a grease encounters can be generated either mechanically or thermally during application or storage.

In an application, a grease gradually releases oil into the working areas of the machine surfaces in order to lubricate them. The greater the amount of sheer stress encountered, the faster the grease’s thickener system releases its hold on the base oils. The thickener system matrix imparts little or no lubricating characteristics. If the thickener system matrix did not release the base oils, the grease would be unable to perform its lubricating properties.

By the same token, a grease also should have the ability to exhibit some type of reversibility characteristics after the stresses are relaxed. Reversibility is defined as a grease’s ability to recapture its base oils in order to return to its original consistency and continue functioning as intended. When a machine is shut off or when the conditions of mechanical or thermal stress are relaxed, the grease must have the ability to recapture its base oils to return to its original consistency. A grease’s reversibility characteristics are dictated by the type and amount of thickener used. Generally, the higher the thickener content, the less the grease’s reversibility.

Types of Oil Release

Although a grease’s thickener system is not soluble in the base oil that it thickens, it does have an attraction to the base oil. Depending upon the amount of thickener system used in the grease’s formulation, this attraction can be strong. The higher the proportion of thickener used, the greater its attraction to the base oil. As the base oil content is increased and the amount of thickener system is decreased, the forces of attraction also decrease, thus resulting in the base oil being loosely held in the thickener system matrix and easily separated.

From these statements, you might think a higher thickener content is better. However, as mentioned previously, a thickener system matrix that does not release its base oils would be unable to perform its lubricating properties. Therefore, it is important for a grease to have the proper balance of base oil and thickener system content to function properly.

Tests for Oil Bleeding

There are a number of different tests that can measure a grease’s bleeding and oil separation characteristics. These tests can be categorized into two groups: static and dynamic bleed tests. The most common tests used to evaluate oil separation and bleeding are:

Static Tests

ASTM D-1742 Oil Separation from Lubricating Grease During Storage – This test predicts the tendency of a grease to separate oil during storage when stored at room temperature.

ASTM D-6184 Test Method for Oil Separation from Lubricating Grease (Conical Sieve Method) – This method determines the tendency of the oil in a lubricating grease to separate at elevated temperatures.

Dynamic Tests

U.S. Steel Pressure Oil Separation Test – This test is used to measure the oil separating and caking characteristics of a grease under fixed conditions that indicate the stability of a grease under high pressures and small clearances in a centralized grease pumping system.

ASTM D-4425 Oil Separation from Grease by Centrifuge – This method evaluates the oil separation tendency of a grease when subjected to high centrifugal forces.

Trabon Method 905A – This test is used to predict the tendency of a grease to separate oil while under pressure in a centralized lubrication system.

Although a grease may exhibit good resistance to oil bleed and separation in these static and dynamic tests, proper storage and handling of the grease are still key components to ensure that it is able to perform its job.

Oil release or separation from greases can be found in two distinct modes: static bleed and dynamic bleed. Static bleed is the release of the grease’s base oil from the thickener system in the container in which it has been placed or in a non-moving part into which it has been introduced. Static bleed, which can also be referred to as oil puddling, occurs naturally for all types of greases and at a rate dependent on their composition.

Static oil bleeding can be affected by storage conditions, including the storage temperature, the length of storage, any vibrations the containers may be exposed to during transport or storage, an uneven grease surface in the container or the natural force of gravity. These factors can cause extremely weak stresses to be placed on the grease, resulting in the release of small amounts of base oil. Over time, a puddle of oil can form on top of the grease.

Static bleeding is more pronounced if the grease is soft in consistency (NLGI grades 00, 0 and 1) and/or if the grease’s base oil viscosity is low (ISO 68 and lighter). It does not result in the grease being unsuitable for use.

Any base oil that has puddled or is lying on top of the grease can be either removed by decanting the free oil from the surface or by manually stirring it back into the grease. The quantity of oil that has separated from the grease is generally insignificant and represents a mere fraction of the total quantity of base oil that is held in the thickener system matrix. This small amount of oil will not adversely affect the consistency of the remaining product and will have little or no effect on the performance of the product.

Dynamic bleed is the actual controlled release of the base oils and additives during use due to temperature or mechanical stresses. It is important for the grease being used to have a controlled rate of bleeding in order for it to do its job properly.

Dynamic bleed conditions can also be caused or aggravated by the following conditions:

Overgreasing – Overgreasing can cause high temperatures, which result in oxidation of the grease and rapid separation of the base oils from the thickener due to churning.

Thermal Runaway – Too much grease in a bearing, mechanical conditions (misalignment, excess preload, etc.) and starvation can lead to higher running temperatures, which cause the base oils to be readily released from the thickener system matrix, leaving the thickener system behind to lubricate.

Cake Locks in an Overgreased Bearing – These cake locks can act as microscopic logjams. They are immobile and block flow paths and even mechanical motion of the bearing. When fresh grease is applied, the grease’s base oils are separated and flow through the built-up thickener due to hydrostatic extrusion, leaving the thickener system behind. Additional build-up of this logjam can lead to elevated operating temperatures, resulting in increased bleeding of the base oils from the grease’s thickener system.

Contamination – Gross contamination by dust, dirt, fly ash and dry powder contaminants can draw out the base oils from the thickener system over time, resulting in the thickening of the grease.

Mixing of Incompatible Thickener Systems – This accelerates de-gelling and oil separation.

Hydrostatic Extrusion – Grease subjected to constant pressure can separate by hydrostatic forces, just like water flowing through a sand filter. The base oils are literally squeezed from the thickener system.

Vibration and Centrifugal Forces – Prolonged vibration and/or centrifugal forces can cause grease separation.

A grease’s oil bleed rate can be affected by a number of factors, including its composition, the type of manufacturing process used to produce the grease and distribute the thickener system within the base oil, and how the grease is stored once it reaches the customer. The ability of the grease to retain or release the oil depends upon all of these factors.

