Lubrication is used during the drilling of aluminum to counter the formation of a built-up-edge (BUE), among other reasons. The elimination of the use of lubricants in drilling of aluminum is important because of the associated high costs of cleaning and disassembly involved in lubrication. The optimal conditions sought in this work include the elimination of the use of lubricants along with the possible attainment of a high material removal rate, which could help in reduction of cost and increase productivity at the same time. BUE has been found to be almost always present in the process of metal cutting at low to moderate speeds. It has been found that a necessary condition for the formation of a BUE is the presence of a negative stress gradient away and normal to the tool rake face. The quantitative equivalence of the effects of temperature and strain rate on flow stress described by the Zener-Hollomon parameter (Z) [5]. The relationship between the Zener-Hollomon parameter (Z) and chip flow stress implies that a negative Z gradient could be considered equivalent to a negative stress gradient. A series of computer simulations with varied cutting conditions were analyzed to determine the combination of machining variables which yielded a low predicted BUE preferably with a high material removal rate. The results presented here include cases which have a low predicted BUE as well as a high material removal rate.

Missions to Mars aim to characterize rock and subsurface soil samples and possibly bring some back to Earth for more thorough and sophisticated examination. The Martian surface is covered with basalt which has high compressive strength (andamp;gt;130 MPa), and is more difficult to drill than the much softer sedimentary formations that are presently being drilled using diamond core drills. The main objective of this thesis work is to provide the requisite groundwork towards the development of improved and sustainable drills for subsurface drilling applications on Mars, when their goals are obtaining samples. Since progressive drill-wear is substantial in sustained drilling, the experiments were designed and conducted to study the tool-wear mechanisms and understand the associated effects on drilling performance in subsurface drilling of basalt. Core drilling experiments are conducted with different drill geometries and cutting conditions in a Martian simulant, basaltic rock; monitoring thrust force, torque and measuring tool-wear for a series of successive depth-increments. Based on the experimental results an optimization model has been developed for maximizing drilling depth with minimum tool-wear. This preliminary work will help the development of smart and sustainable drills for dry drilling applications for future NASA missions to Mars.