Solid Lubricants Used in Small Diameter Drilling

Abstract

Lubricants are either design materials or additional means for metalworking. In the first case, the lubricants should reduce friction and wear of working machines parts. In the second case, they should improve the machinability of the part material when machining this part by cutting or grinding. The paper studies the features of the solid lubricants based on stearic and oleic fatty acids. A comparative experimental study of both solid and liquid lubricants is carried out on a special friction stand. It is established that the solid lubricants provide a lower coefficient of friction and have the technological advantage in drilling small holes without the use of drilling fluid. The effect of molybdenum diselenide, sulfur, and serpentinite additives on drilling torque and axial cutting force, as well as on the increase in the life of drill bits, has been experimentally studied. The use of an electron microscope for chemical analysis made it possible to establish the solid lubricant components diffusion into the surface layer of the drill cutting blade. The solid lubricant formulations experimental studies are performed on modern CNC machine tools using a modern computer data acquisition system NI-DAQmx (hardware) with NI-LabVIEW (software). Each experiment was repeated the required number of times to reduce the influence of random errors on the measurement results.