Without exhibiting some bleeding, whether static or dynamic, a grease will not provide lubrication for the application in which it is being used. The balance between these two modes of bleeding is the key to the grease’s performance.

Storage and Handling Techniques

Like most materials, lubricating grease gradually will deteriorate with time. The rate and degree of deterioration depends on the storage and handling conditions to which the grease is exposed.

Grease may change its characteristics during storage. The product may oxidize, bleed, change in appearance, pick up contaminants or become firmer or softer. The amount of change varies with the length of storage, temperature and nature of the product.

Depending on the storage conditions, some greases can undergo age hardening, which results in the product becoming firmer and increasing in consistency or even softening. These changes in consistency can cause the grease to slip out of its original consistency grade. This behavior can be further aggravated by prolonged storage conditions. Because of this aspect, extended storage periods should be avoided.

If a grease is more than a year old, the National Lubricating Grease Institute (NLGI) recommends that it be inspected and the worked penetration tested to ensure that the grease is still within its intended NLGI grade.

Another recommended industry practice specifies that whenever any type of lubricant is received, the usage and storage methods must follow the first-in/first-out inventory system. This simply requires the user of the lubricating grease to use the grease that was put into the storage system first. In addition, grease manufacturers place a date code or bath number on the individual packages or cartons that can help determine the month, day and year the grease was made.

As previously mentioned, greases tend to bleed and release their base oils during storage. The rate of oil released from the grease will increase with time and vary based on the temperature at which it is stored. Ideally, grease should be stored in a cool, dry indoor area that does not exceed 86 degrees F (30 degrees C) and remains above 32 degrees F (0 degrees C).

It is not unusual to find grease containers in storage areas that have temperatures as high as 130 degrees F (54 degrees C). These storage areas also can be exposed to contaminants such as dust, dirt, moisture or rainwater, which can severely deteriorate the quality of the grease.

A grease container should never be exposed to direct sunlight or be stored in an area directly near a heat source such as a steam pipe, furnace, cab of a truck in hot weather, etc. This will only aggravate the rate of oil release that can occur.

Always store grease in its original packaging and keep the container closed until it is time for it to be used. Wipe the lid or cover of the container before opening and always use clean tools and dispensing equipment when handling or pumping the grease. After use, the container should be closed immediately and kept closed. Before placing the lid back onto the container, wipe off any dust, dirt or excess grease that may have accumulated.

Cartridge tubes of grease should be stored upright at all times. If a cartridge tube is left in a grease gun, the grease gun should be depressurized, wiped with a clean cloth to remove any contaminants and stored in a horizontal position inside a clean, cool, dry area to keep the oil from bleeding out of the grease.

To further ensure a grease’s original quality and cleanliness, as well as to prevent excessive oil separation, the following storage and handling techniques are recommended:

• Do not use lubricating greases that have been stored for long periods of time unless their condition and cleanliness can be verified by a laboratory analysis.
• If accidental mixing is suspected or has occurred, consult the lubricant supplier or conduct compatibility tests.
• The storage room should be separated from areas of contamination such as metal debris, dust, dirt, chemical fumes or moisture. The room should be heated, well-ventilated and contain clean accessories, dispensing equipment and other necessities. Personnel also should be properly trained in storage techniques and inventory control to prevent contamination.
• Grease containers should be clearly labeled with the date they were received, the type and brand of grease, etc. These markings should be kept in a position where they can be easily read.
• Store grease in its original container until it is used. Drums, pails, kegs and boxes should be kept off the floor and supported by a rack, platform or blocks at least several inches high.
• Never leave grease containers improperly covered, uncovered or open. Keep them tightly sealed between uses. If the containers are stored outside, a heavy canvas tarpaulin, plastic sheet or lean-to can be used to keep off water or dirt. Drums, kegs and pails should be raised off the ground and stored either on their sides or tilted at a 45-degree angle to prevent any moisture or dirt from being drawn into the product.
• Any tools used to handle or dispense grease should be cleaned before they are used.
• Never use wooden paddles or spatulas to remove or transfer grease from containers to grease guns or other types of dispensing systems. This practice poses a high risk of contamination.
• If a barrel warmer is used, it should have some type of temperature-regulating mechanism. The grease should never be heated above 75 degrees F, and the barrel warmer should not be left on overnight or unattended. This can cause the grease to readily release its base oils or even thicken in consistency due to oxidation and thermal stress.
• Never use a torch or open flame to warm a grease container. This poses a fire hazard.
• Maintain a separate inventory and utilization record for each product. Tracking how much grease is used and on which machine or piece of equipment will help you keep an accurate inventory of lubricants.
• Use the oldest container received first.
• Before storing or using a grease, inspect the received containers for any damage such as severe dents, corrosion or moisture.
• Some type of coding and tagging system should be used to identify the contents of different lubricant containers, transfer/pumping systems, tools and pipes that carry grease throughout the plant. Make sure all transfer valves, hoses and dispensing equipment are kept clean. Seals and gaskets also should be maintained in proper condition.
• All transfer containers should be filled under clean conditions.

Grease containers should be completely emptied before being discarded.

Five Common Lubrication Problems and How to Fix Them

The following is a list of the most common problems and how they should be resolved.

1. Lack of Procedures

Great lubrication programs are only as good as the people who do the work, just as a chain is only as strong as its weakest link. The retirement of technicians has been the problem of greatest concern. As Baby Boomers are reaching retirement age and subsequently retiring, they are taking with them a great deal of personal experience and knowledge of how they do their jobs. For some plants, the lube-tech position may have been held by a single person for decades. These professionals are the masters of their domains and know every sight, sound and smell of their machines. It is imperative to pass down this type of dedication and understanding to the next generation of professionals. Unfortunately, all of this knowledge usually is not passed down. This results in problems and a steep learning curve.

36% of lubrication professionals say overgreasing is the most common problem at their plant.

Documented procedures can lessen the blow and help new personnel understand the proper way a task should be performed. While countless articles and books have been published on the best way to write procedures, once written, the procedures must be implemented for their full effect to be realized.

