This article will discuss industrial lubricants.
This article will give a better understanding of the topics below:
Industrial lubricants are materials designed to coat surfaces that are in motion relative to each other. Their primary function is to reduce friction and mitigate wear between these surfaces. Besides these main purposes, lubricants can also fulfill other critical functions, such as:
Lubricants can be found in a variety of forms, such as liquids, semi-solids, dry substances, and gases. Oils and gases are among the most commonly utilized types. In mechanical systems, it is vital to achieve a balance between the lubricant’s ability to minimize friction and wear and its other functions. Following manufacturer's guidelines is crucial for ensuring peak performance.
Industrial lubricants are essential for the smooth operation, protection, and longevity of machinery and equipment used across a diverse range of manufacturing, processing, and industrial sectors. These lubricants reduce friction, minimize wear, and assist in dissipating heat in moving parts, thus maximizing operational efficiency and reducing costly downtime. Industrial lubricants come in several forms, with the most prevalent being liquids, solids, and greases. Each lubricant type is specifically engineered for distinct applications, operating environments, and performance requirements. Understanding the different types of lubricants is key for selecting the ideal lubrication solution for machinery, supporting predictive maintenance strategies, and improving the total cost of ownership.
Industrial grease is a semi-solid lubricant consisting of a liquid lubricant base (typically mineral oil or synthetic oil) mixed with a thickening agent, often soap along with advanced performance additives. These additives enhance critical properties such as tackiness, oxidation stability, load-carrying capacity, extreme pressure (EP) resistance, and corrosion protection. Grease generally becomes liquid at a dropping point temperature ranging from 200 to 500°F, depending on the thickening agent and specific formulation. For instance, greases thickened with lime or calcium soaps demonstrate lower dropping points, while those with non-soap thickeners such as modified clays can withstand extremely high temperatures and maintain grease structure for longer durations even in demanding conditions.
The National Lubricating Grease Institute (NLGI) classifies grease consistency on a numeric scale from semifluid (000) to very hard (5) and block type (6). This classification is determined by penetration tests, where standard objects are pressed into the grease at controlled temperatures and times; the measured depth of penetration assesses consistency and suitability for specific applications. For optimal performance, most bearings lubricated with grease typically use an NLGI 2 grade, which balances pumpability and stability for a broad range of bearing designs and speed ranges found in industrial settings.
One of the key advantages of industrial grease is its ability to provide reliable lubrication in challenging environments—especially for hard-to-reach, sealed, vertical, or intermittently operated machine parts—where oil-based lubricants might not remain in place. Unlike oil, the consistency rating of grease does not directly equate to viscosity; it is the viscosity of the base oil within the grease, combined with its thickener, that determines overall performance. Therefore, two greases may share the same NLGI rating but differ substantially in base oil viscosity and application suitability. Reputable manufacturers typically provide detailed technical datasheets specifying their products� performance properties, recommended applications, and compatibility with machine materials.
Industrial greases can be fortified with extreme pressure (EP) additives, anti-wear agents, rust and oxidation inhibitors, and solid lubricants like molybdenum disulfide or graphite. EP greases offer superior protection against wear, scuffing, and pitting under heavy or shock loads, frequent start-stop cycles, and static pressure. However, overuse of some additives may accelerate wear or chemical reactions, particularly under extreme temperature fluctuations, so selection should always align with OEM recommendations and application requirements.
There is a diverse range of industrial greases, each designed for specific lubrication challenges, operational loads, and temperature extremes experienced in automotive, food processing, manufacturing, mining, and power generation industries. Key types include:
When selecting the right industrial grease, consider application factors such as base oil viscosity, operating temperature, vibration, exposure to washouts, load-carrying requirements, and compatibility with seals and elastomers. Matching grease type and NLGI grade to the asset’s demands helps maximize machinery uptime, reduce maintenance costs, and extend service intervals—driving long-term operational efficiency.
Industrial liquid lubricants, including hydraulic oils, circulating oils, compressor oils, turbine oils, and gear oils, are crucial for reducing friction and heat buildup in dynamic systems. These lubricants are predominantly derived from either petroleum-based (mineral) oils or synthetic base stocks. Petroleum oils remain popular due to low cost and availability, while synthetic oils—such as polyalphaolefins (PAOs), esters, and polyglycols—provide superior chemical and thermal stability, extended operating life, and cleaner performance, making them suitable for high-stress industrial applications and critical process equipment.
