It’s safe to say that the world’s engines, turbines, and many other types of machinery run on lubrication first. Without lubricants, machines could not operate — friction and heat buildup among moving parts would, at best, cause them to seize and stop or, worse, break apart.
The nonstop need to protect machinery from friction and heat has created a global market for lubrication products of about $116 billion (2015). It has also created worldwide teams of researchers and practitioners who work to improve lubricants that boost machinery reliability and efficiency, and reduce operational costs.
ASTM International has long been at the forefront of creating standards for lubricant manufacturers, testers, and end users. Since 1904, the committee on petroleum products, liquid fuels, and lubricants (D02) has developed 220 lubricant-specific standards and test methods.
Though the committee defines a lubricant as “any material interposed between two surfaces that reduces friction or wear between them,” traditional oils and greases get the most attention. But as with the D02 standards for fuels, standards for lubricants play an important behind-the-scenes role. Whatever recognition there is for the countless hours of research and testing undertaken to ensure that lubricant products perform flawlessly, it generally occurs long before the products enter service.
Perhaps no industry is more linked to advances in lubrication technology than the world’s automotive sector. Engine oils are now on the front line of automakers’ efforts to gain greater fuel efficiency. New engine designs, for example, will soon call for oils that are much lighter in weight (viscosity) than those now widely used. But automakers must first ensure that these oils perform the same functions as the lubricants they will replace.
They must reduce friction and wear, cushion moving parts, cool bearings and other engine parts, prevent rust and corrosion, and help keep surfaces clean by dissolving and carrying away deposits or deposit precursors.
This is no small task, asserts Frank Farber, the director of ASTM International’s Test Monitoring Center, which monitors lubricant tests for severity, precision, and standardization (see sidebar below article).
Farber notes that, right now, ASTM’s subcommittee on automotive lubricants (D02.B) is going through a major test development cycle to address auto manufacturers’ needs for a new passenger-car engine-oil category.
Targeted for 2018 car models, the new category will be used to evaluate a range of lower viscosity oils like 0W-16 — a very light product that is already used by some Asian carmakers but not yet by U.S. makers. That’s why the Test Monitoring Center, based in Pittsburgh, Pennsylvania, is actively supporting about 30 tests run at various sites, notes Farber. “The results from the test matrices will be used to determine the performance of each after all development is finished,” he says.
One of the desired performance goals is greater fuel economy, which is possible with lighter oils because they flow more easily and reduce the resistance of moving parts. Viscosity for 0W-16 oils, for example, is more like “cooking oil,” says Farber, versus the “maple syrup” of a common 10W-30 oil product. He adds that even lower viscosity oils — grades 0W-12 and 0W-8, for example — are on the radar.
At the same time, lighter oils also present challenges such as reduced film thickness between bearings and wear surfaces, and even the propensity for engine knock, according to Farber. To evaluate these issues, the subcommittee is developing several new test methods, including a Ford-sponsored low-speed pre-ignition test that addresses the lighter oils’ potential to cause combustion too early in the four-stroke cycle, resulting in engine knock.
The test is important, Farber says, “because manufacturers are going to direct-injected, turbocharged engines that do not operate with the same temperatures and pressures as a normally aspirated, lower compression engine might. Even Ford’s F150 pickup trucks are turbocharged now, and all of these elements put different demands on the oils.”
While lubrication developments for on-road vehicles may lead the way, the needs of other industries have just as much impact when it comes to a lubricant’s ultimate performance characteristics.
For example, ASTM International’s heavy-duty diesel engine oil standards are created for all engines without specificity, according to Hind Abi-Akar, an officer on the D02 committee and a technical expert in fluid engineering for Caterpillar Inc. in Peoria, Illinois. Such standards are crucial to supporting the heavy-duty off-road products that Caterpillar makes, such as bulldozers, excavators, and more.
Heavy-duty lubricant needs are unique. “In these applications, you typically have rather low engine speeds coupled with very high engine loads,” says Abi-Akar. “Consider a mining truck, for example, carrying 350 or 400 tons of material and pulling it up out of a mine. You can imagine the tremendous loads that the oils must support. Whether it’s the rings and pistons or the main bearings where the oil is squeezed to a very thin film, it must keep the metal from touching and still carry this load. That requires viscosities and stability that are much higher than for automotive.”
Abi-Akar notes that ASTM creates its lubrication standards in support of the specifications developed by the American Petroleum Institute, Engine Manufacturers Association, and others. She says, “When it comes to heavy duty off-road diesel applications, Caterpillar has a strong voice in this process to ensure that our performance requirements are met. The specifications have to cover the needs of all off- and on-road applications since customers cannot have multiple oils for the various equipment they may use.”