The Remedy

Thorough documentation of every task performed in the lubrication program offers the best method for creating procedures. You want to write a procedure not only for the application of lubricants (oil changes, regreasing, etc.) but also for how lubricants are handled in storage, decontaminated upon arrival and even disposed of after use.

Procedures should be developed with best practices in mind and may not represent what is currently being done in your plant. For instance, if new oil is arriving and being put into service without any testing or decontamination, this is far from best practice. Instead, new oil should be sampled upon delivery to confirm its properties and tested for contaminants. If necessary, the new oil should be decontaminated before being released for service or put into bulk storage containers.

The same holds true for inspections, top-ups and every small task in the lubrication program. It is not enough to simply document what is currently being done. You must design procedures in a manner that enables the program to reach a world-class level.

2. Improper Sampling Points and Hardware

If used correctly, oil analysis can be an extremely valuable tool. It allows you to monitor not only the health of the oil but also the health of the machine, as well as catch failures before they become catastrophic. In order to obtain all the benefits of oil analysis, you first must have the correct sample points and hardware.

Improper sampling points and hardware may result in samples that are full of historic data.

Many plants regard oil sampling as a secondary function and simply take samples from a drain port or with the inconsistent drop-tube method. When sampling from drain ports, you may obtain a sample that is full of historic data (e.g., layers of sediment and sludge). Wear debris trends can also be hard to establish, as these samples often contain a high concentration of contaminants.

In addition to being inconsistent, drop-tube sampling frequently requires the machine to be taken out of service. This can result in particles settling at the bottom of the sump, which may prevent a good, relative sample being taken from the system.

Proper sampling ports can be achieved by modifying the machine. This will allow good samples to be taken consistently from “live” zones or areas inside the system where oil is experiencing turbulent flow.

The Remedy

All machines to be included in the oil analysis program should be evaluated for the proper sampling hardware. Splash-bathed components such as bearings and gearboxes can be equipped with minimess sampling valves with pilot tube extensions. These extenders can be bent up into the “live” zone next to the bearing or gear teeth.

Circulating systems should be examined for the best possible sampling points as well. These systems typically require several points.

A primary point is where routine samples are drawn from to provide a snapshot of the entire system. The best place for a primary sample is on the main return-line manifold, before any return-line filters and in an area of turbulent flow (most often an elbow).

Secondary points should be installed in the oil return line after each lubricated component. Secondary points allow you to pinpoint problems in the system after an alarm has been triggered by the primary point.

In conjunction with sampling hardware installation, all technicians should be trained in the proper way to pull samples. All sample tubing should be flushed with five to 10 times the volume of dead space. Great care should also be taken to reduce the amount of contamination introduced into the sample during the entire process.

3. Overgreasing

Most plants do not recognize that grease guns are precision instruments. They also fail to see the problems that can be caused by the misuse of grease guns. Many people are taught to grease a bearing by simply attaching the grease gun and working the lever until grease was seen purging from somewhere. While this may be effective for hinge pins and other applications where purging grease won’t cause damage, it shouldn’t be employed for all grease applications. Overgreasing is a very common problem and can result in higher operating temperatures, premature bearing failure and an increased risk of contaminant ingression.

Bearings require a set volume of grease to be properly lubricated. A popular formula used to determine the volume of grease needed is the outside diameter (in inches) multiplied by the width (in inches) multiplied by 0.114. This will provide the volume of grease in ounces that the bearing requires.

Once you have calculated the volume of grease for the bearing, you need to know how much grease the grease gun is dispelling per stroke. To do this, simply pump 10 shots of grease onto a plate and weigh it on a digital scale. Next, divide the weight of the grease by 10. This will give you the amount per stroke of output. Remember, certain grease guns can produce pressures up to 15,000 psi and can cause numerous problems if not properly managed.

The Remedy

While calculating the regrease requirements for all bearings onsite and determining the output of grease guns are a great place to start, there are other concerns that must be addressed as well. For instance, the output of grease can vary between guns. The best way to counteract this problem is to standardize with a single type of grease gun so the output will be similar for each one. Grease guns should also be dedicated to a single type of grease and checked at least once a year.

If possible, bearings should be outfitted with grease purge fittings that allow excess grease to be expelled without compromising the integrity of the seal. In addition, all professionals who operate a grease gun should be trained on their operation and the proper way to regrease a bearing.

4. Lack of a Labeling System

Labeling is a key part of any world-class lube program. Not only does it reduce the chance for cross-contamination by minimizing confusion as to which lubricants go where, it also allows individuals who may not be as familiar with the lube program to top-up with the correct oil or grease.

Anything that touches a lubricant should be labeled and dedicated to a single lubricant.

Of course, labels can be used for more than just identifying lubricants. On a recent project, the lube labels were barcoded to allow all assets in the plant to be integrated into the computerized maintenance management system (CMMS) for automatic work-order generation. Although labeling assets is a great first step, a true world-class program would label everything from machines and top-up containers to bulk containers, grease guns and so on. Basically, anything that touches a lubricant should be labeled and dedicated to a single lubricant.

The Remedy

Developing a labeling scheme takes time, but when done properly, it can provide a variety of information not only about the lubricant but also about lubrication intervals as well. The best label design incorporates a color/shape scheme for each lubricant used. This offers a quick visual reference as to which lubricant is inside the machine. You can subscribe to the Lubricant Identification System (LIS), which includes all basic information for a machine type such as base oil, application and viscosity. As mentioned previously, once a labeling system has been established, the labels should be applied to all lubricant storage containers and application devices.

5. Use of OEM Breathers and Dust Caps

Most original equipment manufacturer (OEM) accessories like breathers do little to restrict the ingression of tiny particles into oil and critical spaces, which can damage machine surfaces. Some of these breathers are simply a cap filled with steel wool or a mesh screen that serves as a block for larger particles. Considering the lubricant film in a journal bearing is approximately 5 to 10 microns, any particles of this size contaminating the oil will greatly increase the likelihood of wear and subsequent machine failure. These tolerance-sized particles do the greatest damage and have the highest probability of causing machine wear. Most OEM breathers and dust caps allow particles and moisture to enter the oil.

