Almost every company surveyed in a recent Shell Lubricants study reported unplanned
maintenance shutdowns during the last three years, and more than half attribute the cause
to incorrect lubrication application or management. (Photo: RAASM)

The study estimated coefficients of friction and wear rates of moving mechanical assemblies based on available information taken from literature in four general cases: (1) an average mine in operation today, (2) a mine with today’s best commercial technology, (3) a mine with today’s most advanced technology, and (4) a mine with best futuristic technology forecast in the next 10 years.

The calculations indicated that the cost amounts to roughly €210,000 million annually, distributed in the proportion of 40% for overcoming friction, 27% for production of replacement parts and spare equipment, 26% for maintenance work, and 7% for lost production. The authors suggest that by taking advantage of new technology in friction reduction and wear protection for mining equipment, friction and wear losses could potentially be reduced by 15% in the short term (10 years) and by 30% in the long term (20 years). In the short term, this would annually equal worldwide savings of €31,100 million, 280 TWh (terawatt hours) energy consumption and a CO emission reduction of 145 million metric tons (mt). In the long term, the annual benefit would be €62,200 million, 550 TWh less energy consumption, and a carbon emission reduction of 290 million mt. Potential remedies to reduce friction and wear in mining include the “development and uses of new materials, especially materials with improved strength and hardness properties, more effective surface treatments, high-performance surface coatings, new lubricants and lubricant additives, and new designs of moving parts and surfaces.”

Given the industry’s shrinking portfolio of cost-savings options and alternatives, friction reduction and component protection would seem to be low-hanging fruit, but a recent white paper released by a major lubricants supplier that looks at ongoing problems, lost opportunities and potential for cost savings associated with lubrication selection and management in the mining industry adds to the suspicion that producers should be taking a closer look at their lube products and policies.

Mining companies are significantly undervaluing the potential savings from effective lubrication, according to the study by Shell Lubricants. While 60% of companies recognize they could reduce costs by 5% or more, fewer than 10% realize that the impact of lubricants could be up to six times greater. For the mining industry in North America alone, this could mean potential savings in excess of $29.1 million, according to Shell.

The Shell-sponsored research found that 96% of mining companies report experiencing unplanned equipment shutdowns in the last three years, with more than half (56%) acknowledging this is due to their incorrect selection or management of lubricants. This is having a direct financial impact, at a time when cost competitiveness is a priority for mining companies.

The international study of mining companies across Asia, Europe and the Americas reveals that many businesses do not realize that some of their critical operational factors can be significantly influenced by how lubricants are managed. For example, less than half realize that lubrication can influence unplanned downtime, and 64% are not clear about how extended oil drain intervals can generate cost savings.

Renée Power, Shell’s global sector manager for mining, said, “40% of the companies we surveyed estimated that they had incurred costs of at least $250,000 over the last 3 years from breakdowns due to ineffective lubrication. This shows potential for companies to achieve a significant boost to profits by working closely with a supplier like Shell Lubricants to improve equipment lubrication practices.”

However, with maintenance managers facing budget and time constraints, and only 34% of businesses making use of regular visits from their lubricant supplier’s technical staff, most are not wellequipped to take action. The study revealed that only 41% of companies have all the recommended procedures in place to manage lubricants effectively, and 59% recognize they don’t conduct staff training on lubricants as regularly as they should. Misconceptions about lubricants are also evident, with 44% believing that all lubricants and greases provide the same level of performance.

Power commented, “The impact of lubrication on Total Cost of Ownership is too often underestimated. Almost half of companies surveyed wouldn’t expect to see a reduction in maintenance costs resulting from lubrication, but we have helped deliver more than $44 million in savings to mining companies over the last five years.”

The Big 3
The Shell report looked at three primary lubrication applications in the mining industry: engines, drivetrains and open gears, and many other sources confirm the necessity of “getting it right,” particularly when it comes to lubrication choices for expensive diesel engines. The selection process to choose the best oil for the application involves considerations based on engine design characteristics, operational parameters and environment (temperature, humidity, site used at altitude or underground, etc.). Changes in fleet configuration can complicate the process. For example, recent announcements by Liebherr, Volvo Penta and other suppliers indicate that through replacement, repower or new fleet purchase, Tier 4 and European Union (EU) Stage V compliant diesels are becoming more prevalent in mining applications — and bringing with them new requirements and concerns about lubrication. Liebherr just delivered the first Tier 4 diesel-powered R 9400 hydraulic excavator to a mine in the western U.S., and Volvo Penta said that Sandvik is now installing Volvo Penta’s Stage V engines in its underground loaders and trucks, following prototyping and extensive testing of a Sandvik LH517 LHD with a Stage V engine at a mine site in Finland.

