Industrial Gear Oil

The American Gear Manufacturers Association (AGMA) has gone a step further than the ISO 3448 viscosity classification system for industrial oils in describing lubricant classifications for industrial gear lubricants. The AGMA standard provides the user with viscosity classifications as well as guidelines for minimum performance levels aimed at industrial gear oils. It aligns with the ISO viscosity standards and is verified by the American National Standards Institute (ANSI).

It is published as the AGMA/ANSI 9005 standard and describes the following four types of industrial gear lubricants:

Rust and Oxidation-Inhibited Gear Lubricants (also referred to as R&O gear oils) are petroleum or semisynthetic based oils formulated with additive systems that protect against rust and oxidation. Some R&O gear oils also contain minute amounts of anti-wear additives. The viscosity grades for R&O gear oils are identified by AGMA numbers 0 to 13.

Compounded Gear Lubricants are petroleum based oils with rust and oxidation inhibitors, demulsibility additives and 3 percent to 10 percent fatty oils. These gear lubricants are frequently used in worm gear drives to provide adequate lubrication and prevent sliding wear. Compounded gear oils are identified by single-digit AGMA numbers with the suffix “Comp” from 7 Comp to 8A Comp.

Extreme Pressure Gear Lubricants (commonly referred to as EP gear oils) are petroleum or semisynthetic based and are fortified with multifunctional additive systems. These additive packages generally contain rust and oxidation inhibitors, EP additives, demulsifiers, antifoam agents, and in some cases solid lubricants such as graphite. AGMA numbers combined with the suffix “EP” describe these lubricants and range from 2 EP to 13 EP.

Synthetic Gear Lubricants are formulated with fully synthetic base stocks and are used whenever petroleum based gear oils have reached their performance limit. Synthetic gear lubricants have the advantage of improved thermal and oxidation resistance and being stable over a wide range of operating temperatures. They normally contain additives similar to those found in EP gear oils. Synthetic gear lubricants are identified by AGMA numbers with the suffix “S” from 0 S to 13 S.

The table below illustrates how AGMA gear oil viscosities correspond to ISO industrial oil viscosities:

Residual compounds 14R and 15R (asphaltic cutbacks) are not included above since these lubricants are being phased out.

In this and previous articles we have discussed the following viscosity classification systems: SAE engine oils, SAE gear lubricants, ISO industrial fluids and AGMA industrial gear lubricants. The following chart brings all these together and provides a comparative illustration of all the various viscosity grades:

Not all viscosity grades appear on the chart as only the most commonly used grades are listed.

Viscosities relate horizontally only.

For example, the following oils have similar viscosities: ISO 150, AGMA 4, SAE 40 and SAE 90.

This may surprise you since many people think that gear oil is thicker.

Industrial Oil Viscosity Classification.

After the industrial revolution many classification systems were devised to designate viscosity grades for lubricants used in manufacturing and other industrial applications. While all of these have served useful purposes to some degree or another, it was confusing since different units were used to report viscosities such as Saybolt Universal Seconds, Redwood Seconds, Engler Degrees, Centistokes, and more. To add to the confusion, two measures of temperature (Fahrenheit and Celsius) were used, not to mention that viscosities were specified at either 100°F or 40°C and 212°F or 100°C. This necessitated the need for a universally accepted viscosity classification system for industrial oils.

In response, the International Standards Organization (ISO) in collaboration with the American Society for Testing and Materials (ASTM), Deutsches Institut für Normung (DIN) and others formulated a common viscosity classification during 1975. The result is known as the International Standards Organization Viscosity Classification System, commonly known as ISO VG.

This classification is applicable to fluids for industrial applications, such as bearings, gears, compressor cylinders, hydraulics, turbines, etc. Viscosity values are reported in centistokes (cSt) and the reference temperature is 40°C which represents the operating temperature in machinery. The system comprises of 20 viscosity grades, ranging from 2 cSt to 3200 cSt.  This covers fluids from as thin as paraffin to oils with a consistency similar to that of syrup. The viscosity of each grade within the classification is approximately 50% higher than the viscosity of the previous grade. The minimum and maximum limits of each grade are the mid-point viscosity plus or minus 10%. For example, ISO VG 100 has a mid-point viscosity of 100 cSt at 40°C with viscosity limits 90 cSt and 110 cSt:


ISO 3448 Viscosity Classification

This system does not evaluate the quality of a lubricant and applies to no property of a fluid other than its viscosity at the reference temperature. It does not relate to those lubricants that are used primarily with automotive equipment and are identified with a SAE number.

Base oils are the foundation of most lubricants.

In most instances lubricating oil is a blend of base oil and additives with the base oil content being anything between 70 percent and more than 99 percent depending on the final application of the lubricant. Base oils may be mineral, synthetic or semi-synthetic -a mixture of mineral and synthetic stocks. Most lubricating oils used globally (more than 90 percent) are blended using mineral base oils. Feed stocks from a number of streams at crude oil refineries are processed at base oil refineries to produce various viscosity grades of mineral base oils.