Not only do many OEM breathers allow particles into the oil, they also do nothing to restrict moisture from entering the oil. Oil is hygroscopic, which means it absorbs moisture from the ambient air. In areas with high humidity or steam, moisture will pass through these types of breathers and be absorbed into the oil, causing rust, increased oxidation and hydrolysis rates, and a higher corrosive potential of acids formed by oxidation and hydrolysis.

How Desiccant Breathers Control Contamination

To combat the ingression of particles into oil systems, breathers are often attached to reservoirs and other oil storage components. Whether they are connected to an expensive piece of machinery or a drum of oil, breathers offer the peace of mind that as the oil level fluctuates, the air filling the space will be properly cleaned and mostly free of contaminants.

Desiccant breathers provide a wide range of benefits and are becoming more common. However, you may wonder how a plastic cup full of what looks like plastic beads actually filters incoming air and removes not only harmful particles but also water vapor, which is so dreaded in lubrication systems. The answer involves chemistry.

These breathers use the inherent qualities of two of nature’s most absorbent materials – silica and carbon. Everyone likely has opened a package and found little packets marked “Do not eat.” This is the same silica in desiccant breathers. How it works is quite simple. Silica is a very porous material that can trap and hold nearly 40 percent of its weight in water. As water vapor passes around these beads, it is trapped in the pores of the silica. Any water vapor that isn’t trapped by the silica goes through a layer of activated carbon.

Electronegativity is a chemistry term used to describe an element’s attractive force toward other elements. Carbon and oxygen both have high values and are attracted to each other to form new gases, such as carbon dioxide. Water vapor attaches to carbon by this force. The oxygen in the water binds with the activated carbon in the breather, thus preventing it from going any farther.

Most breathers also have a color-change indicator that shows when their useful life is up. This is accomplished with a water-reactive reagent embedded into the body of the silica. As water vapor attaches, it reacts inertly with the reagent, making it change its color.

Desiccant breathers generally have a synthetic fiber filter at the top to trap larger solid particles such as dust or organic material in the atmosphere. Next, there is a device called a diffuser, which takes incoming air and forces it through the entire volume of silica evenly. After the diffuser is the activated carbon, which serves to remove anything left after the initial filtration. As the container exhales, this process takes place in reverse, with the activated carbon absorbing the oil mist so as not to allow it back into the mass of oil after being in contact with other contaminants.

It is recommended that these breathers be installed in tandem with a vacuum gauge. In the case of dry environments, there may not be enough moisture ingression to cause a color change of the silica beads before the top layer of the synthetic filter is clogged with dust and other contaminants. A vacuum gauge will provide a visual signal as to when this occurs, since the air will not be able to pass through the entire breather.

As with most spin-on breathers, desiccant breathers often have a beta rating associated with them. This is a mark of how well the filter removes incoming contaminants.

Among the other criteria to keep in mind when selecting a filter is the cleanliness of the environment, which can affect its life expectancy. Obviously, the dirtier the air, the more particles the breather will trap. The amount of moisture or humidity in the air will determine how long you can go between filter changes.

The criticality of the machinery the breather is attached to is important to consider as well. If the machine operates on close tolerances with little room for particle ingression, you may need to get a high-quality breather and change it more regularly.

To maximize a breather’s efficiency, ensure the headspace of the oil level is sealed tightly. The volume being protected should breathe only through the filter installed. A loose seal will defeat the purpose and allow a straight path for outside particles to enter the system.

Although breathers are relatively easy to install, the process of how they work is quite involved. Pairing science with real-world need provides the advantage required to tackle the challenges of particle ingression and maintaining the small fluid film on which this industry rides.

3 Key Properties of a Breather

Desiccant breathers can help control both moisture and dirt ingression. A good desiccant breather system is one that:

1. achieves the target level for cleanliness and dryness,
2. has the capacity to enable a sufficient service interval between change-outs,
3. is easily visible for routine inspection during preventive maintenance.

In conclusion, the voice in your oil is an opportunity for those who perform or are considering performing a system flush. It would be rare for a machine to have a flush requirement without both the causes and effects appearing in the oil data well in advance, but only when samples are taken and the right tests are performed. This is just one more reason why learning the language of oil analysis is a valuable, enabling skill in the field of machine reliability.

The Remedy

OEM breathers should be replaced with higher quality versions to restrict particulate and moisture ingression. With several breather manufacturers on the market, the key is to get the breather that is right for your particular environment and operating conditions. In very dry environments, a spin-on particulate filter may work fine provided that ambient humidity is low. In more moist environments, a hybrid-style breather may be the best choice. This type of breather employs a particulate filter to trap hard particles followed by a desiccating phase to strip moisture from the incoming air. All of these breathers can be threaded into the current breather port for quick and easy installation.

3 Other Lubrication Problems to Avoid

Besides the top five problems, there are a few honorable mentions that should be included in any discussion of recurring lubrication issues affecting industry. These are problems that aren’t quite as common but still deserve to be mentioned.

Constant-level Oilers

Although constant-level oilers are great for providing small amounts of oil to a sump and replenishing lost oil, these devices require proper installation and maintenance. They should be installed on the appropriate side of the housing so the shaft rotation is toward the oiler. This is more critical on smaller sumps. Also, the oiler must be installed straight, i.e., level and perpendicular to the ground. Finally, the oil level inside these devices should be set so half of the bearing’s bottom element is submerged in oil.

When using constant-level oilers, it is best practice to install a bull’s-eye sight glass on the opposite side of the housing from the oiler to ensure the proper oil level is maintained. Sediment can block the piping and starve the bearing for oil. Air pressure can raise the oil level, causing increased drag and excess heat in the housing. With the sight glass in place, these issues can be recognized and corrected before any lasting damage is done.

