Abstract
Ultrafine bubbles (UFBs) are microbubbles with a diameter < 1 μm, which are used in a number of applications, including cleaning, sterilization, and water purification. The use of coolants containing UFBs in grinding has been reported to improve performance and machining accuracy. In conventional methods, however, UFB concentrations are relatively low. In this study, we developed a high-concentration UFB generator based on a rotary shear system, and investigated the effects of production conditions on UFB concentration and particle size distribution. Furthermore, we prepared UFB coolant using the developed generator, evaluated its characteristics, and conducted grinding experiments on carbon steel to evaluate the effects of the UFB coolant on grinding performance. The effects of the generation conditions on the UFB concentration were investigated, and the results showed that there is an appropriate range for the gas concentration and that the value of the shear force applied to the liquid containing the gas contributes to achieving a higher concentration. Characterization and grinding experiments with UFB coolant revealed that the grinding ratio improved without impairing the performance of the coolant.