This is evolving, though, due to the demand for efficiency-related benefits of low viscosity oils in the on-road, heavy-duty sector. “Two recently developed heavy-duty diesel engine oil specs are the first demarcation between on-road and off-road needs,” says Abi-Akar. She adds that Caterpillar “does not yet recommend the new, low viscosity, high temperature, high shear oils, such as API FA-4, for use in its products.”
This has much to do with the challenge of calculating off-road equipment efficiency. While operating loads and cycles are fairly consistent in on-road vehicles, “calculating off-road efficiency becomes more difficult because it needs to be based on the amount of work done, the amount of material moved, or similar factor,” she says. “Measuring only engine efficiency would drive the wrong result for optimizing total equipment efficiency.”
A highly practical, user-driven path to equipment efficiency involves the practice of in-service lubricant testing, an area strongly supported by ASTM standards. D02 covers many in-service lubricant test methods, all of which are designed to help end users understand what in-use oil characteristics can tell them about equipment health. For example, the subcommittee on heavy duty engine oils (D02.B0.02) is focused on test standards that provide ways to evaluate oils in heavy-duty use.
“Oil is the canary in the mine,” says Abi-Akar. “If wear metals or dirt in the oil are increasing, for example, this indicates there is something going on in the engine or the component that needs to be addressed.” Regular in-service testing helps operators track changes in oil characteristics and, if needed, take steps to maintain desired levels of oil quality.
Sometimes this means changing the oil. Other times, it means using a “bleed-and-feed” process, which involves draining away some in-service oil and replacing it with fresh oil.
In addition to avoiding lubrication-related failures, in-service testing helps increase equipment “uptime,” avoid or delay some maintenance tasks, and, in the case of certain types of heavy-duty equipment, improve durability and maximize equipment resale values.
More broadly, in-service oil testing is practiced across many industry sectors.
It plays a particularly prominent role in critical fields like power generation. At the Palo Verde Nuclear Generating Station in Arizona, Bryan Johnson, a reliability engineer, monitors lubricant conditions on all plant equipment, especially turbines. He calls ASTM “the industry leader in condition monitoring standards — no one else even comes close.” An on-site lab at his facility has helped him both use ASTM test standards and take part in the development of new ones.
“The lab we installed many years ago has been very helpful,” says Johnson, who serves as chairman of ASTM’s subcommittee on in-service lubricant testing and condition monitoring services (D02.96). “In fact, it’s how I wound up at ASTM.” Early in his career, he was asked to lead a project to set up and install a laboratory to monitor oil conditions, but he could not find standards for the tests they needed to conduct.
“I discovered that very little of the testing performed commercially was standardized,” he explains. “Most of the lubricant standards at that time were targeted at specifications for quality control, marketing, and as an aid to inform and sell product to consumers. This type of testing is very different than in-service testing of a lubricant that has been in a machine,” he adds. “In-service testing requires data to determine how the oil is aging, and if the machine itself is performing in an expected and acceptable manner.”
In 1999, Johnson worked with peers to launch D02.96, which he says has been “extremely successful” in helping shape the condition-monitoring industry, and providing a basis for data quality. The group has also helped Johnson and others expand the reach and importance of data obtained from testing in-service lubricants.
For example: Not only can in service-tests provide signs (such as wear particles) of potential machinery problems, but they can also show how a lubricant ages — how additives are consumed and how viscosity changes — after it is placed in service. This information can be tracked for trends and compared to set criteria to determine when maintenance is required.
Salvatore Rea, the industrial-and-power-generation OEM liaison for Chemtura Corp. in Philadelphia, echoes Johnson’s sentiments. His company is a supplier of lubricant additives and indutrial fluids.
“Once oil is put in the machine, it’s no longer the same fluid,” he says. “The concept of ‘fresh’ fluid becomes past tense.” The transformation from fresh to in-service fluid has created “an entire industry devoted to condition monitoring and maintenance.”
In-service testing is particularly important for turbines used in power plants, says Rea, who chairs ASTM’s subcommittee on turbine oils (D02.C). “This is because turbines operate at much higher temperatures than a car engine, for example,” he says.
“In the case of a turbine, the lubricant is protecting the bearing that holds a shaft that’s spinning at very high speed and in contact with very high temperatures. And because we live on a planet bathed in oxygen and water,” he adds, “those aggressive components find their way into everything. This means turbine oils must also be very resistant to oxidation and hydrolysis.” They must be formulated to minimize degradation from other contaminants.
He adds, “The question then becomes, how well fortified with the correct additives is the fluid and how inherently stable is the original un-additized base oil to counter these degradation mechanisms?”
D02.96’s focus on answering this question has led to additional key ASTM standards. These include a test method to measure lubricant-generated insoluble color bodies in in-service turbine oils (D7843) and a test method for the oxidation stability of steam turbine oils (D2272). The group’s work to standardize and upgrade specifications includes applications for wind turbines, diesel oils, and compressor oils.
