Beyond lithium greases
Beyond lithium greases – Greases made with simple lithium soap thickeners first appeared in the 1940s. Since then, lithium greases have dominated the world of grease lubrication. Known for their versatility, they work well with a variety of base fluids and operate effectively in a wide range of conditions and temperatures.
Lithium greases have long been favored for their advantageous performance-cost ratio and have excelled in most OEM specifications.
Greases that use lithium soap as a thickener have maintained such a strong position that there has been limited incentive to develop alternatives, says Mikael Kruse, group product manager (EU) at AXEL Christiernsson International AB, a leading manufacturer of greases in Europe and the US, based in Sweden. Industries have been reluctant to invest resources in exploring different products.
The grease situation has been stable for a long time. Until now.
Kruse highlighted a “giant in decline” during the Asian Lubricants Industry Association (ALIA) Member Sharing Session on March 5, 2024 in Ho Chi Minh City, Vietnam. He stressed that the current outlook for lithium greases is unfavorable, anticipating a significant change in the grease landscape.
The outlook for lithium supply is a topic of growing importance due to the increasing demand for lithium-ion batteries in electric vehicles (EVs), energy storage systems and various electronic devices.
Lithium, one of the 34 critical raw materials (CRM) identified by the European Union, has experienced price volatility due to fluctuations in supply and demand dynamics.
Demand for lithium is expected to continue to rise sharply in the coming years, driven mainly by the expansion of the EV market and the need for renewable energy storage solutions.
Kruse described an 8% decline in the use of lithium greases in the National Lubricating Grease Institute’s (NLGI) grease production survey from 2019 to 2022. Conventional lithium greases saw a 7% reduction, along with a 1% decline in complex lithium greases.
New and promising alternatives have emerged. Anhydrous calcium greases saw a notable increase of 5.5%, while polyurea (PU) and calcium sulfonate greases saw a slight increase of 1%.
During the recently concluded F+L Week 2024 conference and exhibition in Ho Chi Minh City, Vietnam, Avelyn Lim from Dow Industrial Solutions Singapore described a promising new PU production process with pre-formed PU thickener.
Winner of the best poster award at F+L Week 2024, Lim said that this innovative approach offers several advantages over conventional PU grease production methods and could help satisfy the growing demand for high-performance grease in high-growth applications such as bearings, constant CV joints in steel mills and electric motors.
A simplified and cost-effective process uses a metal kettle with grease and soap without the need for additional systems. Lim noted greater flexibility in the supply chain by offering local grease mixing options. In addition, the PU thickener is stable, with a long shelf life and easy storage.
The main catalyst for the disruption of the status quo is the rise of electric vehicles. EVs require less grease due to their smoother operation, simplified mechanical architecture, direct drive systems, reduced friction and heat generation, and regenerative braking technology.
However, the driving force is the increased competition for lithium, which is one of the main components of EV batteries. The purchasing power of the grease industry has decreased significantly, says Kruse. While the industry previously consumed around 30% of all lithium, demand has fallen to around 3%, he says.
In addition, the supply of lithium is restricted to certain regions with a limited number of suppliers. Availability is susceptible to politics and unrest, posing risks to both costs and supply in the affected regions.
Kruse noted that obtaining materials and delivering on time has become increasingly challenging, as the grease industry is no longer as valuable a customer as it once was. In addition, he emphasized the high, unstable and unpredictable cost of lithium, which is heavily influenced by the battery industry.
Around 70% of grease applications can be served by multi-purpose greases, with high-performance greases (20%) and specialty greases (10%) covering the rest. This distribution is consistent across most segments.
Multi-purpose greases consist predominantly of conventional lithium greases. Fortunately, there is a readily available alternative in anhydrous calcium, says Kruse. Anhydrous calcium offers equal and, in some cases, superior performance. It is also compatible with existing greases, eliminating the need for excessive and frequent cleaning.
When it comes to high-performance greases, it’s a different story, says Kruse.
There is no single alternative with the same versatility as the lithium complex greases commonly used in these applications. Alternatives include calcium sulfonate complex, PU and aluminum complex.
Selecting the appropriate grease depends on the specific task at hand. Kruse advises taking the time to understand the requirements of the application in order to make an informed choice.
For example, in situations involving high temperatures, high loads and humid conditions, greases with a calcium sulphonate complex are often recommended.
For electric vehicles, PU greases are notably more effective. Intense developments regarding grease thickener technology are underway in the grease community, says Kruse.
Specialty greases are the least affected by the decline in the use of lithium greases, he says. These greases represent a smaller proportion of the market and there are a variety of options available. Specialty greases tend to be high-value, high-margin products developed to perform specific tasks. Alternatives include calcium sulfonate complex, PU, aluminum complex and new thickeners.
The greatest need for grease replacement technologies lies in cheaper products; specialty greases remain somewhat isolated from these changes, suggests Kruse.
There is a growing emphasis on sustainability in the lubricant supply chain. AXEL representative Christiernsson noted the sustainability challenges in the extraction and transportation phases of lithium grease production. In addition, Kruse addressed concerns regarding the biodegradability of lithium greases, making them unsuitable for total loss applications, and pending legislation on toxicity issues.
Despite the importance of sustainability, it’s not as simple as switching to a sustainable grease. The same product can be used in different applications and have different effects on sustainability. It is vital to understand how the product will be used in order to assess the impact on sustainability.
Kruse emphasized that the sustainability of individual applications is determined by the combined system and not just the grease itself. He stressed the need to consider the machine’s components, such as bearing production, the impact on energy use and the suitability and use of the machine’s lubricant.
In most cases, the dominant factor affecting sustainability is power loss through friction, said Kruse, highlighting research by SKF, one of the world’s leading bearing manufacturers, based in Sweden.
However, he recognizes the challenges involved in customers’ willingness to adopt sustainable solutions. For a long time, lithium greases have proven to be effective and affordable. Whether consumers are willing to pay the cost of sustainable alternatives remains to be seen. Even cheaper biodegradable greases can be three to four times more expensive, posing a significant challenge for consumers.
