Replacing a petroleum and water mixture with soybean oil as a lubricant and cooling agent for cutting metal would save money, reduce environmental impact, be safer for workers, and potentially help soybean farmers across the U.S., say Missouri University of Science and Technology researchers who are developing the method.
“Conventional metal-cutting cooling methods use a petroleum-based oil combined with water to flood the cutting tool and the metal at the cutting zone. That can cause health issues for workers, and disposal poses environmental risks,” says Dr. Anthony Okafor, professor of mechanical and aerospace engineering at Missouri S&T and primary investigator for the project. “Soybean oil is safe and biodegradable, and our method saves materials costs because only drops of soybean oil are used.”
Cutting fluid plays a vital role in metal cutting by cooling and lubricating the cutting zone, the researchers say. Friction and the resulting high heat from cutting metal cause rapid tool wear, especially with hard-to-cut metals such as Inconel-718. That material is commonly used in oil and gas drilling tools, aerospace manufacturing of components used in the hottest compartment of jet and rocket engines, and in cryogenic tankage. A technique called minimum quantity lubrication (MQL) uses a small amount of lubricant and compressed air to form an aerosol spray to cool and lubricate the cutting area.
Okafor is working with Dr. Monday Okoronkwo, an assistant professor of chemical engineering at S&T, to add nanoparticles to the high oleic soybean oil to increase cooling capability, improve machinability of Inconel-718, enhance viscosity, stability, and thermal conductivity of the soybean oil, and promote new markets for soybeans and other biobased feedstocks.
The research project came about through coincidence. Okafor, whose background is in manufacturing machining, needed a rheometer to measure how fluids and nanofluids behave under varying pressure and temperature. Okoronkwo’s background in chemistry includes work with soft materials such as liquids, gels and granular materials. He had just acquired a rheometer for use in his own lab. Okafor asked to use the equipment, and a partnership was born.