A key characteristic for evaluating liquid lubricants is viscosity. Viscosity is measured in two principal forms: dynamic (or absolute) viscosity and kinematic viscosity. These properties directly affect the lubricant’s hydrodynamic film strength and its ability to protect significant machine components such as bearings, pumps, gears, and compressors under different speeds and temperatures. Viscosity is typically expressed in centistokes (cSt), Saybolt Seconds Universal (SSU), or centipoise (cP), and is influenced by factors such as shear, temperature variation, and pressure.
The viscosity index (VI) is an important metric that indicates how a lubricant’s viscosity changes with temperature. Oils with a high VI offer stable performance across temperature swings, reducing the risk of oil thinning in high heat or thickening in cold startups—key for critical compressors, turbines, hydraulic systems, and gearboxes operating in fluctuating environments. Beyond viscosity, industrial oils possess other critical characteristics:
Extreme pressure (EP) lubricants are specifically engineered to prevent metal-to-metal wear in heady-duty industrial gearboxes, rolling mills, and transmission systems, often using sulfur-phosphorus or metal-organic EP additives. Under very high pressures or shock loading, lubricant viscosity can increase, so selecting the appropriate oil viscosity grade is critical for balancing lubrication in both heavily loaded and lightly loaded systems. Regular oil analysis and condition monitoring are best practices to optimize lubricant service life and avoid equipment failure.
Synthetic lubricants are most often used in scenarios demanding high viscosity index (VI), superior thermal stability, and extended drain intervals. They are formulated from advanced base stocks and can include specialty fluids such as phosphate esters (for fire-resistant hydraulic fluids), polyglycols (for brake fluids and compressors), and silicones (for plastics and rubber machinery). Due to their exceptional stability, synthetic lubricants are recommended when exposed to high loads, wide temperature ranges, or rigorous environmental standards typical in critical manufacturing sectors, cleanrooms, and high-precision instruments. Despite their higher cost, the performance enhancements and reduced maintenance can provide a greater return on investment over the lifecycle of industrial assets. For more information, explore our listing of Synthetic Lubricant Manufacturers.
To further enhance liquid lubricants, manufacturers incorporate a wide range of performance additives, including:
Solid lubricants, sometimes referred to as dry film lubricants, are specialized materials used where traditional liquid or grease lubricants may fail or underperform. Common examples include natural graphite, synthetic compounds, polytetrafluoroethylene (PTFE), and molybdenum disulfide (MoS2), all of which can be used independently or incorporated as additives to enhance the properties of greases and oils. Solid lubricants excel in metalworking, high-vacuum, extreme temperature, and high-load environments such as aerospace, foundries, and power plants.
Molybdenum disulfide is highly valued for its low coefficient of friction, high load-bearing capacity, and stability in oxidative and vacuum environments, making it an ideal solution for space technology, dry machining, and anti-seize applications. Graphite, while also an excellent solid lubricant, requires the presence of humidity to maintain optimal lubricity, making it preferred in foundries, forging, and die-casting. PTFE distinguishes itself by offering low friction even at cryogenic temperatures, but since it lacks a layered lattice structure, it is most commonly used as a performance-enhancing additive in greases, oils, or applied as a coating for sliding surfaces, pistons, conveyor systems, and valves.
Solid lubricants can be used as loose powders, incorporated into lubricant pastes, or applied as bonded or curable coatings using organic or inorganic binders. These coatings are popular for sliding surfaces, splines, gears, cams, and threads, and can be engineered to prevent galling, sticking, and seizure even in harsh operating nations. Vapor-deposited molybdenum disulfide, for example, is often used on compression fittings, threaded fasteners, or critical components requiring excellent anti-seize characteristics in the absence of oil- or grease-based lubrication.
Choosing the appropriate solid lubricant solution—whether as a standalone coating, a powder, or an additive—demands careful consideration of the application’s temperature, environmental exposure, metal compatibility, and performance requirements. Combining solid lubricants with advanced binders or synthetic bases enables their reliable performance in some of the world's most demanding industrial processes.
When selecting a lubrication method, whether oil or grease, it's crucial to address key factors such as viscosity, oil distribution, and heat impact. These considerations include:
For applications like bearing lubrication, it's important to use high-quality synthetic or mineral oils. The choice of oil type depends on factors such as the type of bearing, load, speed, lubrication method, and operating temperature. The benefits and features of oil lubrication include:
Oil can be introduced into the bearing housing through several methods. The common approaches include:
In some bearing housing designs, the rolling bearing elements can move through an oil sump. Generally, the oil level should be kept below the center point of the lowest rolling element. To reduce churning, especially at high speeds, it’s advisable to maintain a lower oil level. Proper oil levels can be regulated and monitored using elevation drains or gauges.