A key to successful selection of an oil or grease for any given application is to ensure that the formulation is capable of
maintaining a consistent protective layer between components during all aspects of operation.

Lubrication – The oil forms a hydrodynamic film between metal surfaces, preventing metal-to-metal contact and reducing friction. When the oil film is not sufficient to prevent metal-to-metal contact, bad things can happen — heat is generated through friction, local welding occurs, and metal transfer results in scuffing or seizing.
Extreme Pressure Wear Control – Modern lubricants contain extreme pressure anti- wear additives. These additives form a chemically bonded molecular film on the metal surfaces at high pressure to prevent direct contact and wear when the load on the parts is high enough to eliminate the hydrodynamic oil film.
Cleaning – Oil acts as a cleaning agent in the engine by flushing contaminants from critical components. Sludge, varnish, and oxidation buildup on the pistons, rings, valve stems and seals will lead to severe engine damage, if not controlled by the oil. Oil formulated with the optimal additives will hold these contaminants in suspension until they are removed by the oil filtration system or during the course of an oil change.
Protection – Oil provides a protective barrier, isolating non-like metals to prevent corrosion. Corrosion, like wear, results in the removal of metal from engine parts. Corrosion works like a slow-acting wear mechanism.
Cooling – Engines need cooling of internal components that the primary cooling system cannot provide. The lubricating oil provides an excellent heat transfer medium. Heat is transferred to the oil through contact with various components, which is then transferred to the primary cooling system at the oil cooler.
Sealing – Oil acts as a combustion seal filling the uneven surfaces of the cylinder liner, piston, valve stem and other internal engine components.
Shock-Damping – The oil film between contacting surfaces provides cushioning and shock-damping. The damping effect is essential to highly loaded areas such as the bearings, pistons, connecting rods, and the gear train.
Hydraulic Action – Oil acts as a working hydraulic media within the engine. Examples of this are the use of oil to operate engine brakes and injector tappets.

What’s surprising is that, even after providing parts protection for up to hundreds of hours of engine operation, oil doesn’t really wear out. It becomes contaminated and the additives that are crucial to its performance become depleted. Additives include detergents or dispersants, which keep insoluble matter in suspension until the oil is changed; inhibitors that maintain the stability of the oil, prevent acids from attacking metal surfaces and prevent rust formation when the engine is not in operation; and others that assist the oil in lubricating highly loaded areas of the engine (such as valves and the injector train), prevent scuffing and seizing, control foaming, and prevent air retention in the oil.

Oil contaminants are products of processes that can occur during both normal and abnormal engine operation. These can take the form of combustion byproducts formed from blowby gases that escape past piston rings, valve guides and turbocharger seals; fuel or coolant leaks; and soot from various combustion problems — and from environmental factors that may range from airborne dust to road-surface stabilization chemicals, for example.

New Standard, New Benefits
The everyday demands that diesel engine operation place on engine oil, coupled with the specific design characteristics and operational systems built into the new Tier 4 engines, made it necessary to create a new engine oil standard that went into effect at the end of 2016. The API (American Petroleum Institute) CK-4 standard superceded the existing CJ-4 standard, and products meeting the new standard provide the highest level of protection and performance for engines equipped with emission-control technologies such as EGR or exhaust aftertreatment. Any CK-4 compliant oil provides at least a minimum level of protection for Tier 4 engines, and premium CK-4 oils can significantly exceed the standard. These oils:

• Resist oxidation, even under high-heat conditions, minimizing engine deposits and extending service intervals.
• Reduce aeration, which helps prevent oil breakdown, cavitation and corrosion.
• Improve shear stability, which translates into consistent viscosity under high loads for better lubrication and protection.