A typical mineral base oil refinery will have the following units to produce suitable quality base oils:

  • Solvent Extraction to remove undesirable aromatic (unsaturated) compounds which are unstable and cause the formation of tar, varnish and carbon in engines,
  • Propane De-asphalting removes asphaltic material from the base stocks to minimise the formation of deposits in machinery, and
  • Dewaxing to improve low-temperature fluidity of the base oil.

These three (extraction) conversion processes generally produce Group 1 base oils with aromatic content between 15 and 20 percent. The colour of Group 1 base oils would normally vary from a light yellow to straw. The quality of such base oils can be further improved by a number of Hydrofinishing Processes. Hydrofinishing changes the remaining unsaturated/aromatic compounds in the oil by a chemical reaction involving hydrogen and produces base oils with improved chemical stability, lower sulphur content and much lighter colour. The final quality of the base oil is determined by the severity of the application, temperature and pressure in the hydrofinishing process and will normally be classified Group 2 or Group 3 base oils. The quality and characteristics of modern Group 3 base oils approach that of synthetics.

Synthetic base oils are manufactured from chemical building blocks and excel mineral oils in viscosity index, shear stability, low and high temperature performance, oxidation stability and volatility. A major disadvantage of synthetics is that they cost approximately 3 to 5 times more than mineral oils. They therefore tend to be used in specialty applications only where the performance of mineral oil is considered unsatisfactory. Typical examples are very high temperature applications and extended oil drain intervals.

The most commonly used synthetic oil is polyalphaolefin (PAO). PAO’s are classified Group Lj base oils and are used in a wide variety of automotive and industrial applications such as engines, transmissions and hydraulic systems. The use of Group 5 base oils (typically synthetic esters) are limited to very special applications such as refrigeration compressor oils and aviation turbine lubricants. The table on the reverse page shows the general  differences between the various Groups.

Mineral and synthetic base oils are produced in a number of viscosity grades. For instance low viscosity (thin) base oils would be used to produce automatic transmission fluids whilst thick, heavy ones are required to blend ISO 680 viscosity grade gear oils.

A final word of advice: avoid mixing different oil Groups. In an emergency situation mineral oils may be mixed with PAO’s, but Group 5 synthetics should preferably not be used with any other oil Group.

With complete control of our raw materials we can guarantee a consistency of product quality matched by few other companies and our customers con have complete confidence in the performance of our products.  To learn more please contact us today by visiting http://www.bcl.co.za

The history of lubricants P2 OilChat#54

In this issue of our newsletter we will discuss what is considered to be the modern history of lubrication.  Early machines were relatively simple and worked satisfactorily using crude oil as a lubricant. Most industrial plants kept a single drum of oil to lubricate all their machines. During the First Industrial Revolution (1760 to 1840) the development of larger machines with tighter specifications which had to run at greater speeds for mass production, triggered the search for more sophisticated and specialised lubricants.

It is impossible to discuss all the highlights in the evolution of modern lubrication in a space like this, but we consider the following milestones worth mentioning:

1848 Scottish chemical engineer James Young (founder of the first commercial oil works in the world and father of the petrochemical industry) discovered natural petroleum seepage in a Derbyshire colliery. From this he distilled a light thin oil for use as lamp oil, and at the same time obtaining a thicker oil suitable for lubricating machinery.

1859 Edwin L. Drake struck oil at Titusville in America. His oil well created a new way to supply petroleum-based oil products, which accelerated the move toward the use of mineral oil in America.

1866 – Dr John Ellis, founder of the Continuous Oil Refining Company in Binghamton, USA, developed an all-mineral, high viscosity lubricant for steam engines – previously using inefficient combinations of petroleum and animal or vegetable fats. His breakthrough oil worked very effectively at high temperatures. This meant no more gummed valves, corroded cylinders or leaking seals.

1872 Elijah McCoy, a Canadian-born American inventor and engineer, developed an automatic lubricator that was used to apply oil through a drip cup to locomotive and ship steam engines. Railroad engineers insisted on McCoy lubrication systems when buying new machines and would take nothing less than what became known as “the real McCoy”.

1885 German engineer Karl Benz produced a petrol-powered automobile. This is also considered to be the first “production” vehicle as Benz made several other identical reproductions. The vehicle was powered by a single cylinder four-stroke engine.

1908 Henry Ford introduced The Ford Model T car on October 1, 1908. During 1913 the Model T became the first automobile to be mass-produced on a moving assembly line.  By 1927, Ford had produced over 15,000,000 Model T cars.

1920 As the demand for automobiles grew, so did the demand for better lubricating oils. Lubricant manufacturers started extracting base oils under vacuum from crude oil to improve the performance of their lubricants. Vacuum distillation is still used today in modern oil refineries.

1923 – The Society of Automotive Engineers (SAE) classified engine oils by viscosity i.e. light, medium and heavy. At the time engine oils contained no additives and had to be replaced every 800 to 1000 miles.

1930s Up to 1930 there were no common standards to regulate the performance of motor oils and every vehicle manufacturer had their own set of requirements for lubricants. Vehicle manufacturers realized that there was a need for fixed standards for lubricant performance so that vehicles could be sold anywhere in the world without major modifications or embarrassing failures. The American Petroleum Institute (API) took on the task of setting common standards for engine oil. Their first attempt described three oil categories: Regular (straight mineral oil); Premium (mineral oil with oxidation inhibitors) and Heavy Duty (mineral oil with oxidation inhibitors plus detergents/dispersants). Zinc dialkyl phosphate additives were developed to provide rust and corrosion protection. The antiwear properties of zinc compounds were only recognised years later.