Typically, a pressurized circulating oil system has a pump, oil reservoir, filter, and piping. In some cases, a heat exchanger is used. The pressurized circulating oil system provides the following advantages:
Oil-mist lubrication systems are ideal for continuous, high-speed operations. These systems allow for precise control over the lubrication reaching the bearings. Oil is either metered and atomized before being mixed with air or drawn from the reservoir using the Venturi effect. In either method, the air is filtered and delivered to the bearings to ensure adequate lubrication.
Monitoring operating temperatures is crucial for effective control of the lubrication system. Labyrinth seals help prevent contaminants from entering the system by providing a continuous pathway for the oil and pressurized air.
Key factors contributing to the success of such a system include:
The oil-mist system should be activated a few minutes before the equipment starts to ensure that the bearings are properly lubricated. This pre-lubrication helps prevent potential damage to the rolling elements and rings.
The lubricating oils are available in various forms across aircraft, automotive, industrial, etc. These oils can be synthetic type, i.e., made from chemical synthesis, or petroleum type, i.e., made from refined crude oil.
When selecting the appropriate oil viscosity for bearing applications, several factors must be taken into account, including speed, load, type of oil, bearing configuration, and environmental conditions. Oil viscosity usually decreases as temperature increases, so viscosity values should be specified with their corresponding temperatures. Generally, high-viscosity oils are used in high ambient temperatures and low-speed applications, while oils with more common viscosities are suited for low ambient temperatures and high-speed conditions.
When evaluating viscosity classes, synthetic oils offer the advantage of functioning well at both extremely cold and hot temperatures and are less susceptible to oxidation. Different types of oils have varying pressure-viscosity coefficients, so careful selection is essential. Polyalphaolefins (PAO) possess pressure-viscosity coefficients and chemical structures akin to those of petroleum hydrocarbons. Consequently, PAO oils are commonly used in bearings operating under extreme temperature conditions.
In contrast, ester, silicone, and polyglycol oils have different oxygen-based chemical structures compared to PAO and petroleum oils. This structural difference results in lower pressure-viscosity coefficients. As a result, these synthetic oils form a thinner elastohydrodynamic film compared to PAO or mineral oils with the same viscosity at operating temperatures. This reduced film thickness can increase bearing wear and shorten bearing fatigue life.
This graphical representation depicts the relationship between friction and variables such as speed, load, and fluid viscosity. The Stribeck curve illustrates how the coefficient of friction varies under different operating conditions. The x-axis represents the lubrication parameter, which is influenced by fluid film thickness, viscosity, load, and speed. As viscosity increases, an increase in speed or a decrease in load results in a larger lubrication parameter and greater fluid film thickness.
In contrast, ester, silicone, and polyglycol oils have distinct oxygen-based chemical structures compared to PAO and petroleum oils. This structural variation results in lower pressure-viscosity coefficients for these synthetic oils. Consequently, they tend to produce a thinner elastohydrodynamic film than PAO or mineral oils with the same viscosity at operating temperatures. This reduction in film thickness can lead to increased wear and reduced fatigue life of bearings.
Grease lubrication is commonly used for low to moderate speed applications with specific temperature limits. Since no single grease is universally suitable for all bearings, each type of grease has unique characteristics and limitations. Typically, greases are formulated from a base oil, various additives, and a thickening agent. Polyurea is increasingly used as a thickener due to its excellent performance in lubricating fluids.
Grease thickeners are typically categorized into complex and simple soaps. Complex soaps are formed by the reaction of a long-chain fatty acid with a difunctional acid and a shorter-chain fatty acid with a single alkaline metal. In contrast, simple soaps result from the reaction of a single fatty acid with a single alkaline metal. Common metal forms used for these thickeners include calcium, lithium, and aluminum hydroxides.
Other examples of grease thickeners include calcium sulfonate, polyurea, fumed silica, and PTFE.
Accurate grease specifications are crucial for ensuring consistent performance. These specifications typically encompass physical properties that depend on the manufacturing process, such as mechanical stability, low-temperature flow, water resistance, consistency, and oil separation. The concentration of the thickener in the grease influences each of these properties. Therefore, variations in the manufacturing process can impact these specifications. Effective control of these process variables helps maintain the grease specifications and ensures reliable performance.