All major lubrication suppliers have a CK-4 product family, including Shell (Rotella), Mobil (Delvac), Total (Rubia), Castrol (Vecton), Valvoline (Premium Blue) and others. Most are eager to share case histories or other evidence of benefits available to fleet operators that have switched to CK-4 oils. Chevron, for example, claims users can achieve up to 35% improved oil oxidation control, 68% improved wear protection and 64% improved piston deposit control with its Delo 400 XLE 15W-40 synthetic oil. According to the company, Delo 400 is for use in new advanced engines developed to meet the latest emissions and reliability standards and in engines equipped with turbocharging, direct injection, higher power density, intercooling, full electronic management of fuel and emissions systems, exhaust selective catalytic reduction, EGR and DPF.

Beyond selecting the most appropriate engine oil — or for that matter, any type of lubricant used on primary production equipment — Shell and others recommend a big-picture approach in which users maintain an ongoing relationship with their lube-product supplier to identify and implement better lubrication management policies and strategies. Shell pointed out that a look at customers who have successfully implemented structured, TCO-driven lubrication projects reveals a number of initial actions that help drive success. These include:

• Senior management support of the TCO-driven approach to lubrication, to help overcome challenges such as resourcing alongside the demands of daily operations.
• Appointing a project lead and allocating appropriate time and resources to a team tasked with implementing changes.
• A good relationship with the lubricant supplier, whose technical teams play a key role in identifying and delivering value.
• A comprehensive analysis to identify, quantify and prioritize TCO-related projects. Importantly, aligning on how value is measured enables savings to be recorded accurately. For example:
o What is the hourly cost of maintenance and time required for repairs?
o What is the cost of replacement parts?
o What is the benchmark failure frequency?
o What is the monetary value of downtime for each piece of equipment, in terms of lost production?
• Setting measurable targets to ensure that progress can be tracked.

As equipment and lubrication technology continue to evolve, regular review will help companies continue to focus effort and resources on projects that deliver greatest value — and with battery-electric and hybrid power systems for off-road applications making increasingly frequent appearances at trade shows, test sites and on the job, lubrication knowledge and choice will undoubtedly need to be broadened to support these new technologies.

Gearing Up
Open gears and bearings used in mining equipment differ markedly in design, fabrication tolerances, materials and the external environments in which they’re used, but both represent major lubrication applications, and both are dependent on proper grease selection and application when it comes to achieving expected service life.

Leading suppliers often can offer greases in comprehensive product families that can function as multipurpose products, or as semi-specialized formulations for specific purposes, and even specific brands of equipment. For example, Mobil’s Dynagear family of greases includes:

• Dynagear 800 Extra and Dynagear 600 SL, which can function as all-season, multipurpose greases and as low-temperature, open-gear lubricants.
• Dynagear 2000: For applications operating at higher ambient temperatures and requiring greater film thickness.
• Dynagear 800 Extra: Meets requirements of P&H shovels for lubrication of open gears.
• Dynagear 4000: Recommended for lubrication of hoist gear on Caterpillar Mining electric shovel hoist drum gear sets and in applications where an extraheavy open-gear lubricant is desired.
• Mobil Dynagear 800 Extra: For use as an all-season, multipurpose grease for onboard systems on heavy-duty equipment where NLGI 00 grade greases are recommended.

The selection of open-gear lubricants available in the commercial market, due to environmental and other issues, has over the past few decades evolved changed from mainly solvent-diluted asphaltic “blackjack” compounds to enhanced formulations that have specific compositions ranging from light-viscosity oils with solid additives, heavy-viscosity oils, to combination fluid grease and synthetic oils. Although the new products are easier on the environment, their composition makes it a bit tricky to achieve the level of grease-film thickness and adhesion needed to provide optimum protection. The approach suggested by most lubrication experts is to apply this type of grease in smaller quantities at more frequent intervals, and if possible, take frequent temperature readings on gear surfaces to confirm that the layer of lubricant is adequate and evenly distributed.

When applied correctly, enhanced gear lubes can offer a number of attractive advantages that include overall material and energy cost savings, a cleaner and safer work environment, and in some cases, the power to heal. The latter advantage was explained in a paper presented by authors from Texas, USA-based Lubrication Engineers Inc. at a 2015 conference sponsored by the South African Institute of Tribology. The problem, they explained, is that when an open gear is damaged, the surface of the gear tooth contact area is roughened by scoring, pitting and spalling. Removal of the metal causes areas of higher stress and loading on the open gears, which over time increases the wear and damage to the gear teeth. However, use of a high-performance open-gear lubricant can help “heal” the gear surface, as the high film strength and film thickness of the lubricant redistributes the load over the surface area. This redistribution of load ultimately evens out to a point of equilibrium and results in a “healed gear” appearance, and small pits often close up completely.

