Enhancement of surface finish using water-miscible nano-cutting fluid in ultra-precision turning

This paper presents an experimental study on the enhancement effect of the low viscosity cutting fluid enriched with nano-droplets (NDCF) in ultra-precision turning. Unlike the conventional method in which the enhancement is done by adding nano-metric particles, no suspension particles are mixed to produce the NDCF in this paper. Instead, the NDCFs are produced by atomisation of the cutting fluid that circulates in a closed-loop treatment device. The atomisation process is found to reduce the viscosity of the NDCF significantly by the formation of nano-droplets (NDs). The reduced viscosity of the NDCFs could be increased by diluting them with water. The bench tests on wetting properties reveal that the NDCF demonstrates two distinct properties: a very linear spreading rate and a relatively low contact angle. These two properties assist the NDCF in penetrating deeper into the tool-chip and tool-work interfaces and hence provides a better lubrication effect at these interfaces. In this paper, the ultra-precision cylindrical turning experiments reveal that the droplet size of the NDCF is a more important factor than viscosity on affecting the surface finish in ultra-precision machining.