Droplet Behavior on a Rotating Surface for Atomization-Based Cutting Fluid Application in Micromachining

Abstract

The droplet behavior on a rotating surface has been studied to better understand the physics underlying atomized cutting fluid application. To this end, microturning experiments are carried out and the cutting performance evaluated for varying cutting fluids and at different droplet speeds. Microturning experiments indicate that a cutting fluid with low surface tension and low viscosity generates lower cutting temperatures, whereas a fluid with low surface tension and high viscosity generates lower cutting forces. Single-droplet impingement experiments are also conducted on a rotating surface using fluids with different surface tension and viscosity values. Upon impact, the droplet shape is observed to be a function of both the droplet speed and the surface speed. The spreading increases with increased surface speed owing to the tangential momentum added by the rotating surface. Spreading is observed to also increase with a decrease in fluid surface tension and does not change with the fluid viscosity. The evaporation rate is observed to increase for a rotating surface owing to convective heat transfer. Low surface tension and low viscosity are observed to increase the evaporation rate. It is concluded that a fluid with low surface tension and low viscosity is an effective coolant of the cutting zone, whereas a fluid with low surface tension and high viscosity is effective for lubrication.