1940s – World War II accelerated the development of lubricant technology and the use of molybdenum disulphide as a solid lubricant dates back to the early days of the war. America and Germany started using ester based synthetic oils in fighter plane engines. Polyalphaolefin (PAO) synthetic oils were developed in the USA and their initial use was in steam turbines. Possibly the first ever use of synthetics for automotive applications was in tank engines. Sherman tanks operating in the intense heat of the Sahara Desert were enormously stressed.  The engines fried their oil and seized solid. The new PAO lubricants were tried out very successfully in the tank engines. In 1947, after the war, the API changed their Engine Oil Classification System to the format still used today.

1950s – It was only during the nineteen-fifties that the antiwear properties of zinc chemistry were fully understood and it became an integral part of many oil formulations. To this day zinc dialkyl phosphates remain the backbone of antiwear additive technology. Solvent oil refining emerged and replaced traditional petroleum distillates owing to their improved lubricant properties. This eventually led to the introduction of API Group 1 lubricating base oils. The world’s first successful multigrade engine oil was launched in 1953. Fire Resistant Hydraulic Fluids were invented in 1958. The first Jet Engine Oil based on polyol-esters were developed and patented in New Jersey, USA. This decade also saw the development of superior grease types, i.e. urea and aluminium.

1960s – Food grade lubricants were introduced and used since the early 1960s.  The Jost Report in 1966 (click to follow link) led by Dr Peter Jost, included the first mention of the term “tribology”.

1970s – The first 100% synthetic di-ester based engine oil passed the API sequence tests and received API qualification in 1972. The following year the first PAO based synthetic engine oil was launched commercially.

1980s – A low-wear tractor hydraulic fluid (THF/UTTO) with satisfactory wet brake performance in a wide variety of tractors was introduced in 1980. The development and design of American and European engines and their appetite for lubricants departed from each other and the CCMC (Committee of Common Market Automobile Constructors) promulgated oil specifications for European automotive engines. 1984 saw the introduction of all-hydroprocessed base oils in the USA. This process combined catalytic dewaxing with hydrocracking and hydrofinishing, which set a new standard for performance (API Group II) in the lubricating base oil industry.

1990s – Germany pioneered SAE 0W-60 engine oil during 1992. The European Automobile Manufacturers’ Association (ACEA) Oil Sequences were introduced in 1996 when they superseded the outdated CCMC

Sequences previously used to define European petrol and diesel engine oil performance.  A revolutionary base oil dewaxing process (hydroisomerization) was commercialized in Richmond, California. Hydroisomerization converts petroleum wax to very high-quality base oil. This represented a major improvement over Group I and II base stocks and allowed the introduction of superior quality Group III base oils. Although these oils were (and still are) produced from mineral feed stocks,
Group III oils closely mirrored the characteristics of PAO synthetic base oils. In fact, during 1999 the National Advertising Division (NAD) in America ruled that hydroisomerized Group III base oil can be classified as ‘synthetic oil’.

2000 and Beyond

The lubricant evolution continues as increasingly advanced products are developed to meet the rising demands of modern machinery for better productivity, performance reliability, energy efficiency and environmental responsibility.  To meet these requirements the trend is towards lower viscosity oil grades, alternative additive technologies and base oils with higher purity and lower volatility. Many modern engines are now calling for SAE 5W-30 and even SAE 0W-20. In fact the SAE (Society of Automotive Engineers) has recently promulgated a new SAE 16 grade as a lighter alternative to SAE 20 engine oil grade. In the interest of the environment, focus has shifted to low ash oil additives with little or no metallic compounds. New Group III base oils have been developed that can actually outperform a full synthetic PAO in several areas important to lubrication, such as additive solubility, lubricity and antiwear performance. Group III base oils can now also rival PAO stocks in pour point, viscosity index and oxidation stability and can be manufactured in volumes and at a price unachievable by PAOs.

With the support of Q8Oils, Blue Chip Lubricants are at the forefront of new product development. Our vast experience, well equipped laboratory and modern production facilities ensure that you always receive a tailor-made solution for your specific lubrication requirements. To learn more please contact us today by visiting http://www.bcl.co.za

The history of lubricants P1 OilChat#53

In a world that depends a great deal on machines, lubrication is absolutely essential. The science of tribology has advanced significantly in recent times, but the roots of lubrication extend back further than one might imagine. Lubrication in simple form has been in existence at least since the beginning of documented times. In this issue of our newsletter we will delve into the ancient history of lubrication.

lubricant is a substance introduced between two surfaces in relative motion to each other to reduce friction (and consequently wear) between them. Our forefathers first became familiar with friction in the Stone Age, when they discovered that they could create fire by rubbing pieces of wood against each other. We do not know for sure exactly when they mastered the art of making fire, but indications are that it was approximately 400,000 years ago.

