The Rising Value of Calcium Sulfonate Complex Grease in Machinery Reliability

Brian Burks, CLS, MLE, OMA I, AMSOIL Industrial

The Rising Value of Calcium Sulfonate Complex Grease in Machinery Reliability

Lubricant choice has a large impact on machinery reliability. Maintenance engineers have many options when selecting the proper grease for their machinery. This choice can largely be driven by OEM specifications or by past experience with a type of grease in an application.  
Grease formulated with lithium-based thickeners account for about 70 percent of the industrial grease market. Lithium-based grease has been prevalent for a long time because it was cost effective, reliable and readily available. Two of those attributes are no longer as true. The rise of lithium batteries used in electric vehicles (EVs) has caused a huge surge in lithium demand, which has greatly impacted the ability of grease manufacturers to reliably and cost effectively supply lithium-based grease.

Understanding Supply Constraints

Before delving into the advantages of alternatives, it's crucial to understand the supply constraints affecting the lithium market. The exponential growth of the EV industry coupled with increasing demand for lithium-ion batteries in other applications has led to a significant imbalance between lithium supply and demand. Grease formulators and blenders are struggling to compete with the battery market for the lithium needed to produce this ubiquitous grease technology, severely limiting the supply of this once common commodity. As a result of lithium prices skyrocketing, operators are finding it challenging to secure stable supplies of lithium-based grease that are essential for machinery lubrication.  

Grease Formulation 101

Grease is made up of three basic components: base oil, additives and thickener. The base oil performs the vast majority of lubrication tasks and makes up 70 to 95 percent of grease volume. Grease performance can be modified with additives that improve extreme-pressure performance or act as corrosion inhibitors, among other enhancements. Additives may add as much as 10 percent to total grease volume. Finally, the grease contains a thickening agent that provides between three to 30 percent of the volume of a grease.  
The thickener is what makes a grease different from an oil, acting as a “sponge” that soaks up the base oil and additives and holds it in a semi-fluid state so the grease stays in place. When pressure is applied, the thickener releases the base oil and additives providing lubrication. When pressure is released, the thickener soaks the components back up, holding them in place until they are needed again.

The Rise of Calcium Sulfonate Complex Grease

Calcium sulfonate complex grease thickeners have been around for at least 50 years. However, they have not been a practical option for many general applications because historically the performance gained by using calcium sulfonate grease did not add value due to its increased cost. These costs have been declining over time due to improved refining methods.
Lithium-based thickeners hold the base oil and additives in place, but they don’t add much tribological benefit to a grease formulation. Lithium-based thickeners create a lattice structure with voids that contain the vital base oil and additives.  
Calcium sulfonate complex thickeners have distinct advantages over lithium-based thickeners, bringing tribological benefits that enhance grease performance. They provide a planar structure with calcite particles forming shear planes between metallic surfaces that boost extreme pressure wear protection. The vastly improved extreme pressure performance stems from multiple response points that absorb and disperse loads.

Enhanced Performance in Extreme Conditions

Calcium sulfonate complex thickeners provide the additional benefit of a long-chain structure, forming a thickening arrangement with high molecular weight to improve wear resistance. This increased extreme pressure wear protection is especially beneficial in heavily loaded and slower moving bearings. Calcium sulfonate complex thickeners provide excellent mechanical stability and oxidation and water resistance for consistent wear protection and performance over the entire service length of a grease charge. Calcium sulfonate complex also excels at providing exceptional fretting wear protection, vital for equipment that sees multiple stop-start cycles or short-period oscillations.

Extended Equipment Life

Another proven benefit of calcium sulfonate complex grease is its ability to maintain mechanical stability over long periods of time. A field trial was performed on large, slow moving wind turbine main bearings that operate under variable and heavy transient loading. In testing, a calcium sulfonate complex grease maintained the maximum loading of 1200N/1200N through 12 months of continuous use in the SRV Step Load EP test (ASTM D5706). This level of consistent extreme-pressure protection was verified through vibration analysis and visual inspection of the bearing rollers and races. A control lithium complex grease was unable to match this performance, dropping to 500N/500N after only three months in service under the same conditions.

Environmental and Regulatory Compliance

In today's environmentally conscious world, operators are under increasing pressure to adopt sustainable practices and comply with stringent regulations. Calcium sulfonate-based grease aligns well with these goals as they are more environmentally friendly. Lithium-based grease may raise environmental concerns due to the amount of water and energy needed during the mining process and the potential for water supply contamination. Calcium is also readily available worldwide and is much easier and less resource intensive to extract and process.

Cost-Effectiveness and Supply Stability

Perhaps the most compelling advantage of calcium sulfonate complex thickened grease in the current landscape is their cost-effectiveness and supply stability. With lithium prices soaring and supply constraints becoming more pronounced, operators are seeking alternatives that offer reliable performance and are readily available when they need it, while not breaking the budget. Calcium sulfonate grease presents a practical solution, as it is often more cost-effective than lithium grease and less susceptible to supply chain disruptions. By diversifying lubricant options and reducing reliance on lithium-based products, businesses can mitigate the impact of fluctuating market conditions and ensure uninterrupted operations.

Embracing Innovation for Machinery Reliability

In the ever-evolving landscape of machinery reliability, adaptation is key to success. As industries face supply constraints in the lithium market, the spotlight is increasingly shifting toward alternative lubrication technologies, with calcium sulfonate complex grease emerging as a frontrunner. Pivoting to calcium sulfonate complex grease technology is an easy decision because it is highly compatible with lithium-based grease and better performing, with a reliable supply and a competitive price. 
Offering superior performance, extended equipment life, environmental compliance and cost-effectiveness, calcium sulfonate complex grease presents a compelling proposition for operators looking to enhance machinery reliability while navigating challenging market conditions. By embracing innovation and diversifying lubricant strategies, businesses can safeguard their operations against disruptions and secure their path to sustainable growth.
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About the Author

A 14-year veteran of the wind industry, Brian Burks received his B.S. in Engineering Technology from Western Carolina University, after which he headed west to Wyoming to pursue a career in wind...