What precisely is molybdenum disulfide? Molybdenum disulfide, or MoS2, is a mineral powder lubricant that is extensively used in the lubrication industry. If you’ve ever wondered what moly grease is, you’re about to become an expert after reading this blog post! We’ll also discuss what the best moly grease for heavy equipment is.
When extracted in its natural state, molybdenum disulfide resembles lead. Both are a shade of gray and have a comparable weight. Most significantly, moly is a much more robust material than lead. It is capable of withstanding tremendous heat. Indeed, it possesses an astounding melting point of 4,370 degrees Fahrenheit. This material has a melting point twice as high as steel!
It has a high strength capacity due to its ability to withstand high temperatures. Molybdenum is a critical component in the manufacturing of the strongest and most durable alloy steels.
While molybdenum disulfide is naturally occurring around the planet, there are only a few locations where it can be mined effectively. Fortunately, Colorado, especially in the Rocky Mountains, has developed a reputation for rich molybdenum mining. These Rocky Mountain mines generate more than 60% of the world’s molybdenum.
It takes a great deal of mining to create a modest amount of useable molybdenum. Over one ton of molybdenite ore must be mined in order to create only four pounds of molybdenum. It’s a significant effort, but well worth it since the extracted black powder has incredible advantages for a variety of businesses. The lubricant business seems to profit the most.
Why Is Moly Such An Excellent Lubricant?
Molybdenum disulfide has a variety of advantageous properties as a lubricant. It is capable of reducing friction and wear, withstanding intense pressures, withstanding high temperatures, absorbing shock loading, carrying huge loads, and resisting rust and corrosion.
The compound molybdenum disulfide is classified as a lamellar solid. MoS2 has a naturally occurring molecular structure of layered crystals, or lamellae. Due to the layered crystal structure, MoS2 is capable of withstanding enormous loads. Its load-bearing capacity has been determined to be up to 500,000 pounds per square inch in laboratory tests. This is much more than the yield point of many metals.
There are two primary reasons why molybdenum disulfide performs so well in terms of friction and wear reduction. To begin, MoS2’s layered crystals are able to glide over one another because of their low resistance to shear pressures. Second, moly has an incredible capacity to endure massive weights. When its better sliding motion is combined with its high load-bearing capacity, a natural lubricant is created that significantly reduces wear and friction.
To demonstrate how molybdenum disulfide works, a simple yet effective method is to use a deck of playing cards. Place the playing cards on any table and exert as much downward pressure as possible on the deck of cards. Take note that regardless of how hard you push down on your cards, they will not compress farther than a specific point. Apply pressure on the same playing cards at an angle. Then watch as the cards begin to slip over one another. Molybdenum slides in a manner quite similar to that of the cards.
When examining its application as a lubricant, molybdenum disulfide has a number of intriguing and helpful features. One of its characteristics is a high affinity to metal. When pressure and heat are applied to any component for which moly is required to lubricate and protect, the layered crystals of moly begin to plate onto the metal surfaces through a natural chemical bonding process.
When one looks at an exposed metal surface with the naked eye, it seems to be smooth. Yet, when seen via a microscope, the same surface that seems to be smooth is really composed of small hills and valleys. This statement is true for all bearing and metal surfaces. Without a lubricant to keep the two metal surfaces apart, the two rough surfaces would generate an enormous amount of heat and friction. A lubricant’s purpose is to keep these two metal surfaces apart.
Most popular lubricants will eventually degrade and burst at excessive pressure or increased temperatures, resulting in wasteful wear and perhaps catastrophic failure. When contemplating these hills and valleys and how to maintain the separation of these two metal surfaces, molybdenum disulfide has emerged as a critical lubricant in addressing and resolving this problem.
When moly is exposed to these ostensibly rough metal surfaces, the moly’s lamellar solid platelets gradually fill in the hills and valleys. Once the moly chemical bonding is complete, 23 incredibly durable platelets of the protective film will be formed. The two metal surfaces now contain two very effective layers of MoS2, which will glide over one another in a manner similar to how playing cards slide, as described before.
Bear in mind that one of the most distinguishing characteristics of moly is its exceptional shock loading capacity. Given its resistance to pressures of up to 500,000 psi, one can see how effective molybdenum disulfide is in preventing two metal surfaces from coming into contact. Additionally, it can tolerate temperatures of up to 700 degrees Fahrenheit, which is higher than the operating temperature of the majority of lubricants. Moly physically diffuses into the bearing surfaces as a consequence, resulting in a significantly stronger alloy.
