5 Reasons to Try Bio-Based Lubricants and Cutting Fluids

Castrol’s website clearly states that its line of more sustainable products is free of chlorine, boron, formaldehyde, heavy metals and secondary amines. That statement also covers the company’s hydraulic oils and way lubricants.

“These also fall under that same Performance Bio brand,” Stiers says. “This simplifies the purchasing process, but it also means they are compatible with one another, so you don’t have to worry about contaminating your plant-based cutting fluid, for example, with a petroleum-based way oil. It’s a symbiotic relationship.”

So what are the super-plants that allow machinists to cut away chunks of steel and Inconel with ease?

“It varies: Canola oil is one of the most prevalent, but soybean is also common,” Stiers says.

Snyder concurs, adding that HyperSol is primarily made of rapeseed, the yellow flowering plant of the mustard family used in canola oil.

Fluid Lubricity, Flash Point and Polar Attraction

Both experts note that the plant materials “are not necessarily the same thing you’ll find in your kitchen cabinet” and are highly refined to provide the best oxidation resistance and other attributes important to industry users. These include:

• Superior Lubricity: Bio-based lubricants and cutting fluids generally have a lower coefficient of friction than those made from petroleum. During metal-cutting operations, that helps to reduce friction, extending tool life and improving part surface finish. It also reduces the need for the sulfur and chlorine EP compounds discussed earlier, many of which are associated with health problems such as dermatitis and irritation of the lungs and eyes.
• Higher Flash Point: No one wants a CNC lathe or mill to catch fire, and that becomes much less likely (though not impossible) when cutting fluids are bio-based. Such fluids often have a flash point (the temperature at which they can ignite) roughly twice that of their petroleum-based cousins. A higher flash point also means less smoke and fewer harmful vapors are emitted during machining.
• Polar Attraction: Lubricants with a strong polar attraction adhere more effectively to metal surfaces, ensuring better lubrication between moving parts, an attribute that is crucial for reducing wear and extending the life span of machinery and components. The resulting film remains effective even under the high pressure and shear conditions common in heavy-duty machinery and high-speed manufacturing operations.
• Cold Temperature Performance: Earthmoving machinery and mining equipment are often used in very cold environments, an area where petroleum-based hydraulic fluids have long had the upper hand, since fluids made from vegetable oils contain natural waxes that tend to thicken as the temperature falls. Thanks to the work of scientists like Master Fluid Solutions’ Snyder, however, the tables are turning in bio-based lubricants’ favor.

And that point brings up another consideration: oxidation resistance. As Castrol’s Stiers explains, oils tend to break down—or oxidize—when subjected to very high temperatures for extended periods of time, which is why most hydraulic systems are equipped with cooling units.

Here again, petroleum-based fluids have a slightly better track record, although newer bio-based alternatives are coming close in terms of performance and longevity.

“A lot of people ask about biodegradability and would like to use more earth-friendly products, but the fact is that most of these fluids aren’t going to end up in the ground or affect our water supplies,” Stiers says. “This is more of a concern with heavy-duty equipment used outdoors, where a leak can lead to these sorts of problems, although for machine shops and most manufacturers, the push is more about their carbon footprint—they want to get away from traditional mineral oils and move to these plant-based solutions. Overall, I think that’s a good thing.”