High-speed Grease

Many facilities use a general-purpose grease for almost everything in the plant. However, a multi-purpose grease can cause problems in high-speed bearings. Fan bearings, motor bearings and other bearings that rotate at several thousand revolutions per minute may require a grease with a lower viscosity than what is used for slower, more highly loaded bearings.

Most electric motors can be effectively lubricated by a grease with a base oil viscosity of 100 centistokes. If a higher viscosity grease is used, viscous drag can occur, which may result in higher operating temperatures and increased torque requirements to turn the bearings. As the temperature increases, grease can drain from the bearing quicker, which in turn can cause the bearing to fail due to high heat or lack of lubricant.

To prevent this problem, assess all bearings and calculate the necessary operating viscosity. Next, select a grease that provides the required viscosity and the appropriate additive package for the application.

One-dimensional Filter Carts

Filter carts offer many benefits, including increased lubricant life and reduced equipment failures. They are great tools for any lubrication program and should be used extensively to decontaminate both new and in-service lubricants. They can be employed to drain oil quickly, top-up with clean oil, flush out lines and hoses, etc.

It is wasteful to see a filter cart not in use but sitting in the lube room. These systems should never sit unused in a room somewhere. The term “one-dimensional” refers to how these machines are often utilized. Many plants only use these carts to transfer oil from a drum to a reservoir, thus limiting their purpose. So avoid type-casting filter carts into a single role and use them for everything you possibly can.

While these are the most common lubrication problems across industry, there are many more. Some may be unique to certain processes or types of machines, but these five hold true for all facilities.

As industry continues to change and evolve, it will become increasingly important to understand the problems being encountered and to look for new ways to solve them. By applying sound problem-solving techniques and searching for the low-hanging fruit, you can start to make lasting changes for the better.

How to Distinguish Between Mineral and Synthetic Oils

Relating to gearboxes on trucks, if the owner or driver doesn’t know if the gear lubes are synthetic, is there a fool-proof way to determine this without having to send a sample to the lab? Some oil manufacturers color their synthetic oils, while others don’t. What would happen if the oils were to be mixed or topped off with the wrong oil?

The color of the lube is simply a dye. There are no standards, and manufacturers can and do change colors whenever they please. Unfortunately, there is no reliable way of differentiating between mineral and synthetic in the field. However, because synthetic base oils are white (meaning transparent) as compared to mineral oils, which have a darker natural color (due to aromatics, sulfur and other impurities), this may be a distinguishing factor.  Note, however, that despite the fact that the base oil of a synthetic is white, the additives can add considerable color (darkening) to the finished oil.

In the laboratory, you could distinguish synthetics from mineral oil by looking at a combination of physical properties including VI, flash point, pour point and aniline point. There may also be different elemental additive chemistry.

Generally, in the type of application you are talking about, the synthetic gear oil will likely be polyalphaolefin (PAO) based. PAOs are very similar chemically to mineral oils, so mixing the two should not cause a compatibility problem, especially if both oils are the same API classification.

However, if a synthetic is required, such as for cold-temperature operation, using a mineral by mistake may cause other problems.

Also, be aware that in industrial applications, some synthetic gear oils are polyglycol (PAG) base stocks, which are chemically incompatible with both PAO synthetics and mineral oils. In this case, mixing will result in serious incompatibility issues.

Prevent Additive Settling in Stored Oil

Do you feel that it is necessary to agitate oil that is stored in larger containers such as drums to avoid a situation where some of the critical additives may settle in the bottom of the container?

It is quite possible to agitate or mix the oil in a drum to redissolve additives, but if you are aware that additives have settled out of the oil, you should seriously consider returning the drum (or any container) of oil back to the supplier.

With the exception of certain gear oils that contain solid, suspended extreme pressure (EP) additives, most additives in lube oils are liquids, which easily dissolve into the base oil with a little heat and mixing during the blending process. A few additives may be in the oil as a suspension (for example, silicone-based anti-foam additives), but they should not settle out under normal circumstances.

If an additive is placed into the oil at too high of a concentration, the excess amount of additive could settle out, particularly at colder storage temperatures. However, this would not be considered normal.

The type of base oil used in the finished product will also have an impact on the additive solubility and thus any separation and settling. Group I base stocks are some of the best at dissolving additives, while polyalphaolefins (PAOs) are at the poorer end of the scale.

Whether you store lubricants in a 10,000-gallon tank or in 55-gallon drums, it is important that the lubricant’s quality is not tainted by contamination or additive settling. To ensure that lubricants stay in an optimal condition, determine how much lubricant should be stored at one time. To aid in this process, certain factors must be considered, such as:

The Lubricant Consumption Rate — Consumption will vary greatly depending on industry and equipment type. To ensure that the right lube quantities are being stored at a facility, you must determine the consumption rate. There are many factors that contribute to consumption, ranging from leaks to excessive drain-and-fill tasks.

The Lubricant Storage Capacity — The required lubricant storage capacity depends on consumption, but often there are too little or too many lubricants stored at one time. The proper storage capacity should maximize shelf life but allow for a certain percent excess of critical lubricants to be stored for emergency situations.

The Lubricant Supplier Turnaround Time — A lubricant supplier’s turnaround time should be a metric used to aid in determining the quantity of lubricants stored. If there is a short time interval between deliveries, fewer lubricants can be stored on site; however, if there is a lengthy time interval between deliveries, the quantity of lubricants stored on site should account for this.

When to Perform an Oil Flush

Just as it should, oil analysis gives rise to many other questions concerning maintenance practices. One that often tops the list is what to do when a lubricant doesn’t get a clean bill of health. More specifically, what must be done with the machine that contained a degraded or contaminated lubricant after the drain? Is a flush required? If the answer is yes, there are a few other questions that follow, such as:

1. What was the root cause that led to a need to flush? Who is to blame?
2. How urgent is the need to flush? Can’t we wait?
3. What are the risks of not flushing? What is the worst that can happen?
4. Are there negative side effects to performing a flush? What dark cloud is hidden beneath the silver lining?
5. What is the best way to perform the flush to reduce cost, risks and business interruption?

