Abstract: In view of the difficulty in observing and analyzing the wetting spreading behavior of cutting fluid droplets in the slit formed by tool-workpiece-chip (TWC) in cutting process, a simulated TWC micro-slit was made up of a transparent quartz brick and a piece of stainless-steel plate with grooves. The dynamic wetting process of droplets in the slit was recorded by a high-speed camera with microscope function. Based on the image processing technology, the data in the experimental video frames were extracted and analyzed. The two-dimensional diffusion process of droplets in micro-slits was described by Logistic model. Combined with the parameters of the model, the relative size of penetration velocity in slits with different heights was qualitatively described. It is found that when the water droplets are spread in slits with height below 200 μm, the flow rate into the slit decreases with the slit height reduces, which indicates that it is still more and more difficult for droplets to infiltrate into the slit although the capillary pressure increases with the decrease of slit. This conclusion was verified by the average results of repeated experiments.

Key words: micro-slit, tool-workpiece-chip (TWC), droplet, two-dimensional diffusion, Logistic model