Not all open-gear lubes are conventional heavy greases. Bel-Ray, for example, recently introduced Molylube open gear and rope lubricant, an aerosol product suitable for use on general industrial open gears, pins and bushings, chains, wire ropes, cables, drive chains and sliding surfaces. The company describes it as a highly tenacious lubricant that ensures adherence to the gear teeth, creating excellent resistance to throw-off and slinging and providing anti-wear, water resistance and rust and corrosion protection associated with demanding mining and other heavy industry equipment applications.

As electric motors increasingly become incorporated into various forms of mobile and stationary mining equipment, correct application and maintenance techniques for motor bearings will become more important as well. In these applications, an overzealous or inattentive worker can cause major motor problems with just a few extra, unneeded squirts from a grease gun or by mixing incompatible grease formulations.

Noria Corp., an Oklahoma, USA-based lubrication consulting, training and publishing firm, noted the ways in which improper motor bearing lubrication can cause equipment failure. These include:

Incorrect Lubricant – Most oil suppliers have grease that is specifically designed for electric motors, which is different from their multipurpose extreme purpose (EP) grease.
Grease Incompatibility – Greases are made with different thickeners, such as lithium, calcium or polyurea. Unfortunately, not all greases are compatible with each other, even those with the same thickener type.
Motor Casing Full of Grease – If the grease cavity is overfilled, and high pressure from the grease gun is applied, the excess grease can find its way between the shaft and the inner bearing cap and press into the inside of the motor. This allows the grease to cover the end windings of the insulation system and can cause both winding insulation and bearing failures.
Lubricant Starvation – There are several possible causes of lubrication starvation. The first is insufficient grease being added during installation. The second is inappropriate, elongated relubrication intervals. The third involves the possibility that the oil has separated from the thickener base due to excessive heat.
Overpressurization of the Bearing Housing – Overpressurization of the bearing housing causes stress on parts that were not designed to handle the pressure. Keep in mind that the standard manual grease gun can produce pressures up to 15,000 psi.
Overheating Due to Excess Grease – Too much volume will cause the rotating bearing elements to churn the grease, trying to push it out of the way. This results in parasitic energy losses and high operating temperatures, and increases the risk of oil separation and bearing failure.

Klüber, a global supplier of specialty lubricants, recently introduced Klubersustain GW 0-460, an industrial gear lube that uses water as a functional constituent. It’s the first product in what Klüber envisions as a family of water-based lubricants that can offer both environmental and performance benefits, and the company sees a good correlation between these future products and the mining industry trend towards electrification of power trains.

E&MJ asked Markus Burbach, Klüber Lubrication’s head of marketing and application engineering-North America, for additional details about the hydro-based product line and its potential advantages for mining applications. “Klüber Lubrication aims to develop a complete portfolio of Hydro Lubricants for a variety of industrial applications by 2025. Klubersustain GW 0 460 is the first available Hydro Lubricant for closed gears on the market. We are currently looking for development partners interested in jointly testing this specialty lubricant and working with us to further advance its properties and determine for what applications it can be most advantageous.

“This can include gearbox applications in the mining industry. The electrification of underground mining equipment could be a potential area of use. This is because of the lubricant’s superior protection against electro-corrosion and the reduced risk of parts damage caused by electric arcs due to the excellent electric-conductivity of Hydro Lubricants. Improved fire protection is another benefit of Hydro Lubricants, which can be of interest to OEMs and operators in the mining industry striving to increase workplace safety.

“The main difference between Hydro Lubricants and conventional lubricants is that water rather than oil serves as base fluid,” he explained. “Base fluid typically accounts for about 70-90% of a lubricant. Lubricants in which oil serves as base fluid can cause environmental pollution when discharged into soil or water. Replacing oil fully or partially by water reduces this risk. Additionally, Hydro Lubricants exhibit super low friction properties and possess excellent cooling capacity which reduce operating temperatures, energy consumption and CO2 emissions.

“We will focus our development efforts on applications where Hydro Lubricants lead to equal or superior performance compared to conventional lubricants. Thus, we do not expect any significant tradeoffs to be necessary [in handling, storage or usage] for applications suitable for Hydro Lubricants,” he concluded.