Flush or Not to Flush

While the broader, procedural subject of flushing goes well beyond the word-count limit of this paragraph, let’s take a closer look at the fundamental question of when performing a flush is justified. When we understand the conditions that trigger the need for a flush, we are better equipped to answer the remaining questions on the list above.

It is our opinion that the items listed in Table 2 are the most common reasons a flush is justified.

Reason for Performing a Flush	Potential Consequences of Not Flushing
1.     Oil Degradation. Oils degrade for a number of reasons. Most often it is associated with thermal degradation, oxidation, nitration, hydrolysis or additive precipitation. Sludge, varnish acids and reactive chemicals are often the products of degradation.	Corrosion, oil flow restriction, mechanical interference of machine movement, infection of next oil change (sequential oil failures).
2.     Filter Collapse/Failure. When a filter fails, releasing debris into an active system, collateral damage can occur unless a successful flush is performed.	Accelerated wear to gears, bearings, pumps, valves, etc.
3.     New or Repaired Machine. New or repaired machines are often internally contaminated with manufacturing and service debris (casting sand, weld slag, drill turnings, burrs, blasting sand, filings, etc.). Also, when a component fails, it will often release a large amount of debris downstream to other sensitive components. This downstream debris remains after the component is replaced unless a flush is performed.	Premature filter plugging, wear and mechanical interference of machine movement. This can lead to infant mortality of new and rebuilt machines.
4.     After Machine Lay-Up. After a machine has been laid-up for a long period of time, water, dirt, sludge and other contaminants often accumulate in the components, lines and sump.	Recommissioning of laid-up equipment can disturb and mobilize low-lying contaminants leading to accelerated wear of gears, bearings, pumps, valves, etc.
5.     After Cooler Failure. When mixed with oil and additives, antifreeze (glycol) produces acids, sludge, deposits and precipitants.	Oil flow restriction, plugged filters, corrosion, mechanical interference of machine movement and impaired fluid properties.
6.     After Mixed or Wrong Lubricants. Mixed lubricants can potentially result in insoluble by-products from the reaction of incompatible additives and base oils. For instance, polyglycols, when mixed with mineral oils, produce a thick pasty sludge.	Oil flow restriction, plugged filters, mechanical interference of machine movement and impaired fluid properties.
7.     Microbial Contamination. When a fluid has been invaded by water and biological contaminants, sludge, varnish, acids and deposits often result.	Corrosion, oil flow restriction, premature filter plugging, wear, mechanical interference of machine movement and impaired fluid properties.

Table 2

 

Often the need to flush is first observed during an inspection or the appearance of sludge in a sight glass, on a used filter, or on the bottom of a sump. This can be confirmed by oil analysis and further inspection. Remediation involves both the removal of the sludge, varnishing or debris (flushing) plus the removal of the root cause before the system is returned to service with normal life expectancy.

The flow chart in Figure 1 can help in deciding whether to perform a flush.

Risky Business

What are the risks associated with a flush? These vary considerably and depend on the flushing procedure, the machine, and the lubricating oil. If the flush procedure involves introducing foreign chemistry (solvents, detergents, etc.) into the oil or machine, this could impair the performance of the lubricant and attack seals and machine surfaces. Lab testing in advance can hedge the risks. In certain cases, flushing can also lead to leakage when deposits are removed around aged seals and gaskets. In addition, problems can also come from the disturbance and resuspension of settled, low-lying contaminants that are not fully carried out of the system during the flush. In general, there are risks any time a machine is invaded by human agency.

11 Tactics for a Strategic Oil Flushing Program

When you consider the large number of machine types in use, each with special needs and the unique problems that flushing must restore to a clean and healthy state, it is no wonder that so many different approaches and technologies have been deployed. Both service and equipment suppliers continue to offer new answers to the age-old problem of how best to purge contaminants and lubricant degradation products from the bowels of the machine.

Flushing Tactics. These are single discrete activities directed at removing unwanted deposits, sediment and risk-prone fluid suspensions.

Flushing Strategies. Strategies are a program of one or more tactics and related steps needed to achieve a complete and successful flush.

Let’s begin this tactical discussion by distinguishing between two closely related cleanup activities: oil reclamation and machine flushing. Unlike flushing, oil reclamation (also known as reconditioning) does not have to involve the machine and its surfaces. It is simply a process of removing health-threatening contaminants from the bulk oil. In certain cases, this may include acid scavenging. For large systems, it may be followed by bleed-and-feed or other top treatments to restore depleted additives and dilute soluble impurities.

As mentioned in the following list of tactics, the removal of harmful contaminants (both soluble and insoluble) from bulk oil can beneficially impact the removal of pre-existing sludge and varnish. It can also substantially mitigate the future formation of internal machine deposits. This has led to a blurred line between the definitions of oil reclamation and flushing. The confusion basically comes from these two cross-linked statements: (1) It can be safely stated that a machine’s internal environment free of deposits, sediment and sludge will by default result in extended oil life expectancy; (2) In a similar fashion, a bulk lubricant scrubbed free of soluble and insoluble impurities by oil reclamation will have a measurable impact on machine service life, cooling and friction. In certain instances, the reconditioned oil can even be an effective agent in removing of varnish-like deposits. This explains why many of the flushing tactics mentioned below are also classical technologies used for oil reclamation.

Choosing the wrong tactic can be not only wasteful, but also risky from the standpoint of potential system upsets and negative side-effects. Anytime you introduce unusual fluid chemistry, temperatures, pressures, flows and turbulence there can be adverse consequential effects to the machine, its seals and the lubricant. Now on to the tactics … the list below describes in limited detail, the practices and technologies used by at least 95 percent of flushing activities in industry.

