Finished Lubricants

Spotlight on Metalworking Fluids


A Cut Above the Rest

Modern manufacturing relies on metalworking fluids to help shape, form and cut, all while offering an optimal finish and extending the life of the tooling. 

Through continuous development, MWF suppliers are looking at how they can offer superior levels of performance and durability and ensure their products cool and lubricate more effectively—and efficiently—than ever before. 

Despite the current economic doldrums and news headlines reporting mixed outlooks for global manufacturing, forecasts for the MWF segment are relatively bullish. It remains a fairly stable market, with modest growth rates expected in the years ahead. In a recently published report from Grand View Research, for example, a 4.4 percent compound annual growth rate is anticipated through to 2027.

“A slowdown in the global economy in general affects global trade and demand for metalworking products, especially automotive products and ancillaries,” noted Sushmita Dutta, project manager at consultancy Kline & Co. 

“However, this does not affect all countries equally. Developing countries in Asia and Latin America, due to their cost advantage, will not be affected as severely as some of the other countries. Europe’s market is shrinking, while the Americas will see moderate growth. In Asia-Pacific, only China is likely to shrink, but other countries’ demand will grow. The market will expand in countries that are developing and expanding their manufacturing sector, while developed countries in Western Europe are likely to contract.” 

Today, those involved in metalworking face innumerable rules, regulations, health concerns and environmental pressures. Current and future trends include using less fluid, minimizing waste, improving disposal and recycling, and a greater focus on sustainability.

MWFs are one of the most regulated types of lubricants, according to Stephen Griffiths, technical services manager at Italmatch Chemicals.

“They tend to have far more significant contact times with humans due to the nature of the process. The question of disposal and incidental contact with the environment has been a constant guiding force in formulation and development of lubricants,” he said. 

“As an industry, we have systematically removed damaging chemicals from fluids over time to protect the environment. The future of the industry continues to focus on sustainable resource management, using rerefined oils, vegetable- and plant-derived base fluids.” 

An innovative approach is essential to meet the ever-changing expectations and requirements in the marketplace. According to Andy Ellinghausen, product manager at Fuchs Lubricants, the emphasis on research and development has accelerated significantly in recent years.

“Companies that are willing to invest in R&D and innovation are the ones that are going to make it in this industry. We’re all looking for new technology to prepare for the future,” he said. 

“Customers need to understand that the cost of the fluid is really only 15 percent of everything else it affects. We still see too many people dwelling only on the cost per gallon and not on the overall impact. They need to consider tooling and filtration; environment, health and safety concerns; scrap; and productivity. Manufacturers have to start looking more at the long-term benefits.”

The automotive sector remains among the most significant outlets for MWFs, yet there remains uncertainty about the likely effect the shift to e-mobility will have on the market. 

Governments worldwide are committing to ambitious targets to encourage the electrification of the motor vehicle and phasing out of the conventional combustion engine. Not only will cars powered by batteries inevitably mean fewer metal components are needed under the hood, but alternative materials are also being specified elsewhere to help reduce weight, increase efficiency and minimize emissions. 

“Whilst I think we accept the advent of e-mobility will significantly affect the volume of traditional component manufacture, what we will see is a transition to possibly more formed components from traditional cut parts,” said Griffiths.

“I see a change in the metalworking market as much as a challenge. New materials and lightweighting will drive the need for different lubricants, and this, allied to changing processes, will lead to opportunities in the market.” 

Ellinghausen pointed out that Fuchs anticipates a 10 percent drop in combustion engines globally by the end of the decade. For passenger cars, hybrid and electric vehicles could have a 20 percent market share by 2030, he noted.

“I’d say e-mobility will mean more of a shift of focus than actually damaging the MWF sector. As long as we adapt and see this as an opportunity, we don’t see any decline in our market,” he said, adding that Fuchs is working more on battery cell production as a result.

Car manufacturers are turning to lighter components made from aluminum or thinner gauge steel, added Ellinghausen, which poses entirely new challenges for MWFs. 

“They are increasing tensile strength and hardness so that they can use less material, but this is harder to form. The more you work it, the molecular structure of the metal makes it harder. That means it’s tougher on tools and results in higher temperatures. The overall effect is that if you’re not reformulating or coming out with innovative metalworking fluids right now, then you’re probably going to struggle in this industry in the future.”

While there are certainly plenty of opportunities in terms of new applications and technologies, users of metalworking fluids have perhaps never been under more scrutiny.

With other new technologies and machining processes making inroads, questions remain whether they will also have a profound effect on MWF volumes in the longer term.

“We are now seeing many disruptive technologies emerging: additive manufacturing [3D printing], dry machining, minimal quantity lubrication and cryogenic machining,” noted Griffiths. 

“However, most of these, possibly with the exception of cryogenic and additive, are not new concepts; they have been used in metalworking for many years. They are extremely good in their area of application. What we have seen so far, however, is they have not made the move to general manufacturing, and this is a trend I see continuing. The exception is additive manufacturing, which I believe will be a disruptor.”

In this Spotlight, Lanxess highlights the versatility of sulfur carriers for metalworking.

Sulfur Carriers, the Versatile Solution for Metalworking Applications

The most commonly-used extreme pressure (EP) additives in metalworking applications are sulfur carriers—a generic name for sulfurized natural or synthetic esters or olefins. German-based specialty chemicals company, LANXESS, is one of the world’s largest producers of sulfur carriers, which it sells under the brand name Additin®

LANXESS has two manufacturing plants where it produces sulfur carriers, located in Mannheim, Germany and Antwerp, Belgium. Both have been expanded over the past few decades to a capacity of several thousand tons.

