Re-Inventing Metalworking Fluids: A Case Study in Greening the U.S. Manufacturing Sector
A metalworking fluid (MWF) technology that is novel, environmentally preferable, and capable of rapid diffusion into the industrial sector has been developed. The process of creating this technology represents a holistic approach to technical innovation that proceeds from conception, technology-proof-of concept, performance evaluation, life cycle assessment, through to technology transfer. Metalworking fluids were selected due to the well-documented environmental and occupational health impacts they present. Despite this threat they are ubiquitous: over 2 billion gallons of MWFs are used annually in the North American manufacturing sector to lubricate and cool in machining operations. The new technology was developed to perform these functions using supercritical carbon dioxide (scCO2) and vegetable oils eliminating the need for large volumes of petroleum products and water. In the new process, an oil-in-CO2 dispersion is sprayed out of a nozzle at high speed and pressure to deliver oil and form dry ice near to the cutting zone in minimal and precise quantities. The rapid expansion of the CO2 leads to cooling at cryogenic temperatures, and the combination of high pressure and low surface tension provides access to interstitial spaces that are inaccessible to conventional MWF oil and water jets which, in many cases, leads to increased performance over conventional fluids. A life cycle study of the new technology suggests that its corresponding environmental impacts are significantly lower than those of conventional MWFs. In particular, greenhouse gas emissions of the new system are lower depending on allocation strategies due to the industrial use of feedstock CO2 that is a byproduct of other processes. Preliminary work with several U.S. auto and aerospace manufacturers suggests that the technology has the potential to quickly diffuse into the market.