Man’s search for effective lubricants and lubrication technologies has a colourful past, going back as far as the recorded history of humankind. Water was probably the first documented lubricant. The Egyptian mural on the right shows a statue being dragged along the ground. A man can be clearly seen on the leading end of the transporting sledge pouring a liquid (water?) on the ground in front of it, presumably as a lubricant. To learn more visit
https://www.youtube.com/watch?v=tR3MnyWD5gE

It is impossible to list all the milestones in the colourful history of lubrication in a condensed publication like this, but the following fascinating highlights are worth mentioning:

4000 B.C. to 3500 B.C. Indications are the Chinese made use of the lubricating properties of water earlier than 3500 B.C.

3500 B.C. Wheels are an example of primitive, caveman technology. It was, however, so ingenious for those times that it took thousands and thousands of years for someone to invent it circa 3500 B.C. Evidence indicates they were first created to serve as potter’s wheels in Mesopotamia (Iraq).

3200 B.C. It took another 300 years before it was figured out how to use wheels on carts to transport objects. Wheels of the era were made of a solid piece of wood or stone with a hole in the centre for a wooden axle. The earliest ‘vehicles‘ were probably ox carts. The use of the wheel spread fast throughout Eurasia (including the Middle East) and the earliest images of wheeled carts surfaced in the remains of Slavic settlements in present-day Poland. It has been speculated that water was initially used to prevent the hubs of wooden wheels from becoming charred as a result of frictional heat.

3000 B.C. Wheeled carts were now in extensive use in the Middle East, although few traces of lubricant materials have been associated with remnants of such vehicles from that era.

3000 B.C. to 2000 B.C.  It was finally discovered that smearing a lump of animal fat or bitumen (black viscous oil seeping out of the ground) on the dry and squeaking parts made the wheel run quietly and cooler, but without scientific knowledge of friction, no one knew why.

2000 B.C. The invention of the spoked wheel allowed the construction of lighter and faster ‘vehicles’.  The earliest known chariots have been found in the Sintashta burials in Russia. The technology spread rapidly throughout the Old World and played an important role in ancient warfare.

2000 B.C. to 1650 B.C. The advent of high speed horse drawn chariots could possibly be seen as the birth of ‘Tribology’. Experimentation at the time led to the use of more sophisticated lubricants, including olive oil and other vegetable matter. The Egyptians discovered that some of the more viscous liquids not only dissipated heat better, but also prevented much of it from forming in the first place. At the same time, they observed that the wheels were turning more freely. These early discoveries marked the dawn of machinery lubrication.

1650 B.C. Olive oil appeared to be a lubricant of choice at the time. The grave of Egyptian king Tehut-Hetep was found to contain a description of the application of olive oil to reduce friction.

1400 B.C. Compounded lubricants have been identified on the axles of Egyptian and Roman chariots dating back to this age. The lubricant was most probably prepared by combining olive oil with lime.

1200 B.C. When metal replaced wood as moving parts in machinery during the Iron Age, crude chunks of animal fat or bitumen became inadequate lubricants. A next generation of lubricants were developed using fatty and oily substances derived from animal fats and vegetable extracts.

780 B.C. The Chinese discovered the friction-reducing properties of a mixture consisting of animal fats or vegetable oils and lead which resulted in the development of a new generation of compounded lubricants.

1760 A.D. to 1840 A.D. The increased demand for animal-based products as lubricants, and also as illuminating oil, during the First Industrial Revolution almost had disastrous consequences. The sperm whale was almost hunted to extinction to meet the demand for sperm oil. This, and the increasing difficulty to obtain other bio-based oils, triggered the search for alternative lubricants, especially petroleum (mineral) oils.

Many things have changed since the early days of lubrication, but machines and tribology endure in our modern technological world … a tribute to the true significance of these early achievements. In the next issue of our newsletter we will look at the modern history of lubrication.

Air Tool Lubrication OilChat#52

An air tool or pneumatic tool is a type of power tool driven by compressed air supplied by an air compressor. Air tools come in various shapes and sizes, ranging from small hand tools to jackhammers (paving breakers) and powerful rig mounted units used in the mining and quarrying industry. General grade air tools with a relative short life span are less expensive and are considered “disposable tools” in the tooling industry.  Industrial grade pneumatic tools are amongst the most indestructible power tools available and yet many of them ‘die at a young age’. To understand why this happens one must first look at the way pneumatic tools operate.

An air compressor is the starting point for any pneumatic circuit. A compressor is a machine that converts ordinary air into compressed air as discussed in OilChat #20. The compressed air delivers potential energy (via a flexible hose) to the actuator at the business end of the pneumatic circuit. The actuator turns the potential energy stored in the compressed air back into kinetic energy and movement. In short, the actuator is the tool that does some or other useful mechanical work for us. Actuators may move back and forth in a straight line (reciprocate) or deliver a rotary motion. Linear-action (percussion) tools like jackhammers typically employ a piston-type actuator. Rotary-action tools such as air-driven drills and grinders use a geared or turbine type motor to do the job.