When the majority of conventional lubricants degrade due to strong loads and high temperatures, moly flourishes. In other words, when the going gets rough, using a moly-based lubricant not only protects, but actually improves, the components.
Molybdenum Grease Uses
What is the purpose of molybdenum disulfide grease? Numerous firms have discovered the advantages of molybdenum disulfide. For instance, when OEMs manufacture their goods, they apply a molybdenum paste or spray to many new components as a break-in protective barrier. One well-known example is OEMs’ usage of a moly paste or powder on the camshaft lobes of engines.
In places with high temperatures or excessive dust, dry moly is a preferred lubricant over oil or grease. Dry moly lubricants are ideal for chain drives, liquid oxygen valves, sleeve bearings, and electrical contacts for relays and switches.
Space exploration is often regarded as one of the most demanding and harsh situations in which a lubricant can be required to operate. Interestingly, NASA* discovered that molybdenum disulfide outperformed most other lubricants in terms of lubricating performance and advantages. NASA’s* space exploration program has profited significantly from the usage of molybdenum. It has been a tremendous help in resolving issues.
As previously indicated, it has a broad spectrum of lubricating properties under adverse situations and temperatures. It is capable of functioning and lubricating at very low cryogenic temperatures and can endure temperatures as high as 750 degrees Fahrenheit in regular atmospheric settings all the way up to exceptionally high temperatures of 2,000 degrees Fahrenheit when required to lubricate in space’s vacuum.
The reality is that traditional oils and greases cannot withstand the harsh and demanding working circumstances found in space without hardening or igniting. Hopefully, you’ve gained a better understanding of this wonder mineral known as molybdenum disulfide. Following that, let’s discuss what moly grease is and why manufacturing and mixing a grease containing moly delivers a better lubricant to the consumer.
Moly Grease: What Is It?
When it comes to the lubricant sector, data show that molybdenum disulfide is mostly employed to manufacture greases. Numerous reputable OEMs, including General Motors*, Ford*, and Caterpillar*, advocate for or utilize moly grease in certain applications. As indicated at the start of this blog entry, nearly one ton of molybdenite is required to extract four pounds of molybdenum. Due to the amount of labor required to extract a little bit of this incredible mineral, it is a pricey and costly component.
Using it in its pure powder form would be prohibitively costly in the majority of applications. Having said that, the advantages of utilizing moly can far surpass the initial expense. It is most cost-efficient when combined with greases. Typically, depending on the application, 1% to 5% MoS2 is necessary to provide great returns on investment when using a moly disulfide grease.
While you may believe that using more moly is better, it has been shown via side-by-side testing that a high-grade moly grease may function similarly to using a large amount of moly alone. Once molybdenum has plated itself onto metal surfaces, experience indicates that it may provide a prolonged service life. Nonetheless, if the moly is not supplemented, it will gradually deteriorate. By creating the right quantity of moly in grease, whether it’s moly grease ball joints, bearings, or any other component, the moly-containing grease acts as a continual reservoir of moly.
This moly grease functions as a reservoir of moly, allowing the molybdenum to plate and replate itself on whatever metal surface it comes into contact with. As long as the grease is there, this moly reservoir will produce an infinite supply of moly. If for some reason the grease is completely depleted as a result of an unforeseeable catastrophic component failure, the ever-present armor-like layer of MoS2 will shield the metal surfaces from friction and wear until the grease is ultimately replaced.
Molybdenum Disulfide: A Historical Perspective
As far back as 1764, historical documents indicate a weird gray-colored mineral material that was employed and rubbed into presses and a variety of equipment during that time period. This gray-colored mineral was meticulously rubbed into metal surfaces and then polished to a high gloss, earning it the moniker “burnished black.”
Numerous ancient documents mention a mineral that was capable of significantly reducing friction and was highly beneficial for preserving metal from corrosion and rust. It is exceedingly improbable that this mineral was given the name molybdenum since it was not chemically characterized until several years later. Having stated so, the only plausible conclusion for those years was that the substance was molybdenum disulfide.
