Mukesh Saxena, Joint President, Star Cement, discusses the different kinds of lubricants used in the cement industry and the sustainable methods of using them.

How are the different types of lubricants corelated to their specific applications at a cement plant?
The term ‘lubricant’ describes a substance used to reduce friction between moving parts in a machine. Applied to individual components and complete engine systems, the main goal of lubricants is to minimise friction during movement. This helps to prevent wear and tear on moving parts and reduce the risk of mechanical failure due
to overheating.
The types of lubricants used in the cement industry include:
Oil lubricants: Thin and highly viscous, oil-based lubricants are made up of long polymer chains enhanced with additives. These can include corrosion inhibitors to prevent rust, antioxidants to prevent oxidisation and detergents to prevent the formation of deposits.
The viscous characteristics of oil-based lubricants make them useful for applications where even the smallest increases in resistance can affect performance. As oil is easy to disperse, these types of lubricants are also useful for applications where it’s not possible to disassemble the entire machine. In these scenarios, oil can be fed into the machine, where it will quickly disperse to all moving parts.
Lubricating Oils SP220, SP320, SP420: Used in gearboxes depending on temperature generations. High viscosity oil is used whereas temperature is high, for normal temperatures SP320 is used, whereas for low temperatures and low ambient temperatures SP220 is used.
Required in VRM gearboxes, kiln main gearboxes, conveyor gearboxes etc. Hydraulic oils used for hydraulic systems are operative and accordingly based on pressure required, for vertical mills hydraulic systems, kiln thruster etc.
Grease lubricants: Generally manufactured by combining an oil (usually mineral based) with thickeners (often a lithium, calcium, or sodium-based soap), greases blend well with existing lubricants in the oil, helping them accumulate on the surface and add an extra layer of lubricity. This type of product is often used to lubricate gears, bearings, linkages and chains.
Grease is also an excellent barrier, helping to protect surfaces from water droplets and dust as well as build ups of debris and contaminants. The viscous consistency of grease gives it good longevity and ongoing performance, winning it points when it comes to minimising maintenance.

• Uses of Grease
• For normal solid lubricants EP2 used
• For high temperatures graphite-based greases are used

Special Synthetic lubricants: High pressure synthetic lubricants are used in specific high temperatures and systems like high pressure hydraulic systems, kiln girth gear etc.
Penetrating lubricants: Unlike oils and grease, penetrating lubricants aren’t designed for long-term performance. This type of lubricant has ultra-low viscosity and is designed to infiltrate small fractures in the surface. The goal is to increase lubrication and break up any rust or debris that may have formed. Penetrating lubricants are often used to loosen seized screws and bolts.
Dry lubricants: Step up when oils and grease are unsuitable. They are capable of withstanding higher temperatures and don’t undergo the same state changes when the mercury rises. Dry lubricants also perform well in the face of excessive wear, migration, and exposure to debris. Rather than degrade in tough conditions, they remain intact and offer ongoing lubrication. This makes them ideal for use with heavy-duty infrastructure.
Dry lubricants are generally available as fluorocarbons (such as PTFE) or crystalline lattice structures (including graphite, tungsten disulphide and molybdenum). Impressive anti-friction, bond strength and chemical resistance capabilities make dry lubricants the product of choice for a wide range of applications in the oil and gas industry.

How do you ensure the quality of the lubricants used in your facility? What certification processes do you use?
A variety of methods are used to test for the quality of lubricants, including globally used standards published by ASTM International. Some of the methods used for lubricant quality testing are:
ASTM D445 for viscometrics: This ASTM test method is designed to determine the kinematic viscosity of both opaque and transparent lubricants. It uses a calibrated glass capillary viscometer to measure the rate at which the lubricant flows
under gravity.
ASTM D5182 for abrasive wear and friction control: This method assesses gear-tooth face wear to determine the scuffing resistance of lubricants. ASTM has strict guidelines, with rigs operated at 1450 rpm and teeth inspected at 15-minute intervals. As well as visible condition, the net weight loss of gear teeth is calculated to assess abrasive wear.
ASTM D943 for oxidation resistance: ASTM D943 is considered the gold-standard method for measuring the oxidation stability of lubricants. It is particularly useful for lubricants that are at risk of water contamination.
ASTM D1401 for water separation: This calculates the water separation characteristics of lubricants exposed to turbulence and H2O contamination.
ASTM D2896 for base number: Acidic titration is used to identify and quantify basic constituents (also known as additives) in lubricants. The ASTM D2896 method calculates the base number of each additive, with the test used to monitor quality assurance in new products and measure degradation in existing lubricants.
ASTM D2711 for demulsibility: Exposure to turbulence caused by circulation and pumping can fast-track water contamination and produce water-in-oil emulsions. The ASTM D2711 test measures the demulsibility characteristics of a lubricant and helps determine suitability for different applications.
ASTM D4951-09 for detergency: In some lubricants, additives can combine to act as detergents that actively prevents the build-up of deposits on solid surfaces.
ASTM D665 for corrosion resistance: Exposure to water and condensation can accelerate corrosion, making lubricants with anti-corrosion properties desirable for applications such as steam turbine gears. The ASTM D665 is used to evaluate the corrosion resistance of a lubricant and can also be used to test for degradation in circulating oils.
ASTM D97 for pour point: Pour point is another characteristic that can affect performance, with the ASTM D97 used to determine the lowest temperature at which flow is compromised and a lubricant becomes semi-solid.

