Supercool: Turning Performance

It’s an ongoing challenge to effectively cool and lubricate the tool/workpiece interface. After 8 years of research at the University of Michigan laboratories of Dr. Steven Skerlos, the university developed a dry, environmentally friendly, single-channel cooling and lubrication technology that simulta- neously enhances both functions, according to Thomas E. Gross, CEO of Fusion Coolant Systems. The company was formed last year to commercialize this technology through the University of Michigan’s Technology Transfer Office.

Marketed as CHiP Lube (Composite High-Pressure Lubrication), the technology is based on supercritical CO₂. Gross explained that above its critical temperature of about 90° F and pressure of 1,200 psi, scCO₂effectively dissolves lubricants, turning CO₂ into a solvent. “Carbon dioxide goes into a kind of mushy base and then you can dissolve oil and other things in the solution,” he said.

The higher the pressure, the better the cooling capability, Gross added, noting 2,500 psi is a typical pressure.

When the supercritical solution exits a coolant delivery system, it rapidly expands, releasing the oil and sending chilled microparticles of lubricant at the cutting zone with high velocity. The coolant nozzle or through-coolant orifice on the tool is positioned no more than 1 ” from the cutting zone to maximize cooling effectiveness, Gross added.

Courtesy of Fusion Coolant Systems

Machining an Inconel casting with CHiP Lube near-dry cryogenic lubrication technology from Fusion Coolant Systems.

He noted that only a small amount of lubricant is used. “The CO₂ evaporates and what’s left is basically a dry chip.”