Drawdown Filtration/Separation. This is the mildest of the flushing strategies. Because many machines have no onboard filtration, the use of periodic filter carts and oil reclamation equipment not only can clean the oil (drawing down the contaminant level) but can also remove loosely deposited sludge and sediment.

High Turbulence, High Fluid Velocity, Low Oil Viscosity. Flushing is improved by enhanced fluid dynamics near machine surface boundaries. The approach involves increasing fluid velocity (sometimes two to four times the normal flow rates) and/or reducing oil viscosity during the flush. Typically, a Reynolds number in the range of 4,000 to 6,000 is generally targeted.

High Flush-Oil Temperature. This strategy also reduces viscosity and increases turbulence, and in addition, it increases oil solvency to aid in the scrubbing of tenacious deposits. Target temperatures range from 175ºF to 195ºF.

Cycling Flush-Oil Temperature. Some practitioners have discovered that shocking the machine with large temperature shifts helps break loose crusty deposits during the flush. They use coolers and heaters to cycle the oil’s temperature repeatedly over a range greater than 100ºF.

Pulsating Oil Flow. Rapidly changing oil flow rates caused by pulsation have been found to help dislodge pesky contaminants from nooks and crannies.

Reverse Oil Flow. By changing fluid flow direction, some contaminants and surface deposits are exposed to bending fatigue reversals and can be dislodged and freed into the oil.

Wand Flush Tool. This tactic is used for wet sumps, gear boxes and reservoirs with convenient access to hatches and clean-out ports. A wand on the end of a flushing hose is used to create high-velocity oil flow to blast away deposits. Alternatively, the wand used in suction mode can be effective at picking up bottom sediment on the sump floor.

Charged Particle (Electrostatic) Separators. Some suppliers of these proprietary reclamation technologies have successfully removed varnish from machine surfaces as well as submicron soft contaminants in the oil, known to be a precursor to varnish and sludge.

Solvent/Detergent Flush. Various solvents and detergents have been used to concoct flush fluids with different degrees of success. These include mineral spirits (petroleum distillates), diesel fuel, motor oils and detergent/dispersant packages. They are typically added to the flush fluid at concentrations of 5 percent to 15 percent, followed by a rinse. Compatibility problems (with the oil, seals and machine surfaces) are the primary concern. Always consult machine and lubricant suppliers before these chemicals are introduced.

Chemical Cleaning. These are chemically active compounds, typically caustics and acids that aid in the removal of the most adherent organic and inorganic surface deposits. The oil must first be removed completely from the system. Following the flush, these chemicals should be thoroughly rinsed from the system, often followed by pacification. Always consult machine and lubricant suppliers before employing chemical flushes.

Mechanical Cleaning. This generally involves the use of scrapers, brushes, abrasives and sometimes an ultrasonic bath. Often, chemicals are also used as the machine components are washed one at a time using a parts-cleaning station.

U = Usually Effective  S = Sometimes Effective  R = Rarely Effective  N = Not Effective or Practical

Table 3
Table 1 summarizes the application and probable effectiveness of these technologies in removing contaminants, sediment and deposits from machinery. So there you have it, 11 tactics for flushing.

We’ve already talked about when to flush, the consequences of not flushing, the differences between flushing and oil reclamation, flushing tactics, flushing strategies and flushing sequence.

This paragraph addresses the role of the voice within your oil in guiding the flushing process. This voice, also known by practitioners as oil analysis, can provide essential information relating to flush avoidance, when to flush, how to flush and when your flush has been successfully executed. This guiding role of oil analysis will be discussed in three phases.

Phase 1 – Before the Flush
In relation to flushing, it is logical that the most important time to perform oil analysis is well in advance of a present flush requirement. However, this is not just to tell you when an impending need is detected – that would be too obvious. Instead, its real value is to proactively stabilize the internal-state conditions that avoid the need to perform the flush all together. In fact, a well-structured oil analysis program should largely focus on proactive maintenance objectives, such as avoiding the future need for a flush. This is due to the fact that nearly all flushes are performed after the following scenarios:

1. needed maintenance was not performed (for example, an oil change)
2. maintenance was wrongly performed (for example, a wrong or incompatible oil was introduced)
3. the machine was invaded by a foreign contaminant (for example, glycol, soot, etc.)

A well-designed oil analysis program should enable these common problems to be detected often before a flush is required. When successful, nothing more than an oil change may be required. Of course, the effectiveness in catching common flush precursors depends on oil samples being taken at the optimum frequency and the proper use of on-site or laboratory screening tests. In the event the condition was not detected on time, oil analysis would still be able to provide both the alert and degree of severity (urgency) of the flush condition.

Going back to the original list of reasons for performing a flush (Part 1 of this series), Table 2 lists example tests that could be used to reveal precursor, impending or severe conditions:

Reason for Performing a Flush	Oil Analysis Tests that Reveal these Conditions (both Precursor and Symptomatic)
1.     Oil Degradation. Oils degrade for a number of reasons. Most often it is associated with thermal degradation, oxidation, nitration, hydrolysis or additive precipitation. Sludge, varnish acids and reactive chemicals are often the products of degradation.	FTIR (for oxidation and nitration), blotter spot test, RPVOT, AN, ultracentrifuge, differential scanning, calorimetry, dielectric properties, flash point, voltammetry, coagulated insolubles
2.     Filter Collapse/Failure. When a filter fails, releasing debris into an active system, collateral damage can occur unless a successful flush is performed.	Particle count, patch test, ultracentrifuge, gravimetric analysis
3.     New or Repaired Machine. New or repaired machines are often internally contaminated with manufacturing and service debris (casting sand, weld slag, drill turnings, burrs, blasting sand, filings, etc.). Also, when a component fails, it will often release a large amount of debris downstream to other sensitive components. This downstream debris remains after the component is replaced unless a flush is performed.	Particle count, patch test, ultracentrifuge, ferrographic analysis, gravimetric analysis
4.     After Machine Lay-Up. After a machine has been laid-up for a long period of time, water, dirt, sludge and other contaminants often accumulate in the components, lines and sump.	Patch test, particle count, patch test, ultracentrifuge, acid number, dielectric properties, volumetry, FTIR
5.     After Cooler Failure. When mixed with oil and additives, antifreeze (glycol) produces acids, sludge, deposits and precipitants.	Acid number, elemental analysis, FTIR, blotter spot test, gas chromatography, moisture analysis, Shiff’s reagent test, viscosity test
6.     After Mixed or Wrong Lubricants. Mixed lubricants can potentially result in insoluble by-products from the reaction of incompatible additives and base oils. For instance, polyglycols, when mixed with mineral oils, produce a thick pasty sludge.	Acid number, FTIR, blotter spot test, ultracentrifuge, elemental analysis, patch test, demulsibility, dielectric properties, flash point, voltammetry, RPVOT, coagulated insolubles
7.     Microbial Contamination. When a fluid has been invaded by water and biological contaminants, sludge, varnish, acids and deposits often result.	Blotter spot test, ultracentrifuge, moisture analysis, microbial analysis test, acid number

