The microbiology of industrial lubricants and emulsions

Microorganisms as a Replacement for Metal Working Fluids

Most of the several billion liters of metalworking fluid (MWF) used worldwide and annually are water-based and thus prone to a microbial contamination. The microbial growth leads to a deterioration and therefore to a loss of quality and technical performance. In most cases, biocides, which pose a potential risk to health and environment, are used to reduce the microbial load. To avoid these limitations, the paradigm shift of using microorganisms in a positive way in a manufacturing process as a lubricant is investigated in this paper. Some microorganisms are able to synthesize equivalent MWF components like e.g. fatty acids or sulfur compounds. Due to this fact, it is possible to create a regenerative system on a microbiological basis for the substitution of mineral oil containing MWF components. To demonstrate the lubrication potential of bacteria, preliminary investigations were conducted on a Brugger-tribotester. Against this background, the approach presented here intends to investigate the lubrication properties of special microorganisms and the influence of the microbial cell counts on the lubrication behavior respectively. The results of the tribological tests show that the microbial-suspensions exhibit Brugger-values as high as highly concentrated conventional MWF and indicate the potential to replace these respective components.