Given their broad variety in sulfur content, molecular size, reactivity and polarity, LANXESS’ Additin® sulfur carriers are hugely versatile, and can be used to reduce friction and to prevent adhesive and abrasive wear in boundary lubrication.

Sulfurized esters were one of the first EP additives used in cutting oils. Although their application was already reported as far back as 1918, sulfur carriers are by no means antiquated or even obsolete. Instead, their properties and performance characteristics are continuously being adapted to the changing requirements of the market.

Leading the Way

LANXESS developed its first light-colored sulfurized ester in 1957. Most sulfur carriers at that time were dark-colored, had a strong odor and limited stability. 

Over the past few decades, modifications to the manufacturing process have resulted in a wide variety of light-colored products with low odor and superior stability, meeting growing demand for low or non-colored metalworking oils.

As the solubility of many conventional sulfur carriers in low polar base oils is fairly poor, the shrinking volume of Group I mineral oil and increase of the less polar Groups II to IV base oils limits the choice of EP additives in modern metalworking oils. 

Through the development of new sulfur carriers with specifically adapted chemical structures, LANXESS makes it possible to formulate metalworking fluids based on low polar Group II or Group III base oils, and even based on polyalphaolefin, without affecting performance.

Sulfur carriers prevent adhesive wear by forming protective layers of metal sulfide on the surface of tools and workpieces. The fast generation of fresh metal surfaces in metalworking processes requires highly active sulfur carriers. However, they also stain and can even corrode copper and its alloys such as brass or bronze. By using a special deactivation process, it is possible to offer Additin® RC 2541 and Additin® RC 2542 active sulfur carriers with a sulfur content of up to 40%, which do not stain yellow metals at temperatures up to 100°C.

Additin® sulfur carriers are a perfect replacement for chlorinated paraffins (CLP), particularly in countries where their use in metalworking fluids is already restricted. Chlorinated paraffins can work as EP additives, although with increased machining speeds that result in higher temperatures of workpiece and tool surfaces, they tend to decompose and cause tremendous chemical wear. 

This effect can be demonstrated in a broaching test using titanium nitride (TiN) coated tools and high alloyed steel work pieces. A broaching oil containing a combination of chlorinated paraffin and sulfurized olefin shows increasing angular wear after manufacturing about a hundred parts. This is caused by the decomposition of the CLP, followed by corrosion of the TiN coating of the broaching tool. 

The CLP-containing formulation is outperformed by a synergistic combination of LANXESS sulfur carriers. Results show that a 50% reduction of tool wear is possible with a broaching oil containing Additin® RC 2540, a sulfurized olefin, and Additin® RC 2526, a special sulfurized EP additive based on hydrocarbon and triglyceride (Figure 1). 

E-mobility is Driving Change

The broad implementation of electromobility in the car industry will lead to a replacement of many chip removing metalworking processes, as they are used for crankshaft, camshaft or engine block manufacturing, which predominantly use water-mixed metalworking fluids. 

These processes will be replaced by forming, stamping and fine blanking operations to produce rotor and stator sheets or cases for electric motors and gearboxes. These commonly use neat metalworking fluids. The lower cooling capabilities of the neat oils have to be compensated by reduced friction. 

The high surface pressures of stamping and fine blanking processes require EP additives that can effectively prevent adhesive wear. 

Both can be achieved by using LANXESS Additin® RC 8000, a polymeric sulfur carrier that can form pressure stable, friction-reducing protective layers. 

In a “Press-In test”—used to simulate the fine blanking process—it is possible to reduce adhesion and friction force by 30% by using a combination of Additin® RC 8000 and the polar LANXESS AW additive Additin® RC 3880, compared with a forming oil containing 40% of chlorinated paraffin (Figure 2).

Additin® sulfur carriers made by LANXESS are powerful and versatile additives. Their EP performance can be even greater through synergistic combinations with other additives such as overbased alkaline earth sulfonates, polycarboxylates and esters, polyisobutenyl succinic anhydrides (PIBSA), succinimides, and chlorinated paraffins.

The synergistic effect between Additin® sulfurized olefin, Calcinate™ overbased calcium sulfonates (OBS), and Additin® polycarboxylate are demonstrated by the 4-ball test (Figure 3). 

The 4-ball weld load of 10% sulfurized olefin Additin® RC 2540 in mineral oil is much higher than the weld load of 10% chlorinated paraffin (CLP), but the 4-ball wear scar is much bigger.

An even higher weld load can be achieved with a combination of 5% Additin® RC 2540 and 5% overbased calcium sulfonate (OBS) CalcinateTM—although the 4-ball wear is still quite high. 

The best results regarding high weld load and low wear scar are achieved by combining 3.3% each of Additin® RC 2540, CalcinateTM overbased calcium sulfonate and Additin® RC 8100 polycarboxylate.

Ecolabel Compliant

In 2019, the European Commission decided to revise the European Ecolabel (EEL) regulation to include metalworking fluids. The reasoning was the fluids could enter the environment by accidental loss and that they may have an impact on waste disposal or on workers’ health. Several LANXESS sulfur carriers fulfill the EU ecolabel criteria and can be used for the formulation of metalworking fluids, according to the EEL. 

LANXESS Additin® sulfur carriers are EP additives that are used in most metalworking fluids. Due to their high versatility and superior performance, they can meet almost any requirement of the different metalworking processes. 

Sulfur carriers may have a long history, but they are far from old-fashioned. In fact, through their continuous development, they instead remain state of the art.