So what then is maiming, crippling and killing those ’indestructible’ pneumatic tools? The most lethal killer is dirty air. If the air going into the system is not properly filtered, grinding grit is introduced into the moving parts inside the actuator. Moisture is another air tool killer. If you impel wet air into a pneumatic tool, you are spraying rust-promoting water right into the guts of the tool. It is therefore good practice to fit an airline filter cum water trap between the compressor and the pneumatic tool. It removes impurities and most of the humidity (moisture) from the air in the line. Perfectly dry air is not always delivered to air tools.

The moving parts of air tools, regardless whether the tool is of a reciprocating or rotary type, require consistent lubrication just like a car engine. The problem is that air tools do not have a sump for the lubricant, so it needs to be fed into the tool with the compressed air that powers the tool. To do this airline lubricators are fitted to the air supply hose. Almost all pneumatic tools perform better when lubricated with oil. Injecting an oil mist into the air-stream lubricate valves, cylinders, and air motors for proper operation and long service life. Locating the lubricator properly in the airline is important to ensure that the correct amount of lubricant reaches the tool. Too little oil will allow excessive wear and can cause premature failure. Excessive oil in the airline is wasteful and can become a contaminant in the ambient area as it is carried out of the tool by the exhaust air.

 

A cross-section of a typical airline lubricator is shown on the right. Airline lubricators dispense oil from a reservoir in the lubricator into the moving airstream. As high-velocity air passes through a venturi inside the airline lubricator, it draws oil from the reservoir through a capillary tube and then drips it into the airstream. The moving air breaks the oil up into a mist or fog, which is then carried down the air line into the air-powered device. The oil feed rate can be controlled manually with an adjusting valve. A sight glass enables the operator to monitor the oil output. A filler plug allows the reservoir to be refilled in situ. Lubricators are generally selected based on pipe connection size, oil reservoir capacity and acceptable pressure loss versus flow rate. Manufacturers usually recommend a minimum air flow rate at which the venturi will function properly.

 

Pneumatic tools are precision built units with close tolerance parts. Many of them operate under heavy loads in adverse conditions. During operation temperatures may vary widely from low ambient to localized hot spots inside the air tool, particularly in reciprocating type tools. Boundary lubrication conditions often prevail due to the sliding action of heavily loaded pistons, which is further accentuated by their reciprocating motion. Moisture in the compressed air can cause rusting and washes the lubricant from critical areas. Adequate lubrication is therefore essential to keep pneumatic tools out of the repair shop.

To ensure extended equipment life air tool lubricants must control wear, protect against rust and corrosion, resist foaming and prevent water wash-off from critical areas when operating with wet air. In addition pneumatic tool lubricants must have low carbon forming characteristics and prevent the formation of sludge and deposits.  Oil fogging can be a health hazard when working in mines and enclosed spaces and the oil must therefore also resist fogging.

The heart and weak link of pneumatic tools are the rubber “O” rings (seals) inside the tool. These need to be lubricated, but many lubricants may attack the rubber. It is thus essential to use a lubricant specifically formulated for pneumatic tools. Such oils are typically blended with highly refined mineral base oils, antiwear, oiliness and tackiness additives, emulsifiers/surfactants, rust and corrosion inhibitors plus antifoam and antifogging agents.

Equally important is the viscosity of the oil. The amount of oil picked up in airline lubricators, depends largely on the viscosity grade of the lubricant and the temperature surrounding the lubricator. Equipment manufacturers’ guidelines on viscosity selection should always be followed. In the absence of such viscosity recommendations the following ambient temperature guidelines may assist in ensuring that adequate atomization is obtained in the airline lubricator:

–  Small hand-held tools: ISO Viscosity Grade 32 will suffice for the majority of applications.
–  Larger industrial tools: ISO Viscosity Grade 100 for temperatures below 20˚C
ISO Viscosity Grade 150 for temperatures between 20˚C and 25˚C
ISO Viscosity Grade 220 for temperatures between 25˚C and 30˚C
ISO Viscosity Grade 320 for temperatures between 30˚C and 35˚C
ISO Viscosity Grade 460 for temperatures above 35˚C

When operators’ health and comfort are the prime considerations when selecting air tool lubricants, grease or emulsions are often the preferred option for larger industrial tools such as rock drills operating in underground mines. Blue Chip Lubricants (Pty Ltd have a complete range of lubricants for a broad range of pneumatic tools working in a wide variety of operating conditions. Please mail us at info@bcl.co.za for details.

Chain Lubrication OilChat#51

It is almost impossible to imagine life without chains. We are familiar with bicycle chains and forklift trucks that use chains to lift loads. Chains are commonly used in conveyor systems, to transmit power and all of us are acquainted with the irritating sound of chainsaws.  Many chains in use today fail prematurely due to inadequate lubrication. Chain lubrication often consists of applying a heavy oil or grease to the chain. While this may lubricate the sprockets and the outside of the chain, it does little to protect the most vulnerable areas, i.e. the contacting surfaces inside the chain. In dusty environments sand may get trapped in such heavy lubricants to produce a fine grinding paste that will shorten the life of the chain dramatically.

The majority of chains fail from the inside. They lengthen or kink up due to wear and corrosion inside the pin and bushing area. To lubricate them properly, the lubricant needs to be applied to penetrate and protect the inside of the chain and leave a solid film of oil behind. Lubrication is essential between the rollers and bushings, but other important areas to lubricate are the contact surfaces between the pins, the bushings and the link plates, which articulate while the chain is in motion.