Notably, D02.96 is also working on test methods related to in-service grease. “One of the most significant grease tests is the cone penetration test, which measures grease consistency,” says Palo Verde’s Johnson. “The problem with this test is that it requires a volume of grease about the size of a tennis ball, and there are few applications where we have that much grease in operation within the machine at all.” He adds, “The existing standards are limited when applied to condition monitoring for in-service greases, so our group is now working hard on this emerging field.”
With end users showing increasing interest in sophisticated condition monitoring techniques, it’s no surprise that ASTM International members expect to pursue this area in greater detail. “We regularly see challenges and opportunities for improvements in test methods and standards in this and all other lubricant areas,” says Rea, “and we expect to continually see new ones.”
He cites current work on standard D1401, which tests the ability of petroleum oils or synthetic fluids to separate from water, as an example. This property, called water demulsification, is a key performance property for most industrial oils. “We have had a work group actively discussing how to characterize and report the end-of-test fluid appearance,” he says. “This can be complicated because you’re separating an oil phase from a water phase, and because they sometimes don’t separate neatly, the resulting emulsions can look very different. So we’re trying to improve the existing test method by providing additional guidance on how to rate and interpret these different emulsion types.”
Other tests under review include D665, which measures the amount of rust (another undesirable component of in-service oil) that develops on a steel rod after exposure to an oil-water mix. A proposed improvement calls for the use of an optical method to determine rust accumulation instead of relying on the eye only.
It may be only the latest of many other advancements that demonstrate how ASTM lubrication performance specifications, practices, guides, and test methods will be relied on for relevancy and value in a changing world — one that depends heavily on lubrication in its many forms.
Don’t miss ASTM’s Symposium on Tribometry and Tribochemistry, June 28-29, at the Sheraton Boston Hotel, Boston, Massachusetts. To be held in conjunction with the ASTM D02 meetings, the symposium is sponsored by D02.L on Industrial Lubricants and Engineering Sciences of High Performance Fluids and Solids, and ASTM Committee G02 on Wear and Erosion.
Rick Carter is a long-time editorial professional who writes from his home near Philadelphia, Pennsylvania.
ASTM International’s Test Monitoring Center: Ensuring Accurate Automotive Oil Test Methods
The Test Monitoring Center is a key component of the efforts of ASTM International’s subcommittee on automotive lubricants (D02.B) to provide useful, accurate test methods that measure the performance and quality of car lubricants. As its name suggests, the TMC monitors lubricant test methods used around the world by ensuring that test equipment is properly calibrated and that proper reference oils are available. It does not conduct tests on its own.
Operating from office and warehouse space near the campus of Carnegie Mellon University in Pittsburgh, Pennsylvania, TMC works on behalf of ASTM International, though its 15 staff members are employed by Carnegie Mellon, says Frank Farber, the TMC director. The Carnegie Mellon-ASTM International partnership has served the automotive lubricant industry for more than 40 years.
Farber, who has been with TMC since 1988, calls the operation unique. “In the auto industry, we’re the sole source for many ASTM test method reference fluids and calibration services,” he says. “It’s written into API [American Petroleum Institute] specifications and others, for example, that if you want to run a test for a certain API certification, and if you want to include the API donut or starburst on your oil can, that product needs to be tested on a TMC-calibrated stand. And if you want to be calibrated,” he adds, “you have to run our reference fluids and participate in the system. That’s our niche.”
TMC’s reference fluids are distinct lubricants with known performance characteristics that the oil industry provides to TMC exclusively. For a fee, TMC ships them to labs for their test purposes.
Other TMC services include on-site inspections of engine test cells. “Our engineers will visit the test labs and look for differences in configuration and operation,” says Farber. “We also verify that the engines are built according to the test method and are being run under the correct conditions.” With potential anomalies removed, tests can be run in a way that will match conditions that exist in all other TMC-calibrated test cells.
“And when we receive test data back from laboratories, it is electronically entered into our industry database of all tests run,” Farber says. “This enables us to calculate how a specific oil performs in producing a certain amount of piston deposits, for example. So when you run the specified test and reference oil, we know the results you should get to verify that your lab is operating according to the test method and is producing acceptable results.”
As a member of test method surveillance panels, TMC also works with the industry to ensure that test standards document current practices and hardware. “We look for variations in build practices, hardware variations and operations, and ensure that these changes are noted,” says Farber. “A change in a piston production run, for example, can mean that a piston made in 2014 may produce different results than one made in 2016. We’re vigilant to pick up those differences.”
TMC is working with engine manufacturers, test laboratories, and oil and additive manufacturers on ASTM test methods to develop a new passenger-car engine-oil category, the goal of which is to help automakers increase new engine fuel efficiency, and provide improved engine protection. Farber notes that TMC stands ready to work with the automotive lubricant industry as new technology and advancements occur, all of which, he says, “are likely to make even more demands on the oils.”