Moly’s Test Results Are Impressive
During the early 1970s, a leading telecommunications corporation was searching for a lubricant that would preserve the microscopic ball bearings utilized in their switching systems’ miniature electric motors. The greases under test were both non-moly and moly-based. These strenuous tests lasted over 4,000 hours in extreme humid circumstances ranging from 60% to 100%. These studies were conducted to determine the efficacy of molybdenum disulfide grease vs lithium grease.
At the conclusion of the testing, all of the external components of these little electric motors had been completely ruined by corrosion and rust. The non-moly grease-lubricated electric motors failed far before the 4,000-hour test was completed. After running this exceedingly demanding 4,000-hour test, the small ball bearings were thoroughly checked under a microscope and greased with moly grease. They demonstrated essentially little pitting, corrosion, or wear, despite the fact that the bearing was driven without the protective shields in place.
As a consequence of these encouraging test findings, this well-known telephone company chose to convert to moly grease not only for its tiny electric motors but also for the bearings of its bigger power generators situated across the United States. Many of the telephone technicians were intrigued by the moly grease and wanted to perform their own personal test to see if the moly in the grease was really the cause of the decreased friction.
Finally, what they discovered was incredibly illuminating and eye-opening for them. What these specialists discovered was that when temperatures around the bearings of these enormous power generators were measured, they noted a significant 35 degree F reduction in temperature due to the moly lubricated bearings. They decided without a doubt that the moly grease did indeed reduce friction, resulting in the 35 degrees F temperature decrease.
Another good effect of reduced friction and heat is an improvement in the lubricant’s life due to less oxidation.
Another fascinating test was undertaken by General Motors’* research department in the 1960s. The purpose of the testing was to see if a non-moly grease might be enhanced merely by adding a trace of moly to it. Engineers at General Motors* created a specialized testing device using Cadillac* ball joints. The tests were designed to put the grease through its paces in terms of wear, torque, and bearing conditions. Initial experiments were conducted using non-moly grease to determine a parameter. The non-moly grease failed poorly in all of these preliminary tests.
The next step consisted of a series of experiments in which engineers added very minute quantities of moly powder to the oil. Surprisingly, the addition of a trace quantity of moly to the grease transformed the test results from failing to passing in all category circumstances of torque, wear, and bearing conditions. In other words, adding moly powder to the non-moly grease resulted in the grease passing the test and addressing any of the grease’s deterioration or breakdown tendencies. In this case, moly grease for ball joints was the way to go.
Ultimately, the General Motors* experts decided that only adding 1% MoS2 to a low-quality grease transformed it into a high-performance lubricant.
OEMs Suggest Using Molybdenum
Numerous original equipment manufacturers specify molybdenum disulfide greases as their preferred lubricant. Caterpillar*, Cadillac*, Ford*, Mercedes-Benz*, Rolls-Royce*, and Terex* are just a few of the OEMs that utilize moly grease as a factory lubricant. Caterpillar Tractor Company* is a unique example. They advocate only moly greases for all grease spots. Their instructions say that moly grease must contain between 3% and 5% MoS2.
Terex* is a great example of a heavy equipment manufacturer using moly grease to address an issue. Owners of Terex* articulated scraper earthmovers were reporting unusually high wear rates on the very massive kingpins utilized in their machines. Terex* experts were able to resolve this issue when testing a lubricant that included 25% moly.
Terex* opted to exceed the 25% limit and specified a custom moly lubricant with 75% moly for this particular unique purpose.
Numerous other fleet operators have discovered through experience that greases containing moly give numerous cost-saving advantages for their equipment and operations. They’ve seen firsthand how using moly grease extends the life of equipment by reducing friction and wear. Additionally, a moly grease user may anticipate the grease lasting longer, extending the time between grease changes. This translates into less time spent re-greasing equipment. Spending less time lubricating and using less grease may result in increased revenues for any organization.
Moly Grease Provides a Return on Investment
While switching to a moly grease requires a slightly higher initial investment than switching to a non-moly grease, the higher initial investment will result in an excellent return on investment (ROI) due to reduced grease consumption and reduced time spent greasing equipment due to extended lube intervals.
