The Working Mechanisms of Microbial-Based Metalworking Fluids

Metalworking fluids (MWF) play an essential role in many machining applications. However, the chemical composition as well as the contamination with microorganisms are accompanied by limitations regarding their applicability. Due to the fact that different cell constituents and inclusions of bacteria, fungi and yeast are equivalent to conventional MWF components, the paradigm shift of intentionally using microorganisms as a substitute for conventional MWFs is possible. However, the paradigm shift is scientifically novel and the working mechanisms of such media are not known yet. In the present work, the working mechanisms were revealed by a combination of microbiological and tribological tests. It was shown that the functional performance of inactivated microbial cells results from a physical working mechanism, in which the cells prevent the metal-To-metal contact without being damaged. Furthermore, new approaches for alternative MWFs were revealed.