Action mechanisms of nanoparticles with defined interfaces in cutting fluids

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Cutting fluids are complex systems consisting of different components (base fluid and additives) which are widely used for metalworking processes to increase process quality and productivity. The effect of the cutting fluid, however, highly depends on its formulation. Several studies have already revealed a positive effect of nanoparticles on the performance of cutting fluids. However, an understanding of the impact of particle properties and particle interactions on the resulting properties of the nanofluids has not been achieved yet. Furthermore, the structure-property relationships of nanofluids for the actual grinding process as well as their effects on the periphery, e.g. extraction and feed unit, have not been sufficiently examined either. Hence, the current state of research does not allow the prediction of the applicability of nanofluids as cutting fluids and in particular for minimum quantity lubrication (MQL), where smallest quantities of the fluid are supplied onto the workpiece. This project aims for a better understanding of the process-structure-property relationships of nanoparticles in nanofluids for the application in MQL. An essential part is the systematic preparation of nanofluids using different nanoparticles and additives in aqueous and hydrophobic media. By chemical surface modifications of the nanoparticles, the colloidal stability of the nanofluids can be adjusted. The effects of particle properties and fluid stability are first investigated at laboratory level and then at machine level in a cylindrical grinding process with regard to the cooling and lubricating effect. The findings should contribute to the development of models for predicting the stability and performance of nanofluid-based cutting fluids in order to enable the use of MQL for grinding processes.