To provide effective protection chain lubricants should be formulated to have the following characteristics:

  • Sufficiently low viscosity to reach all internal moving surfaces
  • Enough ‘body’ to maintain the lubricating film under high pressures
  • Effective protection against rust and corrosion
  • Good resistance to throw-off
  • Ability to maintain lubricating qualities under all operating conditions

Chain lubricants are formulated with relatively high viscosity index base oil to penetrate into critical internal surfaces at low temperatures and yet maintain an effective lubricating film at high loads and temperatures. To provide the desired lubricating qualities under all operating conditions, chain lubricants are fortified with antiwear and/or extreme pressure additives, rust and corrosion inhibitors and tackiness agents. Antifoam additives, pour point depressants and solid lubricants may be added to the oil if required by the application. Food grade chain lubricants should be used in food processing plants. Suggested viscosity grades for various ambient temperature ranges are shown in the following table:

TEMPERATURE, C ISO VISCOSITY GRADE
-30 to + 25 32
-20 to +30 46
-15 to +40 68
-5 to + 50 100
0 to +55 150
+5 to +60 220

Equally important is the method of lubricant application. The recommended methods of lubrication for chain drives are indicated in the power rating tables published in ASME B29 Series Standards and in various

manufacturers’ manuals. The methods normally listed are manual, drip, oil bath, slinger disk, brush and oil stream. Regardless of the application method, the lubricant needs to be aimed into the pin and bushing area as shown in the visual on the previous page. To reach all the moving surfaces, the lubricant should be applied to the edges of the link plates on the inside of the chain shortly before the chain engages a sprocket (as illustrated below). As the chain travels around the sprocket, the lubricant is carried by centrifugal force into the clearances between the pins and bushings. Spillage over the link plates supplies lubricant to the interior and the end surfaces of the rollers.

Chain manufacturers often use grease or petroleum jelly as an initial lubricant, but grease should not be used to lubricate chains in service, because they are too thick to penetrate into the internal bearing surfaces. Grease should only be used when fittings for injecting the grease into the chain joints are provided.

To maximize chain life requires attention to detail. Operating conditions (load, environment, temperature, speed, etc.) must always be considered when selecting a chain lubricant. Tailoring the lubricant to the specific operating environment may be required.  At Blue Chip Lubricants we have the people, products and proficiency to keep the chains of industry moving. Simply mail us at info@bcl.co.za  and put us to the test.

Base Oil Classification OilChat#50

This edition of OilChat commemorates the fourth anniversary of our newsletter. In the very first issue we addressed the various types of Lubricating Base Oils. Base oils are of prime importance since they are the foundation of all lubricants. Considering the number of new visitors to our website and the amount of enquiries we receive regarding base oils, we have deemed it appropriate to revisit the topic, synthetic base oils in particular.

The American Petroleum Institute (API) categorizes hydrocarbon based oils into four main groups. The classifications are based on the refining method and the properties of base oil, including viscosity index (VI), saturates and sulphur content. Base oils that are not included in the first four groups are incorporated in a fifth group.

Group I is the least refined type and consists of conventional petroleum (mineral) base oils, normally produced by Solvent Refining i.e. a solvent extraction process to remove various undesirable compounds and impurities from the base oil. Group I base oils are straw to light brown in colour and typically have a VI somewhere around 100.

Group II represents a better grade of mineral base oil and is normally produced by Hydrocracking. One of the advantages of hydrocracking is its ability to remove most of the remaining unstable aromatic (unsaturated) hydrocarbons and sulphur. With the majority of the undesirable compounds removed they are more stable and have a much clearer colour. Group II base oils typically have a viscosity index of 110 with some high quality oils having a VI of more than 115. They are becoming very common on the market today and are priced very close to Group I base oils.

Group III is the best quality petroleum base oils. They are produced by Hydrocracking, Hydroisomerization, and Hydrotreating which make them much purer than Group I and II. Group III base oils have a VI greater than 120. Although they are produced from mineral feed stocks, high quality Group III candidates closely mimic the characteristics of Group IV synthetic base oils.

Group IV is chemically produced synthetic hydrocarbons (SHC) based on polyalphaolefins (PAO). These base oils do not contain any unsaturated hydrocarbons, sulphur and nitrogen components or waxy hydrocarbons. The absence of these materials results in a very stable base oil with a VI greater than 125, typically 130 or more. PAOs have excellent low and high temperature characteristics, good oxidation stability and are compatible with mineral oils. Polyalphaolefins are by far the most common true synthetic base oil used in automotive and industrial lubricants.

Group V comprises any type of base oil that is not included in the four groups above. Typical examples are esters, polyglycols, naphthalenes, polybutenes, silicones and biolubes. Group V base oils are used for special applications such as gas and refrigeration compressors, very high VI industrial fluids and environmentally-friendly lubricants.  They are often blended with other base stocks to enhance the properties of the oil. A typical example would be a PAO based compressor oil that is mixed with polyolester. Ester oils can endure more abuse at higher temperatures and will provide superior detergency compared to PAO synthetic base oils.