Table 4

Phase 2 – During the Flush

As described in the prior series, many flush strategies involve the use of a program of flush tactics until the original offending contaminant has been scoured from the machine as well as both the flush and rinse fluids. The flush and rinse fluids often contain fluid chemistry that must be thoroughly removed before the lubricant is replaced and the machine is returned to service.

Oil analysis can be used as often as needed to assess what remains in the circulating fluids. In such case, the analyses can aid in guiding the process by defining the type and duration of each step in the sequence. Perhaps certain flush steps (tactics) will need to be repeated based on the results of the analysis. This enables flushing decisions to be made or modified in real time in response to oil analysis data. In addition to laboratory testing of oil samples, various inspections of the machines’ internal surfaces, including gearing, bearings and tanks can help confirm the successful execution of the flush program.

Phase 3 – After the Flush

There are unique and often serious problems that can be an unpleasant side effect of machine flushing. However, evidence of these may not occur immediately. Flushing disturbs a machine in many ways that can’t always be predicted or easily observed. As such, for a period of time after a flush, oil analysis should be performed regularly on critical machinery to ensure that healthy conditions have indeed been restored. Early detection of a problem could be the difference between costly downtime and a nuisance condition that could have been easily corrected. The following is a list of potential problems (side effects) associated with flushing where oil analysis might provide a timely alert:

• Demulsibility – remnants from flush fluids can interfere with this important property.
• Oxidation stability – disturbed sludge and machine deposits may adversely affect this property.
• Viscosity excursion – many flushing and rinse fluids are very low in viscosity compared to the lubricant. When these fluids mix with the lubricant, viscosity can be cut back as much as 50 percent.
• Film strength and rust inhibitor problems – flush and rinse fluids may absorb into machine surface grain boundaries. These absorbed chemicals may interfere with the performance of important surface-active lubricant additives.
• Leakage and seal problems – when new chemistry is added to a machine and/or violent flushing occurs, seal performance may be affected. This may also be due to changes in lubricant viscosity or interfacial intension from fluid mixing problems.
• Oil way and filter plugging – flushing and rinse fluids can resuspend sludge and insoluble contaminants which can cause flow blockage of glands, orifices, oil ways and even filters.

Unearth the benefits of GG Friction Antidote – An investment that pays off and your benefits at a glance:

Innovative tribological solutions are our passion. We’re proud to offer unmatched friction reduction for a better environment and a quick return on your investment. Through personal contact and consultation, we offer reliable service, support and help our clients to be successful in all industries and markets.

Profitability:

Switching over to a high-performance lubricant pays off although purchasing costs may seem higher at first, less maintenance and longer vehicles/machinery parts lifecycle may already mean less strain on your budget in the short to medium term.

Continuous production processes and predictable maintenance intervals reduce production losses to a minimum. Consistently high lubricant quality ensures continuous, maintenance-free long-term lubrication for high plant availability. Continuous supply of fresh GG Friction Antidote treated lubricant to the lubrication points keeps friction low and reduces energy costs.

Safety:

Longer lubrication intervals reduce the frequency of maintenance work and the need for your staff to work in danger zones. Lubrication systems can therefore considerably reduce occupational safety risks in work areas that are difficult to access.

Reliability:

GG Friction Antidote treated lubricants ensure reliable, clean and precise lubrication around the clock. Plant availability is ensured by continuous friction reduction of the application. Lubrication with GG Friction Antidote treated lubricants help to prevent significant rolling bearing failures.

Need a good ROI? How about 3,900%?

It may sound too outrageous to be true, but the Institute of Mechanical Engineers estimates every $1,000 spent on proper lubrication yields $40,000 in savings.

INSTANT ROI FOR OPTIMIZING YOUR LUBRICATION REGIMEN

• How many kilometers do you travel monthly?
• How many hours do you clock monthly?
• How many litres of fuel do you consume monthly?
• What’s the cost of fuel to you monthly?
• How many kilometers or hours do you run per oil change?
• How many litres of oil do you consume per oil change?

What’s the cost of oil to you monthly?

What’s the cost of oil filters per oil change to you?

What’s the cost of grease to you monthly?

What’s the cost of fuel filters per oil change to you?

What’s the cost of air filters per oil change to you?

What’s the average frequency of vehicle/machinery replacement to you?

What’s the cost of vehicle/machinery replacement to you?

Would you like to lower your operating costs, improve uptime and increase your company’s profits?

Let’s do the math together … Learn more >>

The information in this literature is intended to provide education and knowledge to a reader with technical experience for the possible application of GG Friction Antidote.  It constitutes neither an assurance of your vehicle/machinery optimization nor does it release the user from the obligation of performing preliminary tests with GG Friction Antidote. We recommend contacting our technical consulting staff to discuss your specific application. We can offer you services and solutions for your heavy machinery and equipment.

Locate A GG Friction Antidote Dealer