What are the external environmental factors affecting the performance of the lubricants? How do they affect the lubricants?

• Oxidation: The chemical combination of oil or grease with oxygen. Oxidation is the most limiting factor to a lubricant’s useful life. Oil possibly may gel and become unpumpable, and eventually cause severe wear and seizure. Varnish and sludge (polymerised products) increase oil viscosity, decrease viscosity index, reduce heat transfer abilities, block oil ways, and promote foaming and emulsification. Severely oxidised oils tend to become very viscous at low temperatures. Volatile and non-volatile acids attack white-metal bearings, can be water-soluble and are more aggressive when the lubricant is wet. Sludge, varnish, emulsification, poor air release.
• Thermal degradation: Cracking at high temperatures, in the absence of oxygen. Safety hazard due to lowered flash points of the oil. Rapidly forming deposits on metal surfaces are not able to function as lubricants. Thermally degraded oils form carbonaceous residues and volatile gases. Heat built-up.
• Contamination: Most common contaminants of oils or greases are: water, fluid-soluble materials, fluid-insoluble materials erroneous fluid additives and fluid degradation. First, contamination is the most common cause of oil failure or rejection. It affects aeration, foaming, air release and demulsibility. Aeration can cause reduced compressibility of hydraulic fluids: reduced volumetric efficiency of hydraulic system pumps; loss of power transmission efficiency; cavitation damage in pump suctions and servo-valves; inadequate response times for turbine over-speed systems; localised oil oxidation in highly loaded regions; interference to oil flow through filters.
• Foaming: The action of frothy bubbles being formed in the fluid due to excess air. Foam is not a good lubricant. Air or oil foam can accumulate in the headspace of reservoirs, gearboxes, crankcases, sumps, and other components with vapor spaces. Excessive foam may be forced out of the reservoir through the breather cap. May be ingested into the circulation pump. May interfere with the effective lubrication of gears and bearings.
• Air release: Letting air out of bubbles in the oil. This should occur quickly. Significantly affected by oil viscosity and temperature. Poor air release can contribute to oil foaming. High oil viscosity. Low oil temperature. Contamination by diesel engine oils, greases, and corrosion preventives. Presence of rust particles. Contact with very hard water.
• Demulsibility: The ability to release or shed water. Undesirable if water is not separating rapidly from the oil (especially in turbine and gear oils or hydraulic fluids). Poor oil or grease demulsibility can cause corrosion of ferrous metals, significant reduction in the fatigue life of ball bearings, roller bearings and gears; and the removal of rust inhibitors and some anti wear and lubricity additives from oils.

Tell us about recent innovations in lubricant technology that you have implemented.
Use of nanotechnology in lubricants. Nanoparticle additives show significant enhancements in lubricant attributes like anti-oxidation capability, tribological features, and thermal properties. Nanotechnology offers the possibility of using nanosised additives to increase the performance of lubricating oil. The addition of nanoparticles to conventional base oils is a promising method for improving properties like friction and wear resistance in instruments.

How do you ensure proper storage and handling of lubricants at your facility?

• Lube room design and requirements: A properly designed lube room must be functional, safe, and expandable, and provide all necessary storage and handling requirements for the facility. Lube room designs should allow the maximum storage capacity without allowing for too much bulk oil and grease storage. Limiting the amount of bulk oil and grease storage will allow the oils that are stored to be used in a timely manner.
• Bulk oil storage: The first area of a lubricant storage and handling system that requires attention is bulk storage. Whether storing lubricants in a 10,000-gallon tank or 55-gallon drums, it is very important to ensure the lubricants’ quality is not tainted by contamination or additive settling. To help ensure lubricants stay in an optimal condition, one must determine how much lubricant should be stored at one time.
• New oil receiving: Oftentimes, improper receiving techniques do nothing but promote higher risks of contamination ingression, mixing of lubricants, etc. Proper written receiving procedures should be in place to ensure the highest level of consistency and cleanliness is maintained.
• Quality control: Quality control of lubricants delivered from lube suppliers must be verified to ensure the correct product is being delivered and that the cleanliness of the delivered lubricant is up to current target particle and moisture cleanliness levels.
• Presence of mixed or contaminated lubricants: Oil analysis results and other quality assurance variables, such as damaged containers, rusted containers, and any other quality issue, should be well documented and catalogued.
• Dispensing options for stored oils: When stored oil is transferred from the bulk storage system to the top-up container, it is best to filter the dispensing oil. This can be made very easy with the use of a hard plumbed filtration system and a rack mounted storage system fitted with dedicated dispensing nozzles. If using 55-gallon drums, they can be fitted with quick connect fittings, a hand pump, an inline filter manifold breather and sight glass to achieve the same goal.
• Precision top-ups and drain and fills: Once the bulk storage system is properly set up, one should consider the method for transporting oil and filling machines. The best top-up method
• utilises a proper top-up container, one that is sealed from the environment, has a built in spout, hand pump, etc.
• Proper top-up container and grease gun storage: Storage for top-up containers, grease guns, rags, etc., is another important step to ensure contaminants are not introduced to the lubricants as a result of poor housekeeping. These tools should have their own dedicated fire-proof storage cabinets for easy access and organisation.
• Lifecycles and lubricant shelf life: For both oil and grease, one should be aware of their respective shelf life. Exceeding their OEM shelf life may render the product useless or severely hamper its performance. For this reason, it is best to use the First-In, First-Out (FIFO) method.
• Labelling and identification: Lubricant labelling is one aspect of storage and handling that is often overlooked. Labelling is just as critical as periodic filtration and without proper labelling it is very easy for lubricant cross contamination to occur. Lubricant cross contamination is a result of mixing two lubricants together and can yield a devastating result. This happens more often in the dispensing equipment rather than the bulk storage equipment.

