Prediction of Coolant Pressure and Volume Flow Rate in the Gundrilling Process

Abstract

Coolant volume flow rate and pressure critically affect the chip evacuation in the gundrilling process. A predictive fluid model was developed to estimate coolant volume flow rate and pressure, which considered the whole gundrill system of coolant channels as a system of circular and non-circular cross-sections of fluid channels and gundrill geometry. Major contributions to the findings of the following important facts were made through experiments as well as modeling. First, the generation of swarfs in the coolant transport did not create a noticeable hydraulic resistance no matter whether swarfs were carbon steel or aluminum. Second, the size of the coolant holes of the head is not necessarily the most influential factor for determining coolant volume flow rate as believed in general practice. Last, hydraulic resistance by the clearance area of the hole bottom becomes negligible when its size reaches a saturation point.