The API categorizes lubricating base oils according to their chemical and physical properties as shown below:

PROPERTY Gr 1 Gr 2 Gr 3 Gr 4 Gr 5
Saturates <90% >90% >90% P O
and/or and and A T
Sulphur >0.03% <0.03% <0.03% O H
and and and E
Viscosity Index 80 – 120 80 – 120 >120 >125 R

We rewind the clock some twenty years and replay Mobil litigating Castrol in the USA for ‘falsely’ promoting Group III based motor oils as synthetic lubricants. During 1999 Castrol prevailed in proving that their Group III base oil was

modified sufficiently by hydroprocessing to be qualified as synthetic. Subsequently the API has removed all references to synthetic in their base oil classifications and synthetic has become a ‘marketing term’ rather than a measurable quality of base oils.

Fast forward back to the current scenario and we find that hydrocarbon base oils are typically assigned the following descriptions:

Mineral: Group I and II oils are generally referred to as mineral base oils. Occasionally they are simply described as highly refined base stocks.

Semi-synthetic: Group I and/or II mixed with Group III and/or IV. Such mixtures are also referred to as part-synthetic, synthetic based or synthetic technology.

Synthetic: Based on the 1999 ruling in favour of Castrol, Group III based oils are generally tagged synthetic.

Full Synthetic: The description most often used for Group IV Polyalphaolefin base oils.

Group V base oils are normally specifically identified by their chemical name i.e. polyolester, alkylbenzene, polyalkylene glycol, polyisobutylene, etc. The chemical name is sometimes preceded by ‘synthetic’

Dispute raged in 1999 and still does today. You find all kinds of purists who are populating internet forums and who refuse to recognize Group III oils as “synthetic.” To them it is PAO or nothing. It is best not to get caught up in the synthetic base oil debate. The performance that comes out of lubricating oil is just as important as the base oil that goes into it.  Rather look for oils that offer performance claims backed by industry and original equipment manufacturers’ (OEM) testing. Q8 lubricants are blended with the highest quality base oils available and are supported by a wide variety of industry and OEM approvals.

Aeration and foaming in lubricating oil OilChat#49

Foam and air entrainment problems are quite common in lubricating oil circulation systems. Problems that may arise as a result of foaming include fluctuations in oil pressure, oil pump cavitation, loss of oil through breathers and dipsticks and decrease in lubrication and cooling efficiencies. The presence of air bubbles in the fluid can also lead to excessive oxidation. In extreme cases foaming can result in the breakdown of a machine or system.

Most lubricating oils are formulated with antifoam additives. Unlike the name of the additive suggests, foam inhibitors do not prevent the formation of air bubbles (aeration) in oil circulating systems. Air is always to a greater or lesser extent present in circulating oil. Foam is a collection of closely packed air bubbles surrounded by thin films of oil. Antifoam oil additives (usually silicone based) work by reducing the film strength of the air bubbles at the oil/air interface. This results in the rupturing of the air bubbles in the oil causing them to break down and agglomerate. The larger bubbles rise more rapidly to the surface of the oil where they burst readily as illustrated below:

Mechanism of Antifoam Additives

The foaming properties of a fluid are usually determined using the ASTM D892 test method, which measures foam by three sequences that differ only in testing temperature:

  • Sequence I measures the foaming tendency and stability at 24°C.
  • Sequence II measures the foaming tendency and stability at 93.5°C.
  • Sequence III uses the same conditions as Sequence I, except that it is performed on the fluid that has just been measured in Sequence II (See Note Below).

Note: The fluid sample from Sequence I is not used in Sequence II. The fluid sample used in Sequence III is the same sample that was used in Sequence II.

The results are reported as two numbers for each sequence.  For example: 20/0 means 20 milliliters of foam tendency was measured after 5 minutes of aeration followed by no foam stability (0 ml) after a 10 minute settling time. Most new oil specifications require 10 to 50 milliliters tendency maximum after 5 minutes of aeration and 0 milliliters stability after the 10 minute settling period.

Figure 4

This photo of two oils was taken during the five minute aeration period of the ASTM D892 Foam Test. Excessive foam formation can be seen on the surface of the oil on the left which contained no antifoam additive.  The oil on the right was fortified with a foam inhibitor and exhibits negligible foam formation. The photo also shows the larger oil bubbles (that migrate to the surface more readily) in the oil with the antifoam additive.

Although the majority of lubricating oils are formulated with antifoam additives, foam and air entrainment problems are quite common and are usually hard to treat. Traditionally the standard procedure was to run an ASTM D892 foam test on the offending oil, and then indiscriminately add an aftermarket antifoam additive. Generally foam went away quickly, only to return shortly afterwards. More antifoam was added, and the cycle was repeated until the system became so overloaded with foam inhibitor that the oil had to be dumped. Today, there are more practical methods of establishing and treating the source of foam problems and it is therefore usually unnecessary to use aftermarket antifoam additives.

Foaming can be difficult to troubleshoot and for this reason accurate testing to determine the root cause of the problem is essential. The causes of foaming are many. The most common ones include:

  • Water contamination.
  • Solids contamination.
  • Depleted foam inhibitor (possibly due to the use of excessive fine filtration).
  • Mechanical issues (causing excessive aeration of the fluid).
  • Over- or under-filling of the oil sump/reservoir.
  • Cross contamination of the oil with other fluids.
  • Contamination of the oil with grease
  • Too much antifoam additive by adding aftermarket foam inhibitors.