How do you evaluate the cost-effectiveness of different lubricants, and what factors do you consider while making purchasing decisions?
The three main cost areas most organisations consider are parts, labour and downtime. Everyone budgets these items, but ultimately, they are all reactive measurements. The true cost can only be seen after the maintenance events have already occurred. However, there are ways to project or estimate how the changes made in your procedures and equipment while driving your lubrication programme toward excellence will impact overall profitability.
A machine that runs more often should be more profitable in that it is achieving its desired operational purpose and not drawing the attention of the maintenance team for additional parts or labour. Therefore, it makes sense to approach the larger cost-improvement issue from a standpoint of how to reduce equipment downtime by preventing lubrication-related failures.
It is apparent that using the right oils and greases and maintaining them inside the proper operating conditions will go a long way toward correcting or preventing most mechanical failures at your job site.
Generally breaks down the journey to lubrication excellence into six categories: lubricant selection, reception and storage, handling and application, contamination control, lubricant analysis, and environmental disposal. This article will focus on the first five categories and provide examples of how to improve in regard to overall lubrication excellence and cost-effectiveness. While environmental disposal is critical, it’s not necessarily a good place to look for cost savings.
Selecting the proper lubricant from the beginning is the most important step you can take to improve machine productivity. Your equipment’s needs will drive the selection process, but having a thorough understanding of different lubricant properties will allow you to pick the optimum solution.
Three types of base oils make up all lubricants: mineral, synthetic and vegetable. Synthetic-based oils tend to cost more upfront but have more consistent properties and are therefore more stable. Additionally, some synthetics can be used in hazardous plant conditions outside the specific considerations of the machine in question. For example, many synthetic-based oils have a higher flash point and are thus less susceptible as a fire hazard. If your plant
operates at higher temperatures (from the climate or a process), it likely will be beneficial to switch to a synthetic oil.
Similarly, most synthetics have a lower pour point and are better for machines starting up in very cold conditions. Again, synthetics often cost more initially, but by having better fluid properties and a longer useful life, they can pay for themselves in short order.
The most important property to consider when selecting a lubricant is the viscosity, and the first place to look for assistance when choosing the viscosity is the equipment manufacturer. Even if the manufacturer’s recommendation is not always the best advice, it is the best starting point to determine the base range for the machine. For instance, an oil-pumping system may be designed to operate at around 125 degrees F, but at certain times it can run as high as 155 degrees F due to certain plant conditions. The manufacturer’s guide only takes into account the normal operating temperature of 125 degrees F in its viscosity recommendation.
To ensure your lubricant remains viable, select an oil that meets both the minimum and maximum operating conditions and has a viscosity index (VI) that can withstand condition changes. If you work in a climate that is particularly hot or cold, the manufacturer’s recommended lubricant may be incorrect solely because it is assumed the machine is operating in more temperate climates.
Temperature is an important factor to consider, because lubricant life is closely tied to operating temperature. Reducing the oil’s operating temperature by 18 degrees F will double its life expectancy. This means fewer oil changes as well as less labour and downtime. If the system operating temperatures cannot be changed, a similar (but lesser) result can be achieved by making certain that the selected lubricant has the right VI additive to allow for all environmental and climate conditions.
There are many other additives and fluid properties to be considered for a specific machine application, but accounting for the viscosity and VI is the most effective means to improve lubrication. Some lubricant vendors can supply oil and grease with almost any desired package of properties. An easy way to produce cost savings at this stage is by simplifying your overall lubrication order. You may discover that you were needlessly purchasing a more expensive oil or grease. More likely, you will find that most machines can safely use the same type of oil and grease, and another area of savings can be established simply by ordering fewer lubricant types overall. Even if it costs a little more to adjust the oils and greases ordered, savings will be realised when machinery downtime decreases.

How is the role of lubricants evolving, and what steps are you taking to stay ahead of the curve?
Based on analysis, it is predicted that the value in the global lubricant market will increase by 44 per cent in the next 15 years due to more advanced formulated synthetic lubricants and with the increased demand for industrial applications. Recycling and adding more additives will increase the life of oils and greases. The cement industry has to be very cautious with the use of lubricants and to increase its uses and proper handling of used oil for recycling.