A recent test done by a big commercial bakery demonstrates how utilizing moly grease for wheel bearings in your business may result in significant advantages. This bakery maintained a sizable fleet of vehicles, including five semi-trucks, 190 delivery trucks, and 22 sales cars. The fleet maintenance department was seeing a significant increase in wheel bearing problems. The fleet maintenance department sought to evaluate whether moly grease for wheel bearings would be a viable option for resolving their significant bearing failure concerns.
To address this serious issue, the commercial bakery decided to conduct a test on moly grease in wheel bearings. Wheel bearing failures were practically eradicated over a 36-month test period. This is a fantastic real-world illustration of the potential benefit that a high-quality moly grease may provide.
Southwest Research Institute* did another intriguing experiment. 38 semi-trucks, police vehicles, and municipal buses were lubricated with a lithium grease containing 3% moly during a two-year period. In the instance of police vehicles, it was discovered that moly grease reduced chassis point wear by between 26% and 38%. For trucks and buses, wear on the following components was reduced by 18% to 88 percent: shackles, universal joints, and kingpins.
The two-year investigation revealed that the moly grease outperformed the identical grease without moly by a significant margin.
Components of Moly Grease
When examining what is moly grease, one must go beyond moly and consider some of the other components/ingredients required for its manufacture. To create grease, three critical elements are necessary.
The first element that is required is the basic stock oil. Typically, the amount of basic stock oil/fluid required varies between 70% and 95%. The next element is a thickener, which should be used in amounts ranging from 3% to 30%. The third component would be the additive package, which may range in volume from 0% to 10%. Let’s begin by examining the basis stock oils that may be utilized to create moly grease.
Typically, lubricant blenders/manufacturers choose a mineral or petroleum-based base oil. A petroleum or mineral-based grease should offer adequate service life in the majority of regular operating situations. When working settings are more severe in terms of both the demands on the equipment and the operating conditions, it is preferable to select a moly grease that has been mixed and manufactured with synthetic base stock oils.
Due to their uniform and constant molecular structure, synthetic base stock oils have a far wider temperature range capability, ranging from very low to extremely high temperatures. Synthetic base oils outperform mineral-based greases in terms of heat stability and will provide a higher return on investment over time.
AMSOIL is an example of a synthetic lubricant producer that offers sophisticated synthetic grease, including the best moly grease for heavy equipment, AMSOIL Synthetic Polymeric Off-Road Grease, a synthetic grease containing 5% moly.
The grease thickener is the next component we’ll examine. When a thickener is added to base stock oil, it converts the fluid to a solid or semi-solid structure. Metallic soap is the most often utilized thickening by grease makers. Lithium, aluminum, salt, calcium, polyurea, and clay are all examples of metallic soaps. Grease makers are increasingly moving to newly complicated thickener-type greases. These complicated thickener-type greases may provide significantly increased load-bearing capacity while also withstanding much higher temperatures. They often also provide higher water resistance.
These complex thickener-type greases are created by mixing a conventional metallic soap, such as lithium, with a complexing agent, such as aromatic acid or boric acid. In certain instances, the kind of thickening employed in the manufacture of grease may be a better option than other thickener-type greases. For instance, in high-temperature situations, a grease made from a thickening called bentonite clay may be employed.
Additionally, bentonite clay grease is referred to as no-melt grease. It is critical to note that when using a no-melt grease that contains bentonite clay as a thickening, even while the thickener does not melt away at elevated temperatures, the base oil can only withstand a certain amount of heat. As temperatures continue to increase, the base oil will begin to oxidize. It is critical to lubricate more often in these situations.
The last component to consider in terms of the chemicals used to manufacture grease is the additives. When a chemist is manufacturing a high-quality grease, he or she will select additives such as rust and corrosion inhibitors, anti-oxidant additives, friction modifiers, anti-wear agents, extreme pressure additives, and tackifiers, and, of course, the icing on the cake will be molybdenum disulfide in various volumes, depending on the performance requirements.
What is moly grease? The primary role of moly grease is to absorb and cope with high loads and to minimize friction and wear without producing any undesirable chemical reactions on the metal surfaces. Hopefully, we’ve supplied sufficient information and context to adequately address the topic of what is moly grease as well as what the best moly grease for heavy equipment is. Without a question, fleet operators may profit significantly from using moly grease in their toolkit of maintenance procedures. With over 70 years of proven real-world experience, moly will provide long-term advantages and will become an indispensable instrument in the maintenance arsenal of a professional.
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