Starting torque at low temperatures is a crucial factor for grease-lubricated bearings, as resistance to initial movement can be significant depending on the application. Some machinery may have difficulty starting in very cold conditions and therefore requires greases formulated with low-temperature oils that offer a wide operating temperature range. For applications where water ingress is a concern, aluminum and calcium-based greases are preferred due to their water resistance. Additionally, lithium-based greases, known for their multipurpose capabilities, are commonly used in various wheel bearings and industrial applications.
As previously noted, synthetic base oils generally have a higher maximum temperature tolerance compared to petroleum-based greases. Synthetic base oils, including organic esters, esters, and silicones, are often used with traditional additives and thickeners. These synthetic greases can function effectively within a temperature range of -100°F to 550°F.
However, the starting torque of lubricating grease is not directly related to the grease's channel properties or consistency. Instead, it depends on the grease's rheological properties.
In lubricating greases, the high-temperature limit is influenced by the effectiveness of oxidation inhibitors and the oxidation stability of the fluid. The temperature range of the grease is determined by the composition of the base oil and the dropping point of the grease thickener. Generally, the lifespan of the grease is reduced by half for every 50°F increase in operating temperature.
Therefore, selecting grease for high-temperature applications requires consideration of temperature limits, oxidation resistance, and thermal stability. For applications where lubrication is needed at temperatures above 250°F, chemically stable synthetic fluids or highly refined mineral oils are often used as the base oil in the grease.
Moisture and water can contribute to bearing damage. To address this, lubricating greases can be evaluated for their resistance to contamination. As previously mentioned, aluminum and calcium complex greases exhibit good water resistance. In contrast, sodium soap greases are water-soluble and should be avoided in applications where water exposure is a concern.
Suspended or dissolved water in lubricating oils can affect the bearing fatigue life negatively as the water can cause etching of the bearing. As much as it is unknown how water lowers fatigue life, it permeates through bearing rings' microcracks caused by the stress cycles. This causes hydrogen embrittlement and corrosion in the microcracks, thereby quickening these cracks' propagation.
Water-based fluids, such as inverted emulsions and water-glycol solutions, can also reduce bearing fatigue. Although these fluids differ from contaminants, they still contribute to the challenges associated with water-contaminated lubricants.
Grease is typically supplied in 35-pound kegs, while oil is generally available in 5-gallon pails and 55-gallon drums. The shelf life of lubricants is often determined by the additives they contain. To ensure freshness, it's recommended to use the oldest stock first, following the first-in, first-out (FIFO) principle. To maximize shelf life, store lubricants in dry, clean environments with minimal temperature fluctuations. If drums must be stored outdoors, they should be placed on their sides and covered with shelters or tarps for protection.
When handling drums, they can be rolled on their sides but should not be dropped. Forklift blades are unsuitable for gripping drum sides; instead, use drum handling jaws on forklifts, which can securely grasp the drum's perimeter.
Oil cleanliness is crucial for extending equipment life. The International Standards Organization (ISO) rates oil cleanliness based on the size and number of particles per millimeter. However, new oils can sometimes contain high particle counts, making them unsuitable for use without prior filtration to avoid reducing equipment life.
Proper handling of lubricants is vital to prevent contamination and avoid mixing different formulations. This careful handling should be a key component of any lubrication program. Additionally, used lubricants should be disposed of or recovered following environmental safety practices.
Maintaining the condition of lubricants over an extended period can help save on both purchase and disposal costs. The service life of oils can be prolonged by adding solubility enhancers, which are synthetic base oils with high solubility. These enhancers help keep particles in solution, preventing them from causing premature filter fouling and reducing varnish formation.
Filter manufacturers are increasingly designing their casings to be more environmentally friendly, with options for recycling or reuse, thus reducing waste and disposal costs. Fiber or paper inserts can be easily removed and disposed of, while components such as wire meshes and end caps can be reused, leading to an 80-90% reduction in waste.
In larger manufacturing operations, oil intended for waste can be reclaimed. Since oil leaks are inevitable, even in well-designed systems, the leaked oil is collected via drainage sumps. Each type of lubricant is separately collected, dried, and filtered for reuse. This reclaimed oil helps mitigate environmental impact and can reduce lubrication costs by cutting down on disposal expenses and waste.
A lubricant can be used as a substance applied on surfaces with relative motion in between them. The lubricant would aim to reduce friction and wear between the surfaces. However, the lubricant can have other functions apart from these primary functions. These additional functions include serving as a sealing agent, heat transfer agent, corrosion preventative agent, and an agent for trapping and expelling mechanical systems contaminants. Regardless of the system is automated or manual, the objective is to apply the right lubricant type at the right time in the right amount.
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