Although troubleshooting a foaming problem can be challenging, you should be able to identify and correct the root cause through a process of elimination.

If you have any questions regarding foaming or any other lubrication issues, simply mail us at info@bcl.co.za. Our experts are at your disposal and ready to provide you with advice and guidance.

Engine-Oil

Engine oil deterioration and engine deposits OilChat#48

Engine-Oil

The topic of OilChat #47 (Soot in Engine Oil) raised further questions regarding engine oil deterioration and engine deposits, sludge and varnish in particular. Engine deposits are an ever increasing problem. This is caused by global initiatives to increase fuel efficiency and to reduce pollution of the environment.

Modern internal combustion engines operate at higher temperatures to increase thermal efficiency, oil drain intervals are extended and oil sump capacities are reduced to minimise engine size and weight. To aggravate matters airflow around the engine is reduced as a result of better aerodynamics. All of these lead to increased stresses on the oil. In addition, fuel economy pressures have led to the introduction of lower viscosity engine oils. Thin oils are more prone to ‘breaking down’ at elevated temperatures, hence the introduction of the NOACK Volatility Test. This test determines the evaporation loss of lubricants in high-temperature service. The more engine oils evaporate (vaporise), the thicker and heavier the remaining oil becomes. The collective result of all this is poor oil circulation, reduced fuel economy, as well as increased oil consumption, wear and emissions.

Oil deterioration can occur in the best maintained engines. It can also happen when the oil is still fairly new and it can even occur with synthetic lubricants. A frequently asked question is what the difference between sludge and varnish is.

Sludge is best described as soft black deposits formed in engine oil lubricating systems. It consists primarily of oxidised lubricating oil components, water and carbonaceous residues (soot) from incomplete fuel combustion.  Severely oxidized and contaminated oil can thicken to the consistency of grease.

When hot oil mixes with air, it reacts with the oxygen in the air.  This process is called oxidation and it causes the oil to darken and break down to form acids and sludge.  The acids are corrosive to engine metals and the sludge increases the viscosity of the oil, causing it to thicken and even gel in extreme conditions.  This is significantly aggravated in diesel engines by the presence of combustion by-products. Partially burned diesel fuel (soot) gets into the oil as described in OilChat #47 and increases the viscosity dramatically. Once the oil additives are depleted the oil will break down into a gel that sticks to surfaces inside the engine. These sludge deposits restrict oil circulation and engine cooling, resulting in excessive wear, or in extreme cases, a catastrophic failure of the engine due to lack of lubrication.

Oil sludge usually starts in the top end of an engine (valve cover area) as shown in Figure 1 and in the oil sump (Figure 2).  Immediate damage begins to occur when the sludge or gel blocks the oil siphon screen, as depicted in Figure 3.  Once this blockage occurs, failure of the engine is inevitable.  The oil level may look fine but the engine is actually being damaged with every revolution of the crank as the engine loses oil pressure and is no longer lubricated effectively.  This is a serious issue for many cars built since 1996, hence the introduction of OEM oil specifications such as VW 505.00 and MB 229.3.

Figure 1                                             Figure 2                                          Figure 3

 

 

 

 

 

Varnish is a thin, insoluble, non-wipeable

deposit film occurring on internal engine parts. It is largely caused by oxidation of the oil. Varnish can lead to sticking and malfunctioning of close-clearance moving parts. Engine varnish is similar in appearance to lacquer.

Varnish is the result of engine oil degradation, once again largely due to elevated temperatures and the presence of oxygen in the engine. As the oil flows over hot engine surfaces, it heats up and reacts with the oxygen in the air to oxidise. Each time the oil passes over a hot surface, it oxidises a little more.  This oxidation causes the early depletion of antioxidant additives in the oil, and eventually leads to the formation of insolubles, which is the beginning of varnish. The insolubles agglomerate and sooner or later stick to metal surfaces as portrayed in Figures 4, 5 and 6.

Figure 4                                           Figure 5                                            Figure 6

 

 

 

 

 

Varnish build-up causes excessive wear of moving parts, can lead to bearing failures and may cause critical components to seize. Other common names for varnish are lacquer, pigment, gum, and resin.

Engine oil degradation is aggravated by several other influences as discussed in OilChat #26.  Poor filtration will allow contaminants, wear particles, and water to build up and infest the oil.  This in turn accelerates depletion of the oil additives and allows the oil to foam.  To worsen matters wear debris (mainly copper particles) act as a catalyst to promote oil oxidation.

Blue Chip Lubricants and Q8 high performance engine oils are formulated with the latest generation additive technology to control sludge and varnish effectively. Deposit formation in modern engines is an ever increasing reality, but the advanced additive chemistry in our lubricants minimises engine wear associated with oil deterioration during the life of the oil.

If you have any questions concerning lubrication, or need assistance to select suitable lubricants for your machines, simply mail us at info@bcl.co.za. Our experts are at your disposal and ready to provide you with advice and guidance.